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Help with a collet chuck

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Forum topic by Biggamefish posted 07-28-2014 11:29 AM 776 views 0 times favorited 18 replies Add to Favorites Watch
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Biggamefish

14 posts in 76 days


07-28-2014 11:29 AM

I received a collet chuck system.. I also bought some mandrels to use with it. Everything seemed to fit on the lathe great but when I turned it on I get a wobble. I am pretty sure that this isn’t common right? What do I check first to get the wobble out?

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18 replies so far

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SCOTSMAN

5367 posts in 2241 days


#1 posted 07-28-2014 12:43 PM

This is quite a common problem! First check you don’t have any little bits of dust or swdust between the register on the chuck and the spindle. This can happen quite frequently on a new fitting,especially around the shoulder.
it must come up to and meet the spindle shoulder very firmly and without interuption I.E any crud no matter how small can cause this believe me.I have had it on new chucks of mine it takes a few minutes to fix.I would emphasize the chuck must sit firmly against the shoulder see terminology on google if not sure.It might be a small manufacturing problem that needs a file or other sharp instrument taken to it. If in any further doubt show us plenty of photo’s of the set up you have, at all stages. Also show the spindle and the threading area at the back of the collet chuck it all needs to be super clean assuming it has been cleanly machined and no bits of metal swarf are interfering with the fit.Keep us informed and yes you can contact me privately if you want one on one advice I will be only too happy to help you my friend regards and good luck in the meantime Alistair

-- excuse my typing as I have a form of parkinsons disease

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Biggamefish

14 posts in 76 days


#2 posted 07-28-2014 01:20 PM

Thanks so much for the info scotsman. I was going to take pics but ran out of time. I will keep you posted after trying the few things that you said. If it persists I will definitely take pics/video.

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Biggamefish

14 posts in 76 days


#3 posted 07-30-2014 01:41 AM

So I think I have found the problem. The collar doesn’t seem to be cut to center. It would be where the collet seats.

I don’t think that is right?

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bigblockyeti

1548 posts in 377 days


#4 posted 07-30-2014 03:07 AM

If it’s not cut concentric then that’s definitely going to be a problem.

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Jim Jakosh

11480 posts in 1762 days


#5 posted 07-30-2014 04:08 AM

From your photo, it looks to be way off center, but they machine these parts in one set up on a cnc lathe so I would think it would be cut almost perfect. That photo does not look like it was taken perfectly square with the face, because the threads on the left are showing more than on the right. I would mount it in the lathe without a collet in there and put an indicator on the tapered surface that pulls the collet tight to check its concentricity!

Just thinking about how it works, what is behind the collet to seat when you pull it tight with the nut?
Does it go into the Morse taper of the spindle??
...............Jim

-- Jim Jakosh.....Practical Wood Products...........Learn something new every day!! Variety is the Spice of Life!!

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justahobby

19 posts in 1234 days


#6 posted 07-30-2014 02:01 PM

I bought the PSI collect chucking system (LCDOWEL), and the sleeve nut has a single eccentric ring/ shoulder machined in it just as your appears to be. I can easily tip any of the collect inserts about 20 degrees and it slips into the nut fully….proper orientation required, naturally. Then the chuck compresses the insert cleanly and if I recall correctly, I measured ~0.002” radial runout with the 1/2” insert.

I am still very new to lathe work, so I called PSI support and all I can remember is coming away more confused due to both my and the support person’s lack of knowledge. After a couple uses, it dawned on me that the eccentric ring fits the grooves on the outside of each of the collet inserts to remove the compressed collet insert when unscrewing. As you should be able to make out in the image below, the front face (and therefore the seating surface of the sleeve nut) is concentric, which is what matters.

(Sorry the image is so large, but I think you get the gist.) If you’ve already got the inserts fully and properly seated against the sleeve nut interior face, with the faces of the insert and nut parallel, then I believe you have a runout issue.

I am still a novice, so if my terminology is off, this was my reference:
http://www.pennstateind.com/library/LCDOWEL_ins.pdf

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Biggamefish

14 posts in 76 days


#7 posted 07-30-2014 06:12 PM

When I say ground into where the top of the collet sits. If you look at justahobby’s pic the collet face is down and the angled edge sits where it is ground on the collet. I know the picture is slightly off center but you can see that the two circles don’t come close to lining up.

This isn’t common with the cuck collars is it?

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justahobby

19 posts in 1234 days


#8 posted 07-31-2014 01:39 PM

Just for reference, this is the interor of my chuck collar/ nut:

It appears similar to yours, rotated by a few degrees CCW, I think. The green lines are the collet insert mating face (~60deg inclusive angle to front face) and the blue lines are the back plane of that edge. Then there is a ~1mm gap before the beginning of the eccentric collet “shoulder”, the back plane of which is denoted by the red lines.

The manual for this chuck states “This product does not assemble like any other compression type fitting. ... The collet will “SNAP” into place when correctly assembled.” Mine does not need to snap, but hey, it works:

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Biggamefish

14 posts in 76 days


#9 posted 07-31-2014 03:05 PM

Thanks justahobby

I got confirmation from the tool company that this is the way they are made. They also gave me instructions on how to mount it which is a little different than what i read up on the forums. The company says to put the collet in the collar then the collar on the chuck and then put the chuck on the lathe. So I will be trying that and will keep you posted.

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Biggamefish

14 posts in 76 days


#10 posted 08-04-2014 09:26 AM

Alright the saga continues!!! I went back and put it together like the company told me to. I still have the wobble! I proceeded to put on a four jaw chuck with the mandrel and boom runs straight. So I know it isn’t the lathe. The only thing I can think of is that the chuck isn’t sitting on the head stock completely. In the picture you can see a gap. Is that right? The four jaw chuck site all the way back.

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TheDane

3787 posts in 2319 days


#11 posted 08-04-2014 01:38 PM

No, it isn’t right. The collet chuck isn’t deep enough to allow the spindle to be fully seated. I would return it and demand my money back.

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

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TheFridge

828 posts in 142 days


#12 posted 08-04-2014 01:59 PM

Then throw it at them if they won’t take it back.

-- "We build our workshops. Then we enjoy the fruits of our labor by laboring for more fruits." - Me

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69BBNova

326 posts in 873 days


#13 posted 08-04-2014 06:19 PM

Judging by its size that seems to be an ER32 collet chuck, Hard to tell without seeing it in person…

On ER collets the collets are always put into the collet nut first at an angle then snapped to sit straight then inserted into the main body. that’s why inside of the nut is offset, and why there is a groove around the outside dia of the collet. It also helps to pull the collet out of the body is it sticks a bit. To remove the collet from the nut apply side pressure to the collet and it pops out…

But yes the collet body isn’t fully seating on to the spindle anyway so something is not quite right.

Edit…I was just thinking of another possibility that the spindle length from the shoulder to the end of the threads may actually be to long for that brand of collet…

Yours looks to be a Beall which is what mine is but is used on my South Bend 9a… I’ll check the thread length on mine for you.

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Jim Jakosh

11480 posts in 1762 days


#14 posted 08-07-2014 10:50 PM

I have an idea for you where you won’t need that collet set up. I started out with wood collets but now have hard plastic ones with a full range of sizes. But, the wood ones worked very well as long as I used them.

Turn a tenon on a piece of hardwood and then cut the piece to about 1” long. For a 1/2” collet, make the tenon just a little bigger than the minimum your chuck needs to tighten. Then drill or bore an accurate size 1/2” hole into it. Mark the jaw number on the tenon so you put it back in at the same location. Then take the collet out and cut a slot from the outside to the inside hole so it can spring open and closed in the chuck. Then at every 90 degrees cut 3 more slots about halfway in from the outside to give the collet equal movement when tightened. I don’t have a photo of mine now but I use them for external grabbing and also internal grabbing for rings and bracelets!..............Jim

-- Jim Jakosh.....Practical Wood Products...........Learn something new every day!! Variety is the Spice of Life!!

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horologist

95 posts in 2395 days


#15 posted 08-08-2014 01:32 PM

I have a PSI chuck as well and have found it to be reasonably true. As others have mentioned your setup doesn’t look to be seated properly. Also, the longer the collet chuck assembly the more pronounced your error will be. If you are holding metal mandrels and need something more precise you might try collets that are designed to fit the Morse taper of your headstock. I did a comparison of several collet systems a while ago:

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-- Troy in Melrose, Florida

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