Re: [CAD_CAM_EDM_DRO] Encoder count selection for G320

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
>
>
>
>
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