Wanted: A high frequency limit plugin

I realize this is likely quite complicated, but I think it would be highly useful to the reprap community (and me) if someone(s) were to make a plugin for skeinforge which limits the frequency of infill moves to a set value.

Ideally, there would be 3 settings to adjust:

Frequency, minimum angle between moves, minimum number of moves.

Frequency: adjusts how many moves can take place per second, typical value of ~20.

Minimum angle between moves: is to prevent high resolution circles from being affected. If any two moves are less than this value they can be ignored for the frequency calculation. usual value ~45deg

Minimum number of moves: is because short duration high frequency fills usually do not create a problem. usual value of ~4.

Anybody willing to give it a try? I'm more than willing to help out with testing.

Frequency limit, or notch filter? A high enough frequency wouldn't cause a resonance, but it might also be a uselessly short sequence of moves.

Hmmm. Resonance will be axis-specific, unless you have something like the Ultimaker in which the axes' mechanisms are essentially identical. Separate settings for each axis would also eliminate the need to examine the angle between moves.

Edit: I wonder if this should be implemented in firmware instead.

Edited 1 time(s). Last edit at 06/04/2011 11:02PM by Dale Dunn.

Frequency limit.

Above about 20Hz it is in the highly audible range, and your machine sounds terrible regardless of whether it is actually shaking itself apart. Plus, other things on your desk/workbench start to shake. I would also bet for you to greatly exceed the resonant frequency it would be outside the stepper motor's power output. Just my opinion though.

As for per axis, I'd argue each axis has roughly the same resonant frequency anyway. The spring constant for the motor/belt combo should be similar, and the bed weight and extruder weight should be also. Perhaps a wobbly frame could be an issue. I think whichever was easiest to implement would be he way to go for now.

It is certainly a skeinforge issue for 2 reasons:

1) If it's implemented in skeinforge it automatically works for almost every reprap
2) Adding it to firmware would make that many more calculations the tiny Atmega has to do.

I second this request. When you start trying to push the speed there are two issues that get you:
Can your extruder keep up.
Will your motors skip steps.

I have found that I can print less complex parts at higher speed, but if there is a narrow part that does a rapid zig-zag fill, it can skip steps and ruin the print. This frequency limit would allow me to push the speed a bit higher.

There's more to resonate than the motor/belt combo. The Mendel/Prusa X axis is subject to low frequency resonance because there is very little rigidity in that direction. Especially near the top of a tall print. On the Y axis, it's pretty much just the belt and motor.