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ID Help, Please: Mystery collet?

V

VicHobbyGuy

Ultra Member
A friend found this 'in the box of bits' when he bought a milling machine (LC-15) recently.

Any ideas as to what it is?
LOA 1.5"
OD 7/8"
Thanks.
mini-IMG_1042.JPG
mini-IMG_1043.JPG
mini-IMG_1044.JPG
 
The surface finish, especially on the middle clearance cylindrical section, suggests a custom taper collet adapter of some kind that someone made for a very specific purpose.

Does it fit the LC-15 spindle?
If not, does it fit any other devices that fit the spindle?
 
Susquatch said:
Does it fit the LC-15 spindle?
Click to expand...
No. Spindle is MT3 internally, drawbar is 3/8-16
Susquatch said:
If not, does it fit any other devices that fit the spindle?
Click to expand...
Nothng obvious. The mill came with the MT3 spindle and a set of MT collets, and some end mills. There was an end mill installed in the spindle.
I'm not sure it's a collet at all, the bevel is 'wrong' - perhaps it's a tension adjustment of some kind for a shaft? But that doesn't explain the threads.
 
VicHobbyGuy said:
I'm not sure it's a collet at all, the bevel is 'wrong' - perhaps it's a tension adjustment of some kind for a shaft? But that doesn't explain the threads.
Click to expand...
Photo is misleading then. The bevel looks ok to me. Collet should tighten as it is pulled into the collet holder. That goes ok with the threads on the back of the collet which would act like a drawbar.

It isn't really "essential" that the front taper is significant or not. If the collet holder has enough taper it will tighten the collet regardess. It just won't be a very good fit and it won't provide ideal clamping.

Do you have a micrometer or Caliper? If so, what is the internal thread? What is the ID at the collet fingers? What is the main OD of the collet?

I don't think there is much doubt that it's a collet - the question is only for what.

I make all kinds of home made collets and collet holders to do all sorts of things. It's a pretty common thing a machinist might do. But good luck figuring out what they are for!

Eg, what is this? No fair looking back at my past posts.

20220822_122856.jpg


Hint - the bolt does not fit the collet but does fit the nut.

It's ok to give up early.

My only point is that your collet appears to be custom made like mine is. If so it may be a huge waste of time to try to figure out what it's for.

Your dimensions might give us a clue but still, the machining marks suggest to me that its most likely a custom collet for some unknown purpose.
 
Susquatch said:
Photo is misleading then. The bevel looks ok to me. Collet should tighten as it is pulled into the collet holder. That goes ok with the threads on the back of the collet which would act like a drawbar.
Click to expand...
Thanks for the help.
You know more than me, certainly- but I don't understand how pulling a cylinder- which is the outside profile of my friend's piece - will tighten 'fingers' at the end. It seems to me that the threads would have to drive/push the other end of the collet into a taper of some sort.

If you take your part and put a chamfer (tather than a flare or lip) on to the finger end, will it still work?

Your guess that it's some shop-made part (that just got thrown in a box) seems likely.
 
It's simple. After you insert a bigger part into the collet, it will expand bigger than the female holder and then when pulled into the female collet holder, it will tighten. This is a common arrangement, but probably not something you would normally buy.

That's the reason I chose the particular mystery collet I posted. Yes, it has a lip, and no, after removing the lip it will no longer work for its intended purpose. But it will still work as a collet and could be used for other purposes. Give up?
 
Susquatch said:
It's simple. After you insert a bigger part into the collet, it will expand bigger than the female holder and then when pulled into the female collet holder, it will tighten. This is a common arrangement, but probably not something you would normally buy.
Click to expand...
Understood - cylindrical collet holder, cylindrical collet, oversized part. Only contact area is a short length.
It doesn't seem very mechanically sound to me, but if it's common, that's interesting.
Thanks.
 
The collet is a bearing puller.

It might have worked without the lip but I was already in kill the darn thing mode so I wasn't gunna miss a trick in the book......

Here is a link to how it was made and how it works.

Post in thread 'Bridgeport Project' https://canadianhobbymetalworkers.com/threads/bridgeport-project.3521/post-48976

As you can see, collets are useful things in hundreds of ways.
 
So you drive the tapered end into the ID of a bearing until the shoulder makes it 'snap into place' then thread in your puller shaft and extract the bearing?
That makes sense to me; thanks.
 
VicHobbyGuy said:
So you drive the tapered end into the ID of a bearing until the shoulder makes it 'snap into place' then thread in your puller shaft and extract the bearing?
That makes sense to me; thanks.
Click to expand...

Almost.

First you pull the button all the way into the collet with the bolt. Then you snap the collet into the bearing, then you push the button to the other end to jam the fingers into place. Then remove the bolt. Then install a puller or slide hammer and pull the bearing out.

It came out like butter making a rather difficult problem into a piece of cake.

It's amazing what you can all do with collets (and a lathe).
 
I made one out of 16 gauge once for a pilot bushing I couldn’t get out I used a long threaded bolt with a nut on it the 16 gauge was drilled and folded over the nut then ground to fit the bushing dia and flared to grip the base the dia of thread spreads the folded part to hold the bushing.
 
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