Re: CNC flame/plasma cutter

Another item to consider building a flame cutter is the slow final speed
needed. The commercial traveling eye type we have at work has a 40:1
reduction on the analogue servo motors. I am not sure what the final speed
is - something like 1-2 ipm? Our machine does have a rack and pinion drive.

----- Original Message -----
From: Dan Mauch <dmauch@...>
To: <CAD_CAM_EDM_DRO@onelist.com>
Sent: Thursday, June 24, 1999 6:30 AM
Subject: Re: [CAD_CAM_EDM_DRO] CNC flame/plasma cutter


> From: "Dan Mauch" <dmauch@...>
>
> Let me add a few thoughts about racks and pinions..
> They work very well in cnc applications but suffer from two problems. One
is
> the pitch diameter of the pinion. The second is debris that that clogs the
> teeth and jam the mechanisms.
> The pitch diameter for the smallest pinion that works on a neam 23 motor
is
> .5"D. Thus it will travel .00785" per step at 200 steps per rev and half
> that for 400 steps prer rev. Generally a nema 34 motor is used and this
> would have to have a 1" pitch diamter so that there is enought meat for
the
> pinion to be bored for .3755. Then the resolution increades by pi*D or
3.14
> for 1 rev at 200 steps=.0157 per step and half that for the half step
mode.
> You will get very fast travel. I have one system that ran no load at over
> 600" per minute with 150 oz in nea 34 motors.
> An alternative is to then use a belt drive to drive the pinion then you
can
> increase the resolution by the pulley ratio. Some people just use timing
> belts cut and both ends secured for non critcal tolerances.
>
> Dan
> -----Original Message-----
> From: Tim Goldstein <timg@...>
> To: CAD_CAM_EDM_DRO@onelist.com <CAD_CAM_EDM_DRO@onelist.com>
> Date: Wednesday, June 23, 1999 9:15 PM
> Subject: Re: [CAD_CAM_EDM_DRO] CNC flame/plasma cutter
>
>
> >From: "Tim Goldstein" <timg@...>
> >
> >
> >My friend only got the table parts from Torchmate. He is using a bi-polar
> >chopper drive stepper controller (better torque and rpm than a unipolar)
> >that he built from a kit he purchased from Dan at Camtronics. For the
> >software he is currently running DeskNC DOS version which does handle
> >g-code. But, we are soon going to move him over to EMC and Linux as it
> seems
> >to run a stepper machine much smoother.
> >
> >As far as ball screws v/s rack I think it is not a question of what is
> >better, but more a question of what is most appropriate for the job
> >considering the cost. A ball screw is more accurate, but is the rest of
the
> >machine such that the added accuracy will ever be noticed? If you are
> >thinking of a machine that can handle 4' x 8' and figure the cheapest
> >ballscrew material is $1/in and nuts are $20 you will have over $200 in
> >just the parts and I don't think you will see any difference.
> >
> >Tim
> >[Denver, CO]
> >
> >> -----Original Message-----
> >> From: smcdonal [mailto:smcdonal@...]
> >> Sent: Thursday, June 24, 1999 1:11 AM
> >> To: CAD_CAM_EDM_DRO@onelist.com
> >> Subject: Re: [CAD_CAM_EDM_DRO] CNC flame/plasma cutter (was Stepster)
> >>
> >>
> >> From: smcdonal <smcdonal@...>
> >>
> >> Tim Goldstein wrote:
> >> How does the torchmate handle files? Can it read standard g code or
does
> >> it use some other format?
> >>
> >> Also would like to know if rack and pinion is better then ballscrews?
> >>
> >> Thanks
> >> Stan
> >>
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