3d Printing with Tinyg ( rotational axis A trouble )

Here is a link to the Gcode in question – one thought is that this is the longest build that I have run and the extruder values are quite high… Is there a limit to how large the values can be for tinyG to interpet?

https://drive.google.com/open?id=1ErkHDe21Id3d8xbWbCtr_cfjwjFO_ZIO

The trouble seems to happen shortly after the extruder value exceded 25k…

Long-winded. Apologies, please bear with me –

I’m becoming certain that the issue is either my tinyG settings or something that is in the firmware… I haven’t seen any fully operational 3d printers utilizing the tinyG, only short clips of initial tests. if anyone is doing it I would love to get a glimpse of their axis settings.

Thanks cmcgrath5035 – the x,y velocity is constant (plus the pump is stepper controlled), and there are no loops or macros in the code.

Thanks yawstick – I rebuilt my grasshopper definition yesterday so that the extruder value resets to 0 after every curve and the extrusion issue has manifest itself again in an identical pattern.

It looks like my squirrely extrusion rate is exactly repeatable. I have essentially verified that there is nothing in the gcode that should cause this. (A friend ran a simulation with the code that would have shown a change in extrusion rate).

I’m not able to verify that it is not an issue with Coolterm sending – I’ve added line numbering to my gcode this morning and should be able to run code tomorrow that will allow me to trace the placement errors, if there are any…

I fired 2 vases from separate runs of the same code (links to pictures bellow). I counted the layers to confirm that the rate shifts at the same place – there are actually 2 rate shifts: one at the 24th layer and one at the 56th layer. 1 droplet = 1 cycle of the pump. You’ll see in the images that the amount of droplets per linear inch varies at these points:

starting (bottom): 3 cycles per inch
middle: 2 cycles per inch
top: 4 cycles per inch

https://drive.google.com/open?id=1XMMTOHm81IH_v9_QFHlidlF0K5G8V38h

Thanks for staying interested yawstick.

Here’s a link to a video of the whole setup.

https://drive.google.com/open?id=1pqqo1DqOCpieuAcskBBuQdGygUudnrld

You’ll see that these are all parallel walled forms so the linear distance of each layer is identical – this is going to slightly confuse the subjects, as the eratic patterning of the form is created by dropping the pump stepper voltage with the onboard pot until enough steps are skipped to disrupt the the regular pattern (otherwise the layers would build like a brick wall and simply be less interesting).

I don’t think this is current related because it wouldn’t be repeatable. On my current tests the pot is turned up enough that there don’t appear to be missed steps.(regardless, missed steps would not manifest identically in two separate runs of the code).

I’m printing vases that increase in diameter at the same time as those which reduce in diameter – so the linear distance of each layer is ‘relatively’ constant.

To generate the extrusion code with rhino/grasshopper – I’m turning curves into a series of points which are spaced 5mm apart all along the curve. With my current flow rate, the pump should complete 0.625 cyles per 5mm, and this stands up if you review the gcode. Doesn’t stand up in the print.