RE: [CAD_CAM_EDM_DRO] plazma cutter.

I am still alive. I did build a torch/plasma table. It works great using
the oxy acetylene torch. I am using rack and pinion. The only problem I
have observed when using the torch is oscillation in the carriage due to the
low speed of the stepper motors. I will probably change to a timing belt
arrangement (3:1) to drive the drive the pinion. When my shop is finished,
I will start experimenting again with the plasma torch to eliminate the high
frequency jitters in the steppers.

Dave Johnson
Littleton, Colorado

-----Original Message-----
From: Tim Goldstein [mailto:timg@...]
Sent: Sunday, April 23, 2000 3:44 PM
To: CAD_CAM_EDM_DRO@egroups.com
Subject: RE: [CAD_CAM_EDM_DRO] plazma cutter.


It seems the resolution needs to be as high as you want it to be. What I
mean is if your projects only require .010 than that is as high as you need.

Just doing some calculating, if you direct drive the cog that is engaged on
the chain and use a 13 tooth cog (about the smallest you see in use on a
bicycle other than the occasion tension idler) and use a 200 step/rev
stepper in 1/2 step mode your resolution will be about .016

Of course you could then belt drive the cog and use a 2 or 3 to 1 reduction
and increase your resolution. Seems to me that it would work.

I have a friend that occasionally reads the list (Hey Dave, you alive out
there??) that has a plasma table setup that uses rack and pinion. The major
problem he is getting is interference that just drives the steppers crazy
when ever he hits the plasma switch. You may want to start studying how to
avoid this problem.

Tim
[Denver, CO]

> -----Original Message-----
> From: baileys@... [mailto:baileys@...]
> Sent: Sunday, April 23, 2000 2:46 PM
> To: CAD_CAM_EDM_DRO@egroups.com
> Subject: [CAD_CAM_EDM_DRO] plazma cutter.
>
>
> Hello list,
> Does anyone have experience with an x-y table for a plazma cutter. It
> seems to me that the resolution would not have to be high. I was
> thinking about welding bicycle chain to angle iron instead of buying
> rack gears. I know that this technique works well for sawmill tables.
> Comments, suggestions?
> Bob B.

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