Re: [CAD_CAM_EDM_DRO] help with rack-n-pinion setup

carlcnc@... wrote:

> Being a NON engineer[read carpenter] I need some help calculating
> torque to pinion for following:
> Driving from both sides,probably 16pitch 2"dia pinion.
> What I am moving is a gantry with total weight close to 500#
> Using profile rails coE of .006.
> Need to accelerate to 1500ipm @ 4ftpermin/min.Decel about the same.
> best I can do is guess 250lbs needed,which means 4000ozin at shaft?
> Is that enough info for one of the resident experts?
>
> The resulting torque required will determine if I use steppers or
> servos that I have on hand.

500 Lbs, 1500 IPM and accel of 4 Ft/M^2 ? Steppers - no way!
This is a servo job, and a big one! The acceleration really isn't that
big, but the weight is, and so frictional losses are going to be high
no matter what technology you use.

I'm having a little problem here figuring out what you are doing that
would need such high speed with such LOW acceleration. Either
the machine is truly HUGE, it is a very specialized application, or
you specified the acceleration in the wrong units. Otherwise, it could
never get up to a tiny fraction of 1500 IPM before it had to stop.
With your spec, it would take one minute to get up to 4 Ft/minute,
having traveled 2' during that minute. The second minute, it would
get up to 8 Ft/Min, having traveled 8' at the end of the second minute.
It would take a roughly 31 MINUTES to get up to 1500 IPM! So, I think there
must be an error in your specification, here. Maybe 4 Ft/Sec^2, or
something (which would still be a little sluggish).

Before carrying this calculation further, we need to check the numbers
above.

Jon