Re: [CAD_CAM_EDM_DRO] Encoder count selection for G320

Denis,
Mariss sent this to me a few years ago. I think it is what your looking for?

"Determine what is your software's maximum step pulse rate. It'll be
published somewhere. Convert your motor no-load RPM into revs per
second (divide RPM by 60) and divide that by 4. Divide that into
your software's max step frequency. The result will be the maximum
encoder line count. Pick the next lowest standard mfg encoder line
count. In other words, if your result is 566.66 lines, pick a
500-line encoder. "

Hope this helps.

Country Bubba




At 02:25 PM 2/14/2009, you wrote:

>Hi Dan,
>I meant 30 ips not 30 ipm. Encoders arm mounted on motors. I got
>some feedback
>that mentioned about 18 ips would be a better target and that's the range I
>want to target. I'll use a gearhead to divide the speed down by 7 to 60 revs
>per second.
>There is a relationship between PC software output pulse generation and
>encoder line count that has a bearing on top speed. I can not find
>the article
>that mentions how to decide whether the line count is a good choice.
>Would you
>have any information on how to make that choice?
>regards,
>Denis
>
>On Tuesday 10 February 2009 08:00:01 Dan Mauch wrote:
> > You must have made a mistake when you said that you wanted 30 IPM I think
> > you meant 300 ipm. With a 4200 RPM motor and a 3/1 reduction with a .891
> > pitch diameter of the 14xl pulley you would have 4200/3X(piX.891)=3918 IPM
> > negating other factors. That is a tad too fast. You should look to increase
> > the reduction to at least 6/1 . You can also lower the top runaway speed by
> > using a lower voltage power supply. With your current setup and the encoder
> > on the motor shaft I would say that the resolution using a 250 line encoder
> > would adequate and give you plenty of speed and not a high number os steps
> > per in that the programs you mention would be fine with. Dan Mauch
> > economical 3D scanner software and kits
> > low cost stepper and servo motors.
> > cases for Gecko drives
> > kits and assembled 3-4 axis drives
> > www.camtronics-cnc.com
> > www.seanet.com/~dmauch
> > ----- Original Message -----
> > From: dcassyc1
> > To: CAD_CAM_EDM_DRO@yahoogroups.com
> > Sent: Monday, February 09, 2009 9:15 PM
> > Subject: [CAD_CAM_EDM_DRO] Encoder count selection for G320
> >
> >
> > Hello all,
> > I want to use homeshopCNC servo motors on a router. The motor is rated
> > 72VDC and 4200 rpm no load speed, 850 in oz peak torque, 170 oz in
> > continuous torque. My plan for the gantry drive is to go from the
> > motor through a 1:3 reduction and drive a jackshaft with 14 tooth XL
> > gears on each end, which rack over stationary belts fixed to the
> > frame. I calculated the gantry mass at 175lbs aprox. I'd like to
> > achieve 30 ipm traverse speeds for the gantry and carriage. Is that an
> > unrealistic speed?
> > I don't know how to make the choice between 250 or 500 line quadrature
> > encoders. The 'files' sections servo motor files were empty. From what
> > I remember, top speed depends on pulse throughput from the PC. The
> > control software is CNCPRO, Turbocnc, and EMC. Would the 500 line
> > encoder provide greater precision?
> > Would anyone care to show me how to make the line count selection for
> > the Gecko G320 and advise on the PC speed/performance requirements?
> > TIA
> > Denis
> >
> >
> >