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Newbie with Collet Issue

N

NewfoundlandLaw

Plastic
Joined
Aug 24, 2019
Hey All

I am new to the world of milling, but I decided to give it a go. (I am a longtime knife and pen maker, who will mainly be using it to machine knife guards, handle cutouts and other simple tasks.)

I have a King KC-20VS-2 milling machine. I believe this is a common cheap milling machine that has multiple clones, such as the Craftex CX601 and multiple others.

Here is a link to the King Machine I have:

Milling drilling machine with digital readout KING Canada - Power Tools, Woodworking and Metalworking Machines by King Canada

And here is a ink to my R8 ER32 Collet system:

https://www.accusizetools.com/0223-0974-er-32-r8-x-4-12-ps-set-er-collet-systems-with-r8-shank/

My question is simple. While the R8 chuck (collet holder) fits the machine, I cant figure out how to tighten the collet retaining nut to the required specs. My machine doesn't seem to have a breaking system, so the spindle just turns freely.

Am I missing something here?

Thanks for all your help. Reading this forum has been a lifesaver!
 
The obvious question you left unanswered is, how do you tighten and loosen the drawbar for your R8 chuck? If you can tighten the drawbar, then the same method should let you tighten the ER32 collet nut.

If you can't answer that question, then I can only suggest you mill or grind a pair of wrench flats on the R8 chuck body, in the area near the etched size marking. Make it fit a large open end wrench of whatever inch or metric size seems appropriate.

I guess you know that "real" milling machines have spindle brakes or locking pins to make changing the R8 tooling simple. They do not depend upon an 8mm wrench to hold the spindle against normal R8 tightening torque. Yes, I read your machine instructions. I expect that 8mm flat to get rounded off if you have to use it for normal tightening.

Larry
 
I tighten the drawbar for the R8 chuck using an 8mm wrench at the top of the unit. Another locking nut then tightens over it. According to the manual, the 8mm nut should only be hand tightened and the locking nut just snugged.

Here is a picture of the assembly under a small cap on top of the unit:

 
You know that keyway in the shank of the R8 tooling? It is not what drives the cutting tool. It is there as protection against damaged threads in the collet or drawbar creating too much resistance to removing the tool in the normal way. In fact some "real" mills don't even have a pin to engage the keyway. What drives the cutting tools is friction on the tapered part of the R8 tooling, so that drawbar had better be a lot more than "snugged." Once the tapered surfaces slip and spin, the pin (if present) shears and the spindle is wrecked. R8 tooling is cheap, so small loss there, but spindles are not cheap. And that is why the drawbar has to be really tight. I bought my mill new in 1974 and it was built with no collet pin. It does have a spindle brake and the drawbar has a 13/16" hex for the wrench. I use a normal length 3/8" drive ratchet on it, not a long combination wrench. I have never had an R8 tool slip in the spindle.

Larry
 
Ok, that makes a lot more sense to me now.

So the 8mm nut that screws the R8 arbour up into place and the larger drawbar nut then forces the angles of the tooling together to make a "friction connection." Similar to how a MT1 or MT2 wood lathe would work, but pulled much tighter by the draw bar then the drawbar nut.

That actually makes the whole think make sense to me now.

It's also good to see a normal 3/8 ratchet will make it tight enough. Seems like a good tight fit will work without wailing on it.
 
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