R8 Lendex collet won't fit my machine?

[skipper]

Hi All,

I have a HF 33686 mill/drill mill. The only R8 collet I had is the type that is like the 5C where you insert different collets to the same R8 shank. I went to a tool store and I bought a single R8 1/4" collet. The brand was Lendex. When I tried to fit the collet on to my machine it would not fit. The only thing I see is that on my existing R8 shank, the depth of the groove is about .095 which is the spec I found. The lendex groove was only about .068 deep. I took the collet back and checked out the other brand (Harding) that they had and it to was only about .070 deep. Has anyone ever encounter this problem? Does the HF mill/drill R8 shank differ than standard? I can post some pics if would help.

Thanks,
Rene

[thackman]

I have an X3 with exactly that same problem. I had ordered a collet chuck set and the chuck would go up in the spindle. The vendor replaced it and the new chuck would only go 1/2 way into the spindle. At that point took some measurements and compaired them to the standard.

http://www.loganact.com/tips/r8.htm

The keyway on the collet chuck wasn't nearly deep enough and had a very wavy finish that hung up on the interal pin. About 30 minutes with a diamond needle file and it fit perfectly.

[Glennza]

This problem seems to come up with regularity and the problem is that the pin is too long. That also makes it easy to fix, just file/grind/shorten the pin. The pin is only there to keep the collet from turning as you tighten the drawbar - the taper locks the collet when it is pulled tight.

Glenn

[skipper]

Thackman,
So you are saying that you filed the groove on the collet shank to be deeper, correct? Are these collet soft enough that I can machine the groove deeper?

Glenn,

I guess what you are saying is that the pin in the machine chuck needs to be cut so that it is not so long? I am assuming I have to take the machine head apart to get to this pin? Can the pin be machined thinner to fit the shallow collet groove?

Thanks for your replys.

[Adamj12b]

I had the same problem with my Harbor Freight mini mill. But it was only with some of my collects. I just took my Dewalt angle grinder and made the slot a little but deeper. Works great now. -Adam

[thackman]

I found out that the pin on mine was hardend and the R8 shank on my collet chuck was not. The only file that was narrow enough to get into the keyway was a diamond needle file that I had around. It took about 20-30 minutes by hand including a couple of test fits.

[Glennza]

Skipper -

I'd modify the pin so I knew that all of my collets (and any I buy in the future) would slip right in and not need modification before I could use them. The pin is up about 2 inches in the spindle and you should be able to reach it with a die grinder or Dremel with a long shafted bit. It would help to tilt the head or lay the mill on its side, so you're not having to work overhead.

There are many machinists who say you should remove the pin. Since its function is to keep the collet from spinning as you tighten the drawbar, it isn't really necessary to have it. I have seen a tool that had to be hammered out of the spindle because the tool rotated, the pin gouged into the tool shank and that locked the tool into the spindle. It's not a good feeling to see someone beating on a Bridgeport with a drilling hammer to remove a stuck tool. Of course, to remove the pin you'll have to remove the spindle (or just grind it flush with the inner wall of the spindle).

Hope this helps.

Glenn