help with motor torque

[skanner]

hi rich
thanks for the reply the board was set at 75% so i only had one more step up,after setting it to 100% the z worked ok although the motor sounds like its missing a step every now and then but the measurement is ok also the motors are making a little nose when standing still, i worked the z up and down for 15mins and the motor was only warm so i guess this is ok i left it for one hour and the motors got a little hotter but i could keep hold of then with my hand no bother.
i will take a look at the geco site as you suggested. thanks again for the help.
john

[reichert2011]

Hi all, I know I am a little late on this, but hopefully someone will see this.  I too am having issues tuning the motors.  I am running the ebay chinese tb6560 board, 24 volt power supply, I tried 2 different sets of motors and get the same results.  I have everything working correctly, I just can't get any speed.  As soon as I try and increase velocity, the motrs seem to stall.  I can get anything faster that 20 ipm.  I tried setting different current setting, for 25% to 100% and it really doesn't make a difference. I am running 1/2 step, fast decay ( I think, not too sure what this does), my acceration is set to 4,

any ideas on how I can get more speed without the motors stalling out.  I have the motors wired for torgue, ( I thinnk that is parralell?)

any help would be appriciated.
Don

[Hood]

I think your problem is likely the low voltage. Voltage dictates the  speed you will get, so if you dont have enough voltage you are not going to get much speed.
Hood

[reichert2011]

The problem I have is I can get more speed, but loss the power(torque) of the motors, So I set to 60 ipm, and tings might move a little, then you can here the motor grinding almost, but the DRO keeps moving. If I increase voltage, with this also help the torque. I guess I can live with 20 ipm, but I find if I mill plastic, it heats up too much and melts. I tried 2 different sets of steppers and get the same results.

[RICH]

Torque will decrease as the speed increases. Not all steppers are the same and only a torque to speed curve will show you the tested difference. If you increase the voltage you will get more speed but you would be changing the motor curve. Most curves are based on 24 or 36 volts, so if you apply say 60volts  the curve changes.

I just recently changed out my steppers on the mill with the new steppers having 2.5x the torque of the old ones but at the same max voltage. The increase in reliable speed was about 10% so don't assume anything.  You can play with the acceleration some and see what happens as your starting and stopping slower and once the axis is moving you usualy don't need as much torque.

Must add, that depending on how they are wired you can change the operating  characteristics of the motor. Have a look at some of the info on the Gecko site for more detailed information.

FWIW,
RICH