Tree 2UVRC stuck collet

A 1/2" end mill broke off inside of a 1/2" collet and now the collet won't come off the spindle. Usually I just pull out the yoke 3/4" and pull on the handle towards me and the collet just slips off.

Tree mills use a double tapered z type collets that have a special mechanism for clamping on the tool. Here is a video on how the system normally works: Adjusting and using Tree milling machine's Z collet system - YouTube

Any advice would be greatly appreciated.

Thanks

I assume you do not have any access from the top for a small rod to bang on the top of the endmill-collet assembly.
Have you tried unscrewing completely the adjusting ring and tapping on the collet?

Paolo

Yes, I tried tapping on the collet with a soft rubber mallet with no luck.

Without taking the entire head apart, there is no way to bang on the assembly. I might have to break down all of the head, but with so many parts, I really would like to avoid that route.

Remove the collar/ring
Put a bucket/ tray / cardboard box under the collet
Confirm the lowest possible RPM
Source a scrap of wood, perhaps a section of broomstick, or from the plunger in the bathroom.

Wear eye protection
Roll up your sleeves
Wear a hairnet

Start the mill
Aim one end of the stick at the collet
Rap the other end with a hammer

Start with light blows and work heavier in progression


Technique works with B&S tapers, also, especially when drawbar is pushing against the arbor/collet

I'm so desperate, I might actually try this. Thanks.

A couple of "wild" thoughts...

If you haven't done it yet, spray the collet with some penetrating oil, like Kroil or PD Blaster.
After you've done it, you can tap the collet with a brass hammer or equivalent: yes, you need to avoid marring the collet, but you also need to deliver sharper vibrations than leather, plastic, etc.

One of the problems in removing ZZ and similar collets is that you do not have any purchase. It could well be that the force needed is fairly minimal. If you have a couple of strong magnets around, I'd suggest trying to pull the collet with them.

If this were to fail, my next try would be to clean thoroughly the exposed surface of the collet and attach a blob of JB Weld or similar compound binding a long bolt (or a piece of all-thread) to the collet. Once the epoxy is cured, build a slide-hammer on the bolt and attempt to remove it this way.

Acetone, penetrating oil, or heat will then separate the JB Weld from the collet.

Most likely, during the crash the collet spun in the adapter, causing some galling. Therefore, after removing the collet, make sure you stone any bur both in the spindle and on the collet.

Paolo

Thanks for the suggestions. I will try all of this on Monday.

If I forget to take out the tool when I quit it gets tight. Probably from cooling down. Any way, with the tool still in I have to hit the tool sideways to knock it loose.

If the JB weld doesn't work:
Assuming the nut is loose and can be removed, is part of the endmill sticking out? You can hit sideways with a drift pin. Or use a brass or aluminum bar to hit directly on the collet.

If there is no edge (HSS end mill) clamp a carbide drill in the vise and drill a hole in the endmill for a place to hit with a drift.

There is no hole through the spindle, and it is quite an operation to get the spindle out.

I've had the same problem with a 40 taper after running hard and sitting overnight , takes a pretty hard whack with a hammer to break loose.

Dave

Thanks for the suggestion Dave.

I was able to get it out using the JB weld method. There was no part of the end mill that was sticking out. I sprayed the whole assembly with a liberal amount of penetrating oil then I put a big glob of jb weld on an end of a 1/2 steel rod and tapped it into the collet with a hammer. I then let it cure for a day and the next day, i grabbed the rod with locking pliers and the collet came out after a few taps with a hammer.