Re: High Speed Spindle

Great minds think alike? Since getting a series II B-port, not enough room
for my home made router table. I've committed to giving it to my Uncle as
soon as I can get the B-port to do everything the router table did. I
mostly made 1/8" aluminum panels for electronic chassis work, using a
harbor freight trim router at around 30k rpm, with 3/32" used carbide PCB
drill bits. I would hope I have the skills to make a high speed spindle
for the B-port that is at least as good as that setup :-)

What I'm considering is the same 300 series DA collet chuck (can buy
collets from 1/64" to 1/4"), some type R8 bearings from McMaster carr (1/2"
shaft ID, 1 1/8" bearing o.d., 28,200 max rpm, see P.N. 60355K15)) and a 1
1/8" Kwik-Switch End Mill Adaptor (to fit my b-port). Motor would have to
be mounted outside of this spindle, belt fed. It is my understanding that
most collet extensions are undersize, just like end mill shanks are
undersized. If necessary, I wonder if the collet extension can be plated a
few tenths of a thou for a press fit on the bearings? I'd be really
interested in hearing how well turning down the collet extension works. Is
it hardened? How hard to machine without greatly increasing the run
out? Remember, I only want _at least_ as good as the $20 harbor freight
trim router :-)

I imagine inside the end mill holder would be a bearing spacer. Some end
mill holders have a threaded portion at the other end that I believe serves
as an indexing stop for setting end mills in. This could be used for
putting some pre-load on the bearings. I'd also need to figure out how to
keep the assembly from falling out the bottom end; I don't mind welding
something there if I had to, or I'm not sure if I can use the end mill
setscrew.

I imagine tapered roller bearings would be better, but I have not found any
that had O.D.s and I.D.s that wouldn't require precision machining from me.

I hope this discussion continues, because there is a lot I don't know and
would like to benefit from the experience of others.

Thanks,

Steven Ciciora

>I have a 22000 rpm dc motor I want to gear 2 to one for about 40000 rpm.
>Shouldn't the bearing ID be a press fit on the shaft? Or should it be
>a "interference fit" like the OD? I am planning on turning the shaft
>to a shoulder pressing on the bearings with the shim between them then
>screwing in a retainer into the housing. Pulley end I was going to
>have tight sliding fit with ID of bearing to shaft, shoulder not
>touching id when retainer is screwed in. The extension is made for
>high rpm work and I am sure th da collets will work better than what i
>could make at home. Plus they allow different sizes to be used instead
>of just 1/8. BTW Thanks for the reply. Hope this isnt off topic.