# In total shock over my Shars 3-Jaw Chuck



## GrizzlyBagWorks (Jul 10, 2017)

I finished restoring a 1939 Clausing Lathe some time back.  The original chuck had .020" runout and was totally unusable.  I really wanted to put a vintage chuck on the machine but couldn't find one locally and didnt' want to risk ordering one on eBay.... So I purchased a Shars 3-Jaw with removable jaws.

It arrived this afternoon and I had an opportunity to turn/face the backplate and install the chuck.  The fit was absolutely a perfect interference fit.  I bolted on the chuck and tested it with a .0005" indicator.  I was getting around .0025 runout, which I was happy with.  When I was attaching the backplate I noticed one bolt had a little trouble going in so I took a closer look.  The bolt holes on the backplate weren't lining up perfectly with the chuck and I was getting some rubbing on the head of the socket head cap screw which canted the chuck very very slightly.  So  I ground down the head so there wasn't any interference and reinstalled.   

After that runout on the chuck body was less than .0005".   I threw a few test pieces in and the results are below.  I re-chucked all different material and am getting the same results over and over.  I can see almost no movement on the indicator.  I'm guessing .0001-.0002 runout on this.  At this price I'm absolutely blown away.  I was expecting the worst.

Is this normal or did I get really lucky?


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## mikey (Jul 10, 2017)

Impressive! This is a good example of stacking tolerances - the accuracy of the spindle, spindle register, the accuracy of the fit of the backing plate on the spindle, the accuracy of the fit between the backing plate and the chuck, and the chuck itself - all of it will contribute in one way or another to run out. The chuck is just one of the things that gave you that result and as the scroll and jaws wear in, the accuracy will change. I am more impressed that you got your lathe spindle restored so accurately and your backing plate so precisely machined.

So, great result from a Chinese chuck - congrats! More importantly, YOU did a great job on the spindle and machining.


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## Bob Korves (Jul 10, 2017)

The tip of the indicator is supposed to touch the work!  Great job on setting up the chuck...


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## darkzero (Jul 10, 2017)

Awesome! Couldn't have better asked for than close to that!

To answer you question, no it's not normal, just lucky. But in lucky I mean lucky that you got a good scroll & that the jaws were ground well concentrically to the register. That's not common on Chinese chucks, heck even on the quality name brand chucks, most don't guarantee under .002" TIR on plain back chucks.

Like Mikey said, the rest was a good job on your work.


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## Ulma Doctor (Jul 10, 2017)

Nice Work Grizzly!!! 


Stefan Gotteswinter from youtube modifies the register by taking a couple thousandths off and then indicates the work true and locks the chuck retention nuts.
he gets near 0 runout
he has a chinese 922 that he has made into an impressive machine tool


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## darkzero (Jul 10, 2017)

Ulma Doctor said:


> Nice Work Grizzly!!!
> 
> 
> Stefan Gotteswinter from youtube modifies the register by taking a couple thousandths off and then indicates the work true and locks the chuck retention nuts.
> ...



I also did that to the stock 3-jaw that came with my lathe as well as my ER collet chuck for the lathe. Certainly not my idea of course but I call it "Tap-Tru". 

Downside is that it can possible get knocked out of alignment with heavy machining. Never happened to me as I only kept my stock 3-jaw around for a beater chuck & doesn't get much use anyway. Unless you have a large lathe with gobs of power, it'll probably never happen unless you crash. But just don't crash & it's easy enough to tap back into true anyway.


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## brino (Jul 10, 2017)

GrizzlyBagWorks said:


> Is this normal or did I get really lucky?



I don't know, but either way; congratulations, well done!

-brino


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## higgite (Jul 11, 2017)

Congrats Grizzly! I have to use darkzero’s “Tap-Tru” method to get anything close to .0005”.

Which leads me to a question that has been haunting me and is sort of on topic. Regarding taking a couple thousandths off the register and then tapping on the chuck to center the work, why have a register at all? I understand having an undersized register for a Set-Tru type chuck with adjusting screws that bear on the register, but for “tap tru”, what purpose does a register serve? A flat faced adapter plate sure would be easier to make. So, should I patent the heretofore unheard of flat faced chuck adapter plate or just pay better attention in class?

Tom

Note to Mods: If you think this is OT, let me know and I’ll delete it. Or you can.


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## 4GSR (Jul 11, 2017)

higgite said:


> ..................
> 
> Note to Mods: If you think this is OT, let me know and I’ll delete it. Or you can.



You're good..... just pay attention in class.

I have a 6" 3-jaw, bought new, mounted on a chuck adapter I made.  And I did the same, turn a few thousandths off of the regerster to get the chuck running true.  Haven't yet had to adjust it either and it's been in service for over 15 years too.


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## 4ssss (Jul 11, 2017)

darkzero said:


> Awesome! Couldn't have better asked for than close to that!
> 
> To answer you question, no it's not normal, just lucky. But in lucky I mean lucky that you got a good scroll & that the jaws were ground well concentrically to the register. That's not common on Chinese chucks, heck even on the quality name brand chucks, most don't guarantee under .002" TIR on plain back chucks.
> 
> Like Mikey said, the rest was a good job on your work.



While I tend to stay away from Shar's tooling, I did happen to buy one of their diamond wheels for my carbide grinder, and I have to say it performs better than some of the Norton wheels that I've had.  I don't think luck anything to do with it, maybe Shar's quality is going up.


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## RandyWilson (Jul 11, 2017)

For the generation before us, the common theme was "Cheap Junk Japanese Imitations".  Yet now Japanese made equipment is revered.  You would never convince my Father in Law of this, but the Japanese stuff is high quality now.  Remember when "made in Taiwan" or "made in Hong Kong" was synonymous with garbage?    The same progression is happening with the Chinese stuff. Many, included some here, will never accept it, but the Chinese stuff has come a long ways in the last twenty years... especially in the last five. You can buy stuff from Harbor Freight and have a reasonable expectation of function. And the prices are going up to match. Yes, there are items for which lowest possible price is the only manufacturing criteria, but they are fairly easy to spot and avoid.  


 It seems everything advances at some pace... common wisdom being the slowest.


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## mikey (Jul 11, 2017)

higgite said:


> Congrats Grizzly! I have to use darkzero’s “Tap-Tru” method to get anything close to .0005”.
> 
> Which leads me to a question that has been haunting me and is sort of on topic. Regarding taking a couple thousandths off the register and then tapping on the chuck to center the work, why have a register at all? I understand having an undersized register for a Set-Tru type chuck with adjusting screws that bear on the register, but for “tap tru”, what purpose does a register serve? A flat faced adapter plate sure would be easier to make. So, should I patent the heretofore unheard of flat faced chuck adapter plate or just pay better attention in class?
> 
> ...



Tom, there are a number of ways to mount a chuck to a backplate and I'm not sure if there is a right way. I have a 6" Samchully chuck and their manual states that the proper fit is to make the register on the backplate 0.0004" smaller than the mating hole in the back of the chuck. The end of the register should also be shorter than the bottom of the hole in the back of the chuck. This allows you to snug the attachment bolts and align the chuck to the plate with what @darkzero is calling the "tap-tru" method. Once aligned, a little blue LocTite on the locking screws will keep the chuck in place unless you have a crash, at which time a little misalignment is the least of your problems.

Samchully is a Korean maker that supplies OEM chucks for Haas and Hardinge. I figure they know what they're talking about.


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## Silverbullet (Jul 11, 2017)

I think it's time for us to start to produce more for fare prices.


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## Ulma Doctor (Jul 11, 2017)

admin feel free to strike the comment, it's made in partial jest. 
not to get too far into economic debate,
but if you have an entity that has intentionally repressed the value of their currency- you will soon have a trade imbalance.


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## RandyWilson (Jul 11, 2017)

As much as the politicians and talking heads try, fifty years of off-shoring can not be condensed to a 10 second black and white sound byte, or even a single finger pointing. Let's leave it for another thread.


 Now, off to the barn to beat the crap out of my tired ebay chuck and see if it will come into align.


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## higgite (Jul 11, 2017)

RandyWilson said:


> Now, off to the barn to beat the crap out of my tired ebay chuck and see if it will come into align.


I have a rare Starrett 8 lb sledgehammer with optional micrometer adjustment for such fine tuning of my Chijunk 3 jaw chuck.

Tom


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## markba633csi (Jul 12, 2017)

Chinese goods have improved but they are still quite variable on quality control
Mark


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## Bob Korves (Jul 12, 2017)

markba633csi said:


> Chinese goods have improved but they are still quite variable on quality control
> Mark


Correct, Mark.  I do not think that is because of some inherent flaw in their civilization or work ethic culture, rather in doing whatever it takes to meet their customers' price point demands.  We reap what we sow.  For perhaps 10 or 15 percent more cost of manufacture actually applied to QC and QA we could probably learn to expect to receive quality tested goods from China.  I do not know if customers like Shars, MSC, and others buy their goods from the manufacturers or from brokers, but at some level the message that machinists want 'consistently good quality products at the best possible price' has not been communicated.  I think there is a large market for some importer who can actually achieve that in reality.


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## wrmiller (Jul 12, 2017)

To agree with Bob's comments: My iPhone and iMac are made (assembled?) in China and these are some of the highest quality tech pieces I own.

Not exactly apples to apples, but just supporting the 'you get what you pay for' perspective which is something I feel strongly about. Feel free to delete if necessary...


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## strantor (Jul 12, 2017)

My bandwidth sucks here so I can't watch the video except in small pieces which makes it hard to tell what's going.
From what I think I see, it appears the indicator (or maybe just the camera) is moving, but the needle isn't.
Are you sure the indicator isn't bottomed out?


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## RandyWilson (Jul 12, 2017)

He's holding the phone with one hand while spinning the chuck with the other.


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## David S (Jul 12, 2017)

So often we hear the things that are wrong with Chinese products, it is refreshing to hear stories like this where the chuck is so good you may not need collets.

When I was working in consumer appliances and tools we had suppliers in China and our own plant as well.  I can attest that they are absolutely capable of making products to whatever quality level you wish.  On some of my visits there I saw suppliers with dirt floors producing crap and some with clean rooms producing products of the highest quality.

Back a number of years ago a book was published "Poorly made in China".  I could relate to most of the examples that were mentioned in the book.  Our purchasing department would relentlessly demand lower pricing, but eventually in order for them to survive they would start cutting corners.  And yes there were instances where we did it to ourselves.

Glad to hear that this chuck was indeed good value.

David


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## darkzero (Jul 12, 2017)

higgite said:


> Congrats Grizzly! I have to use darkzero’s “Tap-Tru” method to get anything close to .0005”.
> 
> Which leads me to a question that has been haunting me and is sort of on topic. Regarding taking a couple thousandths off the register and then tapping on the chuck to center the work, why have a register at all? I understand having an undersized register for a Set-Tru type chuck with adjusting screws that bear on the register, but for “tap tru”, what purpose does a register serve? A flat faced adapter plate sure would be easier to make. So, should I patent the heretofore unheard of flat faced chuck adapter plate or just pay better attention in class?
> 
> ...



I believe the register is there is to prevent the check from getting knocked out of true. Like on a Set-Tru chuck, the boss on the adapter is slightly smaller than the register on the chuck to allow adjustability but the adjustment screws are there not only for adjustment but also to keep radial alignment. On inexpensive adjustable chucks, sometimes you'll see very small adjustment screws, but on my Bison Set-Trus the adjustment screw are much larger in diameter.

And even with the Tap-Tru method, the boss on the adapter can serve as a "prealignment". Normally probably not too often would you remove the adapter from chuck but when you do at least it'll get you somewhat close to alignment before tapping true. After all, you should take apart the chuck & give it a cleaning/regrease periodically. Yeah, it probably serves no valuable purpose for a Tap-Tru set up but still I would want it there.


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## higgite (Jul 13, 2017)

darkzero said:


> And even with the Tap-Tru method, the boss on the adapter can serve as a "prealignment". Normally probably not too often would you remove the adapter from chuck but when you do at least it'll get you somewhat close to alignment before tapping true. After all, you should take apart the chuck & give it a cleaning/regrease periodically. Yeah, it probably serves no valuable purpose for a Tap-Tru set up but still I would want it there.




Yeah, ballpark pre-alignment is the one benefit I can see for an undersized “Tap-Tru” register. It will help keep from starting the tap-tru process with the chuck so far out of alignment that tapping it into alignment would skew the mounting bolts/screws excessively. I’m calling that a plus. Thanks for spoiling my patented flat faced adapter plate.  Back to the drawing board.

Tom


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## Bob Korves (Jul 13, 2017)

There is nothing that would prevent us from making an oversized back plate that recessed the entire width of the chuck within a shallow counterbore, with radial adjustment screws pointing inward.


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## darkzero (Jul 13, 2017)

higgite said:


> Yeah, ballpark pre-alignment is the one benefit I can see for an undersized “Tap-Tru” register. It will help keep from starting the tap-tru process with the chuck so far out of alignment that tapping it into alignment would skew the mounting bolts/screws excessively. I’m calling that a plus. Thanks for spoiling my patented flat faced adapter plate.  Back to the drawing board.
> 
> Tom



Haha, sorry about that Tom! I'll promise to keep my mouth shut on you next patent idea!


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## darkzero (Jul 13, 2017)

Bob Korves said:


> There is nothing that would prevent us from making an oversized back plate that recessed the entire width of the chuck within a shallow counterbore, with radial adjustment screws pointing inward.



And another haha! Now that's thinking outside the box, or should I say outside the chuck! I wonder if anyone has ever tried it?


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## mikey (Jul 13, 2017)

Bob Korves said:


> There is nothing that would prevent us from making an oversized back plate that recessed the entire width of the chuck within a shallow counterbore, with radial adjustment screws pointing inward.



If someone ever does this, we'll label it a "Korves-Tru" chuck because we'll always remember that we saw it here first! 

"... thinking outside the chuck!"


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## higgite (Jul 13, 2017)

I've got it! To heck with my flat faced adapter or Bob's "Korves-Tru" chuck back plate! I'm going to mount my chuck with a big coil spring between chuck and spindle, sort of like those novelty eyeball glasses, and just let it center itself. Sometimes the simplest solution are the best. "Hello, patent office?"

Tom


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## Bob Korves (Jul 13, 2017)

mikey said:


> If someone ever does this, we'll label it a "Korves-Tru" chuck because we'll always remember that we saw it here first!
> 
> "... thinking outside the chuck!"


Aw, shucks...    I cannot believe that no one has thought of this before, though I have not seen any reference to anything like it.  I do not see much down side to the idea.  The extra diameter width near the back of the chuck would be in an area that is not normally in the way of anything.  It would also be possible to turn down the rear corner of the chuck on some styles of chucks to allow it to be smaller in overall O.D., basically re-inventing the set-tru idea.  It would require a fairly large chunk of metal to make such a thing, but, to me, that is not a deal breaker.

My main issue with the idea is the entire set-tru concept.  I do not particularly see it as a real gain, and do see it as more possibilities for looseness and loss of rigidity.  We still need to dial in the work, and could have done so with a four jaw chuck in the first place.  It might be an advantage if doing quantities of parts with one diameter to chuck that do not need to be dead nuts accurate.  Scrolls being what they are, any change in diameter probably will require dialing the chuck in again.  I really think that Stefan Gotteswinter's tap-tru (or bump-tru) idea is simpler and achieves the same result with a lot less effort and material.

Edit:  If anyone wants to take this on, I will only ask for a small royalty per unit...


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## David S (Jul 13, 2017)

Actually if I am following correctly, I believe they do make such a thing.  One of the people on my clock forum in the UK has a nice small lathe set up with 3-jaw chuck and what he calls and adjustable backplate.  He says with that setup he doesn't need collets.  He chucks up the work and adjusts the back plate to get on center.

David


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## 4GSR (Jul 13, 2017)

Bob,

Hate to bust your bubble, it's been done.  Here's a link of one a good friend of mine did.  I'll see if I can get his missing pictures from him to post here

http://www.practicalmachinist.com/vb/general-archive/shop-built-adjust-true-86789/

Scroll down to the bottom for the pictures.

Ken
Here are the missing pictures from John Oder's post above.  These are courtesy of John Oder.


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## brino (Jul 13, 2017)

Bob Korves said:


> There is nothing that would prevent us from making an oversized back plate that recessed the entire width of the chuck within a shallow counterbore, with radial adjustment screws pointing inward.



Sure that would allow centering the 3-jaw chuck very accurately.
But, isn't that essentially the same as putting your 3-jaw chuck into a four jaw chuck?
-brino


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## mikey (Jul 13, 2017)

4gsr said:


> Bob, hate to bust your bubble, it's been done.



Ahhh, fame is such a fleeting thing! I sort of liked the royalty concept, though.


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## Bob Korves (Jul 13, 2017)

mikey said:


> Ahhh, fame is such a fleeting thing! I sort of liked the royalty concept, though.


Easy come, easy go!


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## Rockytime (Jul 13, 2017)

Speaking of Shars, I do not own a Shars lathe chuck but have a lot of tooling from them and am impressed.


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## COMachinist (Aug 17, 2017)

Hi all
Would be ok to ask what the darkzero "tap- tru" method is? I tried search every where and could not find a thread on it. I' getting ready to mount my plane back Bison chuck and would like do the best job possiable. For the best results.
Any info would be greatly appreciated.
CH


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## rzbill (Aug 17, 2017)

brino said:


> Sure that would allow centering the 3-jaw chuck very accurately.
> But, isn't that essentially the same as putting your 3-jaw chuck into a four jaw chuck?
> -brino



Yes. Its certainly not a new idea. The first one I saw was on a Tubalcain shop tip youtube.  He had an old 3 jaw chuck with the "4 jaw" adjustment feature built in.  His comentary indicated it was a highly desireable unit.
Sorry, don't remember the brand he said.
I was jealous of course.......


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## darkzero (Aug 17, 2017)

COMachinist said:


> Hi all
> Would be ok to ask what the darkzero "tap- tru" method is? I tried search every where and could not find a thread on it. I' getting ready to mount my plane back Bison chuck and would like do the best job possiable. For the best results.
> Any info would be greatly appreciated.
> CH



I certainly didn't come up with the method, that's just what I call it.

For plain back chucks, normally the register on the adapter & chuck have a close tight fit. Whatever the chuck's runout is you are stuck with unless you grind the jaws. For the "tap-tru" method, you turn down the register slightly so you get a loose fit. Now you can adjust the runout of the chuck by leaving the mounting bolts loose, tap with a hammer or whatever to get minimal runout, then tighten the bolts.

If you have a brand new Bison chuck w/ Bison adapter, I wouldn't do it to it but that's just me. I've only done it to inexpensive chucks.


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## COMachinist (Aug 18, 2017)

darkzero said:


> I certainly didn't come up with the method, that's just what I call it.
> 
> For plain back chucks, normally the register on the adapter & chuck have a close tight fit. Whatever the chuck's runout is you are stuck with unless you grind the jaws. For the "tap-tru" method, you turn down the register slightly so you get a loose fit. Now you can adjust the runout of the chuck by leaving the mounting bolts loose, tap with a hammer or whatever to get minimal runout, then tighten the bolts.
> 
> If you have a brand new Bison chuck w/ Bison adapter, I wouldn't do it to it but that's just me. I've only done it to inexpensive chucks.



Ok I understand. It is not a new bison in fact is an older one but new to me, and is a plain back no adjustment at all. It has never been mounted and I just bought a cast iron back plate that needs machining. If it come out good then I won't need to do this. If it does not then I will try to improve it this way.
Thanks for the clarification on the method.
CH


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