Re: MOTOR SIZE CALCULATION FOR RAPID STOPPING

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

> Thanks Les,

You are correct the motor is a bit of a beast but seems to
have plenty of capacity however I won't really know until I test it
under operating conditions but for the moment it is giving me all
that I need and moving the axis along at the desired
speed. I am expecting that the mechanism will work because I am
estimating that the thrust force will not be more than 20kg max.
In hindsight I think that a ball screw would have been a much
better option but I have steered away from the servo motor route
because of the expense ?.
The answers to your questions are:

> 1) total moving mass of the table in kG = 68kg
> 2) minimum pulley diameter for the timing belt you are using =43mm
> 3) total travel in meters= .2M
> 4) desired maximum speed in meters/s .2M/s
> 5) range of travel where speed must be constant (if any)=none

john

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
> Engineering:
> http://www.lmwatts.com/shop.html
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>
> -----Original Message-----
> From: john_glynn57 [mailto:john_glynn57@y...]
> 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@y...