Re: [CAD_CAM_EDM_DRO] Re: Ball screws for CNC plasma cutters

I did this same thing with cable and timing belts. It works fine, but you
do have to dampen the vibration of the cable, belt etc. if you are using
steppers. I made a plasma cutter about 50" x 12' with a huge gantry. The
head has a big half inch drill mounted to pierce start holes in the middle
of the thick steel I used to cut on it. 1/2- 3/4" thick. I cut over water
to obsorb the smoke, noise and dirt. The drill was lowered by steppers in a
subroutine, and torch height control was through voltage monitored while
cutting. I used a basic stamp to control torch height. I do not have any
pictures, but I still have the machine. I just wanted to tell youall what
can be done. I do not have time to tell you all the details. The machine
was slow, since I used the old slo syn AC synchronous motors as steppers the
way Dan Higgins said to in his manuals.
Tom Eldredge, Trustee

----- Original Message -----
From: Smoke <gordonr@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Wednesday, February 14, 2001 4:41 PM
Subject: Re: [CAD_CAM_EDM_DRO] Re: Ball screws for CNC plasma cutters


> Perhaps a system using those "cable gears" from Berg would work well for a
> 20' machine..like Helen wants to build?
> Should be a lot cheaper and easier to build than using a 20 foot long
rack!
> Wouldn't require a precision rack mounting surface either.
>
> An even easier way would be to mount the unit using a plain cable. Fix
both
> ends of the cable to a shaft driven by the servo motor. At the other end
> wrap the cable around a pulley. Use a cable on both sides of the machine
to
> equalize forces. Link the safts on opposite sides with a "cable belt".
> Build the Y axis the same way. All you'd need is a track guide for the
> mechanism holding the torch. You could run a system like this at just
about
> any speed you wanted to.
>
> And for those of you who say a "cable drive" wouldn't work...I ask..."Have
> you tried iit?" I do know of some equipment that uses cable drives very
> effectively.
>
> Smoke
>
>
> >If you've seen a plasma cutter then you have also seen all the
particulate
> slag and grit that is generated. This grit can play havoc
> >with any type of screw. A better solution is a rack and pinion drive. If
> the teeth on the rack are positioned vertically or upside
> >down the grit problem is minimized. Racks can also be of unlimited
length.
> Screws on the other hand suffer from whip lash at longer
> >lengths. My 72 x 126 inch CNC plasma, with rack and pinion drive, holds
the
> same tolerances it did when it was new fifteen years
> >ago.
> >
> >Jay Hayes
> >
>
>
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