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Ordered a 6 Jaw Lathe Chuck

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Ray C

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#1
I've been thinking about a 6 Jaw chuck for a long time and finally ordered this one today. It should be here in a few days. I'll let you know how it goes and maybe do a write-up on it. Like all my chucks, it will probably need a little TLC. I've always wanted to get some really high-end chucks but, just can't justify it.

https://www.amazon.com/gp/product/B07523QQDR/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

Does anyone out there have this same chuck? What do you think of it?

Ray
 

pstemari

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#2
I'll be curious to see what sort of runout you get once it's mounted.

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Z2V

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#3
I’ll be watching for you write up. I’ve given thought to a six jaw also.
 

Dabbler

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#4
that looks like a great deal.When you mount it, can you please chuck up something around 1/2" and 2" and let us know the runouts? The grinding of the scroll is everything in a good lathe chuck, and I am super curious as to how well they are making it! An 8" might be in my future!

thanks!! good luck!
 

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#5
I seem to recall a posting a while ago who I believe purchased this chuck, and it needed a fair amount of TLC. I recall something to the effect that it ended up on his rotary table. I think it was Darkzero, might shoot him a PM if no response here. The other 6 jaw that is in the middle of the pack price wise, and there were a few positive reviews on in this forum many years ago was the Shar's 6J Set-True chuck. One review is at the end of this post: https://www.hobby-machinist.com/threads/pm1340gt-with-a-3-jaw-pratt-burnerd-6-setrite.30758/page-2
 

Ray C

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#6
All,

Rest assured, I'll measure it for runout at a few diameters and check balance at different speeds before taking it apart for inspection or adjustment. My current 3J holds about 2-3 thou over it's useful range and parts can be bumped and re-positioned to improve that a little. The issue is that I'm a fan of carbide inserts which requires greater cutting pressure and therefore, greater jaw pressure to hold the work. I'm hoping the 6J will cut down on the visible bite marks.

On more than one occasion, I've boxed myself in a corner using the 3J and in a mad effort to improve runout, took an allen wrench, loosened the bolts on the back and tapped things around to squeeze some extra accuracy out of the setup. Hey... All's fair in love and war...

I was eyeing the Shars set-tru chuck for a while but can't justify the cost even though it is priced attractively. I remember when Will got his but don't remember how it all turned-out.

Dabbler... This same style chuck is available in 8" from CME. FWIW, I've purchased a lot of stuff from CME over the years and I've been very satisfied with them and their products. They are like a smaller version of Shars.

Ray
 
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#7
I started to buy a chuck from them but instead bought another one out there. I've bought a couple of L-0 and L-00 back plates from them. They were nice and very accurate. They could have done a little more deburring to the back plates, some sharp edges, nothing a file and some emery wouldn't fix. My advice, as many have said, when you get the chuck, take it apart, clean it, put a little grease with moly on the gear side of the scroll, dab the same grease on the teeth on the jaws and assembly. Don't over grease the chuck. If you do, you will wear excess grease as a racing stripe on the left side of your shirt for months on end until depleted from the chuck.
 

Ray C

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#8
Plenty of eye candy today...

Well, it seems CME wasted no time shipping this. It arrived much faster than I imagined possible...

So far... It's impressive. I've been inside quite a few chucks and this is really quite a surprise. It has not been spun on the machine yet but will in a day or two.

It arrived as two items, the backplate and chuck. They are not pre-fitted and, in my opinion, it's not reasonable to expect they would be. BTW, the proof shaft on the table is one I made a few years ago. It's 1" diameter, 1045, TGP and varies no more than +/- 0.0003 over 2 feet. I'll check the chuck with this when the time comes. Unfortunately, I do not have a proof shaft of say 2 or 3" diameter but, there are other tricks up my sleeve.

Anyhow, the chuck came packed in heavy cosmoline-like shipping oil. Anytime you get something packed in grease, it's a sign it should be somewhat disassembled (or at least flushed-out) and lubed properly. As it arrived, it's stiff to spin with the wrench but, I would expect that given it's still in the packing oil and needs to be flushed out.

IMG_20180124_185652.jpg


Here's a few more pics of the guts. Everything looks fine (once you get past the smell of gritty cosmoline) and is a very nice design. I did a quick nondestructive hardness test (LEEB type) and just as I thought, it's hard... -really hard... RC 62.

IMG_20180124_190029.jpg IMG_20180124_190111.jpg IMG_20180124_190227.jpg

The Jaws are very uniform and they took the time to number and serialize them. There are burrs on some areas but, I've seen a lot worse. All of them weighed 437 grams -exactly.

IMG_20180124_190720.jpg IMG_20180124_190742.jpg

Every possible dimension was measured and compared to the same dimension of a different jaw slot. Amazing... Basically, dead-on everywhere I checked with no variances greater than 1 thou -anywhere. The machining is bright and clear in all the areas where bright and clear machining is needed. The thickness of the spiral thread was measured in about a dozen places. -Dead-on everywhere. I do not have a means to measure the the spiral itself however. The proof will be in the pudding.

IMG_20180124_191757.jpg IMG_20180124_191901.jpg IMG_20180124_192102.jpg IMG_20180124_192201.jpg

And best of all, the wrench is decent quality too (no idiot spring on there).
IMG_20180124_192249.jpg

Pleasantly surprised so far. I'm going to deburr a few areas, flush this thing out and get some proper lube in there, slap the back on (as-is) and give it a spin soon. I'll check it on a static balancer beforehand as a measure of caution. I've mounted and tuned a couple dozen chucks and never had a generic backplate that didn't need some tweaking so, there's no doubt this will come apart again for fine tuning. Also, I will probably do a more detailed job of deburring the second time around and am also thinking of converting this to a set-tru type chuck. At quick glance, it should be possible.

Ray
 

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#9
Can you document your process on converting it to a set-tru? I've never done one, nor had to, but I am quite interested!
 
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#10
Converting to set tru? Yes I would sure like to see that.
 
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My set true adapter is easy to make. Turn down the register on the back plate about .010" so it is loose on the chuck body. Mount, leave the socket head cap screws hand snug. Indicate the test bar, bump the OD of the chuck with a block of brass or aluminum. Go easy bumping. When you think you got it, tighten the cap screws, indicate again. Should be able to get it dead nuts. In the 15 years of running a 6" chuck set up like that, I've never knocked it out of true.
 

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#13
cool!
 

Ray C

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#14
Well, well... Surprised again. Because the chuck came in packing grease, all the parts were tossed in the solvent tank then cleaned with 90% alcohol then, lightly lubed. It operated like a totally different piece of equipment. Very smooth. Next step was to fit the backplate to the spindle.

Two words of caution:

1) When working really close-in to a spinning chuck, watch your clothing, fingers... -all body parts.
2) NEVER insert a D-type backplate in a spindle without having the lug locking bolts installed. If you do, that lug can spin when you tighten it and it will not come off w/o taking drastic measures. See the pic...

Those little screws MUST be installed to prevent the lug from spinning.
IMG_20180125_185001.jpg

Right out of the box and to the credit of the manufacturer, the plate is too tight. If it were too loose, give it away to someone with a bigger spindle. The cams are tight and you can see in the image the tiny light-gap between the spindle and plate. Hopefully it renders here on this website. Anyhow, that's a no-go! It must sit perfectly flush when the cams are pulled tight.

IMG_20180125_183642.jpg

How to fix it: Easy!

In my case, based on experience, I estimate the tapered hole is about 2-4 thou too tight. Take a file or some kind of sharp scribe and scratch a radial line in the taper that is about 1-2 thou deep. If you're so inclined, put some dykem on there. Next, mount an existing shop chuck and grab the new plate from the bore.

IMG_20180125_184058.jpg
IMG_20180125_184439.jpg

Next, take a stick and some rough sandpaper and open-up the tapered hole. Use your good senses to be safe and also use a little finesse to maintain the tapered angle. I was spinning about 300 RPM.

IMG_20180125_184610.jpg

After 3 tries of taking it off, re-installing the lugs (AND lug lock screws), I got it nailed pefectly. When I put a little love on those locking cams, the backplate sits flush and an indicator shows absolutely no runout that I can see. The factory that made this, did a good job. It's flat on both sides.

IMG_20180125_190805.jpg

Next, the body was bolted to the plate. Before tightening the screws, the body was indicated until it ran with no perceptible runout. In reality, that appeared to be within a total of 1/2 thou using a TDI.

Next, the proof shaft was mounted and then came the surprise. At the jaws, it was +/- 1 thou. At 18 inches, it was +/- 1 thou. Mind you, I did nothing at all to the jaws other than clean and lube them. I have a video of it but, the system is complaining about the file size. If there's a way I can upload it, I will. It's only 1 minute long.

IMG_20180125_192830.jpg


Finally, upon close inspection, this chuck can be converted to a set-tru in "no-brainer" fashion. I will do it some day soon on this chuck but before then, I'll post a PDF image of the modifications to make. It's all but trivial.
 

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Ray C

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#15
So, here's how I would modify this chuck to make it a set-tru. I've done this same mod on other chucks for friends and years ago, did it for some folks here on this list.

See the picture. The blue parts represent your existing backplate and chuck body. There's a lip on the backplate that needs to be turned down in dia about 5-10 thou. Next, make a ring of that same diameter and affix it to the backplate. How you do that depends on your configuration. You will bolt it for sure (no welding) but, you must decide if the bolts are from inside to outside or, other way around. Once that is in place, drill tap 4 holes 90 degrees apart on your chuck body. Depending on size of chuck use 5/16 to 3/8 socket SET screws. Those screws must always be below the surface of the chuck body or, you will have a terribly dangerous situation that could tear your palm in half if you put your hand on the chuck.

When I do this new chuck, I'll show the precise dimensions. I only know by visual inspection this is very possible. I will probably need to put some slight clearance cuts in the collar to clear the 3 bevel gears that tighten the pinion plate. No problem at all, plenty of room in there for this.

Have at it.

ChuckMod.JPG

PS: I just ordered one of these chucks in 8" version. Only 40 bucks more than the 6". -That's a no-brainer.


Ray C.
 
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#16
Ray, I'm glad the chuck came great! Even if you had to fine tune a little.

The two back plates I've bought from these guys, CME, had an interested feature I was surprised anyone would use.
See the pictures.

20180125_194938.jpg 20180125_195222.jpg
It has a keyway that was cut using a wire EDM.
Last picture is the rough thread start that I'll have to take a file after it to fix it up.

20180125_194957.jpg
 

Ray C

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#17
Now Ken... how much fun would it be if we didn't have to mess and tinker with stuff before we used it? Half the fun of doing this, is getting the opportunity to screw it up in our own, special and unique way. :geek:

Anyhow, for all I know, Amazon sent me the good one because I do so much business with them. I'm hoping they give me the same consideration on the 8" I just ordered.

.... Right now, the chuck is good enough as-is but, I will do the set-tru mod. Before I do that, I will take a small file or stone to some of the burrs on the jaws. Aside from cleaning the grit and storage oil, I did not change anything other than opening-up the taper on the backplate.

Last, in a day or two, I'll do more testing with bigger shafts to see if the scroll is even. I suspect it will be fine.

Ray
 

ddickey

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#18
Next, the proof shaft was mounted and then came the surprise. At the jaws, it was +/- 1 thou. At 18 inches, it was +/- 1 thou. Mind you, I did nothing at all to the jaws other than clean and lube them. I have a video of it but, the system is complaining about the file size. If there's a way I can upload it, I will. It's only 1 minute long.
Why is this? I have two old chucks that came with my lathe and they get really bad the further out you go.
I bought an NOS Rohm three jaw direct mount and there is very little difference closer towards the TS, or I should say significantly less then the old ones.
 

Ray C

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#19
Why is this? I have two old chucks that came with my lathe and they get really bad the further out you go.
I bought an NOS Rohm three jaw direct mount and there is very little difference closer towards the TS, or I should say significantly less then the old ones.
There could be many problems. When diagnosing these issues, you start at the spindle and work your way forward.

1) Are the spindle bearings OK and have proper pre-tension?
2) Is the spindle in a flat plane parallel to the plane of the bed?
3) Is the spindle in a flat plane perpendicular to the bed?
4) Is the back of the backplate flat to a plane perpendicular to the axis of the spindle?
5) Is the front of the backplate in a plane also in a plane flat and perpendicular to the axis of the spindle?
6) Is the back of the chuck flat and properly seated to the back plate?
7) Are the jaws grabbing the piece and holding in a straight line along the axis of the spindle?

Most likely, #7 is your problem but, don't mess around and start adjusting or grinding your jaws until you verified 1 thru 6.
Chucks get old and clapped-out too. The jaws get worn in the front more than the back. The jaw slots gets worn etc...

As far as items 1-7, an experienced machine rebuilder would probably have many things to add. I'm not an experienced machine rebuilder -not by any means but, you won't go wrong by running down that checklist. Warning... It takes a lot of tools and good equipment to check a machine. Recommend you don't make hasty decisions or permanent modifications until you research the topic and have the basic tools for the task.

Ray
 

Ray C

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#20
Just wanted to pass along a thought to folks in case they decide to get this chuck or one like it... The slots for the replaceable jaws have fairly sharp edges and burrs. When the chuck is spinning, these edges are a hazard. Take a look at that edge right at my fingertips.
IMG_20180131_184747.jpg

Took about 3 minutes per jaw to grind that off with a die grinder and follow-up with a hand file.
Much better now.

IMG_20180131_192327.jpg

In other news, this chuck is running very well and the set-tru modifications is not worthwhile to me. Everything re-seats within 1/2 to 1 thou and a 24" proof bar measured at 18" is typically 1.5 to 3 TIR. Old saying... If it ain't broke, don't fix it.

In other news, I have not checked the lathe for a while so, I did a "RDM" health-check. It was out a tiny bit. It took about 15 minutes to make an adjustment and as near as I can tell, using a proof rod, the bed is parallel to the spindle within 0.0007 over 18". I could probably try to tweak that but honestly, the TDI setup and other factored-in errors are probably on-par with the measured values, so I decided to take it and run to the bank with it.


Ray C.
 

19E60

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#21
Rats, mine just arrived today and I was looking forward to seeing your set-tru procedure on this chuck, Oh well I will muddle through and see what I can do.

Chuck looks pretty good overall, some rust on one jaw and a lot of grit inside but I'm optimistic it will end up fine.
 

Ray C

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#23
Rats, mine just arrived today and I was looking forward to seeing your set-tru procedure on this chuck, Oh well I will muddle through and see what I can do.

Chuck looks pretty good overall, some rust on one jaw and a lot of grit inside but I'm optimistic it will end up fine.
If you really need help with the detailed design, I could spec mine out and post detailed drawings. Let me know if you need the diagram. I'm off-the-charts busy with my daytime/real job and the chuck, as-is, stays true to the tune of a few thou over 18 inches. That's pretty good.

Just as with all self-centering chucks, it's a good practice to wiggle the part as you tighten the jaws. This helps the jaws settle into an optimal position right before snugging them up.

When I took the back off after initial assembly, I cut the shoulder back a few thou. I didn't use a cutter; I used a flat file while it spun on the spindle. Upon putting the chuck body back on, a proof bar was mounted, the bolts were lightly snugged and the body was tapped until the indicator zeroed. Since tightening the bolts, it has remained true.

Ray
 

19E60

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#24
Ray, no worries I will figure it out. Just yanking your chain a little, but thanks for the offer.
 

Ray C

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#25
Here's the 8" big brother. I got tired of it sitting in that cute little box. The crate is actually quite nice and is very re-usable. My wife was eyeing it so I suspect it will suddenly disappear.
IMG_20180206_181036.jpg

Aside from an extra 2 inches and what feels like 40lbs, it's identical to the other one inside and out. I took no photos of the insides of this one. Just look back a few posts and see the 6" guts.
IMG_20180206_181258.jpg

After rinsing all the parts individually, applying a light layer of grease and re-assembly, this one was a little stiffer to operate than the smaller one. The jaws were a slightly tighter fit. No worries, in time all chucks loosen-up.

This is really a case of Deja-Vu. The backplate took a touch of adjustment to open-up the tapered hole then, the registration shoulder was turned-down just a few thou so I could loosen the main bolts and bump it around if ever needed.

Just like the other chuck, this one was running like a champ right out of the starting blocks. With the RO adjusted to zero 1" from the jaws, it had +/- 1.5-ish at 20 inches down range. The TIR looked to be 3.25 thou. I was using a half-thou indicator and the probe was properly tangent to the shaft to get a decent reading.

FWIW, I ordered one of these on eBay and one on Amazon. I don't know this CME seller from Adam or Eve but all I can say, is they carry decent cheap chucks. I started cleaning this thing up at 6:45pm and was taking TIR measurements in under 90 minutes. I can live with that and suspect these chucks will be the last ones I'll ever need to buy.

IMG_20180206_201350.jpg

Ray
 

Ray C

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#26
Here's the 8" big brother. I got tired of it sitting in that cute little box. The crate is actually quite nice and is very re-usable. My wife was eyeing it so I suspect it will suddenly disappear.
View attachment 257088
Ray
LOL: I called it! Yep, the cute little crate vanished. Found it up in the wife's art/craft room. I'm sure it will be put to good use...


Ray
 

Ray C

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#27
Quick update on a little tweak to the chucks.

These are abrasive scouring wheels that fit in a die grinder. I believe these were from Lowes, Home Depot or possibly Harbor Freight and are inexpensive.
IMG_20180208_210559.jpg

On both chucks I did a quick pass over all the external burrs on the jaws and a very light touch on some of the outer exposed areas of the body that could possibly contact skin. For the record, I never put my hand on a rotating chuck...
IMG_20180208_210700.jpg

Anyhow, that pretty-much sums-it-up for these two chucks. They are running very well and hold a pretty good zero (about 1 to 1.5 thou) across a range of diameters. I've checked at ranges between 1" to 2" on the small chuck and up to 3.5" on the large chuck. They are very nice and I'm pleased with them. If I ever decide to add the set-tru feature, I'll post that here. For now, these are good enough and if I need to really dial in, I'll loosen the bolts and bump the body to fine-tune the piece.

Regards

Ray
 

3strucking

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#28
where can i get a test bar like yours?
 

Kernbigo

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#29
here is a cushman 6" i converted to a set-tru, done it several years ago and it works great
 

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Kernbigo

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#30
buy a piece of thompson rod, it is used with thompson ball linier bearings
 
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