Setting ADTECH servos with Eding CNC software steps/AppUnit

[D-man]

I'm having trouble calculating the right steps/AppUnit for the servo motors im using...

Can anyone demonstrate how to calculate the correct settings so the motors move the correct distance ?

my setup consists of the following:

· ADTECH servos - http://www.adtechen.com/products/ACH-09075BC%28750W%29-Middle-Inertia-Servo-Motor.html



· 3.2:1 belt reduction - CNCRouterparts pro rack and pinion drive - http://www.cncrouterparts.com/pro-rack-and-pinion-drive-nema-34-p-226.html



· 35 Tooth Pinion and MOD1 Rack

any help would be very much appreciated

[JAZZCNC]

Bloody hell Derick do you realise with 35T and 3.2:1 you have 34mm pitch and with 2000Rpm motors you'll be getting in excess of 68M/min rapids.!!! . . . Tread careful mate the bloody gantry will flying off the end in blink of eye. . .Lol

Ok well you have 2500 count Encoders which will be quadrature so x4 gives 10,000 pulse per rev.
Then workout your Pitch which is 35 x Pi = 109.599mm per rev / 3.2(ratio)=34.361mm per rev

Now Calculation is 10,000 / 34.361 = 291.026 pulses per mm.

Hope you have a nice fast motion control card because you'll need nearly 300Khz to get full RPM from those motors.

[D-man]

Yeah I will have to tame the beast pal. Nearly had one misshap when messing about with the speeds on the X with one motor disengaged and not slaved, I ramped the speed up a little and I capped myself!!

So if I enter that information I should get the correct movement when I enter movement in the MDI? For example: X100 F300 I should get 100mm travel at a feed rate of 300 correct?

[JAZZCNC]

So if I enter that information I should get the correct movement when I enter movement in the MDI? For example: X100 F300 I should get 100mm travel at a feed rate of 300 correct?

Yep should work.! . . . But don't hold me to it. . Lol

[D-man]

Champion I will give it a bash pal cheers

[D-man]

Dean, I will be able to turn those rapids down tho correct?

[D-man]

I think so. I'm new to servos and was told to put what wires I have into the inputs :/ I will get some pics when I get into the unit this morn

[D-man]

OK with those settings Dean i enter X100 F300 in the MDI and it moves 150.5mm so something is still off lol

[JAZZCNC]

Ok well first the Servo drives are dealing with the encoders closing the loop at the drives and all your doing is sending it Step & Dir signals(pulses).

I did make a mistake when I said you'd get +68 M/min because I forgot about the ratio so RPM would be 625rpm at the pinion giving Max Velocity of 34.5 x 625 = 21.5M/min Rapids. . . BUT that would be with full 2000 rpm from motors which you won't get if 125Khz frequency. You'll only get 750(rpm) /3.2(ratio) = 234(rpm) x 34.5(pitch)=8085mm/min.
So really your wasting plenty of the motors potential and machine rapid speeds.

Why those figure didn't work I think can only be because your ratio is not what you think it is.?

[D-man]

Thanks Dean I've managed to get the machine moving exactly 100mm, i'm over the moon! However the software would not disengage the motors when I tured the motors off so I'm having a little trouble with that at the moment. Oh the joys of CNC (Completely - No - Clue) lol