Hi Andrew, Thankyou for the fine videos. If I could make a couple of observations. 1. Your line Boring Bar is wayyy too Long. As a rule ALWAY endeavour(or be prepared to accept less that perfect) to use a short as boring bar as possible. 2. I did not notice how far the tailstock quill was sticking out but it needs to be basically nothing. And of course do up the clamp on the quill(if they have one). There is a clearance (by design) between the quill and the bore of the Tailstock(on ANY centre lathe). 3. How well does your tailstock sit on the ways of the bed? If they are not perfect, then there is another opportunity for vibration. 4. I understand you were taking very small cuts but you need to consider the direction of your cutting forces. They need to be acting down the line of your bore/Bar. Anything else means that there will be some deflection of the bar(another reason for chatter). 5. Your tool geometry is critical. Minimising the radius on the tool may help, but it will need a small radius. To have a pointed tool it has a very high probability of that sharp point failing somewhere along the cut, probably in the first few mm's.(no single point cutting tool(diamond not included) will be sharp(even your thread cutting tool has a flat or radius(of some size). Even the mass of your machine affects vibration(a machine weighing around 100kg when it is that long, and spindle that far above the base. Did you measure the bore at both ends after you finished the machining operation(was it parallel?). If it was not, then, that may mean that your tailstock is not in line with your spindle and or your bed. Even your spindle is unlikely to be exactly in line with your bed. 99.9% of the time it's quite easy to get away with it. You have a great little machine. Like most machines, it has limitations. The boring operation is achievable on your machine I believe. Perhaps if you have a decent quality boring bar, perhaps you could mount it in the 4 jaw chuck (keep the setup with your sleeve mounted on the cross slide). When you take a cut you offset the chuck jaw that is in line with the cutting edge. you can put an indicator on it to check how much you are offsetting it for each cut. Some of my thoughts may apply, there are a lot more variables that could not be identified in the video. All the best.
Hi Andrew. Thanks for showing your failures. It's been my experience that we learn the most from those. Now on to my 2 cents worth.... Some have said to use the 3 jaw for rigidity. If you do that, you lose precision. Keep it between centers and use a dog. My friend,throw that live center away! It might be good for wood turning but it's junk for machining! Either get a precision live center or, better yet, a dead center and use high pressure grease. Dead centers are more precise anyway. When pro's bore between centers, they use supports with bearings. Not a steady rest but more like follow rests in your case. They keep the flex of the bar due to tool pressure to a minimum. I don't think it's your tool that's a problem as much as it is the flex in the bar. Although I'd also recommend a sharp cutting tool, slower rpm and feed. The follow support bearings don't have to be fancy, brass should be good enough but the work should be supported on both sides for best results. The good thing is, if you design them right, you only have to make them once for each boring bar size. When the brass bearings wear out, you can easily replace them if you design the mounts to take standard sizes. Finally, a lot of people have correctly pointed out that the clamping system you have is going to distort the part. You'd be surprised at how much a hollow part flexes even if it's much thicker than what you have. I'd recommend boring out the clamping material to the OD of the cylinder, drill and tap one side to accommodate clamping screws, then slit that side. It will give you even clamping pressure all the way round. You can use hard wood or metal and design it to accommodate the brass bearings mounts if you like. I'm confident that, if you do all these things, you will get great results. Good luck sir
TOP TIP! Get yourself on eBay and buy a length of cold drawn seemless steel tube (CDS) the bore is precision finished to size. That’s what I used for both my model engines. Cast iron Piston is then turned and polished to give 1/2 thou clearance, no piston ring required!
Hi James - a great idea! I think I'll have a look around to see if I can get hold of something close to the dimensions needed. However, I would still like to get to the bottom of the between centres problem. I'm definately interested in CDS as an alternative solution in the future and if I can get hold of some it will at least enable be to ascertain quality and accuracy. Thanks again Andrew
Hi Andrew, thanks for posting this, very helpful and good to see things go wrong, it gets the brain going. A few points struck me from watching that may have caused issues. The driven end centre was held in a 3 jaw Chuck, these are notorious for run out, try a Morse taper centre in the headstock spindle. The clamping looked as if it might have distorted the cylinder, esp as it was thin walled at this point. The hole in hardwood method would have provided more even clamping around the diameter. The live centre looked like an interchangeable one, similar to those used in wood turning. If it is then maybe it’s not as good. Personally I haven’t tried a between centre boring bar, so these are just my thoughts, so bear that in mind.
Hy Taffy - many thanks for your thoughts on this. I'm beginning to wonder whether a hard MT centre might be better in the headstock. Some have suggested this but also with 3 or 4 jaw chuck providing extra support. I will check to see of the cylinder distorted - but it is certainly thinner than it was! Well spotted regarding the woodturning live centre. This came off my woodturning lathe and I did wonder whether it might be a contributing factor. I might buy a live tailstock centre specifically for engineering, or use a dead centre. I'm adding all suggestions to a spreadsheet and I will try to work through the list and experiment. Cheers Andrew
Hello Andrew. I have some experience boring stationary holes with a boring bar. I have not read all of the comments and if someone else has suggested this I apologize. The tool bit has to be referenced on a line that runs through the center of the bar. I noticed that you had the bit ground down fairly close to the center but that is not necessary. If you imagine a line from the center of the bar to the tip of your tool bit and then grind your bit to match that line plus around 5 degrees more it should work fairly well. Of course you would allow some clearance on the cutting face and the end face as well. Form what I could tell from the video it appeared that it was ground almost negatively back toward the bar.
Hi Frank - many thanks for the suggestion. Based on all the other comments I received, I made several adjustments and I've just recently had another go at re-machining the bore - which was a massive success. See Part 5a. All the best. Andrew
Hi Andrew, I've no further suggestions to add to the many excellent ideas already posted, but I must say that your progress and achievements over these past few years has been remarkable, and for what it's worth, I bet my scrap box holds more mistakes than yours ! Keep up the good work, all the best, Brian
I'm probably way late, but the first thing I'd do is tighten up the tailstock. I've got a couple old logan's, 10 by 24 from the forties, and they've got some play in the tailstock and the slides. A live center usually has enough slack in it to cause the chatter.
well done for being honest and sharing, we all make mistakes and mistakes are good because you, and others can learn from them. don't be disheartened, chuck it in your scrap box and it may come in handy someday. BTW my scrap box is massive. keep up the good work and keep learning regards Paul
When you use a hone tool you must you a lot off oil to flush out metal particles or else they will clogging the stone. Also don’t be to disappointed if something doesn’t work the first time. Somethings can take a lot of trying before you get it to work on your machine. Whatever you do some materials are always a b¥#$ to cut and will give you chatter no matter what you do. Also the boring bar between centers on your light lathe can be a big issue why it wasn’t working the first time , remember that what we see a solid machine turns into rubber when your are machining and if there is a slightest change for chatter it wil happen. A possibility is to make the boring bar as short as possible. Love your videos and please keep making more 😀
Hi Andrew, Sorry to see you had so much trouble with the boring bar. Looking at the bar revolving it seemed to be out slightly, as did the live center, One job down to experience mate. Stay well and keep the great video's coming please ,Kind Regards, Mike
Andrew, I am sorry to see you having trouble with this. I thought you were there when you had everything beautifully lined up. The cutter has proved a real disappointment. You have plenty of suggestions and there is nothing I can add. Solving these problems is one of the great pleasures of engineering, but you have to go through the frustration to get there. Have you checked with other Farmboy builders to see how they made the liner? Good luck. Look forward to hearing how you resolve the problem.
Don't give up on the part There seems to be several comments on various issues with the set up and they all are correct. there is always multible issues when a part chatters. From past failures you learn how to adapt to each issue. My approach would have been to bore a piece of waste stock to the outside dimension of the cylinder, saw a slit in it length wise and reinsert in the chuck with the cylinder installed, instant collet. The make as large and short length boring bar as will fit and hold in the tool post. I am not who ever telling you that is THE way to do it as there are always different ways to machine the same part Good luck and keep trying
Hi Andrew, very interesting to watch your video, thanks. I have just finished the Hemingway boring bars myself and had a first attempt at boring two parallel bores yesterday. Rather like you, it didn’t go as well as I’d expected and I spent a lot of hours trying to get things right. I had the same issues with vibration although I found it varied between cuts and on occasion did run quite cleanly. I suddenly got into problems when the cutter was extended just a bit too far from the bar. There was no gradual deterioration, just a switch from smooth cutting to judder. This was particularly noticeable using the narrowest bar of the set. For what it’s worth, and I am only a rank amateur at these things, I’m inclined to think that Haforn44 has diagnosed correctly and the grind of the cutting tool bit is the critical issue. I think you were going this way yourself too. I’m going to rethink my grinding profiles and try again. Good luck with your next cylinder, I look forward to hearing of your success or ‘learning opportunities’!
Hi- you mention you got into problems when the cutter was extended just a bit too far from the bar. This is the torque effect; the friction of the cutter on the work, even if you have a good grind and the tool is aligned, is amplified by the length of the cutter, which acts as a lever twisting the bar to a much greater effect. The further the tool protrudes from the bar, the more it will show up imperfections in tool geometry.
@@Haforn44 Hi, I think you’ve explained at least part of my problem, thanks. The light dawned for me when I read your ‘ Bite, bend, scrape, bite, bend, scrape’. That’s just what it felt like! Changing to a larger diameter bar and much smaller cutter extension really helped. Can’t claim the super smooth finish yet but I’m working on it! Thanks again.
Your vibration could be caused at the tail stock end from round about 18:02 in the video you can see some movement, Mr Crispin also had the luxury of a thicker boring bar, ... I've got some cylinders to bore out so that'll most likely happen to me as well .. if it can go wrong it will lol ... thank you for the upload though i'm sure you'll work through it you always do, a new day brings new results .. Regards Andy
Hi Andy - many thanks for the suggestion. I've decided to put all suggestions into a spreadsheet and try to work though each one. One thing I will definately get is a 2MT dead centre for the tailstock. Hopefully in the end I will have a workable solution. Onwards and upwards! Cheers Andrew
Andrew, I agree with the steady rest on the borimg bar, calculated SFPM, and chip load. Look at tail stock quill for excess play, and gib adjustment on cross slide.
Hi Don - many thanks for the suggestions. A steady rest sounds like a good idea. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution. Cheers Andrew
The chatter in bore was caused by cylinder wall may been to thin. as to remove the chatter and get a good finish. you must sharpen the tool to very sharp point and cut under the chatter with a slower rpm and higher feed.
Hi Peter - many thanks for the suggestions. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution. Cheers Andrew
The cause of the original taper in the bore could be due to the axis of the spindle not being aligned with the lathe bed. This is easy to check. Mark longitudinal lines 90 degrees apart on a hefty round, parallel bar (say, 25mm diameter silver steel). Chuck it in the 3-jaw without any tail stock support. Record the deflections of a dial indicator in the horizontal direction at the 0 & 180 degree positions near the chuck and at, say, 150mm from the chuck. Take the average of the two 0 degree measurements away from the average of the two 180 degree measurements. The result is the amount of misalignment over 150mm in the horizontal plane. Repeat at the 90 & 270 degree positions with the dial indicator pointing vertically down to check the misalignment in the vertical plane. (There may be some sag in the vertical plane that affects this measurement.)
Hi Chris - thanks for the suggestion. I've not checked headstock alignment but a couple of days ago I checked the tailstock alignment with the headstock, by putting a long bar between centres and turning it down to a specific amount (using the cross slide) on each end. I then checked the diameter of both the machined sides using a micrometer. I found that the tailstock was a tad out, which I suspect is what caused the taper in the first place. Unfortunately when I adjusted it, one of the 'fingers' broke off the casting in the base of the tailstock - disaster! I contacted Arc Euro Trade to see if they had a spare tailstock base, but all they could offer was to put in a request at the Sieg factory for a replacement - which could take 3 months to arrive. I decided to try JB Weld in addition to some extra support offered with some bits of steel. I know that JB Weld hasn't got the tensile strength of cast iron, but it seems to have worked a treat. If it does break again, I will machine a pair of 'fingers' and bolt them to the base. I will check the spindle axis as you suggest though - once I acquire a parallel bar. One job leads to another! Cheers Andrew
Just a suggestion Andrew You may like to watch Kieth Fenner's you tube videos entitled "My go to bar" which he bores out large popeller shaft supports foe a boat and I notice his boring bar is very nearly the diameter of the hole. secondly why can you not leave the tool adjuster on the shaft just slid out of the way? Cheers Andy A
Hi Andrew - many thanks for the suggestion - I will check Keith's video out. I think the tool adjuster would introduce balancing/vibration issues - but I could be wrong! Anyway, I had another go at re-machining the bore. Check out Part 5a to see how I got on. Cheers Andrew
For what you're doing a steady rest would be the easiest way. Line boring is best for more extreme situations. Steady rest examples in abom79, line boring in Keith Fenner.
The boring bar looks to be running out quite a lot. If you look back you can see the tailstock centre wobbling quite a bit. Did you try grinding the HSS to a nice fairly large radius to the tip?
Hi - many thanks for the suggestions. I'll review the footage. No, I didn't experiment with a large radius tip. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution.
Hi Andrew, I wondered if the problem is that you don't seem to be putting the boring bar between centres. If you look again at Crispin's video he has the bar between centres and driven by a dog on the bar. That means that he can take the block out for meassurement and putitback in the same spot and its relatoin to the bar is always the same. It looks like you’re using the 3 jaw for the driven end of the bar so each time you take it out and put it back the runout will be different. If the lathe is aligned properly then there will be trivial runout when you bore between centres and remove and replace the bar. Googling will give you a lot of information.
Hi Nick - I don't think my video shows the bigger picture. I am putting the bar between centres and driving it with a dog. Like you, I thought that would enable me to remove the bar without introducing runout when replaced. However, others are suggesting using a 3 jaw chuck to help reduce vibration. I think I need to experiment and see if I can keep the bar in situ. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution. Many thanks for your input. Andrew
Myford Boy uses the method you initially suggested only employing MDF. No chance of distorting the bore and should mitigate tool chatter along with slower spindle speed.
Hi Andrew, would there be any value with taking a small piece of say iron pipe, and practicing on that? I have been toying with the idea of experimenting with some pipe to use as a cylinder liner for small engines but I haven't had the time to try it out. Also, I would have to do it with a boring head on my mill as I would have to do some serious modifications to my lathe in order to do line boring like you are doing.
Hi Robert - Yeah it would be good to be able to try out many of the suggestions and practice on something - not sure what though. I'll have a rummage! Take care. Andrew
Andrew, excellent videos, I think you were almost there when you machined the cylinder liner on the previous video. Perhaps a larger diameter boring bar for the final cuts would have made the difference. As others have suggested for your spreadsheet; fixed centres both ends, this will reduce the overhang and live centres have to have some clearance to enable them to rotate. Are you able to reduce the length of the boring bar which will improve the stiffness of the bar?
Many thanks for the suggestions. I think someone else has suggested on similar lines. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution. Cheers Andrew
Can You use that piece of cast making something like an oil can and have some use of it? The rigging looks hopelessly difficult. How do other people do when making cylinders for such machines?
Hi Stefan - oil can is a good idea - shame its got a hole in the side of it - ha ha. As I understand it, between centres boring (aka line boring) is the way to go. Obviously a bit of a black art. All the best. Andrew
Hi Andrew, I have to echo what others have said, and it looks quite obvious that you tailstock centre is wobbling about. Also, as I understand it, a coaxial indicator will only give true run-out at a specific diameter (depending on the probe used). The dial divisions in all other cases, being of no particular dimension.
Hi Steve - many thanks for the suggestion. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution. Yeah - I'm not sure my use of the coaxial indicator not turning was good. However, I would have thought that it should show differences when spinning and moving up and down the bore. But then I am definately no expert. All the best. Andrew
Hi John - maybe, but I'm coming to the conclusion that it could be a combination of many factors. I've made a record of all suggestions and I hope have another try soon. Watch this space! Cheers Andrew
On those photos at the end, is the tailstock end of the boring bar in the right of the picture? If so, and this can't be right, but it looks to me like the tool is the wrong way round - i.e. cutting with back side. The one picture you didn't include is the side tool profile, so probably I'm just getting the perspective wrong from the 2D shots. But in the first of your 2 pics, you are showing us the back of the tool, aren't you - not sure why.
Hi mate, I know where you are coming from. I think the grey mist had started to set in at that stage. I took pictures of the boring bar the opposite way round to how it eas in the lathe. When I made the cuts on the lathe the cutter was in the correct way round. Thanks for the suggestion though. Cheers Andrew
Hello Andrew ....really like your content....we are of similar age and skill. I may be missing something but did your coaxial indicator show the bore was not tapered?
Hi Ray - well spotted - I noticed that too - not sure why, but I don't think that moving the gauge down the bore without it spinning is an accurate method. However after adding the extra thou of packing it did show a slight difference at one end when turning. The bore was definately out by a couple of thou initially, but I'm beginning to wonder whether I would have got away with it. Anyway, damage done. At least it showed that my method of boring between centres isn't good and that it's a problem that needs sorting. Better to know now rater than later. All the best. Andrew
Hi Andrew - first of all, thanks for posting this. Always good to see your projects, really well executed. However, my heart went out to you re the look on your face at the end of this video. I guess we've all had days and subsequent sleepless nights like that. I certainly have. Can I offer some advice? (Sorry if I'm repeating what others have said), but when I was an apprentice toolmaker waaay back in the 1970's I cut my teeth on cast iron and jig boring. I think you have a few issues here which are combining into one problem; I also think you're closer than you feel to getting this spot on. 1) Between centres boring should be exactly that - you will get run out with a chuck; I'd do it between two centres, with the headstock one in a faceplate, and drive the shaft with a dog. That will get the boring bar running true. 2) Tool geometry is everything. I'd use a slightly rounded tool with negative rake. Don't forget that the tool geometry is also affected by the position of the cutter in the boring bar. When the tool is horizontal (ie facing you) relative to the x axis of the lathe the tool must not be twisted in its seat; otherwise you are effectively changing the tool geometry by lowering or raising the approach angle. When you outside turn on the lathe, you get the tool flat in the toolpost; the boring bar position relative to the work is just as important. Also the tool must be ground and positioned to make sure it doesn't rub. 3) My apprentice master told me to imagine the tools being made of flexible rubber. If you can get that picture in your head you'll see that as the cutter fails to cut cleanly, resistance will develop and the torque will twist the whole boring bar as the tool bites. The torque will then overcome the bite, and it will cut (roughly) until the torque builds up again, and forces the tool through the work. Hence the intermittent scraping noice. Bite, bend, scrape, bite, bend, scrape, etc. You get an amazing amount of torque in shafts - in the rope shop in the shipyard (many moons ago) when they started the motor on the line-shaft the motor did 1/4 of a turn before the far pulley even moved. With that in mind, the boring bar should be as short as is practical as well; a lot of commercial boring bars are hardened and ground for maximum rigidity. 4) Cut depth. We used to cut cast iron fairly deep to break the skin, then very lightly thereafter, running slow with a slow feed. When it is running without chatter, and you have made your final cut, I used to reverse the carriage feed so the tool was cutting in reverse for the final polish. Gives a mirror finish! 5) I'd think about clamping as well. As someone else said, your clamping is tending to crush the part (Think rubber again!). It does look very thin; had you considered roughing the outside round, finishing the bore, then machining the outside to the bore? That's how they do gun barrels. Good luck! I really think you're a few tweeks away from a good bore!
Your cross slide was bouncing around a lot. I would look at your gibs on your cross slide and your saddle. Also try a shorter bar. Regardless, I think you would have ended up with an oval anyway because the clamp would have squashed your part. The hardwood block is a good idea. Anyway, it was an interesting video!
Hi John - many thanks for the suggestions. I did put a lock on the cross slide, but maybe I need to put one both ends. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution. I'll check to see if I squashed it too. Watch this space! All the best Andrew
I think you are really brave showing failures and for showing how the boring between centres works. Thanks for the video. Any chance that the tailstock is flexing?
Hi John - a lot of the time I end up doing things I've never attempted before. If I show it as it is it might inspire others to take up the hobby, and I also get great advice from folks like you. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution. All the best. Andrew
One thing I noticed is that your revolving center is being held in what looks like a jacobs style chuck, I may be wrong as I didn't see it clearly. If it was I think that could be causing your run out. I am viewing this on a small phone so it's not perfectly clear
Hi Tony - many thanks for the suggestion. It is actually a 2MT revolving centre, but it could still be a contributing factor. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution. All the best. Andrew
Andrew. Try wrapping some sheet lead around the bar on either side of the tool to dampen out the tool harmonics. Also try an almost sharp tool to cut down on surface area and finally run it much slower.
Many thanks for the suggestions Dave. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution. All the best. Andrew
Don't throw it away yet, bore it out again using a DEAD center in the tailstock. That would eliminate any movement in the live center.. It's all good fun , isn't it ! Peter
Hi Peter- many thanks for the suggestion. I think I must have lost my 2MT dead centre - so I'll get on and order one asap. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution. The walls of the cylinder are starting to get rather thin - I'll soon be machining fresh air! Yeah - all good fun. I really enjoyed setting it up in the lathe. Shame it all went pear shaped in the end. Cheers Andrew
I agree with the use of the dead center do not forget to grease the hole. Also on that small lathe the cross slide might be lifting off the ways a bit making the bore bounce hence chatter. Also I have had bad results from wd 40 use on steel try cutting oil for steel.
Interesting that you used slip guages to measure the height from the cross slide to the centre line of lathe: I'd have thought it quicker and easier to use your digital height gauge to measure the height from cross slide to the top of the bar turned in the lathe. Then use your micrometer to measure the dia. of the bar, divide by two and subtract that from the height you measured - end result is the distance from cross-slide to the lathe centre line.
Ha ha - cheers Craig. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution. All the best. Andrew
On the video it looks like you are getting noticeable run out on your boring bar. After you cut the angle you can't remove the soft center held by the 3 jaw chuck or you will lose concentricty (I know you marked the center). If the live center in the tail stock is the culprit, you might need to use a dead center instead. Splitting those thousands is fun, eh? :() Mr Ticehurt's one-time use wood fixture is sounding better all the time...
Hi Douglas - many thanks for the suggestions. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution. Ha ha, using a calculator I often forget how small some of those numbers represent. Having said that I've just ordered a couple of Mitutoyo calipers with 1/10th of thou graduations! All good fun! All the best. Andrew
Two things No 1 wood lathes cut wood metal lathes cut metal No 2 you know when you are an engineer when you can repair your mess ups without anyone finding out. This is what they don't tell you, very few lathes will cut parallel out of the box especially One from China. Even if it does you will get work deflection and tool deflection. the more depth of cut you take the more the bar will Spring away, hence a spring cut. so we counter act this by returning the cut without altering it or taking a second cut without altering it. also a fixed steady on the work would have stopped deflection. the finer the cut the smaller the tool radius I could go on for days. apart from that you are having fun doing it and I am having fun watching it. more info if you need it keep up the good work
Hi Jonathan - many thanks for the suggestions. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution. Yeah - it was real fun until it went all pear shaped! Cheers Andrew
I'd think that this way of machining is not suited for a liner, since it will be deformed by the clamping force. I'd mount it in the chuck, rather a 6 jaw instead of a 3 jaw and use a normal boring bar.
Yeah - In my previous video I spent quite a large sum on a boring bar with a carbide shaft. It did machine well but it was just out by 2 thou at each end. I might have to go back to that approach if I can't get between centres boring sorted. Cheers Andrew
I believe your chatter problems result from too much cutting force. The sidewall of the cylinder is too thin, the tool it too blunt. Your tool was cutting below center. The only thing you can easily change is the cutting tool geometry. I looks to me that your tool had either a neutral or negative rake. I would try changing the cutting angle to a more positive 5 to 10 degree, and reduce the cutter clearance angle. Cut the tool such that it shaves chips and uses the clearance angle as a running pad. The clearance angle rides on the newly cut surface, this controls the chip size.
Should have slowed it right down Andrew. Slowest speed possible. In the glass manufacturing industry when making the dies they always turn at dead slow speed. Barrels of guns is the same. I would recommend that. How slow does your lathe go? I would run at 50 rpms. People would disagree but if you have everything locked tight then I guarantee it will work. I would using a live centre for the centring of the shaft. My biggest concern is does your lathe travel that slow? Also if everything goes wrong (vibration again then ) then leave it 10 thou smaller and use hone and kero to bring it up to specs. The main thing is to drop your speed and feed. Also with your boring bar the cutting point should be lower than centre slightly. Not bad remembering back to the day when I was a full blown machinist. That was 1986 and I know nothing has changed since. I must also state where I did over time done relieving machining so but that was 20 years ago. You never really forget it. Following you does rekindle the memory. Just hope this solve your problem for the future. Enjoy your channel very much. Thanks for your honesty too. Never be ashamed to discuss your problems. We all learn or remember.
Hi Gary - many thanks for the suggestions and I'm glad you enjoy the channel - warts and all. Best way to learn is from mistakes. I think the slowest my lathe can go is 100 rpm, but I guess I could alter the fine feed by altering the gear configuration - I need to investigate. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution. Take care. Andrew
Learning Turning Metal - by Andrew Whale - No worries Andrew. I am looking at buying a small lathe and maybe a milling machine. Looked at some today but not impressed so far. The small lathes don’t have a cross feed which sort of hit me by surprise. Then there was lathes with large spindle internal diameter but could not cut 8 tpi threads. Have to so careful today buying these small lathes. Lucky I went armed with plenty of notes of things I did not pick up on their webpage which I need to see if suitable for me to use... I went away very disappointed. Instead of a small hobby lathe I would have to spend lot more money and get something ideal for hobby making and also can at least do have enough torque to cut the thread I have questioned above it would be able to manage with ease.
I think the cutter bit was rubbish. I would prefer a nice sharp carbide tipped cutter. I also think the boring bar was flexing due to the cutter not cutting but rubbing along the surface. Nice learning experiment though.
Hi Dave - yeah I would have preferred a carbide tipped cutter too. Unfortunately I don't think I can get one to fit into a between centres bar. All good fun! All the best. Andrew
Hi Andrew, Thankyou for the fine videos. If I could make a couple of observations. 1. Your line Boring Bar is wayyy too Long. As a rule ALWAY endeavour(or be prepared to accept less that perfect) to use a short as boring bar as possible. 2. I did not notice how far the tailstock quill was sticking out but it needs to be basically nothing. And of course do up the clamp on the quill(if they have one). There is a clearance (by design) between the quill and the bore of the Tailstock(on ANY centre lathe). 3. How well does your tailstock sit on the ways of the bed? If they are not perfect, then there is another opportunity for vibration. 4. I understand you were taking very small cuts but you need to consider the direction of your cutting forces. They need to be acting down the line of your bore/Bar. Anything else means that there will be some deflection of the bar(another reason for chatter). 5. Your tool geometry is critical. Minimising the radius on the tool may help, but it will need a small radius. To have a pointed tool it has a very high probability of that sharp point failing somewhere along the cut, probably in the first few mm's.(no single point cutting tool(diamond not included) will be sharp(even your thread cutting tool has a flat or radius(of some size). Even the mass of your machine affects vibration(a machine weighing around 100kg when it is that long, and spindle that far above the base. Did you measure the bore at both ends after you finished the machining operation(was it parallel?). If it was not, then, that may mean that your tailstock is not in line with your spindle and or your bed. Even your spindle is unlikely to be exactly in line with your bed. 99.9% of the time it's quite easy to get away with it. You have a great little machine. Like most machines, it has limitations. The boring operation is achievable on your machine I believe. Perhaps if you have a decent quality boring bar, perhaps you could mount it in the 4 jaw chuck (keep the setup with your sleeve mounted on the cross slide). When you take a cut you offset the chuck jaw that is in line with the cutting edge. you can put an indicator on it to check how much you are offsetting it for each cut. Some of my thoughts may apply, there are a lot more variables that could not be identified in the video. All the best.
Hi Andrew. Thanks for showing your failures. It's been my experience that we learn the most from those.
Now on to my 2 cents worth....
Some have said to use the 3 jaw for rigidity. If you do that, you lose precision. Keep it between centers and use a dog.
My friend,throw that live center away! It might be good for wood turning but it's junk for machining! Either get a precision live center or, better yet, a dead center and use high pressure grease. Dead centers are more precise anyway.
When pro's bore between centers, they use supports with bearings. Not a steady rest but more like follow rests in your case. They keep the flex of the bar due to tool pressure to a minimum. I don't think it's your tool that's a problem as much as it is the flex in the bar. Although I'd also recommend a sharp cutting tool, slower rpm and feed. The follow support bearings don't have to be fancy, brass should be good enough but the work should be supported on both sides for best results. The good thing is, if you design them right, you only have to make them once for each boring bar size. When the brass bearings wear out, you can easily replace them if you design the mounts to take standard sizes.
Finally, a lot of people have correctly pointed out that the clamping system you have is going to distort the part. You'd be surprised at how much a hollow part flexes even if it's much thicker than what you have. I'd recommend boring out the clamping material to the OD of the cylinder, drill and tap one side to accommodate clamping screws, then slit that side. It will give you even clamping pressure all the way round. You can use hard wood or metal and design it to accommodate the brass bearings mounts if you like.
I'm confident that, if you do all these things, you will get great results.
Good luck sir
Many thanks for all the suggestions. You are definately right regarding the wood turning chuck. Watch this space!
All the best.
Andrew
TOP TIP! Get yourself on eBay and buy a length of cold drawn seemless steel tube (CDS) the bore is precision finished to size. That’s what I used for both my model engines. Cast iron Piston is then turned and polished to give 1/2 thou clearance, no piston ring required!
Hi James - a great idea! I think I'll have a look around to see if I can get hold of something close to the dimensions needed. However, I would still like to get to the bottom of the between centres problem. I'm definately interested in CDS as an alternative solution in the future and if I can get hold of some it will at least enable be to ascertain quality and accuracy.
Thanks again
Andrew
Hi Andrew, thanks for posting this, very helpful and good to see things go wrong, it gets the brain going.
A few points struck me from watching that may have caused issues. The driven end centre was held in a 3 jaw Chuck, these are notorious for run out, try a Morse taper centre in the headstock spindle. The clamping looked as if it might have distorted the cylinder, esp as it was thin walled at this point. The hole in hardwood method would have provided more even clamping around the diameter.
The live centre looked like an interchangeable one, similar to those used in wood turning. If it is then maybe it’s not as good.
Personally I haven’t tried a between centre boring bar, so these are just my thoughts, so bear that in mind.
Hy Taffy - many thanks for your thoughts on this. I'm beginning to wonder whether a hard MT centre might be better in the headstock. Some have suggested this but also with 3 or 4 jaw chuck providing extra support. I will check to see of the cylinder distorted - but it is certainly thinner than it was! Well spotted regarding the woodturning live centre. This came off my woodturning lathe and I did wonder whether it might be a contributing factor. I might buy a live tailstock centre specifically for engineering, or use a dead centre. I'm adding all suggestions to a spreadsheet and I will try to work through the list and experiment.
Cheers
Andrew
Hello Andrew
Been sitting and watching your videos today, and would just like to say thanks for the show - great work your done
Nice attempt! I'd put that part on the shelf right in front of me as a reminder of the learning experience. (I have several on my shelves... :) )
Ha ha - thanks Jim. Fortunately I manage to recycle it in Part 5a!
Cheers
Andrew
Hello Andrew. I have some experience boring stationary holes with a boring bar. I have not read all of the comments and if someone else has suggested this I apologize. The tool bit has to be referenced on a line that runs through the center of the bar. I noticed that you had the bit ground down fairly close to the center but that is not necessary. If you imagine a line from the center of the bar to the tip of your tool bit and then grind your bit to match that line plus around 5 degrees more it should work fairly well. Of course you would allow some clearance on the cutting face and the end face as well. Form what I could tell from the video it appeared that it was ground almost negatively back toward the bar.
Hi Frank - many thanks for the suggestion. Based on all the other comments I received, I made several adjustments and I've just recently had another go at re-machining the bore - which was a massive success. See Part 5a.
All the best.
Andrew
Hi Andrew, I've no further suggestions to add to the many excellent ideas already posted, but I must say that your progress and achievements over these past few years has been remarkable, and for what it's worth, I bet my scrap box holds more mistakes than yours ! Keep up the good work, all the best, Brian
Thank you< Andrew - I admire your Cromwell philosophy (Warts and all). Very informative.
Thanks Richard - hopefully I will be able to get to the bottom of it.
Cheers
Andrew
I'm probably way late, but the first thing I'd do is tighten up the tailstock. I've got a couple old logan's, 10 by 24 from the forties, and they've got some play in the tailstock and the slides. A live center usually has enough slack in it to cause the chatter.
well done for being honest and sharing, we all make mistakes and mistakes are good because you, and others can learn from them.
don't be disheartened, chuck it in your scrap box and it may come in handy someday. BTW my scrap box is massive.
keep up the good work and keep learning
regards
Paul
When you use a hone tool you must you a lot off oil to flush out metal particles or else they will clogging the stone.
Also don’t be to disappointed if something doesn’t work the first time.
Somethings can take a lot of trying before you get it to work on your machine.
Whatever you do some materials are always a b¥#$ to cut and will give you chatter no matter what you do.
Also the boring bar between centers on your light lathe can be a big issue why it wasn’t working the first time , remember that what we see a solid machine turns into rubber when your are machining and if there is a slightest change for chatter it wil happen.
A possibility is to make the boring bar as short as possible.
Love your videos and please keep making more 😀
Many thanks for the advice.
Cheers
Andrew
Hi Andrew, Sorry to see you had so much trouble with the boring bar. Looking at the bar revolving it seemed to be out slightly, as did the live center, One job down to experience mate. Stay well and keep the great video's coming please ,Kind Regards, Mike
Thanks Mike - you are correct about the live centre. Watch this space!
Cheers
Andrew
Andrew, I am sorry to see you having trouble with this. I thought you were there when you had everything beautifully lined up. The cutter has proved a real disappointment. You have plenty of suggestions and there is nothing I can add. Solving these problems is one of the great pleasures of engineering, but you have to go through the frustration to get there. Have you checked with other Farmboy builders to see how they made the liner? Good luck. Look forward to hearing how you resolve the problem.
Cheers Tim - watch this space!
All the best.
Andrew
Don't give up on the part There seems to be several comments on various issues with the set up and they all are correct. there is always multible issues when a part chatters. From past failures you learn how to adapt to each issue. My approach would have been to bore a piece of waste stock to the outside dimension of the cylinder, saw a slit in it length wise and reinsert in the chuck with the cylinder installed, instant collet. The make as large and short length boring bar as will fit and hold in the tool post. I am not who ever telling you that is THE way to do it as there are always different ways to machine the same part Good luck and keep trying
Hi Andrew, very interesting to watch your video, thanks. I have just finished the Hemingway boring bars myself and had a first attempt at boring two parallel bores yesterday. Rather like you, it didn’t go as well as I’d expected and I spent a lot of hours trying to get things right. I had the same issues with vibration although I found it varied between cuts and on occasion did run quite cleanly. I suddenly got into problems when the cutter was extended just a bit too far from the bar. There was no gradual deterioration, just a switch from smooth cutting to judder. This was particularly noticeable using the narrowest bar of the set.
For what it’s worth, and I am only a rank amateur at these things, I’m inclined to think that Haforn44 has diagnosed correctly and the grind of the cutting tool bit is the critical issue. I think you were going this way yourself too. I’m going to rethink my grinding profiles and try again. Good luck with your next cylinder, I look forward to hearing of your success or ‘learning opportunities’!
Hi- you mention you got into problems when the cutter was extended just a bit too far from the bar. This is the torque effect; the friction of the cutter on the work, even if you have a good grind and the tool is aligned, is amplified by the length of the cutter, which acts as a lever twisting the bar to a much greater effect. The further the tool protrudes from the bar, the more it will show up imperfections in tool geometry.
@@Haforn44 Hi, I think you’ve explained at least part of my problem, thanks. The light dawned for me when I read your ‘ Bite, bend, scrape, bite, bend, scrape’. That’s just what it felt like! Changing to a larger diameter bar and much smaller cutter extension really helped. Can’t claim the super smooth finish yet but I’m working on it! Thanks again.
Your vibration could be caused at the tail stock end from round about 18:02 in the video you can see some movement, Mr Crispin also had the luxury of a thicker boring bar, ... I've got some cylinders to bore out so that'll most likely happen to me as well .. if it can go wrong it will lol ... thank you for the upload though i'm sure you'll work through it you always do, a new day brings new results .. Regards Andy
Hi Andy - many thanks for the suggestion. I've decided to put all suggestions into a spreadsheet and try to work though each one. One thing I will definately get is a 2MT dead centre for the tailstock. Hopefully in the end I will have a workable solution.
Onwards and upwards!
Cheers
Andrew
Andrew, I agree with the steady rest on the borimg bar, calculated SFPM, and chip load. Look at tail stock quill for excess play, and gib adjustment on cross slide.
Hi Don - many thanks for the suggestions. A steady rest sounds like a good idea. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution.
Cheers
Andrew
The chatter in bore was caused by cylinder wall may been to thin. as to remove the chatter and get a good
finish. you must sharpen the tool to very sharp point and cut under the chatter with a slower rpm and higher feed.
Hi John - many thanks for the suggestions. Very much appreciated.
All the best.
Andrew
Good Andrew not much I could offer except for shorter boring bar and reduced rpm. Good luck Cheers
Peter
Hi Peter - many thanks for the suggestions. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution.
Cheers
Andrew
The cause of the original taper in the bore could be due to the axis of the spindle not being aligned with the lathe bed. This is easy to check. Mark longitudinal lines 90 degrees apart on a hefty round, parallel bar (say, 25mm diameter silver steel). Chuck it in the 3-jaw without any tail stock support. Record the deflections of a dial indicator in the horizontal direction at the 0 & 180 degree positions near the chuck and at, say, 150mm from the chuck. Take the average of the two 0 degree measurements away from the average of the two 180 degree measurements. The result is the amount of misalignment over 150mm in the horizontal plane. Repeat at the 90 & 270 degree positions with the dial indicator pointing vertically down to check the misalignment in the vertical plane. (There may be some sag in the vertical plane that affects this measurement.)
Hi Chris - thanks for the suggestion. I've not checked headstock alignment but a couple of days ago I checked the tailstock alignment with the headstock, by putting a long bar between centres and turning it down to a specific amount (using the cross slide) on each end. I then checked the diameter of both the machined sides using a micrometer. I found that the tailstock was a tad out, which I suspect is what caused the taper in the first place. Unfortunately when I adjusted it, one of the 'fingers' broke off the casting in the base of the tailstock - disaster! I contacted Arc Euro Trade to see if they had a spare tailstock base, but all they could offer was to put in a request at the Sieg factory for a replacement - which could take 3 months to arrive. I decided to try JB Weld in addition to some extra support offered with some bits of steel. I know that JB Weld hasn't got the tensile strength of cast iron, but it seems to have worked a treat. If it does break again, I will machine a pair of 'fingers' and bolt them to the base.
I will check the spindle axis as you suggest though - once I acquire a parallel bar. One job leads to another!
Cheers
Andrew
Just a suggestion Andrew You may like to watch Kieth Fenner's you tube videos entitled "My go to bar" which he bores out large popeller shaft supports foe a boat and I notice his boring bar is very nearly the diameter of the hole. secondly why can you not leave the tool adjuster on the shaft just slid out of the way? Cheers Andy A
Hi Andrew - many thanks for the suggestion - I will check Keith's video out. I think the tool adjuster would introduce balancing/vibration issues - but I could be wrong! Anyway, I had another go at re-machining the bore. Check out Part 5a to see how I got on.
Cheers
Andrew
For what you're doing a steady rest would be the easiest way. Line boring is best for more extreme situations. Steady rest examples in abom79, line boring in Keith Fenner.
Hi Jim, many thanks for the links, I'll check them out. I did actually nail it in the end - see my part 5a video.
All the best.
Andrew
It looked like the live centre had a minute wobble.
The boring bar looks to be running out quite a lot. If you look back you can see the tailstock centre wobbling quite a bit. Did you try grinding the HSS to a nice fairly large radius to the tip?
Hi - many thanks for the suggestions. I'll review the footage. No, I didn't experiment with a large radius tip. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution.
Hi Andrew,
I wondered if the problem is that you don't seem to be putting the boring bar between centres. If you look again at Crispin's video he has the bar between centres and driven by a dog on the bar. That means that he can take the block out for meassurement and putitback in the same spot and its relatoin to the bar is always the same. It looks like you’re using the 3 jaw for the driven end of the bar so each time you take it out and put it back the runout will be different. If the lathe is aligned properly then there will be trivial runout when you bore between centres and remove and replace the bar. Googling will give you a lot of information.
Hi Nick - I don't think my video shows the bigger picture. I am putting the bar between centres and driving it with a dog. Like you, I thought that would enable me to remove the bar without introducing runout when replaced. However, others are suggesting using a 3 jaw chuck to help reduce vibration. I think I need to experiment and see if I can keep the bar in situ. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution.
Many thanks for your input.
Andrew
Myford Boy uses the method you initially suggested only employing MDF. No chance of distorting the bore and should mitigate tool chatter along with slower spindle speed.
Hi David - very interesting. I will check out Myford Boy's vid asap!
Cheers
Andrew
@@learningturningmetal It's in the series building the Essex Hot Air Engine part six
Hi Andrew, would there be any value with taking a small piece of say iron pipe, and practicing on that? I have been toying with the idea of experimenting with some pipe to use as a cylinder liner for small engines but I haven't had the time to try it out. Also, I would have to do it with a boring head on my mill as I would have to do some serious modifications to my lathe in order to do line boring like you are doing.
Be careful of using water pipe it is horrible to machine
Hi Robert - Yeah it would be good to be able to try out many of the suggestions and practice on something - not sure what though. I'll have a rummage!
Take care.
Andrew
Never throw away tour failures they are perfect for practising on steve
Yeah Steve, and my box is starting to overflow with them!
Cheers
Andrew
Andrew, excellent videos, I think you were almost there when you machined the cylinder liner on the previous video. Perhaps a larger diameter boring bar for the final cuts would have made the difference.
As others have suggested for your spreadsheet; fixed centres both ends, this will reduce the overhang and live centres have to have some clearance to enable them to rotate. Are you able to reduce the length of the boring bar which will improve the stiffness of the bar?
Thanks for the suggestions Philip - very much appreciated.
Cheers
Andrew
Did you use the chuck to hold the boring bar between center?
Maybe if you use dead center directly in spindle bore you will get better results.
Many thanks for the suggestions. I think someone else has suggested on similar lines. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution.
Cheers
Andrew
Can You use that piece of cast making something like an oil can and have some use of it?
The rigging looks hopelessly difficult. How do other people do when making cylinders for such machines?
Hi Stefan - oil can is a good idea - shame its got a hole in the side of it - ha ha.
As I understand it, between centres boring (aka line boring) is the way to go. Obviously a bit of a black art.
All the best.
Andrew
Hi Andrew, I have to echo what others have said, and it looks quite obvious that you tailstock centre is wobbling about. Also, as I understand it, a coaxial indicator will only give true run-out at a specific diameter (depending on the probe used). The dial divisions in all other cases, being of no particular dimension.
Hi Steve - many thanks for the suggestion. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution.
Yeah - I'm not sure my use of the coaxial indicator not turning was good. However, I would have thought that it should show differences when spinning and moving up and down the bore. But then I am definately no expert.
All the best.
Andrew
Yes Andrew, the coaxial indicator will show differences, but not the actual dimension.
Would having removed the center point from the three jaw and then re installing it make a difference ??
Hi John - maybe, but I'm coming to the conclusion that it could be a combination of many factors. I've made a record of all suggestions and I hope have another try soon. Watch this space!
Cheers
Andrew
On those photos at the end, is the tailstock end of the boring bar in the right of the picture? If so, and this can't be right, but it looks to me like the tool is the wrong way round - i.e. cutting with back side. The one picture you didn't include is the side tool profile, so probably I'm just getting the perspective wrong from the 2D shots. But in the first of your 2 pics, you are showing us the back of the tool, aren't you - not sure why.
Hi mate, I know where you are coming from. I think the grey mist had started to set in at that stage. I took pictures of the boring bar the opposite way round to how it eas in the lathe. When I made the cuts on the lathe the cutter was in the correct way round. Thanks for the suggestion though.
Cheers
Andrew
Hello Andrew ....really like your content....we are of similar age and skill. I may be missing something but did your coaxial indicator show the bore was not tapered?
Hi Ray - well spotted - I noticed that too - not sure why, but I don't think that moving the gauge down the bore without it spinning is an accurate method. However after adding the extra thou of packing it did show a slight difference at one end when turning. The bore was definately out by a couple of thou initially, but I'm beginning to wonder whether I would have got away with it. Anyway, damage done. At least it showed that my method of boring between centres isn't good and that it's a problem that needs sorting. Better to know now rater than later.
All the best.
Andrew
Hi Andrew - first of all, thanks for posting this. Always good to see your projects, really well executed. However, my heart went out to you re the look on your face at the end of this video. I guess we've all had days and subsequent sleepless nights like that. I certainly have. Can I offer some advice? (Sorry if I'm repeating what others have said), but when I was an apprentice toolmaker waaay back in the 1970's I cut my teeth on cast iron and jig boring.
I think you have a few issues here which are combining into one problem; I also think you're closer than you feel to getting this spot on.
1) Between centres boring should be exactly that - you will get run out with a chuck; I'd do it between two centres, with the headstock one in a faceplate, and drive the shaft with a dog. That will get the boring bar running true.
2) Tool geometry is everything. I'd use a slightly rounded tool with negative rake. Don't forget that the tool geometry is also affected by the position of the cutter in the boring bar. When the tool is horizontal (ie facing you) relative to the x axis of the lathe the tool must not be twisted in its seat; otherwise you are effectively changing the tool geometry by lowering or raising the approach angle. When you outside turn on the lathe, you get the tool flat in the toolpost; the boring bar position relative to the work is just as important. Also the tool must be ground and positioned to make sure it doesn't rub.
3) My apprentice master told me to imagine the tools being made of flexible rubber. If you can get that picture in your head you'll see that as the cutter fails to cut cleanly, resistance will develop and the torque will twist the whole boring bar as the tool bites. The torque will then overcome the bite, and it will cut (roughly) until the torque builds up again, and forces the tool through the work. Hence the intermittent scraping noice. Bite, bend, scrape, bite, bend, scrape, etc. You get an amazing amount of torque in shafts - in the rope shop in the shipyard (many moons ago) when they started the motor on the line-shaft the motor did 1/4 of a turn before the far pulley even moved. With that in mind, the boring bar should be as short as is practical as well; a lot of commercial boring bars are hardened and ground for maximum rigidity.
4) Cut depth. We used to cut cast iron fairly deep to break the skin, then very lightly thereafter, running slow with a slow feed. When it is running without chatter, and you have made your final cut, I used to reverse the carriage feed so the tool was cutting in reverse for the final polish. Gives a mirror finish!
5) I'd think about clamping as well. As someone else said, your clamping is tending to crush the part (Think rubber again!). It does look very thin; had you considered roughing the outside round, finishing the bore, then machining the outside to the bore? That's how they do gun barrels.
Good luck! I really think you're a few tweeks away from a good bore!
Many thanks for the suggestions. Watch this space.
Cheers
Andrew
I know the feeling, I wasted two H0 scale locomotive boilers before getting the third one spot on.
Try using a shorter and thicker bar. Make one from a hydraulic piston or piece of chromemoly 4140.
Use a carbide tool on cast iron.
Hi mate - thanks for the suggestion. I had another go a re-machining the bore - check out Part5a to see how I got on.
Cheers
Andrew
Your cross slide was bouncing around a lot. I would look at your gibs on your cross slide and your saddle. Also try a shorter bar. Regardless, I think you would have ended up with an oval anyway because the clamp would have squashed your part. The hardwood block is a good idea. Anyway, it was an interesting video!
Hi John - many thanks for the suggestions. I did put a lock on the cross slide, but maybe I need to put one both ends. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution. I'll check to see if I squashed it too. Watch this space!
All the best
Andrew
Learning Turning Metal - by Andrew Whale yes put a clock on it and measure the deflection when you tighten it up.
I think you are really brave showing failures and for showing how the boring between centres works. Thanks for the video. Any chance that the tailstock is flexing?
Hi John - a lot of the time I end up doing things I've never attempted before. If I show it as it is it might inspire others to take up the hobby, and I also get great advice from folks like you.
I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution.
All the best.
Andrew
One thing I noticed is that your revolving center is being held in what looks like a jacobs style chuck, I may be wrong as I didn't see it clearly.
If it was I think that could be causing your run out.
I am viewing this on a small phone so it's not perfectly clear
Hi Tony - many thanks for the suggestion. It is actually a 2MT revolving centre, but it could still be a contributing factor. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution.
All the best.
Andrew
Andrew. Try wrapping some sheet lead around the bar on either side of the tool to dampen out the tool harmonics. Also try an almost sharp tool to cut down on surface area and finally run it much slower.
I agree with Mr Ticehurst, sharp tool and much slower. Also, what about a steady rest for supporting the bar to help dampen harmonics?
Many thanks for the suggestions Dave. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution.
All the best.
Andrew
Hi Chris - a steady rest is a greta idea. One to add to the list.
Cheers
Andrew
There is no such thing as failure in the home shop, only learning opportunities.
Cheers Chris - I agree entirely.
All the best.
Andrew
Don't throw it away yet, bore it out again using a DEAD center in the tailstock. That would eliminate any movement in the live center.. It's all good fun , isn't it ! Peter
Hi Peter- many thanks for the suggestion. I think I must have lost my 2MT dead centre - so I'll get on and order one asap. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution. The walls of the cylinder are starting to get rather thin - I'll soon be machining fresh air!
Yeah - all good fun. I really enjoyed setting it up in the lathe. Shame it all went pear shaped in the end.
Cheers
Andrew
I agree with the use of the dead center do not forget to grease the hole. Also on that small lathe the cross slide might be lifting off the ways a bit making the bore bounce hence chatter. Also I have had bad results from wd 40 use on steel try cutting oil for steel.
Interesting that you used slip guages to measure the height from the cross slide to the centre line of lathe: I'd have thought it quicker and easier to use your digital height gauge to measure the height from cross slide to the top of the bar turned in the lathe. Then use your micrometer to measure the dia. of the bar, divide by two and subtract that from the height you measured - end result is the distance from cross-slide to the lathe centre line.
Hi mate - maybe, but it's always good to have a play with new toys.
Cheers
Andrew
Andrew you have to take Edison's philosophy in times like these, You learned one method how not to bore a cylinder. Chin up someone got the answer.
Ha ha - cheers Craig. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution.
All the best.
Andrew
On the video it looks like you are getting noticeable run out on your boring bar. After you cut the angle you can't remove the soft center held by the 3 jaw chuck or you will lose concentricty (I know you marked the center). If the live center in the tail stock is the culprit, you might need to use a dead center instead.
Splitting those thousands is fun, eh? :() Mr Ticehurt's one-time use wood fixture is sounding better all the time...
Hi Douglas - many thanks for the suggestions. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution. Ha ha, using a calculator I often forget how small some of those numbers represent. Having said that I've just ordered a couple of Mitutoyo calipers with 1/10th of thou graduations! All good fun!
All the best.
Andrew
Two things
No 1 wood lathes cut wood metal lathes cut metal
No 2 you know when you are an engineer when you can repair your mess ups without anyone finding out.
This is what they don't tell you, very few lathes will cut parallel out of the box especially
One from China.
Even if it does you will get work deflection and tool deflection. the more depth of cut you take the more the bar will
Spring away, hence a spring cut. so we counter act this by returning the cut without altering it or taking a second cut without altering it.
also a fixed steady on the work would have stopped deflection.
the finer the cut the smaller the tool radius I could go on for days.
apart from that you are having fun doing it and I am having fun watching it.
more info if you need it keep up the good work
Hi Jonathan - many thanks for the suggestions. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution.
Yeah - it was real fun until it went all pear shaped!
Cheers
Andrew
I'd think that this way of machining is not suited for a liner, since it will be deformed by the clamping force. I'd mount it in the chuck, rather a 6 jaw instead of a 3 jaw and use a normal boring bar.
Yeah - In my previous video I spent quite a large sum on a boring bar with a carbide shaft. It did machine well but it was just out by 2 thou at each end. I might have to go back to that approach if I can't get between centres boring sorted.
Cheers
Andrew
Nice try lets see what you do I think it is a bit problem
Hi Joseph - I've received loads of suggestions, so hopefully I will be able sort the problem out. Fingers crossed!
Cheers
Andrew
I believe your chatter problems result from too much cutting force. The sidewall of the cylinder is too thin, the tool it too blunt. Your tool was cutting below center. The only thing you can easily change is the cutting tool geometry. I looks to me that your tool had either a neutral or negative rake. I would try changing the cutting angle to a more positive 5 to 10 degree, and reduce the cutter clearance angle. Cut the tool such that it shaves chips and uses the clearance angle as a running pad. The clearance angle rides on the newly cut surface, this controls the chip size.
Should have slowed it right down Andrew. Slowest speed possible. In the glass manufacturing industry when making the dies they always turn at dead slow speed. Barrels of guns is the same. I would recommend that. How slow does your lathe go? I would run at 50 rpms. People would disagree but if you have everything locked tight then I guarantee it will work. I would using a live centre for the centring of the shaft. My biggest concern is does your lathe travel that slow? Also if everything goes wrong (vibration again then ) then leave it 10 thou smaller and use hone and kero to bring it up to specs. The main thing is to drop your speed and feed. Also with your boring bar the cutting point should be lower than centre slightly. Not bad remembering back to the day when I was a full blown machinist. That was 1986 and I know nothing has changed since. I must also state where I did over time done relieving machining so but that was 20 years ago. You never really forget it. Following you does rekindle the memory. Just hope this solve your problem for the future. Enjoy your channel very much. Thanks for your honesty too. Never be ashamed to discuss your problems. We all learn or remember.
Hi Gary - many thanks for the suggestions and I'm glad you enjoy the channel - warts and all. Best way to learn is from mistakes. I think the slowest my lathe can go is 100 rpm, but I guess I could alter the fine feed by altering the gear configuration - I need to investigate. I've decided to put all suggestions into a spreadsheet and try to work though each one. Hopefully in the end I will have a workable solution.
Take care.
Andrew
Learning Turning Metal - by Andrew Whale - No worries Andrew. I am looking at buying a small lathe and maybe a milling machine. Looked at some today but not impressed so far. The small lathes don’t have a cross feed which sort of hit me by surprise. Then there was lathes with large spindle internal diameter but could not cut 8 tpi threads. Have to so careful today buying these small lathes. Lucky I went armed with plenty of notes of things I did not pick up on their webpage which I need to see if suitable for me to use... I went away very disappointed. Instead of a small hobby lathe I would have to spend lot more money and get something ideal for hobby making and also can at least do have enough torque to cut the thread I have questioned above it would be able to manage with ease.
I think the cutter bit was rubbish. I would prefer a nice sharp carbide tipped cutter. I also think the boring bar was flexing due to the cutter not cutting but rubbing along the surface. Nice learning experiment though.
Hi Dave - yeah I would have preferred a carbide tipped cutter too. Unfortunately I don't think I can get one to fit into a between centres bar. All good fun!
All the best.
Andrew
I think the bar is to long. M
Hi Mark - thanks for the suggestion. Check out video 5a for an update on findings.
Cheers
Andrew