Let me get this straight John he needs belts for what reason? (keep his trousers up from the weight of the stuff he is pilthering in his pockets). And the 2 pulleys are his accomplices i take it that keep watch?
LOL!If the nagging gets really bad......Get a bigger shed:naughty:
Right then, looks like I better get the van loaded up and head round to johns with a couple of packets of hobnobs before it's too late.
Probably find a couple of polyvee belts lying around whilst I am there.:whistling:
Been playing with the Spindle2 board today and have interfaced it with my controller, got it all working but I have got a little bit of discrepancy with the volts coming out of it and the programmed spindle speed.
Configured my spare A axis to output to the Spindle2 board and ended up with my spindle motor tuning set at 1000 steps per unit and velocity at 130, tried tweaking above and below these but these settings seemed to give me the best output voltages from the Spindle2.
Set the max speed in mach (pulley selection) to 6500.
I now get 10.00V exactly from the Spindle2 board when I program the speed in mach to S6500, but when I set it to half (S3250) I get 5.7V. Tried lots of different values in the motor tuning settings which do change what voltages you get but 5.7V is the lowest I can get it to when the speed is programmed at 3250, I would like to see it closer to 5V but can not see any other settings which influence it. Have i missed something??
Sounds like your pulse rate -> voltage conversion is not linear. According to the spindle2 manual its intended to be used at 2000 steps/min for 10v and tweaked using the adjustment on the board to get this spot on. I suspect your starting point of 1000 is too low and at 500ppm the board is having difficulty adjusting to it...
To adjust these correctly you need a special screwdriver shaped like Roy Harding.John S -
Thanks for that Irving, seems like you were on the right track.
Seems that the steps/unit and velocity were linked (which makes sense), if I increased the steps to 2000 then I had to decrease the velocity to 65 to give me 10V at full speed which releated to my original 1000steps/130 velocity. This still did not give me 5V at half speed, still the same 5.7 as before.
I have increased the pulse width from my original setting of 1 up to 10 and now it is giving me a much better linear relationship. Now have 10.00V at full speed and 5.01V at half speed.
Increasing the pulse width to 10 effects all the motor settings, what effect will it have on the steppers if any at all?? Everything seems to be running fine still.
Last edited by HiltonSteve; 03-05-2010 at 09:05 PM.
shouldnt affect the others at all... at the default 25khz kernal speed the nomiinal cycle time is 40uS so a pulse width of 10uS isnt going to be an issue. Most stepper drivers need a pulse width of not less than 1 or 2uS but as they are edge triggered the larger width isn't an issue.
I thought that the pulse width might be the issue at that lower frequency. I am surprised though, I would have thought Roy would have put pulse-width conditioning if he was doing frequency to voltage rather then pulse-width to voltage conversion, I would have, but then I'm not designing for commercial supply (since he knew that pulse width can be adjusted in MACH3 maybe thats a cost he didnt need to bear).
I have left the direction pulse width at 1, shall I increase that to something similar to the step width to keep the 2 the same?
John, you are right about the screwdriver, had to modify the smallest one I had to tweak the pot!
shouldnt be necessary, as long as its all working OK... direction isn't a pulse as such, its a level - hi is forward, low is reverse (generally)... I can't think why you'd actually ever specify a pulse width for the direction signals...
The Following User Says Thank You to irving2008 For This Useful Post:
Just got the tacho on my spindle to see how close it was running to the programmed speed and after a couple of tweaks to the max pulley speed in mach3 it worked out pretty good!
Turns out that my calculated max speed of 6500rpm was a little bit out, the motor must be running faster than the 2000rpm printed on the legend plate which is a bonus.
Just a few RPM out which is plenty close enough for me!
Last edited by HiltonSteve; 05-05-2010 at 09:57 PM.
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