Chuck jaw truing tool

Do you have a worn chuck that is only gripping on the back of the jaws, here is a way to fix it.
This simple tool will do the job if your chuck has hardened jaws, by gripping the jaws by the front only (where most work is done) while allowing a grinding wheel access though the length of the chuck.
My 50 year old 5 inch 3 jaw will grip a 5 inch long test bar with the same run out at the end as at the jaws (usually within a thou) after this treatment.
You would think that working in a tool room everything would be looked after but sadly not so, I have seen chucks tightened with extension bars and metal being torn out of 3 jaws when 4 jaws should have been used (laziness is the common culprit), this obviously renders them useless for accurate work unless the jaws are ground true. I am not suggesting that anyone here would do these things but maybe you have an old chuck that could be reclaimed.
On the subject of trueness of 3 jaw chucks I have used a method which is is a little unusual and may not meet with everyone’s approval. I have turned the backplate register -.008 thou to allow a small amount of movement for final adjustment if needed, after which the mounting bolts are tightened, I can almost here the disapproval but I can say I have never had the chuck move while in use, indeed all faceplate work is clamped so why not a chuck. If you don’t like this idea I find that a few taps with a soft drift on the offending chuck jaw to settle the scroll before final tightening will often do the trick.Attachment 13436Attachment 13437Attachment 13438Attachment 13439

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Thanks olderdan! We've added your Chuck Jaw Truing Tool to our Machining category,
as well as to your builder page: olderdan's Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="http://www.homemadetools.net/homemade-chuck-jaw-truing-tool"> <img src="/uploads/156593/homemade-chuck-jaw-truing-tool.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="http://www.homemadetools.net/homemade-chuck-jaw-truing-tool">Chuck Jaw Truing Tool</a> <span> by <a href="http://www.homemadetools.net/builder/olderdan">olderdan</a></span> </div> <div class="tags">tags: <a href='http://www.homemadetools.net/tag/chuck'>chuck</a>, <a href='http://www.homemadetools.net/tag/truing'>truing</a> </div> </div> </div> </div>
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Thanks olderdan for posting this. I'm not a trained machinist so there's no disapproval here. But my impression of being a machinist is not only a constant creative application of what you have to do the job at hand, but also to make the tooling to repair and improve your equipment.

So this is to me a novel way to true the jaws. I saw Mr. Pete take a ring and put it on the outside of the jaws and open them to tighten then grind them. As a FNG/noob can you give details how to make your rings because they obviously need to be done accurately. Or is that going to be in your plans for sale?

Thanks C-Bag, not a lot wrong with your definition of a machinist.
No need for great precision in making the rings as they only have to stop the the jaws from moving and simulate gripping a diameter.
You could at a pinch make one from tube with the cut outs sawn and filed, the accuracy comes from the chuck itself.
You mention using a ring on the outside to do this, the problem with that is the jaws tilt inwards at the front whilst grinding, ending up with the condition you started with of only gripping on the back of the jaws when holding a shaft.
Hope that makes sense.
I dont intend to sell plans , I would rather just pass on what I know and further the cause of home engineering.

Thank you! Your chuck jaw truing tool is brilliant and easy to find the raw materials compared to other designs I have seen using round steel plates with holes precisely drilled to catch the chuck jaw edges. If you have time, I found it is a good practice to dismantle and clean the 3-jaw chucks before grinding the jaws to help ensure repeatable jaw clamping. It is amazing how much gunk gets into the scroll plate behind the jaws and can affect the jaw positions.

I too have turned the backplate register on my mini lathe chucks to be slightly smaller than what comes from the factory. These are bolt mounted so an easy modification and never found any slippage. The ER32 collet chuck now runs with almost no measurable TIR.The larger lathe and chucks have a D1-4 mounts and already run extremely true. However, I do use a 0.0001" division indicator to measure the chuck OD run-out after mounting to makes sure I didn't get a chip lodged on the D1-4 surfaces.

Thank you for sharing your designs and experience with chuck jaw truing.

Regards,

Paul

Having never worked as a machinist but as a mechanic there are still some common concepts/lingo to machining that I'm going to have to bone up on. Like register. I think I get the concept. Like what taper is to X axis, but in the Y axis?

But in the shops I worked in the machines that were used by everybody were always suspect. Alignment racks were a good example where you give up a precision machine to the horde and always with a bad outcome. Especially with the electronic racks. All it took was for one of those wheel sensors to not be mounted right and it hit the floor and you were no longer doing a real alignment. Same thing with the valve grinding equipment, line boring, even brake lathe. So I can't even imagine sharing a lathe or mill.

Both my Chinese hobby lathe and mill/drill were owned by several people who thought they were improving them. So all this kind of info of checking and possibly correcting problems is invaluable to me. As I learn more and do more precision work it points up sometimes the limitation of the machine but more often than not shows a botched "improvement". And probably why I was able to pick it up so cheap :)

My problem is you can't probably drop it down to a low enough gear for me to get all the nuances. Like, your test bar. Obviously you have to buy one, but is that what it's called? Sorry for all the stupid noob questions.

Post withdrawn by brianhw.

Hi C-Bag
There are no stupid questions, only stupid answers, an inquiring mind will always get there.
A register usually refers to a radial location diameter where a taper is not used I.E. screw on chucks, the thread hold it on, the register aligns it.
The test bar can be anything you know to be parallel and straight, the one I use most often is a 1/2 inch dowel 5 inches long, these are centerless ground and case hardened and quite cheap
Hope that helps.

Quote:

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Originally Posted by olderdan

Do you have a worn chuck that is only gripping on the back of the jaws, here is a way to fix it.
This simple tool will do the job if your chuck has hardened jaws, by gripping the jaws by the front only (where most work is done) while allowing a grinding wheel access though the length of the chuck.
My 50 year old 5 inch 3 jaw will grip a 5 inch long test bar with the same run out at the end as at the jaws (usually within a thou) after this treatment.
You would think that working in a tool room everything would be looked after but sadly not so, I have seen chucks tightened with extension bars and metal being torn out of 3 jaws when 4 jaws should have been used (laziness is the common culprit), this obviously renders them useless for accurate work unless the jaws are ground true. I am not suggesting that anyone here would do these things but maybe you have an old chuck that could be reclaimed.
On the subject of trueness of 3 jaw chucks I have used a method which is is a little unusual and may not meet with everyone’s approval. I have turned the backplate register -.008 thou to allow a small amount of movement for final adjustment if needed, after which the mounting bolts are tightened, I can almost here the disapproval but I can say I have never had the chuck move while in use, indeed all faceplate work is clamped so why not a chuck. If you don’t like this idea I find that a few taps with a soft drift on the offending chuck jaw to settle the scroll before final tightening will often do the trick.Attachment 13436Attachment 13437Attachment 13438Attachment 13439

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I have done the same thing to my back plate except I drilled and tapped the chuck for three 5/16" set screws to make adjusting the chuck easy and it can not move after you tighten the set screws.

Thanks Chris
I would have installed set screws as you have done but the register on my old chuck is only 1/8 deep.
I used to operate a Myford cyl grinder with a griptrue chuck which had three tapered screws to bear on the register, I always wished it had four so it could be adjusted as you would a 4 jaw chuck.

Quote:

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Originally Posted by olderdan

Thanks Chris
I would have installed set screws as you have done but the register on my old chuck is only 1/8 deep.
I used to operate a Myford cyl grinder with a griptrue chuck which had three tapered screws to bear on the register, I always wished it had four so it could be adjusted as you would a 4 jaw chuck.

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I used only three set screws, as I find it easier to set the chuck, instead of four screws. Probably some sort of mental thing with me.:headscratch:

Hi olderdan, I've been working my way to being able to true up the chucks on my lathe. I'm having a hard time sourcing a 1/2"x5" test bar to set my headstock parallel to the ways. Can you post a link to where you would get one?

After that hurdle is over I'm going to make some truing rings like you show and true the chucks, but first thing first.

Quote:

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Originally Posted by C-Bag

Hi olderdan, I've been working my way to being able to true up the chucks on my lathe. I'm having a hard time sourcing a 1/2"x5" test bar to set my headstock parallel to the ways. Can you post a link to where you would get one?

After that hurdle is over I'm going to make some truing rings like you show and true the chucks, but first thing first.

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Reamer blank!!!!!! They're long, even center drilled already, hardened HSS, pretty damn straight and round. Couldn't really ask for better.

Example of item not price 1/2 Inch Diameter x 6 Inch Overall Length, 71110324 - MSC. Make sure they're center drilled, photo and description don't state. Diameters will = +.0002 -.0000 normally, straightness not much concern as they are ground after heat-treat.

Quote:

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Originally Posted by Toolmaker51

Reamer blank!!!!!!

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We have a WINNER! Thanks TM51. Can't search for what I don't know what the thing is called, so good call. Ordered! Step one in progress.

Hi C-bag
Sorry I did not reply to your question, My dog has had to have an eye removed and I have not slept for 72 hours, next doors car alarm has been sounding off all day, the dog running all over the place trying to get its collar off has tripped me up and I now have a black eye in sympathy, you couldn’t make it up.
Feels like I am in the cast of that John Cleese film Clockwise.
In belated answer to your question I assume your lathe has an adjustable headstock alignment, if so I would start the process with a Morse taper test bar to fit your mandrel, or run a DTI across a faceplate to set it square,(I have always understood that lathes are set to turn faces very sightly concave but your choice).
Sounds like TM51 has got you sorted though.
Good luck
Olderdan

Olderdan I'm so sorry about your dog! That's horrible. I hope it it all gets sorted. I have this huge soft spot for dogs and there is nothing that gets to me like one of my 4 legged buddies getting sick or injured. My heart goes out to you and your dog.

Thanks for the tip on the collet, another purchase but worthwhile. If I'm going to actually try and do this right it makes sense, but being a noob it's good thing I have somebody like you to set me straight.

Get some rest.

Olderdan can you tell me what would be an appropriate rotary tool bit for truing the jaws with? Abrasive, carbide burr? I'm finally to the point with things to make the ring and think my Foredom mounted in sturdy mount would be able to do the job as it's the heavy duty model. It can mount a 1/4" shank, so I'm trying to figure what bit I'd need to do the cutting with.

I also assume after the Chuck is trued, it should be disassembled and completely cleaned, no?

I'm ringing in, but not to usurp Olderdan, just two-centzin'.
Cover ways with plastic wrap 'glued on with grease or oil, draped wide to protect lead screw.
a] By ring, do you mean that which tightens on the outside of the jaws? They need to be 'secured' as if they are clamped on stock. Otherwise they float; sometimes the scroll will catch inertia and they exit the chuck. Not good, or worse....
To me, the choice would be abrasive. A burr's hard put to deliver a fine finish. Clamp the dresser somewhere to get whatever roundness the tool can produce. A proper feed rate and RPM will be apparent. In this case feed is more of an influence than speed. Misting some sort of mild detergent might work to keep wheel from loading. Visually the tooling marks shouldn't be pronounced. There must be some 'ideal' minimum chucking diameter per chuck size to achieve, guiding choice of wheel diameter, minus .050 or so, and narrow. Rotation is opposite that of grinder [as in conventional milling]. Surprise will be cuts deeper than a thou or two per pass.
The wheel shaft is sure to deflect contacting two jaws semi-simultaneously. Dykem or ink the jaws to monitor progress. Cleaning afterward won't hurt a thing; but I'd clean the scroll before hand so fines aren't inducing jaw position.
Disassembly easiest in most chucks by reversing the capscrews for 'handles' on the backplate. Set the chuck upright on bar or tubing that fit chuck body bore but not pas through the inner [adjacent to spindle]. Tap downward with hardwood in the jaw channels. Decently grease the various spuds and holes and scroll; I like a flux brush applying a thin coat. My/ our chucks all are on water-base coolant lathes, so I use boat trailer lubes.

This might be a nickel's worth, and bet a few bucks more coming in from our esteemed forum.
What more could a guy want? Have fun?

C-Bag drew my attention to Olderdans "Truing Ring". That post escaped me until now. Quite an improvement compared to commercial versions, especially for chuck sizes most of our forum likely use.
http://www.homemadetools.net/forum/c...ing-tool-50544

Which points out more details.
1. Test which pinion produces accurate chucking.
2. Typically those are stamped with something like ||| or |0|. Most chucks identify that as #1.
3. Consider modifying your chuck for an adjustable back. While yours is apart the opportunity is perfect.
The debate on using all three or one individual is ongoing. Lots of adjustable chucks have but one pinion. Drill chucks seem to tighten best with all three positions used...When it matters, I use all three and the |0| last.
And a nod to Frank S. All this is pointless if the spindle bearing is culprit.

TM51 pretty much nailed the additional input log.
I just have 1 or 2 additional points which may not be germane to your particular lathe. I Just feel that it is important for someone to consider when attempting or wanting to true the jaws of their chuck/s By the time the top jaws become worn or out of true most lathes have already had a pretty hard life especially if they have been to use a truck driving term slip seated with multiple operators.
Like Tm51 stated cleaning the scroll is very important. I like to completely disassemble my chucks and wash them in diesel with a stiff brush. and re lube as he stated. But my point here is not the chuck at all but the spindle and its bearings. almost all older lathes I have encountered have had play in the spindle bearings.
old Babbitt bearings wear a lot and require attention form time to time by removing a few shims at a time. Newer bronze bearings usually are made like collets and will have a large adjusting nut to tighten them. the same goes for spindles with tapered roller bearings. Ball bearing mounted spindles are normally made with thrust bearings plus radial ball bearings Better lathes with ball bearings and thrust bearings will use angular contact bearings as well again there usually is a nut to set the pre-load.
SO I guess my point is check the spindle for run out before moving on the truing the chuck. because even if the chuck has been trued it is was done on a lathe with a loose spindle the best any turned part can be expected to turn out will be +/- the run out of the spindle

Thanks TM51, great tips like cleaning the chuck before grinding. And the protection of the ways. The ring is the ring that was the original post by Olderdan, which tensions from inside, not outside.

Thanks Frank. Good points, and ones that I've had to consider and check. I like what you mention had to go through these checks not because it was over used, but because some things were never assembled right. Some things were not adjusted right. Some things were not machined right. So it's taken all this time to learn how to fix, check and go through all the different problems. Now I'm to the point where truing the chuck is a possibility. I am deeply appreciative that there are so many that share their knowledge freely here.

Quote:

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Originally Posted by C-Bag

Olderdan can you tell me what would be an appropriate rotary tool bit for truing the jaws with? Abrasive, carbide burr? I'm finally to the point with things to make the ring and think my Foredom mounted in sturdy mount would be able to do the job as it's the heavy duty model. It can mount a 1/4" shank, so I'm trying to figure what bit I'd need to do the cutting with.

I also assume after the Chuck is trued, it should be disassembled and completely cleaned, no?

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Hi C-Bag
I start with saying that I avoid using the lathe for grinding if poss, having said that it is sometimes the only option.
The main enemy is loose wheel grit which is unavoidable as grit wheels are designed to shed the blunt particles to keep working and then there is wheel dressing to cope with.
My preference is a diamond coated wheel known as Speed pins in the UK these do not create loose grit and do not need dressing.
They will also cut hardened tool steel and have a good shelf life if not pushed to hard and with a vacuum dust is minimal.
The 1/4 shank one pictured should ideally run at about 25,000 rpm, my spindle only reaches 7,000 but still seems to do the job, chuck speed about 50 rpm and slow traverse in and out until it stops cutting.
And yes cover everything (spray oiled newspaper) and as you say strip and clean afterwards.

Attachment 17854
Hope this helps.

Thanks Olderdan. Once again having the proper name got me to the appropriate place. All I could think of before was diamond grinding bits after trying several other terms. But they never had the larger head which is needed to clear the shank and the grinder like the one in your picture. Doing a search with diamond speed pins got me into a whole 'nuther and proper universe. The net can be a wonderful tool, but without the proper nomenclature it's useless.

Quote:

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Originally Posted by olderdan

On the subject of trueness of 3 jaw chucks I have used a method which is is a little unusual and may not meet with everyone’s approval. I have turned the backplate register -.008 thou to allow a small amount of movement for final adjustment if needed, after which the mounting bolts are tightened, I can almost here the disapproval but I can say I have never had the chuck move while in use, indeed all faceplate work is clamped so why not a chuck.

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This was commonly done decades ago, before commercial chuck manufactures 'named' the work and patented it. Then other manufacturers renamed it and followed suit.
My largest 3 jaw, a genuine Buck, has them, so that chuck is the go to for repeatable work. Unbeatable with pie jaws, every bit accurate as collets. And collets with 15'' capacity are quite rare...Single drawback, shouldn't run past 1500 RPM. American Tool Works Pacemaker 16" x 54" tops out at 2000, one feature making it IMHO epitome of toolroom lathes. Been looking for time to produce collet chucks for #215's and 5C's. Also have Jacobs Rubber Flex, that I keep at work. You really can't have too many options, when it comes to workholding.
Interested parties might research the Jacobs as they are reasonable used, no longer appear to be made. They are simple, easy to maintain and repair. The Sjogren Speed Chuck is similar and perhaps somewhat superior. being tied to Hardinge makes it $$$.
One thing I've not seen commented on is chuck size and RPM. Many mini-lathe chucks are cast iron and balanced only to RPM range of the intended machine.
Better chucks are "semi-steel", with increased longevity, repeatability, and balance characteristics. But all chucks have maximum safe RPM's.

Here's something from 'Popular Science'. There was a post recently by someone who suggested using a ring cut from pipe set on the outside of the jaws and the jaws wound out which I think would allow the backlash in the scroll to introduce inaccuracy. This works for me.

Attachment 17893Attachment 17894

Quote:

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Originally Posted by NortonDommi

Here's something from 'Popular Science'. There was a post recently by someone who suggested using a ring cut from pipe set on the outside of the jaws and the jaws wound out which I think would allow the backlash in the scroll to introduce inaccuracy. This works for me.

Attachment 17893Attachment 17894

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Funny that's the very article I used to make mine several years ago! Works a dream holding the tips of the jaws bell mouthed the way most wear is on older chucks!

Like I said; comparatively nothing new under the sun. Mechanics and physics, like mathematics have enduring qualities making them not just interesting or useful. They are the very foundations of civilization.

Chuck wear occurs in several areas, depending first on construction of chuck itself. How they are used magnifies all of them.
By far, the degree of wear is due to who owns the chuck.
Lax supervision, ineptitude or poorly instructed users are main perpetrators.
Over-tightening and short parts are the next culprits, followed directly by maintenance.

Hard to say how many generations back truing rings go. The 'Popular Science' page is very telling; re the brick-drill made of pipe. How long has it been since fedoras were associated with workmen? Lol. Certainly after machinists wore waistcoats and neckties. I personally recall articles in Popular Science that belonged in Popular Mechanics. Never figured out how they were 'science' per se. Nothing's changed, look how term 'technology' is overused by advertising cause it sounds impressive. Not factual, just impressive to those susceptible.

OlderDan-

How is your dog doing now? (Have you gotten any sleep?)

Hi Basil3w
Thanks for asking about our shiatsu, I am afraid we lost the poor little thing 6 months after the eye op due to kidney failure, we would not have put her through it had we known.
We now have a miniature poodle to keep our bishon (my avatar) company and now he has problems so a good nights sleep is a thing of the past, at least I no longer have to go to work at 6 in the morning so it doesn't matter that much.

OlderDan,

Sorry to about you loosing you Shiatsu.

Yesterday I had to euthanize our 13 year old Miniature Schnauzer, Emme, due to kidney failure. She was number seven in a long line of nine schnauzers we owned over a 35 year period. Emme was one of my most favorite Miniature Schnauzers because when we were at the breeders in 2005 (born March 4 ) selecting from a litter to pick for a female puppy when she choose us by falling asleep on my shoe. My wife took a photo of the event and that sealed the deal.

Below is another photo. Emme is the one on the left with her older sister Morgan (our number 6). Both beautiful, loving and energetic dogs but no longer with us. I built the hallway gate for them ( http://www.homemadetools.net/forum/h...dog-gate-37959 ) but in her day, Emme could fly over this barrier with ease and I would just laugh seeing it.

Attachment 22139

We always have at least two Miniature Schnauzers to keep each other company and currently have an 11 and 8 month old females with lots of energy. We are considering having miniature poodles to provide us and the schnauzers company when I retire this summer. My wife and I love dogs.

Sincerely,
Paul R Jones

Hi olderdan
Not a problem to have a backplate slightly smaller. I am a mechanical craftsman and I have always turned the backplate for a new chuck 0.004"/0.008" smaller for the reasons you have made.
Great post. Thank you
The Home Engineer

Olderdan and Paul,

My Heartfelt condolences on your losses. Your stories brought back memories of my Mom's Teacup Poodle, Bear. She name him that because when you looked at him straight on he looked like a mini bear. One of the greatest loving and smart companions I have ever known. Unfortunately at 15 he started having mini strokes and we had to put him down. I find myself thinking of him regularly and the fun and loving times we had together. He could easily jump straight up 3' without blinking, loved to chase golf balls bounced on concrete (true cartoon picture) and would jump up in my lap and snuggle in between my leg and the arm of one my moms rockers while we watched a movie or just talked. Once I thought I could teach him to jump a bar and set up an elaborate rig to work with him. We got up to about 2 feet and when I called/coaxed him to do it he looked at me like "What the...You do it!" I busted up and then he jumped the bar straight onto me and I fell over laughing and him getting all over me. He was great for mom in so many ways over the years and especially in her hard later years. She passed a few years after him.

The best part of the story is about a year after moms passing I was thinking about Bear and Mom and some of those "moments" and when I looked up in the sky I saw this cloud that looked just like Bear chasing a golf ball. That was special and why these wonderful companions bring such a joy to our lives, I think. May your memories fill your hearts with the Joy and Love they shared with you.

:hattip: ~PJ

Thanks for the sympathy guys, end game is part of having pets and we have all been there, ours are all rescue dogs so at least we gave them a better life and they do reward you for it. We have had Greyhounds in the past but now find smaller dogs easier to manage. Never could figure out why they like us so much, I guess that is part of the fascination.

Thank you for the sympathy. Each dog was a unique personality and both they and us like each other so very much.

We are also fond of cats as well We have had several: lilac Siamese, Mostlys (mostly black with some white furnishings) and Calicos. Each with its own unique personality.They seem to get along very well with our dogs and respected each other's space.

Hi olderdan,

I really like your method of using a section of tube to simulate the way the jaws clamp on the O.D. of material in the same direction they are used. Your method was new to me.
I also have floated my mini lathe 3" 3 jaw chuck on the back plate and have never had a problem ever. A few years back I also did the same with a 4" 3 jaw that was mounted on a 5C adapter. I could dial that in right on the money and never had it slip.

Dick

olderdan,

Thanks for posting this.
This is really a great idea to hold the jaws with the the load on the scroll in the same direction in which the jaws will be used. I wish I had thought of it myself!

Dick

Alan,

I use a similar device but with a difference. Depending the amount of wear on the sliding grooves it may produce slightly different results.
I use a tube which is longer than the width of the jaws and cut grooves like yours but to take the full width of the jaws not just the front. This results in a chuck which clamps a bar evenly over the width of the jaws rather than aiming for best results with short pieces.
I have never understood why anyone would expand the jaws into a ring for truing the inside of the jaws, and vice versa.

I have never found a need to true the jaws by grinding or any other means. That is not to say it can’t be done but any chuck I have seen has never required that drastic kind of surgery.

Quote:

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Originally Posted by old_toolmaker

I have never found a need to true the jaws by grinding or any other means. That is not to say it can’t be done but any chuck I have seen has never required that drastic kind of surgery.

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Agreed a chuck that has been looked after from new should not truing. The 3 jaw I have is an original South Bend about 80 years old and was much abused so this improved it.

Your way is a definte improvement.