Changing gears (on a mill)? "gearchange"? Examples

12 Sep 2009 17:39 #828 by nickm

I'm converting a MAHO 700-C from a (broken) Philips 432 to EMC. Basic things are working, but now I'm stuck with changing gears.

I could turn the motors to switch gears and check for positions by my modbus-interface. But I can't figure out how to integrate that. I found thar there is a "gearchange" command in HAL, but I couldn't find an example.

Could someone point me in the right direction?


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12 Sep 2009 19:58 #829 by BigJohnT
There's some stuff on the EMC wiki site about the Mazak...

The gearchange comp is used to get the correct pwm signal to the spindle drive. For example if your first gear is 1 to 1 then the pwm in is the same as the pwm out. If your other gear is 2 to 1 ie the drive needs 1/2 the amout of pwm to go the same speed as gear one the gearchange comp does this function.

If you have some means of changing gears automagicly then you might look at using a M100 to output a pin change the gears and wait for a completed pin from the gear changer. Things like waiting for the spindle to stop if that is important need to be considered.


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13 Sep 2009 06:11 #831 by nickm
Thanks John!

I had found both links before, but they didn't help me that much. :-)
I'm completely new to EMC and the MAHO is my first project*) with EMC. So call me a noob!
I wounldn't have problems switching the gears in classic ladder I think, but I have no clue at all how to connect the pieces.
I'd like to have something that selects the right gear depending on the requested RPM.
I'd need to know how I can hook into a function something like "SetRPM" and send / receive coils / inputs to CL and control the RPM (sloooooow for changing gears).

My brain works in examples and not in man-pages. :-)

Designed my own expandable ModBus-interface that could have hundreds of INs and OUTs (but I only have 32 of each), built an isolation amplifier for the servos and the spindle amp, optocouplers for the glass-scales. The aim was, to keep the original cabling of the Philips including all connectors and the relais-chain. I wanted a plug & play solution.
I'm using a 5i20 and a 7i33 (a second one will be used for the 4th and 5th axis later on).


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15 Sep 2009 11:27 #834 by BigJohnT

You might pop over to the IRC and inquire there as well. I think I've seen some talk there about having the correct gear selected for the speed there. My thought is that would be a job for the post processor in your cam software or the programmer when the speed is computed the proper gear should be picked. You might want to look at the M100 series to change gears with. EMC does wait for the spindle at speed bit after a speed change so that would be part of the puzzle.

"motion.spindle-at-speed IN bit

Motion will pause until this pin is TRUE, under the following conditions: before the first feed move after each spindle start or speed change; before the start of every chain of spindle-synchronized moves; and if in CSS mode, at every rapid->feed transition."

My brain works the same way :) but at some point you need the man pages for reference.

You should add your modbus interface to the Wiki site that sounds neat.


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