Re: [CAD_CAM_EDM_DRO] Re: VFD Selection

Dave,
I made a spindle from one of those. It's an ER16 collet chuck. I didn't use
angular contact or tappered roller bearings, just standard good quality
bearings, two of them, of course.Then a smaller one at the top end. I made
'rings' with a tight pressfit together with loctite to hold the bearings in
place and to space the two lower bearings apart. The bearings are then
slightly preloaded by pressing the outer rings together with a flange. It's
driven by a 1100watt (overkill, but that's what i had) 3-phase motor via
beltdrive and a VFD.

When I put it togeher I locked the bearings with locktite and got the
preload a little high, I think. So when run at 10.000 rpm for an hour or so
it got pretty hot. So a friend of mine made a 'cooler' for it out of a piece
of alumium extrusion.

This is not a optimal design but it works in aluminum and other 'soft'
metals. And it's pretty cheap.

I was going to upload a photo or two of it but I cant find the upload button
or the create folder button on Yahoo any more. I'll send them to you off
list if you like.

/Henrik Olsson.

----- Original Message -----
> This brings up a question about an idea I have had floating around in my
> mind for some time. Has anyone attempted to build a spindle out of
> one of those "ER" extensions. A long one of course, seven or eight
> inches may allow enough space for a set of bearings and a drive pulley.
>
> Just a thought that has been rolling around in my head for some time
> now. Since these are normally built to reasonably tight tolerances I
> could see this as being feasable for both a plain bearing spindle and a
> ball bearing supported spindle. An ER extension can be had for around
> $100 dollars which is not a bad price considering what a full blown
> cartridge spindle would cost.
>
> Thanks
> Dave