cmcgrath5035

tinyGV8 vs DUE ?
Hard to say what differences you might see as you are doing a lot of fiddling with parameters that are not “main stream” (CNC)centric. I don’t believe Line Mode protocol has been backported to tinyG yet.

In a bigger picture sense, you might find that some tweaks to the code are desired, the fw build system for G2core could be your friend.

A major focus for G2Core is 3Dprinter support (in addition to CNC milling, etc.). That translates to precision control of low mass print heads, sort of what you need.
More compute horsepower is almost always a good thing, which implies to me that G2core and DUE might be a better bet.

• This reply was modified 6 years, 8 months ago by cmcgrath5035.

I believe you assumption on 1) is correct.

You might want to post this query at https://github.com/synthetos/g2/issues, it is , as you point out, a bit off the beaten path and Line Mode is very new. Issues is closer to folks who like the far side of the bleeding edge

Hmmmm, of course anything is possible but I would chase “choppy sounding” as a possible mechanical issue with the lead screw setup overloading the stepper, i.e. more torque is needed to move the spindle than is available.
A NEMA 23 should be able to manage the typical 400W DC spindles, I still use a NEMA 17 on my SO2 machine.

It would help to see your tinyG parameter set, a $$ DUMP.
copy the results to a cloud drive and post a URL.

Perhaps explain a bit more about what you mean when you say board is level.
Do you mean that the board is absolutely of uniform thickness across the area of interest and that your machine is absolutely equidistant from the work surface to a reference point on the Z axis across the X,Y surface to be milled?
Something does sound strange about your settings (need for $_tr=1.27″).

On my V8, PWM is LED D7, next to Spindir.

SpOn and SpDir operating as expected.

Do you have something connected to the PWM output?
If so, disconnect it and retry.

Otherwise, sounds like the PWM output port on the microcontroller has failed or is somehow shorted to gnd on the pwb.

• This reply was modified 6 years, 8 months ago by cmcgrath5035.

With these parameters, the following commands should:
M3 S5000 Turn on the Spin LED, turn the PWM LED on domewhat dimmer
M5 Turn SPIN and PWM off

Also Try
M4 S5000 Turn on Spin, SpinDir and PWM somewhat dimmer
M5 Turn all 3 LEDs off (SpinDir might stay on, not sure)

Do any of these work as described?

It is very interesting what you are doing.
With regards to yawsticks observation that pump motion seems to be slow-fast-slow, that is likely due to jerk – the concept of jerk is to manage momentum as smoothly as possible; a move form stop accelerates slowly at first, then acceleration increases to achieve the set max velocity, then the motion decelerates on a similar curve. You could try to modify $ajm to see how that affects results.

Some comments relative to your manipulation of stepper A drive current to induce waves. The on board pots adjust the amount of power delivered to the stepper, not the voltage. The stepper driver monitors the current as it ramps up in the motor windings and cut off pulses of full voltage when the set current (by the pot) is achieved. The current thru an inductor (the winding) changes based on the drive impedance of the stepper driver and the inductance of the winding. I would expect operating, as you are, right on the threshold of missing steps, would produce rather random results and be subject to thermal issues, since the stepper will tend to miss more steps when driven by marginal currents at high temperatures. That does not explain the repeatability of your erratic results.