Re: [CAD_CAM_EDM_DRO] Ball-screws

James Owens wrote:

> Hi Jon,
>
> I have a tool and cutter grinder, which I use mainly as a 12" surface
> grinder, and a tool-post grinder. Is there any reason why I must use
> angular
> contact bearings. Can't they be Timken taper rollers.

Yes, Timken-type bearings would also work, they are just often more
expensive
and larger.

> I don't quite understand your description of how the bearing block
> should be
> designed and what about the other end? If one end of the ball-screw is
> fixed
> with no axial movement should not the other end be just a plain
> bearing or
> ball-race.

Right, just a simple, single-row ball bearing to keep the free end from
flailing
around.

Here's some ascii art for the bearing block :

| |
| |
------ --------
| |
-----



____
| |
------ --------
| |
| |

This shows the cross section view, with the lip for the outer
races to press against.

> It is my intention to keep the handwheels and dials, fitting the
> encoder and
> motor drive pulley to the other end out of the way (X axis). The only
> problem I can see with this arrangement is protecting the motor bits
> from
> cuttings and cutting oil.

Once you have a full CNC system, and get used to it, the ease of
doing everything precisely will make you forget about dials and
handwheels.
Yes, I suppose if I had handwheels I could move the machine table out
of the way without turning the CNC computer on, or something
like that, but really I don't miss the manual control much at all.
My setup has most of the works UNDER the plate that mounts
most of the mechanical stuff. The Z axis is protected by some
pieces of thin plexiglas-like material that was bent on a brake
to wrap around the ballscrew and belt drive. It works quite well,
even though it is FAR from airtight.


Jon