Re: [CAD_CAM_EDM_DRO] Re: Plasma table gear reduction

As for the de-rating. As it appears to me, a 3/4hp dc motor at 90
volts would be something like a 1/4 hp at 30 volts ? That 3,000 rpm
would then be 1,000 rpm (still shakey on this after reading notes on
DC motors)

///If it be a 90 volt motor and controlled by a Gecko 320, why 30 volts? Run it at about 75 volts DC(power supply with a 53 volts AC secondary). This would result in a bit lesser RPM however still maintaining the torque providing the power supply can keep up with the amps. No point in limiting the motor. More than required torque and speed is better than not enough. The speed and torque can be adjusted within the software via "accelleration" and "velocity" with Mach2.///

So, the motor range would be from zero to 1,000 RPM. and 0-30 volts.

It appears to me that the motors are available surplus in many
different sources so the cost will be pretty low. under $50.00
anyway.

Using the motor at low speeds also means low volts and I assume low
amps so the motor 'should' not be overheating.

///I'm a little gray in this area as well. I think with lower voltages it will require higher amperage than normal to result in the same output of torque of a higher voltage configuration. And would result in motor heating. The same reason they went from 6 volts to 12 volts and now 24 volts on car electrical. Smaller wires, windings, etc.carrying more volts and less amps to perform the same task. One half as much copper saves money and weight. ///

I think I've got a few pieces together.

Waiting on delivery of the Gecko's from the Customer Appreciaton Sale.

I already have a couple 16 watt Pittman motors from old hp plotter
and a couple DC motors from a couple old-old-old printers. One has a
plastic film wheel with two seperate tracks of lines. I haven't
pulled the back off the other as yet, but would bet it is similar. I
did find one to be listed with 35v and 1.1 amps.

I do have a 2,000 encoder so it would seem that between the pittmans
this unit and the encoder, I should have enough to set up a couple
axies to try things out.

//// A 2000 CPR (500 quadrature) encoder is going to eat the step pulse capability of the PC. A Gecko340 with step mulitplication might be required to attain higher speeds. Lower resolution encoders like 200 Quadrature on a servo at optimum RPM are the easiest. ///

One thing I seem to remember is to put end switches pretty far in-
board to offer some protection from a run-away.

Anyone have an idea how long Gecko is taking for shipping ?
I was one of the guys who waited till the 15th.

I'm in no rush as with the holiday I seem to only have time to surf.

Dave









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