Nice lathe. A lot of people have converted their lathes with VFDs. Clough 42 has a very good series on this. It eliminates the nightmare of change gears and gives you unlimited feeds and speeds and any thread combination you need - metric or standard - all at the touch of a screen. The problem I have with my lathe, while a very good lathe, is no change gears and I've never cut gears before though I am planning on learning in the not-too-distant future. Still the idea of converting my lathe to a VFD is still in the back of my mind. Check him out, I think you will find his channel very interesting. He is in the process of making his surface grinder into a CNC surface grinder. And, I'm sure I have seen your voice heading down one of the canals on a long boat. 😁😎👍👣
Hi Opie, ah yes I think I've watched Clough 42's vid on that. I've seen stepper motors and controllers applied to all sorts of projects like differential indexing on a dividing head for cutting helical gears etc. It may be the modern and better way but I do find a load of clanking gears quite satisfying and reliable 😁.
We have a VFD attached to our 3ph air compressor and it makes a great job of controlling the speed. We can also drive the lathe from it, but l don’t understand how it would help with thread cutting. Are you simply generically calling the stepper motors VFDs? We are expecting to use Clough42’s design.
hi Paul You need a lie down now Paul, its interesting to play around with the gearing, iv'e had fun on my micro lathe i'm making, to get the various possible ratio's in a given physically small space, in fact i still keep revisiting it. when i've nothing to do !! 😄😄 (that'll be the day) Many hobby lathe workers i see shy away from using the lathe to cut threads, suppose it seems a bit scary to to some but like everything, practice makes perfect, i take my hat off to Kimber Zelic he always has a go at it, and with having a go he's learning quickly. plus it saves a fortune on taps and die's See you when you've recovered.😄😄👍👍👍👍👍👍 atb Kev
Hi Kev, these subjects are often much deeper than they appear and the sometimes the only way to understand is just to have a go. There is only so much one can do at a desk. I wondered if I could find a gear combo for 2tpi that would allow me to close the end cover but I can't think of a way to find that other than trial and error plugging in all the possible gears into the spreadsheet initially then doing the physical check on the ones that worked mathematically (lengthy and tedious). Cheers
Hi Paul. Brilliant stuff. This is what I enjoy about home engineering. Real problem solving which requires mathematics, lateral thinking and trial and error. Well done on achieving the 2tpi. I look forward to part 2. 👏👏👍😀
Paul, I definitely enjoyed the mathmatics behind your choice of gearing. I’m still working though such things and appreciate the details behind your thinking! Cheers!
HI Russell, there may be other valid combinations of gears that would give me 2tpi in some or other position on the gearbox but I only had finite patience to go through all the permutations and having found one that worked I stopped there. When I saw the 70T would get me 8, 10, 12 & 15mm 'bonus pitches' I banked it. Empirical approach. Cheers
Really good explanation - the detail is very much appreciated. Sometimes you just have to get into the nitty gritty like that to really show the thought process. Seems like multi start threads are a popular subject right now - looking forward to part 2!
Hi Stuart, Kimber and I have exchanged a couple of emails on this and I will mention him next week. There may be other gear combinations where I might be able to close the end cover on the lathe but my money was in by then. Cheers
I love your thinking on this Paul, should I ever need to do something similar I'll be coming back to this video. My head would hurt too much to try to do it all myself these days. It's a very long time since I had to try and calculate gear ratios for a lathe. 50 years since my apprenticeship, in fact. At least we have spreadsheets to automate some of it now, calculators had only just come out back then and I couldn't afford one.
Hi Bill, I remember calculators were becoming more widely available during my first year at college (day release then) and would cost about a 80% of a week's wage for an apprentice. I saved up for one. Cheers
Thats a beautiful Lathe you have there. I really like it. Interesting setup on the change gears. I guess I’m just spoiled, my lathe doesn’t have change gears. Metric or imperial threads. I just select and go. I have two of the Clausing Metosa C1330S. One I’m still repairing and making parts for. But I’m still a little bit jealous of your Harrison 140. Can’t beat the old Iron workhorses. But thanks for sharing your insight. You are a very capable machinist sir. 🫡
Hi Jason, I googled 'Clausing Metosa C1330S' and I can see it is a very nice lathe. I'm not sure if it has any access to change the screw cutting gears to add pitches not in the box. I was feeling pretty pleased with getting 2pti and now somebody just mentioned 27tpi for NTP (which I don't have as standard)🙄, so that would be another gear combo hunt (if I did not have a tap). Cheers
Hi thesjyoungjr, TH-cam gives me lots of stats. For my channel the viewing devices are 44% phone, 31% computer, 15% TV and 9% tablet. Like you, I do nearly all my viewing on TV but if I want to be commenting I cast to the TV from my phone (I write my comments on the phone). I try to keep all formats in mind when I'm making my videos. I often see videos where the presenter says "you will see it on screen now" and there is nothing to see??? I presume in that case it's something you would see on a phone but not a TV. Cheers
@HaxbyShed I was just saying how good your videos look so good on the big screen. I also have to go to the itty bitty phone to chat. I want to thank you again for inviting us into your shop for a visit. It is always a good time.
I think the great thing about this how you take on difficult problems and techniques. It's how we as humans learn more, think about problems in different ways and come up with new ideas. It doesn't matter how old or new the subject or concept is. Thanks Paul!
Thank you Sir. I find that people draw on their own past experiences when approaching problems, which leads to many different approaches. A carpenter would nail it on, a fabricator would weld it on, an artist would paint it on, & etc.
Hello Paul. I enjoyed that. I had similar issues when cutting the imperial nut for my milling machine knee. I also have done multistart threads. In fact I am doing one now, so your film is highly apposite! Machine is set up to cut the pitch I want (for a metric thread) so say 3mm pitch. I put the cut on using the cross slide, with the topslide set parallel to the work, ie at 90 Deg to the cross slide. Half nuts engaged and kept engaged throughout, reversing the lathe to get back to the start after each cut. Cut the first start to depth in this way. Once first start is cut and tool back at the beginning I proceed as follows. Set up a clock on the top slide and move the tool forwards, ie towards the chuck by half of the pitch being cut. So for 3mm move the top slide towards the chuck by 1.5mm. Once this is done, remove the clock and start the threading process again. The tool will now start cutting the workpiece 180 Deg around from the first start. Continue like this until the second start is correctly depthed. In your case with an imperial thread of 2tpi the pitch is 0.5 inch so you'd move the topslide forward by that amount. I'm doing this at the moment but not for a screw to fit a nut, it's for a swirl inducer that is part of a fuel injector. Thanks again for the film I really enjoyed it.
Hi Carl, you will see next week that I landed on an easy dodge to index 2, 3 and 6 start threads on my Harrison 140. For others I would have to use the 'tool advance' method you describe. Somebody is going to comment, so it may as well be me, that the tool advance to add in the interleaved thread on 2 tpi would be 1/4 inch (not 1/2). Cheers Paul
@@HaxbyShed Yes you are right of course. Half the pitch to advance or 0.25" in this case. I am looking forward to your next film to show how you did it.
You can actually disengage the half-nuts at the end of the thread. Note (or mark) the position on the threading dial that aligns with the fiducial mark on the body while the half-nuts are engaged. Disengage the half-nuts at the end of the thread as per normal and stop the lathe before the threading dial does a full turn. Don't move the carriage manually! Run the lathe in reverse and re-engage the half nuts when the dial returns to its marked position.
There is something very satisfying about the sum of the misinterpretation that led to this video project! Looking forward to part 2!! All the best, Matthew
Great episode! Can't wait for part 2. I know with my lathe and its 2mm pitch leadscrew, cutting any thread above about 4mm pitch really puts a load on the motor such that it can stall out. A "solution" (such as it is) is to turn the lathe from leads screw. which now has leverage on the spindle. But the way I actually do it is turn the chuck by hand with a big wrench (spanner) and take super light cuts. I have also used a tool post mounted dremel tool to rough out the thread before switching to a threading tool. There is a also a video that shows how to use the compound slide parallel to the ways to cut course threads by adding small increments over many passes. I wrote a simple program to find all possible gear combinations on my lathe but as you point out, not all of them are physically realizable.
Hi bkoh, through this little exercise I've learnt a lot about lathe screw cutting gearing but I'm still some way off really knowing all the detail fully in depth. My lathe will cope with 2tpi threading at 34rpm but it must put quite a big strain on the gear train and screwcutting gearbox. Partly why I chose to work with delrin this time. Cheers
Makes me wonder if the people who designed the banjo and gear train knew this and provided JUST enough room between the main shaft and the lead screw to accommodate these gears This must be at the practical limit for a lathe of this size, although perhaps by using something like a tool post grinder...? Thank you for taking the trouble to explain this in detail, much appreciated. One of the reasons I look forward to your videos. Robert
Thank you Robert. Standard it cuts 60tpi to 4tpi (with the extra 63T and 40T gears), or 0.2mm to 7mm. These lathes were made in their hundreds for schools and colleges, and small workshops. I guess they thought 4tpi was as fast as an apprentice should be permitted due to danger of saddle to chuck crash 😁
Hi Paul, What a task that was, very enjoyable to watch. Well done for getting there and only out by 0.012%. Did you think about cutting the gear yourself? It did make me think back to my Grandpa's lathe which had all the gears unguarded. It was there I made my first cuts. In the end it became my Dads and then we donated it to the Portsmouth Historical Dockyard. Turns out it was of a type that was used onboard submarines. Funny old world as that is the industry that Im working in down here. Look forward to seeing you cut the doublestart thread. Have a great weekend!!
Hi David, one day I will cut my own gears but a set of cutters can be expensive. You can get a set of 14DP 14.5pa cutters on ebay for about £80 from China but they are for a 22mm arbour and I only have 27mm and 1 inch arbors. I must get or make myself a 22mm stub arbor one day. (Do we spell it arbor or arbour - I can't make my mind up?).
@@HaxbyShed Hi Paul, well the answer to that one depends on what side of the pond you are on!! From HarperCollins Publishers arbor in British English NOUN 1. a rotating shaft in a machine or power tool on which a milling cutter or grinding wheel is fitted I seem to recall a comment about the cost of machine tools and the cost of associated tooling being at least double All the best
christ!!! ,,,, your brain needs a rest! that done me in(LOL).looking forward to the next bit Paul, i am fortunate to have 2 lathes that do 2 TPI or 4 TPI very old english one of them. 2 start thread should be fun,, cheers
Hi Graedon, it was just a case of plugging in gear combinations until I got a result. Trial and error really. Multi-start on a large pitch looks very nice, almost a bit of art. Cheers
Great result Paul, enjoyed watching your method to achieved the desired pitch, using your own mathematics. Like you say the error is minute on the length of thread required. Looking forward to part two. I did similar a while ago, hit n miss lol, single start though, same lathe. Cheers Tony
Hi Tony, I find these Harrison training and small workshop machines (lathes & mills) are just so capable. Lovely machines and a joy to operate. I am so grateful for the clutch/brake on the lathe and one reason why I did not buy a Bantam. Cheers
Hi Paul. It must have been a cost issue for Harrison to discontinue the clutch drive on their newer M model lathes. I agree it's a brilliant feature to have for fine control. Cheers Tony
I'm working towards cutting a 3/4" 2TPI double start left hand stub acme (nearly square) thread to repair an old artisan lathe. This is great information for what I'm working towards.
@@HaxbyShedI think the person saying it's a 4tpi threads were confused about actual tpi, the thread count, and effective thread travel or effective lead pitch. A 2tpi double start thread is still a 2tpi thread but the effective thread travel equivalent is 4tpi because there is 2 threads. It's a funny thing that happens when you have multi start threads. You can directly replace a 2tpi double start thread with a 4tpi single start thread and the travel is the same (ignoring all the other reasons for multi start threads) Multi start threads have a longer effective lead pitch as each physical thread is apart of the total effective lead pitch. The multi start thread tables typically show the effective lead pitch for single thread, double thread and triple thread. But that doesn't change the physical tpi. If you didn't know it was a double start thread and you blindly counted physical threads you would mistakenly determine it's a 4tpi thread because the physical thread count and the effective thread pitch are the same.
That was a very interesting and fascinating "lesson". It was easy to follow your "thinking aloud" video. Personally, I wouldn't modify the cover of your beautiful lathe and live with the (not so health and safety compliant) work-around. My approach for cutting "special gears" is as follows: I wrote a little program in the scripting language Matlab/octave which combines all available change gears and calculates the ratios which are subsequently sorted. Thus I can pick the required set of gears. As you explain: in many cases they don't fit physically but there are alternatives in most cases. In your particular case you might have been able to "fill the gap" between the gears with an additional idler gear. For extremely steep pitches you might experience an other "physical problem": the forces required to drive the carriage might be too high and even damage the wheels in your gear train. I experienced this problem when I had to cut a 3 start worm-gear with a pitch of about 18.85 mm. Even though I found a suitable set of change gears, I couldn't cut the "thread" due to the excessive forces and ended up spiral-milling it. Again, thank you very much for your well thought explanations. I enjoyed every second.
Thank you Harald, your encouragement is appreciated. I was indeed concerned about the load on the gear train and that's why I cut the thread in delrin. I have cut 5tpi ok straight-in in silver steel so maybe 2tpi would be ok but there was no need to risk it for this self-training exercise. The idler gear is a good thought. Many years ago I used to write simple programs in Pascal (as a hobby). Excel is very powerful with macros and visual basic, I should probably take the trouble to learn. Cheers
Thank you Jason, now somebody has mentioned 27tpi, another my lathe won't do. I'll park that unless/until I ever need it to cut NPT or some odd ball. Cheers
Thanks for the video. Very interesting challenge. I may have a similar challenge for M33 x 3.5 thread for some local wood lathes. I have imperial lathe but my threading chart shows I can make 3, 3.75 and 4 mm pitches but no 3.5. I have not tried a two start thread. I will be eagerly waiting for the next part video. Dave.
That's interesting Dave, you will see all the metric threads I can cut in the next part. It includes 3.5mm pitch but now I've just noted I could also cut 3.75mm pitch, although it's not listed. If you are able to construct a spreadsheet you may find you can cut pitches you did not know (i.e. they are not listed on the gearbox plate). On the plate my metric fine range runs up to 0.9mm pitch but my spreadsheet tells me that I can actually cut up to 1.5mm pitch with those gears. That overlaps with the next range, so these are not extra pitches, but it means I can cut 1.5mm pitch without changing the fine range gears. It was very revealing/enlightening. Cheers
My lathe has a 4TPI lead screw for imperial threads. The gear train had a 120 tooth gear for imperial, we use 127 tooth for metric. The appropriate selection of pinion gears gives exact metric. You just can’t disengage the half nut or your synchronization messes up.
Thanks, Paul, for the thought put into presentation let alone getting the job done! I wonder how many times you needed to walk between workshop and house washing your hands each time!
Hello Mr. Phil I'm glad to see your show and very nice info. I have some questions about the gears for my homemade Lathe the hold body of the lathe is finished and ready but now I'm stuck on how to get the gears to contact the gears box and track the south bend and my is doesn't know gears teeth numbers. I tried looking in my place but never founded. I saw gears lathe in Amazon but I can't get it because no shipping to my country. Thanks
Hi Mr Rany, one option might be 3D printed gears. I have two gears cut from POM/Delrin/Acetal and they are strong enough. Just a suggestion ....... Cheers
Awesome Paul, wonderful job on the brain twisting math challenge. What did we do before spreadsheets...Lol Interesting project I'll be following along... Cheers....
The surprising thing Dean is the spreadsheets show more threads than listed on the machine plates. And with my lathe, what you get in the manual is only a majority listing - not all possibilities. Cheers
Whilst this must be the most tricky conversion from Imperial to SI it’s important to understand it. Our Colchester Student has both SI and Imperial but that’s presumably only the dial markings. We will most likely buy a Clough42 (Cloud 42) digital conversion and like today’s digital welders, let the Silicon do the hard work. In the meantime this video helps us understand the situation. No wonder you need a break
@@HaxbyShed Some months ago l was aiming to revise my threading standards from Whitworth (lathe);to Metric (mill), including AN. (Aeroplane). Americans like quoting numbers at every opportunity so l bought an unused legacy-book with many of the detail threading dimensions. It was a vast array of lookups, but will only be used as a reference. After buying a test string of nuts and bolts, its getting easier to instantly recognise such. In the last two days we have been collecting materials, oak from Scawston and 550W solar panels from Felixstowe. Having known Sutton Bank from my childhood l took the route via. Bylands Abbey on the way up. Never appreciated how extensive the Hambletons are, with so few roads. Almost went via, Haxby to lower the 25% gradient. A1 to Felixstowe is a road repair nightmare, almost dangerous at night. Took a coastal and country route back only to discover several more road diversions (508 mile trip). Staying home for a while now.
I hear what you say Steve but disengaging the lead screw and turning the chuck 180, then slipping it back in gear, took just a few seconds, was accurate, and was 'fail safe'. You will see in Part 2 I can do it for 2, 3 and 6 starts. For others I would need to use the method you mention. Cheers
My brain is still recovering from doing the calculations to cut a 27tpi thread on my metric lathe, the Myford could have done it but I have the gearbox Super7 so can't fit the appropriate change gears i would need and I wasn't going to buy yet another lathe!😕
@@HaxbyShed unfortunately not, 3/16"×27 is a proprietary Douglas motorcycle thread, taps and dies are like hen's teeth and a friend wanted some stainless bolts and screws. That was what I made the special style steady for in one of my videos.
![[#2024MAMA] ROSÉ (로제), Bruno Mars - APT. | Mnet 241122 방송](http://i.ytimg.com/vi/dgGqD28J6aQ/mqdefault.jpg)
good video paul
Thank you. 👍
Nice lathe. A lot of people have converted their lathes with VFDs. Clough 42 has a very good series on this. It eliminates the nightmare of change gears and gives you unlimited feeds and speeds and any thread combination you need - metric or standard - all at the touch of a screen. The problem I have with my lathe, while a very good lathe, is no change gears and I've never cut gears before though I am planning on learning in the not-too-distant future. Still the idea of converting my lathe to a VFD is still in the back of my mind. Check him out, I think you will find his channel very interesting. He is in the process of making his surface grinder into a CNC surface grinder.
And, I'm sure I have seen your voice heading down one of the canals on a long boat.
😁😎👍👣
Hi Opie, ah yes I think I've watched Clough 42's vid on that. I've seen stepper motors and controllers applied to all sorts of projects like differential indexing on a dividing head for cutting helical gears etc. It may be the modern and better way but I do find a load of clanking gears quite satisfying and reliable 😁.
We have a VFD attached to our 3ph air compressor and it makes a great job of controlling the speed. We can also drive the lathe from it, but l don’t understand how it would help with thread cutting. Are you simply generically calling the stepper motors VFDs? We are expecting to use Clough42’s design.
@@GeoffHome-u6r I just made a simple comment. You need to ask clough 42.
hi Paul
You need a lie down now Paul, its interesting to play around with the gearing, iv'e had fun on my micro lathe i'm making, to get the various possible ratio's in a given physically small space, in fact i still keep revisiting it. when i've nothing to do !! 😄😄 (that'll be the day)
Many hobby lathe workers i see shy away from using the lathe to cut threads, suppose it seems a bit scary to to some but like everything, practice makes perfect, i take my hat off to Kimber Zelic he always has a go at it, and with having a go he's learning quickly. plus it saves a fortune on taps and die's
See you when you've recovered.😄😄👍👍👍👍👍👍
atb
Kev
Hi Kev, these subjects are often much deeper than they appear and the sometimes the only way to understand is just to have a go. There is only so much one can do at a desk. I wondered if I could find a gear combo for 2tpi that would allow me to close the end cover but I can't think of a way to find that other than trial and error plugging in all the possible gears into the spreadsheet initially then doing the physical check on the ones that worked mathematically (lengthy and tedious). Cheers
Hi Paul. Brilliant stuff. This is what I enjoy about home engineering. Real problem solving which requires mathematics, lateral thinking and trial and error. Well done on achieving the 2tpi. I look forward to part 2. 👏👏👍😀
Andrew I'm glad you could follow my thread 🤣🤣🤣🤣😁
OUTSTANDING
Thank you Kimber, in Part 2 I will show the multi-start threading instructions you sent me. Cheers
Paul, I definitely enjoyed the mathmatics behind your choice of gearing. I’m still working though such things and appreciate the details behind your thinking! Cheers!
HI Russell, there may be other valid combinations of gears that would give me 2tpi in some or other position on the gearbox but I only had finite patience to go through all the permutations and having found one that worked I stopped there. When I saw the 70T would get me 8, 10, 12 & 15mm 'bonus pitches' I banked it. Empirical approach. Cheers
Really good explanation - the detail is very much appreciated. Sometimes you just have to get into the nitty gritty like that to really show the thought process. Seems like multi start threads are a popular subject right now - looking forward to part 2!
Hi Stuart, Kimber and I have exchanged a couple of emails on this and I will mention him next week. There may be other gear combinations where I might be able to close the end cover on the lathe but my money was in by then. Cheers
I love your thinking on this Paul, should I ever need to do something similar I'll be coming back to this video. My head would hurt too much to try to do it all myself these days.
It's a very long time since I had to try and calculate gear ratios for a lathe. 50 years since my apprenticeship, in fact. At least we have spreadsheets to automate some of it now, calculators had only just come out back then and I couldn't afford one.
Hi Bill, I remember calculators were becoming more widely available during my first year at college (day release then) and would cost about a 80% of a week's wage for an apprentice. I saved up for one. Cheers
Thats a beautiful Lathe you have there. I really like it. Interesting setup on the change gears.
I guess I’m just spoiled, my lathe doesn’t have change gears. Metric or imperial threads. I just select and go. I have two of the Clausing Metosa C1330S. One I’m still repairing and making parts for. But I’m still a little bit jealous of your Harrison 140. Can’t beat the old Iron workhorses.
But thanks for sharing your insight. You are a very capable machinist sir. 🫡
Hi Jason, I googled 'Clausing Metosa C1330S' and I can see it is a very nice lathe. I'm not sure if it has any access to change the screw cutting gears to add pitches not in the box. I was feeling pretty pleased with getting 2pti and now somebody just mentioned 27tpi for NTP (which I don't have as standard)🙄, so that would be another gear combo hunt (if I did not have a tap). Cheers
So, you did spend some time doing a bit of thingking again :) That's good. Just make the impossible possible.
It would be nice to tackle a job with no new thinking required, but that would be no fun would it? Cheers.
I've got you on a 64 inch Sony. I must say your explanation was prefect😊😊. Your chart was ready to read😊😊
Hi thesjyoungjr, TH-cam gives me lots of stats. For my channel the viewing devices are 44% phone, 31% computer, 15% TV and 9% tablet. Like you, I do nearly all my viewing on TV but if I want to be commenting I cast to the TV from my phone (I write my comments on the phone). I try to keep all formats in mind when I'm making my videos. I often see videos where the presenter says "you will see it on screen now" and there is nothing to see??? I presume in that case it's something you would see on a phone but not a TV. Cheers
@HaxbyShed I was just saying how good your videos look so good on the big screen. I also have to go to the itty bitty phone to chat. I want to thank you again for inviting us into your shop for a visit. It is always a good time.
I think the great thing about this how you take on difficult problems and techniques. It's how we as humans learn more, think about problems in different ways and come up with new ideas. It doesn't matter how old or new the subject or concept is. Thanks Paul!
Thank you Sir. I find that people draw on their own past experiences when approaching problems, which leads to many different approaches. A carpenter would nail it on, a fabricator would weld it on, an artist would paint it on, & etc.
Hello Paul. I enjoyed that. I had similar issues when cutting the imperial nut for my milling machine knee. I also have done multistart threads. In fact I am doing one now, so your film is highly apposite!
Machine is set up to cut the pitch I want (for a metric thread) so say 3mm pitch. I put the cut on using the cross slide, with the topslide set parallel to the work, ie at 90 Deg to the cross slide. Half nuts engaged and kept engaged throughout, reversing the lathe to get back to the start after each cut. Cut the first start to depth in this way. Once first start is cut and tool back at the beginning I proceed as follows.
Set up a clock on the top slide and move the tool forwards, ie towards the chuck by half of the pitch being cut. So for 3mm move the top slide towards the chuck by 1.5mm. Once this is done, remove the clock and start the threading process again. The tool will now start cutting the workpiece 180 Deg around from the first start. Continue like this until the second start is correctly depthed.
In your case with an imperial thread of 2tpi the pitch is 0.5 inch so you'd move the topslide forward by that amount.
I'm doing this at the moment but not for a screw to fit a nut, it's for a swirl inducer that is part of a fuel injector.
Thanks again for the film I really enjoyed it.
Hi Carl, you will see next week that I landed on an easy dodge to index 2, 3 and 6 start threads on my Harrison 140. For others I would have to use the 'tool advance' method you describe. Somebody is going to comment, so it may as well be me, that the tool advance to add in the interleaved thread on 2 tpi would be 1/4 inch (not 1/2). Cheers Paul
@@HaxbyShed Yes you are right of course. Half the pitch to advance or 0.25" in this case. I am looking forward to your next film to show how you did it.
You can actually disengage the half-nuts at the end of the thread. Note (or mark) the position on the threading dial that aligns with the fiducial mark on the body while the half-nuts are engaged. Disengage the half-nuts at the end of the thread as per normal and stop the lathe before the threading dial does a full turn. Don't move the carriage manually! Run the lathe in reverse and re-engage the half nuts when the dial returns to its marked position.
I'm with you Chris. 👍
There is something very satisfying about the sum of the misinterpretation that led to this video project! Looking forward to part 2!! All the best, Matthew
Matthew, some of my best endeavours/investigations stem from comments (whether I have understood them or not). Cheers
Brilliant treatise on lathe gear ratios, spreadsheets are my favourite PC/calculation tool.
Looking forward to Part 2.
I meant to finish the surface grinder before getting into this but I got fed up of tripping over the lathe change gears I'd left out on the floor !!
Great episode! Can't wait for part 2. I know with my lathe and its 2mm pitch leadscrew, cutting any thread above about 4mm pitch really puts a load on the motor such that it can stall out. A "solution" (such as it is) is to turn the lathe from leads screw. which now has leverage on the spindle. But the way I actually do it is turn the chuck by hand with a big wrench (spanner) and take super light cuts. I have also used a tool post mounted dremel tool to rough out the thread before switching to a threading tool. There is a also a video that shows how to use the compound slide parallel to the ways to cut course threads by adding small increments over many passes. I wrote a simple program to find all possible gear combinations on my lathe but as you point out, not all of them are physically realizable.
Hi bkoh, through this little exercise I've learnt a lot about lathe screw cutting gearing but I'm still some way off really knowing all the detail fully in depth. My lathe will cope with 2tpi threading at 34rpm but it must put quite a big strain on the gear train and screwcutting gearbox. Partly why I chose to work with delrin this time. Cheers
Makes me wonder if the people who designed the banjo and gear train knew this and provided JUST enough room between the main shaft and the lead screw to accommodate these gears This must be at the practical limit for a lathe of this size, although perhaps by using something like a tool post grinder...?
Thank you for taking the trouble to explain this in detail, much appreciated. One of the reasons I look forward to your videos. Robert
Thank you Robert. Standard it cuts 60tpi to 4tpi (with the extra 63T and 40T gears), or 0.2mm to 7mm. These lathes were made in their hundreds for schools and colleges, and small workshops. I guess they thought 4tpi was as fast as an apprentice should be permitted due to danger of saddle to chuck crash 😁
Hi Paul, What a task that was, very enjoyable to watch. Well done for getting there and only out by 0.012%. Did you think about cutting the gear yourself?
It did make me think back to my Grandpa's lathe which had all the gears unguarded. It was there I made my first cuts. In the end it became my Dads and then we donated it to the Portsmouth Historical Dockyard. Turns out it was of a type that was used onboard submarines. Funny old world as that is the industry that Im working in down here.
Look forward to seeing you cut the doublestart thread.
Have a great weekend!!
Hi David, one day I will cut my own gears but a set of cutters can be expensive. You can get a set of 14DP 14.5pa cutters on ebay for about £80 from China but they are for a 22mm arbour and I only have 27mm and 1 inch arbors. I must get or make myself a 22mm stub arbor one day. (Do we spell it arbor or arbour - I can't make my mind up?).
@@HaxbyShed Hi Paul, well the answer to that one depends on what side of the pond you are on!!
From HarperCollins Publishers
arbor
in British English
NOUN
1. a rotating shaft in a machine or power tool on which a milling cutter or grinding wheel is fitted
I seem to recall a comment about the cost of machine tools and the cost of associated tooling being at least double
All the best
christ!!! ,,,, your brain needs a rest! that done me in(LOL).looking forward to the next bit Paul, i am fortunate to have 2 lathes that do 2 TPI or 4 TPI very old english one of them. 2 start thread should be fun,, cheers
Hi Graedon, it was just a case of plugging in gear combinations until I got a result. Trial and error really. Multi-start on a large pitch looks very nice, almost a bit of art. Cheers
Great result Paul, enjoyed watching your method to achieved the desired pitch, using your own mathematics. Like you say the error is minute
on the length of thread required. Looking forward to part two. I did similar a while ago, hit n miss lol, single start though, same lathe. Cheers Tony
Hi Tony, I find these Harrison training and small workshop machines (lathes & mills) are just so capable. Lovely machines and a joy to operate. I am so grateful for the clutch/brake on the lathe and one reason why I did not buy a Bantam. Cheers
Hi Paul. It must have been a cost issue for Harrison to discontinue the clutch drive on their newer M model lathes. I agree it's a brilliant feature to have for fine control. Cheers Tony
I'm working towards cutting a 3/4" 2TPI double start left hand stub acme (nearly square) thread to repair an old artisan lathe. This is great information for what I'm working towards.
Hiya, somebody has pointed out to me that I actually produced 4tpi 2 start (2 x 2tpi interleaved). Anyway I'm glad if it's useful. Cheers
@@HaxbyShedI think the person saying it's a 4tpi threads were confused about actual tpi, the thread count, and effective thread travel or effective lead pitch. A 2tpi double start thread is still a 2tpi thread but the effective thread travel equivalent is 4tpi because there is 2 threads. It's a funny thing that happens when you have multi start threads. You can directly replace a 2tpi double start thread with a 4tpi single start thread and the travel is the same (ignoring all the other reasons for multi start threads) Multi start threads have a longer effective lead pitch as each physical thread is apart of the total effective lead pitch. The multi start thread tables typically show the effective lead pitch for single thread, double thread and triple thread. But that doesn't change the physical tpi. If you didn't know it was a double start thread and you blindly counted physical threads you would mistakenly determine it's a 4tpi thread because the physical thread count and the effective thread pitch are the same.
@@askquestionstrythings Thank you for explaining that 👍
That was a very interesting and fascinating "lesson". It was easy to follow your "thinking aloud" video.
Personally, I wouldn't modify the cover of your beautiful lathe and live with the (not so health and safety compliant) work-around.
My approach for cutting "special gears" is as follows:
I wrote a little program in the scripting language Matlab/octave which combines all available change gears and calculates the ratios which are subsequently sorted. Thus I can pick the required set of gears. As you explain: in many cases they don't fit physically but there are alternatives in most cases.
In your particular case you might have been able to "fill the gap" between the gears with an additional idler gear.
For extremely steep pitches you might experience an other "physical problem": the forces required to drive the carriage might be too high and even damage the wheels in your gear train. I experienced this problem when I had to cut a 3 start worm-gear with a pitch of about 18.85 mm. Even though I found a suitable set of change gears, I couldn't cut the "thread" due to the excessive forces and ended up spiral-milling it.
Again, thank you very much for your well thought explanations. I enjoyed every second.
Thank you Harald, your encouragement is appreciated. I was indeed concerned about the load on the gear train and that's why I cut the thread in delrin. I have cut 5tpi ok straight-in in silver steel so maybe 2tpi would be ok but there was no need to risk it for this self-training exercise. The idler gear is a good thought. Many years ago I used to write simple programs in Pascal (as a hobby). Excel is very powerful with macros and visual basic, I should probably take the trouble to learn. Cheers
Fascinating work Paul and congratulations on solving the puzzle and achieving 2tpi
Thank you Jason, now somebody has mentioned 27tpi, another my lathe won't do. I'll park that unless/until I ever need it to cut NPT or some odd ball. Cheers
Thanks for the video. Very interesting challenge. I may have a similar challenge for M33 x 3.5 thread for some local wood lathes. I have imperial lathe but my threading chart shows I can make 3, 3.75 and 4 mm pitches but no 3.5.
I have not tried a two start thread. I will be eagerly waiting for the next part video.
Dave.
That's interesting Dave, you will see all the metric threads I can cut in the next part. It includes 3.5mm pitch but now I've just noted I could also cut 3.75mm pitch, although it's not listed. If you are able to construct a spreadsheet you may find you can cut pitches you did not know (i.e. they are not listed on the gearbox plate). On the plate my metric fine range runs up to 0.9mm pitch but my spreadsheet tells me that I can actually cut up to 1.5mm pitch with those gears. That overlaps with the next range, so these are not extra pitches, but it means I can cut 1.5mm pitch without changing the fine range gears. It was very revealing/enlightening. Cheers
My lathe has a 4TPI lead screw for imperial threads. The gear train had a 120 tooth gear for imperial, we use 127 tooth for metric. The appropriate selection of pinion gears gives exact metric. You just can’t disengage the half nut or your synchronization messes up.
Hi Glenn, there is something magic about the prime number 127. I will investigate ...... Cheers
@@HaxbyShed it is exactly 1/2 of 254,
Where there's a will... There's often a way...😀
Indeed Paul. Cheers
Thanks, Paul, for the thought put into presentation let alone getting the job done! I wonder how many times you needed to walk between workshop and house washing your hands each time!
👍😁 Thanks Clive.
Quite interesting video, Thx.
Thank you. 👍
Very nice work sir
Thank you. 👍
Hello Mr. Phil
I'm glad to see your show and very nice info.
I have some questions about the gears for my homemade Lathe the hold body of the lathe is finished and ready but now I'm stuck on how to get the gears to contact the gears box and track the south bend and my is doesn't know gears teeth numbers.
I tried looking in my place but never founded. I saw gears lathe in Amazon but I can't get it because no shipping to my country.
Thanks
Hi Mr Rany, one option might be 3D printed gears. I have two gears cut from POM/Delrin/Acetal and they are strong enough. Just a suggestion ....... Cheers
I like it! Thank you.
Thank you. 👍
Good one !!
Thank you. 👍
Awesome Paul, wonderful job on the brain twisting math challenge. What did we do before spreadsheets...Lol
Interesting project I'll be following along...
Cheers....
The surprising thing Dean is the spreadsheets show more threads than listed on the machine plates. And with my lathe, what you get in the manual is only a majority listing - not all possibilities. Cheers
Whilst this must be the most tricky conversion from Imperial to SI it’s important to understand it. Our Colchester Student has both SI and Imperial but that’s presumably only the dial markings. We will most likely buy a Clough42 (Cloud 42) digital conversion and like today’s digital welders, let the Silicon do the hard work. In the meantime this video helps us understand the situation. No wonder you need a break
Hi Geoff, the big lookup table in my head of all the imperial and metric equivalences is getting bigger. 🤪
@@HaxbyShed Some months ago l was aiming to revise my threading standards from Whitworth (lathe);to Metric (mill), including AN. (Aeroplane). Americans like quoting numbers at every opportunity so l bought an unused legacy-book with many of the detail threading dimensions. It was a vast array of lookups, but will only be used as a reference. After buying a test string of nuts and bolts, its getting easier to instantly recognise such. In the last two days we have been collecting materials, oak from Scawston and 550W solar panels from Felixstowe. Having known Sutton Bank from my childhood l took the route via. Bylands Abbey on the way up. Never appreciated how extensive the Hambletons are, with so few roads. Almost went via, Haxby to lower the 25% gradient. A1 to Felixstowe is a road repair nightmare, almost dangerous at night. Took a coastal and country route back only to discover several more road diversions (508 mile trip). Staying home for a while now.
Hi, With regards to disengag lead screw, leave it in place Move top slide along the pitch 1 inch.
Steve
I hear what you say Steve but disengaging the lead screw and turning the chuck 180, then slipping it back in gear, took just a few seconds, was accurate, and was 'fail safe'. You will see in Part 2 I can do it for 2, 3 and 6 starts. For others I would need to use the method you mention. Cheers
My brain is still recovering from doing the calculations to cut a 27tpi thread on my metric lathe, the Myford could have done it but I have the gearbox Super7 so can't fit the appropriate change gears i would need and I wasn't going to buy yet another lathe!😕
Hi Chris, 27tpi NPT I'm guessing? Mine won't cut 27tpi from standard. I'd have to play "hunt the gear" again on the spreadsheets. Cheers
@@HaxbyShed unfortunately not, 3/16"×27 is a proprietary Douglas motorcycle thread, taps and dies are like hen's teeth and a friend wanted some stainless bolts and screws. That was what I made the special style steady for in one of my videos.