Re: linear bearing based on ground flat stock

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "ballendo" <ballendo@...> wrote:

> Consider swarf in the equation...

The three rails are in the "roof" of the machine, swarf will be foam
dust for this machine. Main purpose of the machine is to say "look it
really does work" and then get a simple parallel kinematics
programming system done for the g-rex by the powers that be :)

> A roller bearing on round rails will be far easier to use
> successfully, IMO. However it seems you might want the added
> constraint to torque rotation that you'd lose using a single round
> rail?`

Yes I would need to use a pair which puts me off a little but I
haven't ruled it out, manufacture is easy enough anyway and it could
be very light, the aluminium carriage with the two bevelled edges
could be pocketed out substantially.

> Oops. On re-read I see cheap AND light.
>
> The Zoltar plain bearing idea works well--and uses a flat bar as
> you've suggested--and if your materials are chosen carefully, it can
> be used high speed. Very easy to mfr. as well. We use a version of
> it in our smallest gantry routers.

Not convinced about the high speed part I really do mean high speed.
I showed an expert on parallel kinematic machines one of my 2-axis
machines running with these belt drives, he thought they were linear
motors. For that I was using some tiny 9mm wide thomson rails, just a
single carriage on them but I only have two and they are a tad short.

Graham