Re: [CAD_CAM_EDM_DRO] roller chain instead of screws or rack?

Hello,
The chain sounds like a novel idea, but wouldn't it have backlash between
the chain and sprocket?
Add that to play in the gearbox and you are starting to lose ground.
Also, the chain is covered in oil and a plasma kicks up an enormous amount
of very fine metallic dust.
I have also been considering building a Plasma and Oxy/acet. torch CNC
cutter.
I have a track torch now but you have to cut a pattern out of metal first.
http://www.stepperworld.com/ sells stepper motors and controls as a unit.
Check it out and see if you think his SP-3/HT unit would do the trick.
Let me know what you think.
Thanks, John

----- Original Message -----
From: <deanc500@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Thursday, July 26, 2001 11:37 AM
Subject: [CAD_CAM_EDM_DRO] roller chain instead of screws or rack?


> Hi, I have built several small router tables out of both wood and
> metal with varying degrees of success. I used lead screws and
> anti-backlash nuts on all of them. I am now building a 5'x10' plasma
> cutter. At first I thought rack and pinion was the best option, but
> then while recently visiting a sign shop for supplies, I noticed a
> large CNC router in the back. I asked to have a closer look and was
> surprised to see a #35 roller chain drive. There are 34 frame steppers
> driving the chain through a 3.5:1 reduction. Since the gantry only
> goes back and forth, the chain did not make an entire loop, but
> instead, half the chain was replaced with aircraft cable. At the far
> end of the table, the cable loops around a simple pulley, which is
> tensioned with a large spring, getting rid of any backlash. The table
> has been in service for 12 years and the owner is very happy with it.
> This system seems to be much simpler and cheaper than rack and pinion
> and allows for greater flexibility regarding gear reduction.
>
> Has anyone used chain drive before? Are there any drawbacks to a
> roller chain drive system?
> Thanks
>
>
>
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