Re: Collet chuck for PCB router bits?

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "vrsculptor" <vrsculptor@h...>
wrote:

>
> Any suggestions or references for a collet chuck to hold the PCB

bits

> with the plastic collers on a PCB router?
>
> Roger
>

I have built some spindles with collet chucks but not tried them on a
machine as yet.

The Collet chuck is the proxxon micromot, as it seems to be much
higher quality than the dremmel version, The collets are hardened
steel and split 3 ways rather than the 4 of the dremmel.

I bought the collet nut and collets in a set (only cost a few $), then
built the shaft to suit..

The thread for the collet nut is M8 x 0.75 and it took a few days to
get a die.

The only tricky bit was making a tapered reamer to make the internal
taper on the shaft that the collets sit in.

I have built this on both 10mm and 8mm shafts on what I call Silver
Steel, some would call Drill Rod.. then hardened and tempered them..

The advantage of building them on 10mm rod was that I machined the
shafts where the 8mm internal bearings sit, removing any runout
introduced by the lathe.

I ended up with shafts that hold the tool with no detectable runout
using my mechanical dial guage.

I tested the shafts in 3 ABEC 9 skate bearings (two at the workpeice
end and one at the pulley end) up to 40,000 rpm and they ran sweet. My
next job was going to be adjusting the pre-load of the work peice end
bearings with shims to see if I could minimise the last bit (0.0001")
of play

Chris (-=Spiyda=-)