RE: [CAD_CAM_EDM_DRO] Re: MOTOR SIZE CALCULATION FOR RAPID STOPPING

Hi John

I think you might be having some further confusion with units.

A 15 NM peak torque makes a lot more sense than a 15 KN peak
linear force though!

Just as a sanity check... a 15NM stepper would be quite large...
big enough to be unpleasant to pick up off the floor!

I can do a run for you as a check if I have a good physical description
of the system. I need to know thae following:

1) total moving mass of the table in kG
2) minimum pulley diameter for the timing belt you are using
3) total travel in meters
4) desired maximum speed in meters/s
5) range of travel where speed must be constant (if any)

I can guess the friction from your statement that it is a ball bearing
mechanism.

The other figures don't have to be exact...just a good guess.

I have built some large reciprocating timing belt drives similar
to your description before. I usually ended up using servo motors
because a stepper required an expensive gear down transmission.
This made it more expensive for the same level of performance.


Les

Leslie M.Watts
L M Watts Furniture
Tiger Georgia

Main page:
http://www.lmwatts.com
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http://www.lmwatts.com/shop.html
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-----Original Message-----
From: john_glynn57 [mailto:john_glynn57@...]
Sent: Thursday, August 26, 2004 6:07 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Re: MOTOR SIZE CALCULATION FOR RAPID STOPPING


--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Leslie Watts"
<leswatts@a...> wrote:

>Hi Leslie,

Thanks for the advise. I meant 15NM stepper motor (not
15KN). I have
downloaded the software as you advised and am using the rack and
pinion model to simulate my requirement however I am still not
convinced that all is correct as I am getting a very low torque
requirement for the motor of 2.3NM which is definately too small as
I have already tried a 2.0NM motor which is totally unsuitable.
In my application I am using a toothed belt to drive the slide
directly from the stepper motor pulley. Also, there is very little
inertia in the system as I am using ball bearings in the "V" slide.

john
PS The work on your website is really nice.
john_glynn57@...