Re: Ways, guides etc.

Tom,

These solid ground THK type linear bearings are available in sizes/ stiffness which is used in full size machining centers, so it probably ISN'T a question of their capability! However, they get VERY 'pricey' quickly as you increase size!

So you are probably going to have to decide the age old time vs. money thing... You can buy dovetail slides, and they MAY be less expensive, BUT you will probably need beefier motors/ drives so it might just balance out. If so, I'd use the linear rails.

Making box ways is not THAT hard, but it does take time, and the results depend entirely on your skills...

The linear systems still require accurate surfaces to mount to, but from that point they are a given...

So, whaddya have, time or money?

Ballendo

P.S. I think a lot of your success or failure is going to have more to do with the support structure FOR the boring bar, than the linear bearings. Both are important, but I think you will be money ahead to have a solid, stiff place to mount the "cutting' part of the machine...

> Thanks for the helpful responses. I use one of these pre-loaded assemblies (that Peter mentioned) for a big gantry cnc plasma cutter I built a few years ago (12' x 4.5 '). <snip>

> I also like the idea Ballendo has for spinning the ball screws. It > would allow the drive to be tucked away under the rail.

I appreciate the plug, but I was talking about spinning the NUTS, and it's not an original idea!