I do like the idea of modifying the standard chuck. This is a great video showing this process. In my journey using these chucks. I find it best to loosen all the set true screws and tighten the one necessary to move the chuck, then loosen it up again. As the back plate is snug enough the chuck will stay in this position, spin it and adjust the next one, continue until its's real nice and concentric. Rarely you might have to adjust two to move it in the right direction, put it there and loosen them up and when you finish then snug them all up, getting that last little bit. Using multiple screws kind-a snug can distort the chuck making the process more difficult. Try it you will like the results, Cheers!,
Did this to my 3 jaw a few years ago. It made a huge difference to the accuracy and repeatability. Definitely worth the time to do it. Take the gears out when you do this modification.
@@fredfarnackle5455 It was a technical issue during the editing process. It's the only video (out of the 34 currently published) with this problem. Of course it became the most popular video of our channel :) Our apologies.
I did this a couple of months ago and couldn't be more happy that I did. Just posting to atest to the goodness and benefit of doing this. Even if you have a 4 jaw chuck this is still a very useful mod.
Honest question here. What is the benefit of adjusting the concentricity of a four jaw chuck? Doesn't the part get centered independently of the chuck?
@@peterkim5394 Sorry for the confusion. I should have said "Even if you already have a 4 jaw chuck this is still a very useful mod for your 3 jaw chuck."
I don't know how many times I've heard about people with 3 jaw chucks.....brand new ones too....... running out a thou or two..........they will all run out even the best and they are not meant to be blindingly accurate to a thou. Most of the time you will grip raw material and then turn it down to a size so run out is not important, but when a second op is performed where you really need to re-grip a work piece and then machine it true and concentric a trick I use can be employed and my Chinese 160mm 3 jaw chuck is 40 years old but runs dead true.......just cut the register on the back plate a few thou slack and this will give you room to slacken the holding bolts and bump it to run true every time you really need to have it dead true......for the most times you can live with it as it is. 3 jaw chucks on dividing heads should ALWAYS have a slack register as this will allow you to "adjust" them to run dead true for cutting gears where the mandrel holding the gear blank must run dead true.
Agreed, scroll chucks, no matter how many jaws, are broad tolerance tools. They are very susceptible to scroll and jaw wear and jaw flex, as well as a bunch of other internal and external factors that make them that way. However, they are quick and easy to set up, and ideal for general purpose professional and almost all amateur jobs. You know, unless you're NASA, General Dynamics or Rolls-Royce, they're usually good enough. If you need, or more likely just want, near micron accuracy, try independent jaw chucks (or good quality collets). IF used correctly, they are much more versatile and accurate than scroll chucks can ever be. The downside is that they can be a bear to set up every time you use them. And if you don't have rock solid ways, bearings and tooling, you're still just pissing into the wind anyway.
A+ for effort and build. I would still recommend watching Robin Renzetti's video on a different design to reduce distortion. It's more involved, but very similar to how Rohm Hi-Tru works.
Yeah looked at all comments and knew this would have been mentioned. Just found the channel the guy is very knowledgeable on explains things perfectly for myself whose thinking of getting a lathe.
Really interesting way to do it, i was taught if you want something precise then use a 4 jaw chuck....but its one of those things the more ability you have to adapt an overcome the better, especially when you don't want to spend lots on high precision chucks from good brands (i do miss my 4 jaw, i knew i shouldn't of sold it)
I agree about using the largest possible set screws but also surely it makes more sense to use softer set screws better to replace a damaged set screw than to have to strip a chuck to get at a guoged damaged part. Great video by the way, I did enjoy it.
You can learn something every day if you pay attention. Great informative video. I bought a SKAND 6" 3-Jaw self-centering chuck that was slightly used. It was supposed to be within .0005". It has American Standard Tonge & Groove removeable jaws. It was .009" out when I put it on my lathe. So, I tried to adjust it by getting all I could out of the Allen head screws and was Lucky to get withing .0025", but I have to use a live center to keep it on the money. There is no adjusting this lathe chuck like it is. Every piece from the backing plate to the chuck housing shows a different runout. The jaws when screwed in all the way have a 1/16" space between #3 and #1 jaws. I can see why it was up for sale. I am a Hobbyist learning as I go and couldn't figure it out until it was too late to return. I have a threaded nose spindle, 2-1/4"x8TPI on a 13" South Bend engine lathe 3-step pully. The belt is 2-1/4" wide, and it has a lot of torque for making big cuts when needed. I'm changing my threaded nose piece to a D1-4 Camlock. I'm going to make an adapter to thread on, lock tight it and pin it to the existing spindle. I learned my lesson from all the research trying to get this chuck dialed in. I've been told that on any 3-jaw scroll chuck if it's got a runout of .002" you are doing good. You have an interesting variety of videos, so I went ahead and Subscribed to your channel. Thanks for sharing your knowledge and skills
I did this on a decent 8" Cushman chuck oh geez, 30 years ago? Only used 3 setscrews requiring a bit more, uhm - foreplay early on. I did modify that internal casting into a sleeve to capture between the chuck mount face and the scroll plate surface. Prevents the scroll skewing around and improved repeatability at the current grip diameter. You can test the repeatability by re-gripping using a different pinion gear. Best practice of course is to mark one and use it exclusively. One concern I remain aware of is that industrial set-true chucks typically have a steel body and mount. Import grade chuck bodies may not even be malleable cast iron.
Yes 3 setscrews will provide the correct movement but I have never seen a production chuck with anything but 4 so I stuck with that. Yes most set true chucks are beefier and usually steel, although some import ones seem to be some kind if soft iron. Good judgement is required when modifying any rotating tool like a chuck.
@@TigermothRacingTV Much easier with 4 adjusting screws. No matter what I tried, 4 conflicted with another element. Notice the max rpm limits between steel and cast iron chuck sizes. Just because it fits doesn't mean it's safe. 🥵
I will apply this mod on my lathe, but before drilling I will protect the internal gears against chips with a cloth or tissue paper. Thanks for the video.
Nudging set screws, not needed. Reduce backplate register by about 0.040" to allow enough adjustment movement and then use the backplate set screws/bolts to hold the chuck by light friction, tap the part piece true using a lead knocker, tighten a little more and check run-out is still ok, fully tighten and machine part piece. You will never be able to displace the chuck on its backplate when the backplate screws are fully tightened. This method is suitable for chucks in excess of 8" diameter.
Ive done this before on small chucks and it works fine but I like knowing the position is held by some physical limit. And the fine adjustment of the setscrews is quite nice.
@@TigermothRacingTV I will use the finest thread set screws I can find. Two reasons. the kids wont strip them right away and for very fine adjustments.
@@davidsymalla4785 Without nudge screws applied, Initial knocking true of the part-piece can quickly be achieved with the chuck rotating at about 120rpm, although you need a good eye to get down to about 0.002 to 0.004" run-out, then perfecting the run-out by hand cranking the chuck.
@@TigermothRacingTV Yes, as you wish, personal choice. Using nudge screws has an advantage that NO knocking is applied to the spindle bearings, depending on the type of bearings in use. I find it quicker to run the lathe spindle at 120rpm with the backplate set lightly tensioned and knocking the chuck true, with lead, then finishing off rotating the chuck by hand to achieve final perfection.
I could see this being a useful mod over swapping to a 4 jaw. You get the speed of a scrolling 3 jaw when you don't care about accuracy, or you can take the time to dial it in without switching chucks when you do.
Yeah, well, its like having a horsecock and complaining about the size... Its the nature of the beast, if you need to work with square stock, get a 4 jaw, also, there be 4 jaws that are scroll actuated, and you can do the same thing to them and have the speed of what most people ascribe to a 3 jaw, but in fact is a common trait among all scroll chucks, while having this mod and giving the scroll chuck of any number of jaws, be it 3, 4 or 6 the x/y alignment capabilities associated with a 4 jaw... Also, consider taking a 3 jaw, getting 3 more jaws, hardmilling it out and fitting in those 3 more jaws and voila, you have a set true 6 jaw chuck for the price of a 3 jaw chuck and 3 additional jaws...
That was awesome! Wow, thanks for posting. Loved it. Music was too loud when it started after each talking section, had to keep turning the volume up and down. But the content was excellent!
Great video. Most of the advantages of a 4 jaw, and all the advantages of a 3 jaw when you don't need super precision. Music was too loud. Had to turn the volume and and down repeatedly.
Also, not mentioned is that one of chuck key holes usually tightens a part more concentric than the other two. Good if you are just looking for quick improvement in runout. Some shops I have worked in have had one chuck key hole marked for quick reference.
Interesting. I have heard that sometimes you can get a part clamped slightly tighter using all the key holes rather than one but the idea of affecting concentricity is interesting. At that point you are just messing with inherent play in the chuck assembly. How much adjustment do you usually get?
Interesting. Just a note on set screw size. It is not necessary to rely on the set screws for any more than positioning. Tightening the screws that hold the back to the chuck will be enough, if tightened sufficiently. Many folks do not know this, but every joint in a drill string used for drilling oil and gas wells relies on friction between the shoulders and NOT the threads to transfer torque from one section to the next. This torque being many thousands of foot pounds. Perhaps just a wee bit more than the lathe will induce.
Correct, the setscrew size is not very important. However when you are measuring in tenths, you may see some drift in concentricity of the chuck if you wack the chuck or take a very heavy cut because the tips of the setscrews can deform or the thread will compress slightly but this is to be expected if you make a high load mistake like that. Most people do not put a death grip tightness on the chuck mounting bolts because they are adjusting it all the time.
@@TigermothRacingTV Every time I put an endmill in a collet, I tighten enough to prevent slip. I tighten a work piece in a vice or chuck to the same end. I do these frequently, so I don’t buy your argument. Who, when working to tenths, takes a huge cut, or fails to tighten sufficiently?
Will you be making a video showing chuck jaw grinding? I have seen several videos with opinions about preloading them, etc. but wondering your approach. Good stuff!
Good idea, but it would really come down to how fast you can swap Chuck's vs fiddling with 4 set screws and 3 bolts. 4 jaws are quick with practice, at least faster then all that set screw tensioning.
@@hedning003 not true. You have to do it every time you put a different diaper part in the chuck. The point of this is to make it repeatable for parts you have multipacks of to do. Yes it can help with a bad chuck. But it won’t fix it for all diameter parts.
I would have liked to see what the repeatability was if after setting it up to near 0 t.i.r. You took the pin out and reinstalled it in the chuck. I know it would be perfect but how good would it be? Great video.
That depends mostly on jaw surface and surface and concentricity of the thing chucked up, also somewhat on the surface and grind of the scroll and the jaw blades that interact with the scroll... heck, a chunk of schmoo in there or some grit that finds its way between the scroll and jaw will displace the said one jaw for quite some tolerance, so the repeatability here is a syndrome rather than something easily demandable, but if all things are even marginally ok, the thing should be relatively repeatable on stock of same diameter and even larger/different if the internal grinds and jaw and part concentricity are on paar and surfaces are nor like a grass field...
This an old thread but very useful. I’m just confused on one detail, at the end you tightened the Chuck to the back plate on the bench that was already on the lathe, then you screw the Chuck back into the lathe and start adjusting using the adjusting screws. My question is, how tight were the back plate screws into the Chuck 11:04 ? And if they were very tight, as I imagine, will the adjusting screws still move them 13 thou 11:30 ? Thank you so much for this video!
I turned down the register diameter on my cheap 7x Chinese lathe about .002" or .004" total ...No set screws....I just snug the hold down nuts enough to be able to tap the chuck true then tighten them....Works well.
Good to hear. If you start doing some hard turning you might want the screws but it is amazing how much force a simple bolted together assembly can take.
@@TigermothRacingTV I have an 8" Pratt chuck that is adjusted by the tap true and undersized register method. It has been modified like that for years and never moved from where it is set once the back bolts are tightened. there is no need for the radial adjustment screws to hold it firm.
Nice job. Do you leave the backplate screws semi-tight, enough so they can slide a bit, but then do NOT tighten them after getting runout true? Or do you tighten them every time you get the runout true at whatever diameter you are holding. Thanks.
This depends. I am not going to tell you what to do because of the safety liability and you will need to follow the protocols of your shop. I will tell you that the chuck will hold position very well even if the mounting bolts are not extremely tight. It is of course better to tighten them before running the chuck but if you are making a batch of parts where you have to indicate each one perfect, and the cut load is nothing big, it is easiest to leave the mounting bolts semi tight so all you have to do is adjust the setscrews when you load a new part. Up to you.
@@TigermothRacingTV Thanks. I've never owned an adust-tru chuck. I saw another TH-camr recently did a conversion like yours, but he did it the way the set-tru are typically from the factory, with the chuck body held onto the backplate from the front with very long, and thinner screws. He was saying the long screws were so they could pivot slightly to get the free play. He didn't specify whether he tightens them each use. I don't know what the manufacturers like Buck Chuck recommend? I suppose with the long screws in the front, when they pivot slightly their length would barely change, because the length change would be the cosine of a very small number, so it may not appreciably affect the clamping force of the screws.
Copy that on the vacuum cleaner and the special considerations for machining cast iron. Again, I always have a vacuum cleaner present so I don't disperse chips and and using compressed air around an open tool receiver is bad news. Cleaning as you go saves so much time and not sealing with an accumulating mess. Always take a clean finger and check the receiver opening before inserting a tool. Nice upgrade and Im considering the modification to a chuck based on your work.
Good points and I agree, always wipe the taper of your spindle before inserting a new tool, especially when cutting messy materials. It is an automatic habit for me on the TRAK mill. Most VMCs these days have positive pressure air purge on the taper for this very reason..keeps them clean.
It should not be scary. In fact you could drill the holes with a hand held power drill if you want to. The location of the holes does not have to be very precise.
That's a really good mod! Don't worry about the nit picker comments I've just read, if it works for you then whatever floats your boat. Unfortunately my lathe backplate is integral with the spindle, so this mod is out for me.
Without machining the back plate to exact depth to meet center hole collar inside the back of the chuck, how do you keep any swarf and debris from getting inside the chuck through that gap and causing wear to the pinions and scroll?
My experience has been that not much crap makes it back there even over years of use. The chucks are stored jaws up too so that keeps the dust out. Just hasn't been a problem. Might be different in a big flood coolant automated situation but tool making/prototyping it doesn't seem to be an issue.
Changing the diameter of the chuck faceplate so that it doesn't fit within the H7 tolerance that it's is design for, will course the chuck to vibrate undet heavy load. No need for any form of adjustment, just use soft chuck jaws if you need precession within a thousandth of a millimetre. Or for general work, buy a good quality chuck. I have a German Trekarter 200 m/m chuck, it runs within 0.02 m/m and is repeatable within that tolerance and soft jaws are easily mounted but, then again you are look at a price of ca. 2100$. Using a 4 jaw non self-centring chuck will give greater stability and it can be adjusted tobe extremely accurate. Good quality video T/U
Yes this is exactly the point. Most home or hobby machinists will never spend the money on a Buck or Bison adjustable chuck. There is no need. This method is simply an easy solution for anyone to get the same precision out of any $100 import chuck. Most of which do not have soft jaws available and are 1pc jaws. If anyone sees soft one piece jaws let me know, those would be very handy as well. Making a 3 jaw adjustable is handy because you can still do production work with a clamping repeatability easily within .001in. This would be a nightmare with an independent 4 jaw. The chuck body can be eccentric seveal thousandths before any vibration will occur at common speeds. For home shop speeds, not usually an issue, in a bigger machine shop, they are gonna have an adjustable chuck or collet system anyway.
@@TigermothRacingTV For home shop the only thing you can do is to grind the jaws of the chucks - even that comes with a lot of assumptions and limits. You may want to see how a real adjust true chuck looks like - th-cam.com/video/E_Ks6GKKcs8/w-d-xo.html also every part of this adjust true is precision made. With chucks usually what you pay is what you get - with some exceptions here and there. For example, I grind all my 4 jaw chucks when they arrives home in a box from China. It improves things a lot but is no Bison. You cannot make them more precise as there simply is no way to add metal to make tolerances tighter. If you want quickly add some precision to a 3 jaw, as others pointed out the soft jaws are the thing for production run. Then again, most hobby guys do not run huge production runs.
I'm going to have to do this to my clausing machine now, my chuck used to be less than one thou- but the one time someone else used my machine, they left the key in the chuck and after a few hours of work I can only get it back to 3 thou...
I wonder if doing something like sandblasting the contact surfaces of the chuck and backing plate might make the "grip" better when locking down the mounting bolts...
I think sand blasting it could make the mating surfaces no longer flat. My concern would be adding runout from a non flat mating surface and you could cause chuck warpage.
When is use my buck adjust true chucks, i always leave the mounting holes relativly tight. they are larger set screws though 3/8 -24 .for a 6" dia chuck. I never mess with the mounting bolts
I bought a cheap chinese 3 jaw for my 9 inch southbend and somehow that thing runs out less than a thou regardless of the size part i put in it. Never expected that in a million years.
The plate you leave out @3:16 holds the scroll parallel to the inside of the face as well as keeps the scroll from floating on the spur gears.. i don't like my chuck without it installed.
@@TigermothRacingTV yep. I have to tap the jaws or the job lightly to even the pressure on each jaw when clamping down on small diameter work.I also got more crud in the scroll.
I can see how it might hold the scroll parallel to the inside of the face, but wouldn't that preclude keeping the scroll from floating on the spur gears? I mean, to do the 1st, it has to apply pressure away from the spur gears... Doesn't it? Maybe what you are feeling is extra pressure on the spur gears, reducing to normal? I am asking because 3 days ago, I decided it is time to do this same mod, and started searching TH-cam University ;) to see if anyone else had tried it then after reading your comment yesterday, I removed the plate to see.... Also, do you see any downside to thinning the plate, on the spindle side,spur gears by 3/64ths to 1/32nd, to make the screw heads fit flush? (yes I am old school, they didn't introduce the metric system in Canada until I was in grade 5, my Machinist course in college was all imperial, and I have worked as a carpenter most of my life, a trade which is only now starting to be metricified... ;) ) Oh, 1 more question, how do you get more crud in the scroll? Doesn't the inside throat of the chuck stick through, into the backing plate?
Not dissing your personal preference of method, but I haven't used a three jaw in 20 years. Their inaccuracy and laughable grip strength drove me up the wall. My four machines have Bison Four jaws on them, never removed, and I've gotten real good at setting them to tenths quickly, and I'm happy with that. The three jaw that came with the Grizzly in 2003 started life as a door stop to my shop and I finally got tired of tripping over it for 17 years and threw it out. It has never been mounted.
Like you I am a 4 jaw user by preference. If used frequently then setting work true in a 4 jaw independent becomes quick and easy to achieve. I do disagree with you though that all 3 jaw chucks are inaccurate. Some 3 jaw chucks made by reputable manufacturers are highly accurate for concentric repeatability throughout the gripping range. They are rather expensive at that level of precision though. As for gripping force of a 3 jaw that is very much dependent on the helix angle of the scroll. Think of it as a spiral wedge. The shallower the scroll helix angle is the greater the gripping force for a set amount of effort applied at the key. The other commercial alternative is as already mentioned the 'Grip Tru' type. They also are rather expensive for a hobbyist shop.
Tigermoth, what kind of an edge finder did you use? I was under the impression it was a mechanical one which has to spin at approx. 600 rpm. The bottom part then "breaks" out and you can set your diameter of the edge finder or move to the center and set zero on your DRO. Or is it an electronic one? The latter is less accurate and doesn't work on plastic parts. Thank you for your answer! Best, Job
How loose do you have to leave the back plate screws for you to be able to adjust the set screws? Seems like you would have to constantly check the back plate screws?
Just slight finger tight with an allen wrench. You only need them to hold the chuck in flush contact with the backplate. You can set your concentricity and then tighten the mounting bolts. The concentricity should hold very well even wile tightening the mounting bolts.
Hmm yes I like Rob Renzetti's concept of keeping the chuck back plate as it is integral to the stiffness. I have an independent 4-jaw as well as a nice Forkardt 3-jaw which both need a hard jaw boring job. I wonder if there is a use anyway for a set-tru type chuck once you have the jaws bored properly. In fact my Forkardt runs around 0.02 TIR as it now is. But yes there is air at the front part of the jaws. If you are interested I have made a blog post about a novel way to machine hard chuck jaws. It has been proven nearly impossible to share a link in the comments so if you are interested I can mail the link.
There is always a use for set true chucks no matter your jaws. A nice hard jaw set ground concetric may not be concentric everywhere on the scroll. Really, people tend to obsess too much over hard jaw concentricity when we can just cut soft jaws and have better clamping grip whenever needed. The set true adjustment is just the fastest way to make it "perfect" with no cutting or changing of the jaws, (least work).
@@TigermothRacingTV Well I always tend to look at the product as it was intended, and for a self-centering 3-jaw obviously 'perfect' centering was never a (design) goal. Now, a good quality chuck achieves like 20 to 30 microns (mm) TIR which is fine and great for any normal job, I have a machine at work which is out by like 0.2 mm and that can be a bit of a nuisance. My main concern with boring hard jaws is not 'perfect' centering, it's the bellmouthing correction. Having it centering well after a boring job I consider a bonus. I have chucks of 'A' brands like Forkardt and Rohm as well as 'B' like Bison and none of them have left the factory 'bellmouth corrected' (as far as I can tell) which I find disappointing to say the least. In fact my Bison 200 mm 4-jaw is bellmouthed so bad I have to go back and measure, it looks is if the jaws were counter-corrected, LOL. At work I program and operate two Okuma CNC lathes both running Kitagawa chucks which also air gap in the front. Work to be done there. My only goal is stability and the chuck jaws are an obvious weak link. When you want 'perfect' (re-)centering use a 4-jaw or bored soft jaws. I tend to avoid them on the CNCs because of the hassle involved, most of the times we can get away with the hard jaws and protective material like sheet metal between the jaws and the product in second operation situations. Obviously here you want the chuck to center within 0.03 TIR mm or so which the Kitagawas do.
I see, yes the bell mouth is an issue. I have noticed on some chucks the bell taper can be worse if you are clamping partially on a part and not using the whole length of the jaw. At that point I think it is usally from play in the jaw channels. Taper from wear is certainly annoying and a nice cut to freshen them up is ideal.
@@TigermothRacingTV The worst case actually is using the whole length of the jaws and then do heavy machining and parting off. It's been explained already in many videos (as well as in my blog) that essentially it's having shorter jaws and working with a larger overhang. Both are stability killers.
Every chuck I have seen, that back plate does not support the gears at all. It seems to be mainly a chip cover and based on the fit, sometimes may also support the body from warpage under very high load.
I see. I saw the round overhangs on the cover and they sorta looked like bearing surfaces. Been working on an old cushman that's split in half and each half provides half of the bearing@@TigermothRacingTV
I would be tempted to install some kind of bearing surface so that the set screws son't mar that little ledge they are bearing against/ Maybe a ball mill and little steel bearings to seat in the recess
That's a good idea but I have never seen that done. All the high quality industrial set true chucks I have used simply have flat head set screws. If the screw and the part are hard, very little wear occurs.
Why not use soft jaws bored in position with jaws preloaded over a dummy piece at distance deeper than intended gripping area? This is better if you have more than one piece to turn.
It is important to use flat tip setscrews to avoid any marring but even the marring is not a big deal. Remember that the setscrews are contacting the backplate in the same spot every time you adjust it so any marring is just re-engaged with as you "buck" it around.
@@morganmcintire2853 I was thinking this same thing. If anything I would have made the depth of cut on the threaded backplate to minimize the gap spacing left when the rear plate was removed, and find some thin foam gasket material to fill any air gap into the bevel gear compartment, to stop any swarf from getting into the bevel gears. But I like the idea very much. Now I need to check if I can remove that plate, as my experience on my cheap chucks, they hold the gears in.
One wants to be able to adjust the chuck body quite easily because the wear in the jaws (and the scroll) will almost certainly be uneven. This is why the TIR changes at different diameters on cheap chucks like these. The idea is to get the adjustability of a 4 jaw, but the rapid repeatability of a 3 jaw for a given diameter. Changing diameters, and you'll want to double check TIR and adjust the set screws again.
@@carneeki I was assuming once the set screws were adjusted and the chuck zero'd there should not be a need to re-adjust. So in my mind you wouldnt want the set screws to move once you had them where you wanted them. But I guess you are saying that would defeat the entire purpose of the adjustability. I didnt consider the potential centering differences in the chuck at different diameters.. I get it..
I have never seen a lathe that came with an independent 3 jaw chuck. This is geared more toward people that want to do super precision work with what they already have and not spending any money.
A word of advice .. stop using the cheesy music .. it's VERY annoying and useless .. we want to hear you talk and the sound of the machines is fine
I do like the idea of modifying the standard chuck. This is a great video showing this process. In my journey using these chucks. I find it best to loosen all the set true screws and tighten the one necessary to move the chuck, then loosen it up again. As the back plate is snug enough the chuck will stay in this position, spin it and adjust the next one, continue until its's real nice and concentric. Rarely you might have to adjust two to move it in the right direction, put it there and loosen them up and when you finish then snug them all up, getting that last little bit. Using multiple screws kind-a snug can distort the chuck making the process more difficult. Try it you will like the results, Cheers!,
Did this to my 3 jaw a few years ago. It made a huge difference to the accuracy and repeatability. Definitely worth the time to do it. Take the gears out when you do this modification.
Nice but please tone down the loud music.
Yes, why is it so damned LOUD!!!
@@fredfarnackle5455 It was a technical issue during the editing process. It's the only video (out of the 34 currently published) with this problem. Of course it became the most popular video of our channel :)
Our apologies.
Perfect solution. It's especially useful when one just got a hobby machine. You know these aren't the most accurate so very well worth this trick. :)
Glad it was helpful!
I did this a couple of months ago and couldn't be more happy that I did. Just posting to atest to the goodness and benefit of doing this. Even if you have a 4 jaw chuck this is still a very useful mod.
Honest question here. What is the benefit of adjusting the concentricity of a four jaw chuck? Doesn't the part get centered independently of the chuck?
@@peterkim5394 Sorry for the confusion. I should have said "Even if you already have a 4 jaw chuck this is still a very useful mod for your 3 jaw chuck."
I don't know how many times I've heard about people with 3 jaw chucks.....brand new ones too....... running out a thou or two..........they will all run out even the best and they are not meant to be blindingly accurate to a thou.
Most of the time you will grip raw material and then turn it down to a size so run out is not important, but when a second op is performed where you really need to re-grip a work piece and then machine it true and concentric a trick I use can be employed and my Chinese 160mm 3 jaw chuck is 40 years old but runs dead true.......just cut the register on the back plate a few thou slack and this will give you room to slacken the holding bolts and bump it to run true every time you really need to have it dead true......for the most times you can live with it as it is.
3 jaw chucks on dividing heads should ALWAYS have a slack register as this will allow you to "adjust" them to run dead true for cutting gears where the mandrel holding the gear blank must run dead true.
Agreed, scroll chucks, no matter how many jaws, are broad tolerance tools. They are very susceptible to scroll and jaw wear and jaw flex, as well as a bunch of other internal and external factors that make them that way. However, they are quick and easy to set up, and ideal for general purpose professional and almost all amateur jobs. You know, unless you're NASA, General Dynamics or Rolls-Royce, they're usually good enough.
If you need, or more likely just want, near micron accuracy, try independent jaw chucks (or good quality collets). IF used correctly, they are much more versatile and accurate than scroll chucks can ever be. The downside is that they can be a bear to set up every time you use them. And if you don't have rock solid ways, bearings and tooling, you're still just pissing into the wind anyway.
the music killed this
A+ for effort and build. I would still recommend watching Robin Renzetti's video on a different design to reduce distortion. It's more involved, but very similar to how Rohm Hi-Tru works.
這是一個很好的方法，讓三爪卡盤可以像四爪一樣調整車件的迴轉同心度，我在前段時間我也對我的車床做了同樣的改造，這是讓車件二次加工時精度更好的一個好的改造。
Turn down the volume of the music when you produce your videos. This is far too loud compared to the dialog.
Yeah, wow.
@@generalawareness101 Ruined the video with the ridiculously loud music. Could not watch it all as family in bed.
@@Steviegtr52 invest in some buds ?
Yeah looked at all comments and knew this would have been mentioned. Just found the channel the guy is very knowledgeable on explains things perfectly for myself whose thinking of getting a lathe.
Holy Loud Music - ears blown
Sorry about that. It’s the only video we experienced sound malfunction.
Great idea. I will definitely look at my Chuck to see if I can do the same.
Good luck!
Really interesting way to do it, i was taught if you want something precise then use a 4 jaw chuck....but its one of those things the more ability you have to adapt an overcome the better, especially when you don't want to spend lots on high precision chucks from good brands (i do miss my 4 jaw, i knew i shouldn't of sold it)
I agree about using the largest possible set screws but also surely it makes more sense to use softer set screws better to replace a damaged set screw than to have to strip a chuck to get at a guoged damaged part. Great video by the way, I did enjoy it.
Thats an option for sure, you could even use brass setscrews if you like.
You can learn something every day if you pay attention. Great informative video. I bought a SKAND 6" 3-Jaw self-centering chuck that was slightly used. It was supposed to be within .0005". It has American Standard Tonge & Groove removeable jaws. It was .009" out when I put it on my lathe. So, I tried to adjust it by getting all I could out of the Allen head screws and was Lucky to get withing .0025", but I have to use a live center to keep it on the money. There is no adjusting this lathe chuck like it is. Every piece from the backing plate to the chuck housing shows a different runout. The jaws when screwed in all the way have a 1/16" space between #3 and #1 jaws. I can see why it was up for sale. I am a Hobbyist learning as I go and couldn't figure it out until it was too late to return. I have a threaded nose spindle, 2-1/4"x8TPI on a 13" South Bend engine lathe 3-step pully. The belt is 2-1/4" wide, and it has a lot of torque for making big cuts when needed. I'm changing my threaded nose piece to a D1-4 Camlock. I'm going to make an adapter to thread on, lock tight it and pin it to the existing spindle. I learned my lesson from all the research trying to get this chuck dialed in. I've been told that on any 3-jaw scroll chuck if it's got a runout of .002" you are doing good. You have an interesting variety of videos, so I went ahead and Subscribed to your channel. Thanks for sharing your knowledge and skills
Thank you so much! Glad we could help and happy tool hunting, it is a never ending process..
My current favorite is the SANOU chucks sold through CME.
This was a while ago I know but how did converting the threaded nose to D1-4 go? Sounds ambitious but if it works you're the man.
I did this on a decent 8" Cushman chuck oh geez, 30 years ago? Only used 3 setscrews requiring a bit more, uhm - foreplay early on. I did modify that internal casting into a sleeve to capture between the chuck mount face and the scroll plate surface. Prevents the scroll skewing around and improved repeatability at the current grip diameter. You can test the repeatability by re-gripping using a different pinion gear. Best practice of course is to mark one and use it exclusively.
One concern I remain aware of is that industrial set-true chucks typically have a steel body and mount. Import grade chuck bodies may not even be malleable cast iron.
Yes 3 setscrews will provide the correct movement but I have never seen a production chuck with anything but 4 so I stuck with that. Yes most set true chucks are beefier and usually steel, although some import ones seem to be some kind if soft iron. Good judgement is required when modifying any rotating tool like a chuck.
@@TigermothRacingTV Much easier with 4 adjusting screws. No matter what I tried, 4 conflicted with another element.
Notice the max rpm limits between steel and cast iron chuck sizes. Just because it fits doesn't mean it's safe. 🥵
I will apply this mod on my lathe,
but before drilling I will protect the internal gears against chips with a cloth or tissue paper.
Thanks for the video.
Nudging set screws, not needed. Reduce backplate register by about 0.040" to allow enough adjustment movement and then use the backplate set screws/bolts to hold the chuck by light friction, tap the part piece true using a lead knocker, tighten a little more and check run-out is still ok, fully tighten and machine part piece. You will never be able to displace the chuck on its backplate when the backplate screws are fully tightened. This method is suitable for chucks in excess of 8" diameter.
Ive done this before on small chucks and it works fine but I like knowing the position is held by some physical limit. And the fine adjustment of the setscrews is quite nice.
@@TigermothRacingTV I will use the finest thread set screws I can find. Two reasons. the kids wont strip them right away and for very fine adjustments.
@@davidsymalla4785 Without nudge screws applied, Initial knocking true of the part-piece can quickly be achieved with the chuck rotating at about 120rpm, although you need a good eye to get down to about 0.002 to 0.004" run-out, then perfecting the run-out by hand cranking the chuck.
@@TigermothRacingTV Yes, as you wish, personal choice. Using nudge screws has an advantage that NO knocking is applied to the spindle bearings, depending on the type of bearings in use.
I find it quicker to run the lathe spindle at 120rpm with the backplate set lightly tensioned and knocking the chuck true, with lead, then finishing off rotating the chuck by hand to achieve final perfection.
@@davidsymalla4785 Using nudge screws has an advantage that NO knocking is applied to the spindle bearings, depending on the type of bearings in use.
Thanks for your guidance. Bought a Chinese cheaper Chuck. Followed your instructions and pulled it into 1 thou runout.
Glad to hear it helped out!
I could see this being a useful mod over swapping to a 4 jaw. You get the speed of a scrolling 3 jaw when you don't care about accuracy, or you can take the time to dial it in without switching chucks when you do.
You can get accuracy equivalent to a 4 jaw, but you are still limited to holding round, triangular/hex etc workpieces with 3 jaw.
Yeah, well, its like having a horsecock and complaining about the size... Its the nature of the beast, if you need to work with square stock, get a 4 jaw, also, there be 4 jaws that are scroll actuated, and you can do the same thing to them and have the speed of what most people ascribe to a 3 jaw, but in fact is a common trait among all scroll chucks, while having this mod and giving the scroll chuck of any number of jaws, be it 3, 4 or 6 the x/y alignment capabilities associated with a 4 jaw... Also, consider taking a 3 jaw, getting 3 more jaws, hardmilling it out and fitting in those 3 more jaws and voila, you have a set true 6 jaw chuck for the price of a 3 jaw chuck and 3 additional jaws...
Go buy a collet closer if you need to run close
That was awesome! Wow, thanks for posting. Loved it. Music was too loud when it started after each talking section, had to keep turning the volume up and down. But the content was excellent!
Awesome! I've been talking about doing this to my chuck for about 4 years! I think it's about time...
Nice! Give it a try!
Great video. Most of the advantages of a 4 jaw, and all the advantages of a 3 jaw when you don't need super precision. Music was too loud. Had to turn the volume and and down repeatedly.
Good video except for the music that goes from background to blaring.
Also, not mentioned is that one of chuck key holes usually tightens a part more concentric than the other two. Good if you are just looking for quick improvement in runout. Some shops I have worked in have had one chuck key hole marked for quick reference.
Interesting. I have heard that sometimes you can get a part clamped slightly tighter using all the key holes rather than one but the idea of affecting concentricity is interesting. At that point you are just messing with inherent play in the chuck assembly. How much adjustment do you usually get?
Robin Renzetti says the same in his 8" chuck upgrade video.
That plate you say you remove is what holds the gears in on a lot of chucks
Interesting. Just a note on set screw size. It is not necessary to rely on the set screws for any more than positioning. Tightening the screws that hold the back to the chuck will be enough, if tightened sufficiently. Many folks do not know this, but every joint in a drill string used for drilling oil and gas wells relies on friction between the shoulders and NOT the threads to transfer torque from one section to the next. This torque being many thousands of foot pounds. Perhaps just a wee bit more than the lathe will induce.
Correct, the setscrew size is not very important. However when you are measuring in tenths, you may see some drift in concentricity of the chuck if you wack the chuck or take a very heavy cut because the tips of the setscrews can deform or the thread will compress slightly but this is to be expected if you make a high load mistake like that. Most people do not put a death grip tightness on the chuck mounting bolts because they are adjusting it all the time.
@@TigermothRacingTV Every time I put an endmill in a collet, I tighten enough to prevent slip. I tighten a work piece in a vice or chuck to the same end. I do these frequently, so I don’t buy your argument. Who, when working to tenths, takes a huge cut, or fails to tighten sufficiently?
Will you be making a video showing chuck jaw grinding? I have seen several videos with opinions about preloading them, etc. but wondering your approach. Good stuff!
@sourand jaded Thanks for the reply. My concerns exactly!
I'm 16 and learning THANK YOU ! This is what happens when Dad gives you a lathe instead of a video game lol
Good idea, but it would really come down to how fast you can swap Chuck's vs fiddling with 4 set screws and 3 bolts. 4 jaws are quick with practice, at least faster then all that set screw tensioning.
you only have to do this once,you know
@@hedning003 not true. You have to do it every time you put a different diaper part in the chuck. The point of this is to make it repeatable for parts you have multipacks of to do. Yes it can help with a bad chuck. But it won’t fix it for all diameter parts.
A great informative video I just happened to come upon. I'll definitely be doing this to my three jaw chuck!
I would have liked to see what the repeatability was if after setting it up to near 0 t.i.r. You took the pin out and reinstalled it in the chuck. I know it would be perfect but how good would it be? Great video.
Good idea. I didn't think to include that in the video. It will vary chuck to chuck but if the stock size is the same it should be very close.
That depends mostly on jaw surface and surface and concentricity of the thing chucked up, also somewhat on the surface and grind of the scroll and the jaw blades that interact with the scroll... heck, a chunk of schmoo in there or some grit that finds its way between the scroll and jaw will displace the said one jaw for quite some tolerance, so the repeatability here is a syndrome rather than something easily demandable, but if all things are even marginally ok, the thing should be relatively repeatable on stock of same diameter and even larger/different if the internal grinds and jaw and part concentricity are on paar and surfaces are nor like a grass field...
What a great idea.. Learnt something new.. after all, I'm just a newbie. Thanks!
Glad that you found it useful. Thanks for watching!
TigerMoth - Good Stuff - Two Thumbs up --- Jim
This an old thread but very useful. I’m just confused on one detail, at the end you tightened the Chuck to the back plate on the bench that was already on the lathe, then you screw the Chuck back into the lathe and start adjusting using the adjusting screws. My question is, how tight were the back plate screws into the Chuck 11:04 ? And if they were very tight, as I imagine, will the adjusting screws still move them 13 thou 11:30 ? Thank you so much for this video!
Yeah you have to leave the mounting screws not totally tight so you can adjust the concentricity, then tighten them.
I turned down the register diameter on my cheap 7x Chinese lathe about .002" or .004" total ...No set screws....I just snug the hold down nuts enough to be able to tap the chuck true then tighten them....Works well.
Good to hear. If you start doing some hard turning you might want the screws but it is amazing how much force a simple bolted together assembly can take.
@@TigermothRacingTV I have an 8" Pratt chuck that is adjusted by the tap true and undersized register method. It has been modified like that for years and never moved from where it is set once the back bolts are tightened. there is no need for the radial adjustment screws to hold it firm.
had to turn it off due to varying volume levels. turn it up to hear you talk, then bam, loud music.
Nicely done! Very useful!
Nice job. Do you leave the backplate screws semi-tight, enough so they can slide a bit, but then do NOT tighten them after getting runout true? Or do you tighten them every time you get the runout true at whatever diameter you are holding. Thanks.
This depends. I am not going to tell you what to do because of the safety liability and you will need to follow the protocols of your shop. I will tell you that the chuck will hold position very well even if the mounting bolts are not extremely tight. It is of course better to tighten them before running the chuck but if you are making a batch of parts where you have to indicate each one perfect, and the cut load is nothing big, it is easiest to leave the mounting bolts semi tight so all you have to do is adjust the setscrews when you load a new part. Up to you.
@@TigermothRacingTV Thanks. I've never owned an adust-tru chuck. I saw another TH-camr recently did a conversion like yours, but he did it the way the set-tru are typically from the factory, with the chuck body held onto the backplate from the front with very long, and thinner screws. He was saying the long screws were so they could pivot slightly to get the free play. He didn't specify whether he tightens them each use. I don't know what the manufacturers like Buck Chuck recommend? I suppose with the long screws in the front, when they pivot slightly their length would barely change, because the length change would be the cosine of a very small number, so it may not appreciably affect the clamping force of the screws.
Copy that on the vacuum cleaner and the special considerations for machining cast iron. Again, I always have a vacuum cleaner present so I don't disperse chips and and using compressed air around an open tool receiver is bad news. Cleaning as you go saves so much time and not sealing with an accumulating mess. Always take a clean finger and check the receiver opening before inserting a tool. Nice upgrade and Im considering the modification to a chuck based on your work.
Good points and I agree, always wipe the taper of your spindle before inserting a new tool, especially when cutting messy materials. It is an automatic habit for me on the TRAK mill. Most VMCs these days have positive pressure air purge on the taper for this very reason..keeps them clean.
That is a great mod, thank you.
Used your tips and my 1948 3jaw runs at 0.0002” Thank you
Glad to hear it worked out for you. Will keep that old chuck alive!
Very cool, if slightly scary looking to do.. thanks for sharing this one
It should not be scary. In fact you could drill the holes with a hand held power drill if you want to. The location of the holes does not have to be very precise.
That is very cool idea thanks for sharing this with us.
Thanks for watching, Danny!
That's a really good mod! Don't worry about the nit picker comments I've just read, if it works for you then whatever floats your boat. Unfortunately my lathe backplate is integral with the spindle, so this mod is out for me.
Without machining the back plate to exact depth to meet center hole collar inside the back of the chuck, how do you keep any swarf and debris from getting inside the chuck through that gap and causing wear to the pinions and scroll?
My experience has been that not much crap makes it back there even over years of use. The chucks are stored jaws up too so that keeps the dust out. Just hasn't been a problem. Might be different in a big flood coolant automated situation but tool making/prototyping it doesn't seem to be an issue.
Changing the diameter of the chuck faceplate so that it doesn't fit within the H7 tolerance that it's is design for, will course the chuck to vibrate undet heavy load. No need for any form of adjustment, just use soft chuck jaws if you need precession within a thousandth of a millimetre. Or for general work, buy a good quality chuck. I have a German Trekarter 200 m/m chuck, it runs within 0.02 m/m and is repeatable within that tolerance and soft jaws are easily mounted but, then again you are look at a price of ca. 2100$. Using a 4 jaw non self-centring chuck will give greater stability and it can be adjusted tobe extremely accurate. Good quality video T/U
Yes this is exactly the point. Most home or hobby machinists will never spend the money on a Buck or Bison adjustable chuck. There is no need. This method is simply an easy solution for anyone to get the same precision out of any $100 import chuck. Most of which do not have soft jaws available and are 1pc jaws. If anyone sees soft one piece jaws let me know, those would be very handy as well. Making a 3 jaw adjustable is handy because you can still do production work with a clamping repeatability easily within .001in. This would be a nightmare with an independent 4 jaw. The chuck body can be eccentric seveal thousandths before any vibration will occur at common speeds. For home shop speeds, not usually an issue, in a bigger machine shop, they are gonna have an adjustable chuck or collet system anyway.
@@TigermothRacingTV For home shop the only thing you can do is to grind the jaws of the chucks - even that comes with a lot of assumptions and limits. You may want to see how a real adjust true chuck looks like - th-cam.com/video/E_Ks6GKKcs8/w-d-xo.html
also every part of this adjust true is precision made. With chucks usually what you pay is what you get - with some exceptions here and there. For example, I grind all my 4 jaw chucks when they arrives home in a box from China. It improves things a lot but is no Bison. You cannot make them more precise as there simply is no way to add metal to make tolerances tighter.
If you want quickly add some precision to a 3 jaw, as others pointed out the soft jaws are the thing for production run. Then again, most hobby guys do not run huge production runs.
Cool idea and project!
Excellent idea, but if you have a chuck directly mounted on the spindle and not a threaded plate that you can exchange if something will go wrong...
Then you may need to get a different chuck with a back plate?
@@TigermothRacingTV It's possible, but I'd not going to the middle of the lathe 😅
I'm going to have to do this to my clausing machine now, my chuck used to be less than one thou- but the one time someone else used my machine, they left the key in the chuck and after a few hours of work I can only get it back to 3 thou...
Sorry to hear that. A crash can forever change the character of a machine. At least the chuck can be adjusted.
I wonder if doing something like sandblasting the contact surfaces of the chuck and backing plate might make the "grip" better when locking down the mounting bolts...
I think sand blasting it could make the mating surfaces no longer flat. My concern would be adding runout from a non flat mating surface and you could cause chuck warpage.
thank you for the video and taking the effort to make the video
Glad it was helpful!
Cool tip!
You guys have some great info in your videos! Thank you. Subscribed.
Thank you, and welcome to our channel!
Lovely clever trick !!
When is use my buck adjust true chucks, i always leave the mounting holes relativly tight.
they are larger set screws though 3/8 -24 .for a 6" dia chuck. I never mess with the mounting bolts
I bought a cheap chinese 3 jaw for my 9 inch southbend and somehow that thing runs out less than a thou regardless of the size part i put in it. Never expected that in a million years.
Same here. Bought one from Shars for my 9" Southbend and it is within tenths.
@@hootinouts That is where i got mine.
Loudness aside very cool
I just adopted to a 4 jaw and gave up on small three jaws..my big engine lathe is spot on though with its three jaw.
far beyond what I can do is an absolute beginner, but awesome video.
You will get there quick if you do much turning work. Thank you!
The plate you leave out @3:16 holds the scroll parallel to the inside of the face as well as keeps the scroll from floating on the spur gears.. i don't like my chuck without it installed.
Does it change the way the chuck feels without it?
@@TigermothRacingTV yep. I have to tap the jaws or the job lightly to even the pressure on each jaw when clamping down on small diameter work.I also got more crud in the scroll.
I can see how it might hold the scroll parallel to the inside of the face, but wouldn't that preclude keeping the scroll from floating on the spur gears? I mean, to do the 1st, it has to apply pressure away from the spur gears... Doesn't it? Maybe what you are feeling is extra pressure on the spur gears, reducing to normal? I am asking because 3 days ago, I decided it is time to do this same mod, and started searching TH-cam University ;) to see if anyone else had tried it then after reading your comment yesterday, I removed the plate to see.... Also, do you see any downside to thinning the plate, on the spindle side,spur gears by 3/64ths to 1/32nd, to make the screw heads fit flush? (yes I am old school, they didn't introduce the metric system in Canada until I was in grade 5, my Machinist course in college was all imperial, and I have worked as a carpenter most of my life, a trade which is only now starting to be metricified... ;) ) Oh, 1 more question, how do you get more crud in the scroll? Doesn't the inside throat of the chuck stick through, into the backing plate?
I have a 4 jaw chuck that has 2 piece jaws that let them be adjusted independently and also the scroll in the back. Factory made.
Not dissing your personal preference of method, but I haven't used a three jaw in 20 years. Their inaccuracy and laughable grip strength drove me up the wall. My four machines have Bison Four jaws on them, never removed, and I've gotten real good at setting them to tenths quickly, and I'm happy with that. The three jaw that came with the Grizzly in 2003 started life as a door stop to my shop and I finally got tired of tripping over it for 17 years and threw it out. It has never been mounted.
😂😂😂
Like you I am a 4 jaw user by preference. If used frequently then setting work true in a 4 jaw independent becomes quick and easy to achieve.
I do disagree with you though that all 3 jaw chucks are inaccurate. Some 3 jaw chucks made by reputable manufacturers are highly accurate for concentric repeatability throughout the gripping range. They are rather expensive at that level of precision though. As for gripping force of a 3 jaw that is very much dependent on the helix angle of the scroll. Think of it as a spiral wedge. The shallower the scroll helix angle is the greater the gripping force for a set amount of effort applied at the key. The other commercial alternative is as already mentioned the 'Grip Tru' type. They also are rather expensive for a hobbyist shop.
Bit hard holding a hexagon in a 4 jaw.
@@charliebaron9657 on 2 flats and opposing on 2 points. Easy enough to do.
Amazing!! Thank you for this.
Glad you liked it!
Nice, Love the video !! Great !!
Thank you very much!
inspired me top do mine and i love the result. Thanks :)
Great to hear and glad it worked out for you!
I would have liked to see you setting that indexing head on the table in the video...
Its about as heavy as 1 person can manage!
I'm definitely going to do this to mine.
Tigermoth, what kind of an edge finder did you use? I was under the impression it was a mechanical one which has to spin at approx. 600 rpm. The bottom part then "breaks" out and you can set your diameter of the edge finder or move to the center and set zero on your DRO. Or is it an electronic one? The latter is less accurate and doesn't work on plastic parts. Thank you for your answer! Best, Job
It is a mechanical one, the classic Starrett #827B. See our video on how to use edge finders. Thanks!
Thanks for the idea sir
Vídeos muito bom 👏👏👏👏
Brigado
Ok now you need a farly large mill to. Most of us just wasted some time on this O'Neal 😊
You can do this with a hand held power drill if you have to. The location of the setscrews is not very important. No mill or rotary required.
How loose do you have to leave the back plate screws for you to be able to adjust the set screws? Seems like you would have to constantly check the back plate screws?
Just slight finger tight with an allen wrench. You only need them to hold the chuck in flush contact with the backplate. You can set your concentricity and then tighten the mounting bolts. The concentricity should hold very well even wile tightening the mounting bolts.
Hmm yes I like Rob Renzetti's concept of keeping the chuck back plate as it is integral to the stiffness. I have an independent 4-jaw as well as a nice Forkardt 3-jaw which both need a hard jaw boring job. I wonder if there is a use anyway for a set-tru type chuck once you have the jaws bored properly. In fact my Forkardt runs around 0.02 TIR as it now is. But yes there is air at the front part of the jaws.
If you are interested I have made a blog post about a novel way to machine hard chuck jaws. It has been proven nearly impossible to share a link in the comments so if you are interested I can mail the link.
There is always a use for set true chucks no matter your jaws. A nice hard jaw set ground concetric may not be concentric everywhere on the scroll. Really, people tend to obsess too much over hard jaw concentricity when we can just cut soft jaws and have better clamping grip whenever needed. The set true adjustment is just the fastest way to make it "perfect" with no cutting or changing of the jaws, (least work).
@@TigermothRacingTV Well I always tend to look at the product as it was intended, and for a self-centering 3-jaw obviously 'perfect' centering was never a (design) goal. Now, a good quality chuck achieves like 20 to 30 microns (mm) TIR which is fine and great for any normal job, I have a machine at work which is out by like 0.2 mm and that can be a bit of a nuisance.
My main concern with boring hard jaws is not 'perfect' centering, it's the bellmouthing correction. Having it centering well after a boring job I consider a bonus. I have chucks of 'A' brands like Forkardt and Rohm as well as 'B' like Bison and none of them have left the factory 'bellmouth corrected' (as far as I can tell) which I find disappointing to say the least. In fact my Bison 200 mm 4-jaw is bellmouthed so bad I have to go back and measure, it looks is if the jaws were counter-corrected, LOL.
At work I program and operate two Okuma CNC lathes both running Kitagawa chucks which also air gap in the front. Work to be done there. My only goal is stability and the chuck jaws are an obvious weak link. When you want 'perfect' (re-)centering use a 4-jaw or bored soft jaws. I tend to avoid them on the CNCs because of the hassle involved, most of the times we can get away with the hard jaws and protective material like sheet metal between the jaws and the product in second operation situations. Obviously here you want the chuck to center within 0.03 TIR mm or so which the Kitagawas do.
I see, yes the bell mouth is an issue. I have noticed on some chucks the bell taper can be worse if you are clamping partially on a part and not using the whole length of the jaw. At that point I think it is usally from play in the jaw channels. Taper from wear is certainly annoying and a nice cut to freshen them up is ideal.
@@TigermothRacingTV The worst case actually is using the whole length of the jaws and then do heavy machining and parting off. It's been explained already in many videos (as well as in my blog) that essentially it's having shorter jaws and working with a larger overhang. Both are stability killers.
does ditching the pinion bearing surface that the original back cover provides not cause engagement /alignment issues?
Every chuck I have seen, that back plate does not support the gears at all. It seems to be mainly a chip cover and based on the fit, sometimes may also support the body from warpage under very high load.
I see. I saw the round overhangs on the cover and they sorta looked like bearing surfaces. Been working on an old cushman that's split in half and each half provides half of the bearing@@TigermothRacingTV
I would be tempted to install some kind of bearing surface so that the set screws son't mar that little ledge they are bearing against/ Maybe a ball mill and little steel bearings to seat in the recess
That's a good idea but I have never seen that done. All the high quality industrial set true chucks I have used simply have flat head set screws. If the screw and the part are hard, very little wear occurs.
Super und 1000 Dank
I'm rocking out right now..
🤘🏼
Great video now I can by more metal instead of buy a true set Chuck.Thanks Bruce Foster
Why not use soft jaws bored in position with jaws preloaded over a dummy piece at distance deeper than intended gripping area? This is better if you have more than one piece to turn.
Yes it is, but most small shops don't have a chuck that you can get soft jaws for.
thanks mister
So do the bolt holes need to be made slightly larger, to allow for movement?
You should not need to. Usually the mounting bolt holes are slightly oversize and allow for some movement.
thank you so much!
Super Idea. 👍👍👍
Nice idea, work and presentation! Thanx.
Thanks for watching
Won't the set screws dig in a bit enough to always try to set into the first grooves it made ?
It is important to use flat tip setscrews to avoid any marring but even the marring is not a big deal. Remember that the setscrews are contacting the backplate in the same spot every time you adjust it so any marring is just re-engaged with as you "buck" it around.
That is awesome!
Note that the rear plate holds the bevel gears in place on some chucks, so can't be left out.
also keeps the chips out of the gears.... so I am not sure why anyone would run it without the plate...
@@morganmcintire2853 I was thinking this same thing. If anything I would have made the depth of cut on the threaded backplate to minimize the gap spacing left when the rear plate was removed, and find some thin foam gasket material to fill any air gap into the bevel gear compartment, to stop any swarf from getting into the bevel gears. But I like the idea very much. Now I need to check if I can remove that plate, as my experience on my cheap chucks, they hold the gears in.
thank you , it's usefull
One word comes to mind here. LOCTITE!!!
Where would you put loctite?
@@TigermothRacingTV I was thinking on the set screws..
One wants to be able to adjust the chuck body quite easily because the wear in the jaws (and the scroll) will almost certainly be uneven. This is why the TIR changes at different diameters on cheap chucks like these. The idea is to get the adjustability of a 4 jaw, but the rapid repeatability of a 3 jaw for a given diameter. Changing diameters, and you'll want to double check TIR and adjust the set screws again.
@@carneeki I was assuming once the set screws were adjusted and the chuck zero'd there should not be a need to re-adjust. So in my mind you wouldnt want the set screws to move once you had them where you wanted them. But I guess you are saying that would defeat the entire purpose of the adjustability. I didnt consider the potential centering differences in the chuck at different diameters.. I get it..
I may be missing something, but wouldn't it be easier and simpler to just use an independent 3 jaw chuck?
I have never seen a lathe that came with an independent 3 jaw chuck. This is geared more toward people that want to do super precision work with what they already have and not spending any money.
Physically tuning static engineering.
Real science on top of real science.
Good video
Great video! Would have been even better if there were no loud music jumps.. it's irritating.. :)
Merci
Noooice!!!!!
I wonder why the play, if any, on the scroll and jaws are not checked...
If you check your mating surface on the back of the chuck I bet you'll find local high spots around where you tapped the set screws
Use a sharp tap, no problem. Just don't get too close to the edge. If you do get a bump, just stone it.
@@TigermothRacingTV u right
Thanks for sharing! Very useful !
Glad you liked it!