Re: [CAD_CAM_EDM_DRO] rack and pinion advice

Troy,

In the past Multicam used a rack and pinion drive on their X axis. They
built a 10 to 1 gear box using belts. Since then I believe that they are
using gear motors with the same 10 to 1 ratio. You will need something like
10 to 1 to give you the power to drive the gantry.

Bob Campbell
http://www.campbelldesigns.com
Breakout Boards
VisualMill 5.0 basic
Stepper motors
Plasma Torch Height, THC 300 boards

----- Original Message -----
From: "Troy" <superscooby3000@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Saturday, January 03, 2004 10:26 AM
Subject: [CAD_CAM_EDM_DRO] rack and pinion advice


> I am designing a 4'x8'gantry router with rack and pinion on the x
> and y. Does anyone have any advice on wether I should gear down
> nema 34 stepper motors with timing belts and pullys?
>
> I am thinking without gearing down I would get the fastest rapids
> and at cutting speed, and I think I would get the most torque
> because the motor wouldn't have to run as fast to move the gantry
> (I was under the impression that the faster you ran a stepper motor
> the less torque you get.) Am I correct in this thinking or am I
> missing something?
>
> I was planning on using pullys and timing belts anyways figuring it
> would be easier to upgrade to servos if I wanted to in the future.
> I just cannot decide if I need a 1:1 ratio or something else. If I
> did need a different ratio does anyone have advice on what that
> should be? I was figuring on using the smallest spur gear I could
> get, or do I need something with more teeth engaged.
>
>
> Another question: I was planning on using 14deg 20pitch gears and
> rack because that seems to be the cheapest route at Mcmaster, and it
> seems mcmaster doesn't carry long lenghts of 20deg rack.
> Does 20deg make much of a difference on smoothness and is it worth
> the extra expense? (and does someone have a better source for 20deg
> rack?) How about gears and rack with helical teeth, I saw
> somewhere on the net but can no longer find the site, is that worth
> while?
>
> any other advice you rack and pinioners and give would be greatly
> appreciated.
>
> Troy
>
>
>
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