Advise on removing a stuck collet (lathe)

I am using a schaublin 70 lathe, where a 8mm collet and it's adaptor is stuck in the headstock.

A project required me to chuck a 0.25mm rod, and I do not have a W12 collet that size.
I got a 8mm watchmaker lathe collet adaptor (forgot where/when i bought it from).
So I decided to "try" this adaptor. This is the first time i used this adaptor.

Basically this "home make adaptor" allow me to chuck a 8mm watchmaker collet onto the schaublin 70.
It is make up of 3 parts. (photos are not real and actual, they are built from my memory)




Currently, the 3 parts adaptor is stuck in the headstock.
The Part A goes in from the handwheel direction, it won't come out.
Part B and C is as seen below, protruding out.





I have tried a method using 3 jaws/4 jaws chuck onto tailstock to grab hold of part B. But it won't grab well, and it "slipping" the part B.
I know the forum has experienced people that may have heard of this problem, i wish to get the advises.
Please assist, thanks.

So you need to unscrew the draw tube from the collet?

Would a similar tool to this do it?
Royal Heavy-Duty Collet Wrench, 5C, 3 Slots - 45187 - Penn Tool Co., Inc

With the pieces screwed together and opposite tapers on both ends, the only hope is to unscrew from one end or the other. I suggest making an extractor that screws onto the “middle man” from the knob side and thread in on with with strong thread locker. Use the external part of the extractor the unscrew the middle man. Once extracted, you can the middle man to remove the extractor. Good luck!

Jon

Now we know a way to make a sub-collet arrangement that does not work. Having the W12 drawbar screw onto a second reducing drawbar that screws onto the 8 mm collet allows the W12 drawbar to unscrew and withdraw from the spindle leaving the 8 mm collet and the reducing drawbar trapped in the spindle.

So here are some ways to avoid that problem once the offending parts are removed with an extractor. The extracting tool might be as simple as a flat blade screwdriver that can be wedged inside the bore of that reducing drawbar.

1. Hold the 8 mm collet in a W12 collet with an 8 mm bore, lining up the three slits in the two collets so that the big collet closes the small collet. There is a risk of ruining the 8 mm collet if you squeeze too hard.

2. Here is how Levin makes their 3C to D (10 mm) reducer. A solid 3C collet is hardened and precision ground to hold a D collet and this adapter has a pin to engage the keyway in the D collet. The normal 3C drawbar holds the 3C adapter in the spindle. There is a second drawbar that fits inside the 3C drawbar and screws onto the D collet. See pictures below.

3. Here is how Derbyshire makes their 10 mm to 8 mm reducer. The adapter is a solid 10 mm collet with an 8 mm bore and cone to match the 8 mm collet. This reducer has no threads, but does have the usual external keyway and a pin to engage the 8 mm collet keyway. There is a special drawbar that fits inside the spindle and has internal threads to fit the 8 mm collet. You already have the reducer collet with no threads, so you just need to make a special drawbar.

Larry

vmipacman said:

So you need to unscrew the draw tube from the collet?

Would a similar tool to this do it?
Royal Heavy-Duty Collet Wrench, 5C, 3 Slots - 45187 - Penn Tool Co., Inc

Click to expand...

No. The 8 mm collet and the reducer collet are pinned inside the spindle so that they cannot rotate in the spindle. The reducing drawbar must be unscrewed from the 8 mm collet using a tool from the left end of the spindle.

Larry

What?

Does nobody just back a collet drawbar off one turn and give it a smack with a soft faced hammer anymore?

If you don't mind destroying the collet, couldn't you tap it for a bolt and use a slidehammer?

trevj said:

What?

Does nobody just back a collet drawbar off one turn and give it a smack with a soft faced hammer anymore?

Click to expand...

Works great for stuck Morse taper collets. But the problem in this thread is totally different. It is just a question of how to reach inside the left end of the spindle and unscrew a short piece of drawbar.

Larry

Arclight said:

If you don't mind destroying the collet, couldn't you tap it for a bolt and use a slidehammer?

Click to expand...

Again, that is not the solution to the problem. But it does suggest a more or less workable solution. The lathe still runs and the collet is solidly locked in the spindle and sub-collet, so the 8 mm collet could have the conical head machined away with a carbide boring bar. This should be done carefully so that the sub-collet is not damaged. Once the head is gone, the remaining portion of the collet shank and short drawbar can be pushed out the left end of the spindle. Then there is nothing to keep the sub-collet from being removed. Chinese 8 mm collets are very cheap, so there is little loss.

I think the screwdriver trick is still the best way.

Larry

L Vanice said:

Works great for stuck Morse taper collets. But the problem in this thread is totally different. It is just a question of how to reach inside the left end of the spindle and unscrew a short piece of drawbar.

Larry

Click to expand...

You have called it exactly. It is now akin to trying to remove a well-seated Red-Head or Wej-It anchor bolt!

The solution requires the REVERSE of what the OP has been attempting:

- Do NOT try to pull the collet toward the TS.

- Push it away from the TS instead.

This will seat it ever so VERY slightly DEEPER.

Which will relieve "some of" the tension between its taper and the stub drawbar.
Making said stub drawbar ever-so-slightly easier to back-off.

Even so, you'll not get the OTHER drawbar to be able to unscrew it. Nature of each beast.

You'll have to apply force to it with a hasty-rig internal expander. Plumbers need these -in larger sizes - to remove broke shards of Iron pipe PREVIOUS plumbers have run into Brass fittings all over Hong Kong. There's a seriously well-stocked plumbing shop near the Wanchai MTR station as may have one small enough in their upper storage deck if not at street level. Or so it seems! I mean if they can shrink half of Reclamation Street into one room...



ELSE a tool that can dig into the walls of the stub drawbar.

- candidates include "Easy Outs", left-hand drills, taper reamers, diamond-point or cape chisel or steel shaped accordingly.

In all cases, "reach" to get the tool into the arse-end of the stub drawbar down a skinny spindle bore is part of the challenge. If you can get "enough" pressure relieved by sinking the collet deeper, the aforementioned screwdriver blade might do it. Not just flat. Phillips, Torx, or square are also valid candidates.

The adaptor needs to be redesigned "regardless", the collet already insulted by the bit of crushing with chuck jaws my no longer run true nor release cleanly, so the ONLY thing you must try to protect is the spindle. And its bearings.

Protecting sanity and good-nature, avoiding excessive use of "foul language" in Guangdonghua are as-had. AKA mere "bystanders" subject to possible collateral damage.

寄件者

L Vanice said:

Again, that is not the solution to the problem. But it does suggest a more or less workable solution. The lathe still runs and the collet is solidly locked in the spindle and sub-collet, so the 8 mm collet could have the conical head machined away with a carbide boring bar. This should be done carefully so that the sub-collet is not damaged. Once the head is gone, the remaining portion of the collet shank and short drawbar can be pushed out the left end of the spindle. Then there is nothing to keep the sub-collet from being removed. Chinese 8 mm collets are very cheap, so there is little loss.

I think the screwdriver trick is still the best way.

Larry

Click to expand...

I will try machining away the collet head, it is a levin collet

I am unclear about the screw driver trick, can you please explain again.

jdgoguen said:

With the pieces screwed together and opposite tapers on both ends, the only hope is to unscrew from one end or the other. I suggest making an extractor that screws onto the “middle man” from the knob side and thread in on with with strong thread locker. Use the external part of the extractor the unscrew the middle man. Once extracted, you can the middle man to remove the extractor. Good luck!

Jon

Click to expand...

This will be the method i will try too, thanks

Did you back off the screw only a bit and then tap knob lightly with a dead blow hammer? First things first. Once you get it out check for a sheared pin.

Asus said:

I will try machining away the collet head, it is a levin collet

I am unclear about the screw driver trick, can you please explain again.

Click to expand...

A common form of screw extractor is a tapered square with sharp corners. They are driven into a hole in a broken screw and used to turn the broken screw to remove it from the tapped hole. Most flat blade screwdrivers have tapered ends, a handle and a long blade. Find a screwdriver that reaches down your lathe spindle and partly enters the hole in your short drawbar, Then grind the edges of the blade, producing sharp corners on the tapered end. Lock the lathe spindle and push hard, driving the end of the screwdriver blade into the hole in the short drawbar while twisting the handle counterclockwise. It should not take much torque to unscrew the short drawbar from the 8 mm collet. The US$1500 Levin WW 8 mm size 2.5 collet and the W12 subcollet should remain undamaged.

Then you can make a proper one-piece drawbar to tighten the 8 mm collet with the original W12 drawbar not in the spindle.

Larry

Trueturning said:

Did you back off the screw only a bit and then tap knob lightly with a dead blow hammer? First things first. Once you get it out check for a sheared pin.

Click to expand...

Are you referring to the same technique Larry is describing ? I haven't try it yet.

L Vanice said:

A common form of screw extractor is a tapered square with sharp corners. They are driven into a hole in a broken screw and used to turn the broken screw to remove it from the tapped hole. Most flat blade screwdrivers have tapered ends, a handle and a long blade. Find a screwdriver that reaches down your lathe spindle and partly enters the hole in your short drawbar, Then grind the edges of the blade, producing sharp corners on the tapered end. Lock the lathe spindle and push hard, driving the end of the screwdriver blade into the hole in the short drawbar while twisting the handle counterclockwise. It should not take much torque to unscrew the short drawbar from the 8 mm collet. The US$1500 Levin WW 8 mm size 2.5 collet and the W12 subcollet should remain undamaged.

Then you can make a proper one-piece drawbar to tighten the 8 mm collet with the original W12 drawbar not in the spindle.

Larry

Click to expand...

Larry, is this what you described ? I will try this method, thanks.

These machines are designed intelligently. Many skills which we who have used these kinds of machines are not used very much. Every manual machine has its capabilities and keep in mind pre CNC these machines made everything.

Ability, craftsmanship and skill are diminishing and largely unknown. That is why we would simply walk up and fiddle with this and that and do the simplest thing first. With the internet even most of the time a problem can be easily solved even though it is a lot easier to do this in person.

That was designed to work and a lot of money went into designing and making that fine machine that you are blessed with.

Many so called experts and computer jockeys of Mastercam fame think they know everything. Truth is most of what is needed to make a part can easily be hand written with practice if allowed in any shop. Now features which are complex enough to need a programmer who simply enters in data properly and pushes a couple of buttons to produce three weeks of code take it for granted that the software is doing most of the work and they are there to facilitate the software.

In the real world a experienced machinist is best in that position and where they are not such they do well to ask a experienced machinist how to regulate the process they program out otherwise good parts can not come out if done wrong.

Anyway many persons even think money can not be made with them at all. I have used them a lot and completed parts before a programmer admires themselves in a mirror and combs their hair and complains about how they should be making more money.

I was going to suggest a square bar with a round roller inserted into the collet, rotation should cam a corner into the collet split
Mark

Asus said:

Are you referring to the same technique Larry is describing ? I haven't try it yet.

Larry, is this what you described ? I will try this method, thanks.

Click to expand...

Yes, exactly.

Larry

boslab said:

I was going to suggest a square bar with a round roller inserted into the collet, rotation should cam a corner into the collet split
Mark

Click to expand...

For those unaware of what a Levin size 2.5 (.25 mm or .0098 inch) WW 8 mm collet looks like, here are some pictures of a full set of Levin WW collets and the face of a 2.5 size. The current price from Levin for the size 1, 1.5, 2 and 2.5 collets is $1500 each. Chinese 8 mm collets are only $14, but .3 mm may be the smallest size available. Just to be clear, the collet body is 8 mm (5/16 inch) diameter.

Larry

L Vanice said:

Works great for stuck Morse taper collets. But the problem in this thread is totally different. It is just a question of how to reach inside the left end of the spindle and unscrew a short piece of drawbar.

Larry

Click to expand...

OK, got it. Some moron made the adapter too big to push out the front, and too loose to stay on the other drawbar. Morons!

Sharpen the edges of a piece of key stock and tap it into the inside of the shitty adapter until it grips, then carefully unscrew it.

Or solder a Easy-Out to the end of some tube, reach in and do same.

Destroy the frikken stupid adapter and build a full length one so this dumb shit does not happen again.