Re: SLO-SYN 12.7 Amp motors

I have retrofitted several full sized machines removing old technology servo systems and installing current technology stepper systems which are properly sized to the application and using properly configured software. These machine are all running and making parts.

People seem to really be afraid of stepper systems because of the potential for lost steps. A properly configured machine will have a window in which it will operate very reliably. It will be as accurate and repeatable as the mechanics and positional accuracy of the steppers will allow, assuming the software is working correctly. In some respects, the stepper system may be somewhat better in the fact that it doesn't have a following error.

I do realize that in the past with the older technology that machines commonly lost steps, motors were ruined because of excessive heat and current. Stepper drivers were terribly inefficient, un reliable and costly to maintain. The newer stepper systems are light years ahead of the older drives and are not plagued by the same problems.

I have an Ikegai FX20 20hp turret lathe that pretty much runs day and night producing forklift replacement bushings or various threaded inserts, weldments etc. this machine is using a 1600 oz in pac sci motor on the x axis, and a 2100 oz in motor on the z. The turret is automated with a macro which reads standard tool change commands. this machines just runs and runs and makes parts which are very repeatable for a machine of this vintage. this machine is about the size of a mini van and I know that the Z axis is moving lot more weight than 800#.

I have a mill in the field that is running some surplus superior electric motors on the Ahha software and driver. The owner is using it to machine injection moulds in tool steel. You can see it at: http://www.grifftek.com/mina.htm

I recently finished a modification job on a small table top light machine that has been retrofitted with the Ahha software. The job consisted of machining 4500 pcs of a glass filled polycarbonate part to a +- 0.0020" tolerance. I was able to keep the parts within 0.0020" using an automated air clamping fixture The machine uses some off the shelf stepper drives driving the original MO63 superior electric 23 frame motors. this machine is capable of running 300 ipm but I keep it below 200 to prevent unnecessary wear and tear on the hardware. You can see this machine at: http://www.grifftek.com/light.htm and http://www.grifftek.com/images/misc/machined_parts/trojan_gear/trojan_gear.htm

All I am saying is that stepper systems can be very reliable if properly sized to the application and are driven with compatible software and drivers capable of the required performance (not all steppers and drivers are created equal).

bill griffin
www.grifftek.com
bill@...

>Message: 17

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>I have finished the mechanics on my big gantry mill and am ready to hang >motors. I am faced with big bucks to
>buy 4 axes of servos (400+ in oz peak torque) and amplifiers.

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>I had no intention of using an open loop system on my machine. I have seen the >unfortunate effects of slipped steps before. That would be fairly violent when >one is moving an 800 lb gantry.

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>Leslie M.Watts

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