[CAD_CAM_EDM_DRO] MiniRobo

> I'm curious how you are supporting your lead screw on the end
> opposite your stepper (on the X and Y stages). It appears from your
> drawing, so kindly offered for our education, that you have two T-
> section collars, with set screws, set in opposition. Is this
> arrangement functioning as your bearing? Are the collars Al? Your
> arrangement of the Thrust Plate seems unique. Did you go this way to
> reduce cost for the machine?

There are two steel collar clamps then two Nylon washers. They are arranged
to act as thrust bearings. One collar and nylon washer on each side of a
plate and it keeps the lead screw from moving back and forth. It's ok if it
moves up and down alittle.

It is a cheap way of absorbing the Axial thrust. A better design is to use
two angular bearings, but the cost is considerably higher. Each bearing
costing about 12.50 each and two required per lead screw.

I have found you can scrimp many places but one place you cannot is the
coupler between the stepper motor and the lead screw. A rubber hose is far
better than a rigid coupler. I use Helical couplers. Rigid coupling has no
compensation for off center rotation and ultimately something gives out.

I designed the MiniRobo to be made with one of my computerized routers. I
figured it would be a great project for students to make with one of my
computerized routers. My thinking was to keep the cost as low as possible.
I would put a sheet of acrylic down on the router table and start cutting.
Six hours later I'd have all the parts machined and ready to put together.
The sheet would come off the table with all the parts attached by break away
tabs. It worked.

I put the parts together with acrylic glue, the kind that welds the parts
together. The rods and lead screws had to be in place before the parts
could be glued together. This solves alot of alignment problems. I used
rubber bands and weights to hold the pieces in place while the glue set.

When done, it makes a pretty good little computerize dremel drill. You can
burn out alot of dremel drills before wearing it out.

There is a whole lot of ways to make it better. There is many ways to skin
the cat this is just one.
http://www.super-tech.com/root/minirobo.htm

You can make alot of things with a computerized tool. I found it
fascinating to make machines with my machines. I tried to make it so there
is no part bigger than what can be made on the minirobo. The exception
being the base.

Dennis
http://www.super-tech.com/