Hi all,
Does anyone know the maximum voltage I can supply the K8200 stepper motors/motor drivers without causing damage during to over-heating of the stepper drivers?
I need to increase the torque I am getting from my X-axis stepper as I have replaced the steel x-axis guide rods with teflon-coated rods with has increased the friction to movement of the axes; I need to avoid using exposed metal rods near the build-plate with my modified system. I have seen elsewhere on the forum that a voltage of 0.6 V should be okay without any active cooling, but this voltage is still a little too low for my purpose.
If I use the extruder fan at 100% output to cool the stepper driver, will i be able to raise the operating voltage to somewhere near 0.9 V or so. If possible, I would like to avoid having to purchase a small PCB heatsink and thermal paste to use with the fan, but if I did this, how much further could I increase the stepper driver voltage?
If nobody has an answer to hand, I will try putting a thermistor/thermocouple on the stepper driver and observing the temperatures reached at each voltage. Am I correct that a temperature above 80 degC will damage the controller, and that a temperature below 60 degC is preferred?
Also, would overheating of the driver cause damage to the board elsewhere, or would I just need to replace the driver itself.
Thanks in advance.
Hi, going above 0.6v with the standard driver is unlikely to work. You can try it as the drivers have a thermal shutdown so should just shut down when they get to hot without causing any damage (the printer doesn’t know that they have shut down so it will keep printing but with no movement on that axis until it has cooled down, then it will resume but the print will not be aligned).
Options are:
Do a GT2 belt modification with the 16 tooth pulley that should increase your torque by about 50% (100 steps / mm as opposed to 64 with your current pulley). It doesn’t come without problems as the belts have to be guided around the 10mm guide rods (look it up it’s not an uncommon mod).
Use the DRV8825 driver as it has a higher current rating and better heat dissipation. Again this has some issues, when just plugged into the K8200 main board it is configured for 32nd micro stepping, which by its nature has less torque than 16th micro stepping. I would think that you need to revert it back to 16th (if you do the GT2 mod you could even drop down to 8th with little effect on the resolution (50 steps / mm as opposed to 64 with your current) again you can look this up).
Use a motor with a reduction gear.
I might try some of those steps in the future, but I have solved the friction issues by replacing the linear bearings. I 3D printed some bearings in PLA using another 3D printer; they appear to be working very well so far. As the bearings and rods begin to wear, some of the PTFE should start to be deposited on the PLA bearings, which will further improve their performance.
Thanks for your help.