Re: Double Engraving Problem - NOT A MECHANICAL ISSUE
Posted: Sat Jan 16, 2021 8:57 am
Results of the oscilloscope testing confirms what I thought. All 3 of the DM series drivers I tested in the machine are the low budget version of these drivers that have the smoothing features enabled but lack any way to tune or disable them. They don't have a RS232 port for programming with ProTuner nor dip switches for disabling these features. What that appears to do is apply acceleration control in the driver itself which throws off the timing of the firing of the laser. The controller applies acceleration and then it is compounded with the acceleration in the driver making the pulses get out of sync and the motor steps lag behind. Here is a diagram of what testing with the oscilloscope shows:
So this was a lot of testing, trial and error, and headache to come up with a very simple answer, don't buy cheap drivers!
I ordered some good ones today from LightObject and looking forward to wrapping up the build, photos to follow.
When the controller fires, the carriage is slightly lagging behind due to the acceleration applied in the driver itself. Since the ramp up is only at the very beginning of the movement, it does not deform the image, it just shifts it a little opposite the direction of travel. This is even worse for bi-directional etching because the image doubles and the shifting occurs in both directions. So this was a lot of testing, trial and error, and headache to come up with a very simple answer, don't buy cheap drivers!
I ordered some good ones today from LightObject and looking forward to wrapping up the build, photos to follow.