Re: Homemade high-speed spindles/speed multiplier. What bearings to use?

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Abby Katt <cncgroupnospam@...>
wrote:

>
> Hi All,
>
> I'm looking at making my own belt/pulley based spindle speed multiplier
> for my CNC mill, and was wondering what bearings I should be using? The
> milling cutter itself will be quite small (1/8" or 3mm), and high-speed
> so it doesn't need to be too-beefy.. the reason I ask is that angular
> contact bearings are quite a bit larger than regular sealed-race
> ballbearings - and more expensive, I'm not sure though if the price
> warrants the extra expenditure - a ballbearing based spindle would be
> more streamline and easier to make...
>
> I've seen some fantastic pages of people (on this list) who've made
> their own fantastic spindles - so this is why I ask. :)
> I intend to "open source" the design when it's done, and post all

plans,

> drawings, 3D models, construction pics, and a how-to guide on my

website....

>
> Thanks for any advice,
> Regards,
> Abby
> (http://www.silverkatt.co.uk)

On my PCB spindle, I used a pair of standard roller bearings and used
a Belville washer on it, along with a pulley. I compressed the washer
and then tightened up the pulley. that put pressure on the bearings
so there is no play.

Do a little reading on the bearings. some bearings can be run faster
if they are lubed with oil. Grease lube can be too thick and cause
too much resistance and either take away some power, or get hot.

For the 1/8 inch bits, this has worked out very well.

I took a thick walled tube, bored it out for bearings on each end.
then took a 1/2" shaft and turned the OD down to 1/4" as that was the
bearing size. the end left long for the shaft of the tool. And it
was drilled and reamed to 1/8". Finally, I put a set-screw in the
side to hold the bit.

Dave