broken tool stuck in heat shrink holder

Karl_Kunkle · Dec 7, 2016

Hi,

I have a couple of 5/16" diameter cat 40 heat shrink holders with carbide tools broken off flush with nose. The through hole is only 1/16". I'm trying to save the holders.

I have a haimer induction shrink fit station.

I tried double heating nose and banging it out. That failed. Next was double heating holder while chilling the the bore with cold air and water. Failed.

1st thought of having the tool burned out with edm. That was shot down by edm operator.

Any ideas? Thanks

trevj · Dec 7, 2016

EDM guy give any reason?

Seems that punching a hole through the shank and being able to hook a puller behind the end of the remnant of the end mill shank, would be the path to take.

Any damage to the holder that would stop the shank coming forth that way?

Cheers
Trev

HuFlungDung · Dec 7, 2016

I don't know anything about EDM, but the guy shouldn't have to try to burn exactly centered, because he could leave a thin shell to be cracked out later. Or, he could edm threads in the carbide and then pull it out

Would it work to try to pump the thing out with a grease gun? You'd have to make a good fitting to go in where the retention knob goes, if there is passageway through that way. Take care around the high pressure stuff.

capital7 · Dec 7, 2016

HuFlungDung said:
I don't know anything about EDM, but the guy shouldn't have to try to burn exactly centered, because he could leave a thin shell to be cracked out later. Or, he could edm threads in the carbide and then pull it out

Would it work to try to pump the thing out with a grease gun? You'd have to make a good fitting to go in where the retention knob goes, if there is passageway through that way. Take care around the high pressure stuff.

EDM threads would be a little more expensive than just burning a hole through, with the same end result.

Not sure why the EDM guy thought it would be a problem, drills get burned out all the time, same with taps...

DDoug · Dec 7, 2016

Why not machine that 1/16" back hole out to 1/4" ?

First I would try a piece of 1/16" drill rod, they are very tough.

Next (if that didn't work) machine out the hole and try a large punch (always with the induction heat on
of course)

John Welden · Dec 7, 2016

Get this system instead of shrink fit.

TDegenhart · Dec 7, 2016

Good system when you break a tool, but you have with the collet one more tolerance buildup and sliding wear to contend with.

Tom

D.D.Machine · Dec 7, 2016

I think the grease gun would work ,,, I use a gas torch on my shrink holders and have had good luck with it... use a gas torch and grease gun outside in that its going to smoke a lot.

Rewt · Dec 7, 2016

Gotta agree with our resident curmudgeon on this one, shrink fit is not the way to go. We did the research, and your example came up from no less than 4 toolmakers, w/o them seeing the equipment. There is no reason, however, a competent wire man couldn't solve your problem by lunch. I know mine can.

John Welden · Dec 7, 2016

TDegenhart said:
Good system when you break a tool, but you have with the collet one more tolerance buildup and sliding wear to contend with.

Tom

Keep them clean and they work great. The benifits far outweigh any negatives.

Mike C. · Dec 7, 2016

How much is a new holder versus the amount of time spent trying to fix this?

TeachMePlease · Dec 8, 2016

Rewt said:
Gotta agree with our resident curmudgeon on this one, shrink fit is not the way to go. We did the research, and your example came up from no less than 4 toolmakers, w/o them seeing the equipment. There is no reason, however, a competent wire man couldn't solve your problem by lunch. I know mine can.

Wire? Where's the start hole coming from? I was thinking sinker...

Rewt · Dec 8, 2016

We would use an edm drill we have then thread and burn, but that's just because of the equipment we have.

5 axis Fidia guy · Dec 8, 2016

I have many times just pushed them out from the back with a tiny pin, are you sure the nose of the holder is not buggered up? sometimes you have to push them in a little bit, take the burr off then reheat them and push them from the backside.

Karl_Kunkle · Dec 9, 2016

I'll try that. The nose might be buggered up.

I appreciate all the help.

partsproduction · Dec 9, 2016

I thought those used an induction heater to expand the holder.

It may not be applicable but reloaders sometimes used inertial bullet pullers. You would have to come up with a way to heat it up and before it loses much heat slam it against a solid heavy object, inertia can be 50-100 G's if you could accelerate it.
Just a tube large enough to slip the holder, at the bottom a heavy steel plate on concrete, and a hole in the plate for the broken tool to go out, the higher you drop it the more G's you will get.

And here is an idea from crankshaft drilling for liberty ships in the early forties.

They had like 1/2" oil holes going at an angle from one bearing journal to the next, or to the adjacent main bearing, and sometimes drilling them a drill would break. Well, these were expensive huge assemblies worth thousands of dollars, and it was a serious problem, one of them tried crumbling dynamite down through the flutes with a wire pick, not much, but setting then off with a fuse type cap would blow the broken drill out into a stop pad, problem done, and it became the standard answer to the problem.

So, I was wondering if black powder night work, fed through that hole. I guess it depends on how much of a void is between the bottom of the hole and the bottom of the tool.

[486] · Dec 10, 2016

put some oil in the hole behind
plug the drawbar hole real tight, grade 8 or 10.9 bolt and a copper washer
heat it up and the oil will vaporize and pressurize behind the end mill shank, it'll come out with one hell of a BANG

Do it all the time with disc brake caliper brackets, the slide pins rust and sieze in their blind holes, they've always got a nice pocket of silicone grease in the end of the blind hole. Get it red and the pin will dent the roof of the shop, 15' up.

mark costello · Dec 10, 2016

You could clamp it into a 2x4 4-6' long heat it up and probably get impressive g forces with a good swing.Cheap and easy. Loads of connections to Me.

partsproduction · Dec 10, 2016

Yeah, I was also thinking of filling the void at the bottom of the hole, if there is one, with grease, plug the hole in either the back of the holder or the one in the broken tool, and use a piece of hardened dowel s a piston in the hole left open, a sharp smack with a hammer would develop tremendous a hydraulic spike.

I've used that to force berdan primers out of their pockets before.

To the OP, please let us know what worked.

Karl_Kunkle · Dec 11, 2016

Thanks for the responses.

What worked was packing full of grease and heating the tip. Shot out like a bullet. It stuck in the foam insulation 10 ft in the air.

Just did it this am.

I might have been over zealous. I hooked grease gun to end in place of retention knob. Pumped it full , no budge started heating end with small rosebud. Kept pumping pumping grease and after 5 mins, boom.

broken tool stuck in heat shrink holder

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