whitecloud

Still having some trouble. I’ve experimented a bit with adjusting the jerk settings on the A axis.

If I understand, reducing the jerk would create smoother acceleration

I have reduced the value by half and then quartered – it hasn’t seemed to help. I have not tried increasing the jerk value. Any advice on tuning the A axis?

Also – could the erratic steps be heat related? Thinking about heatsinks and/or a better fan. I currently have a 12v 40mm fan blowing directly down on the board from just a few inches away – I could mount a small blower directly toward the chip on the A driver.

thanks again yawstick – trouble seems to have developed recently – in the past I had some irregularity that was easily managed with the onboard pot or addressing material consistency. My ceramic slurry is very consistant now.

thanks cmcgarth – That sounds like a good test. I think I can run it today. If you still think that the jerk may need to be addressed, would you suggest that I increase or decrease the value?

I ran a test yesterday – without slip – ran single curves from the bottom, middle, and top of the vases from the video I previously posted. I timed extruder rotations per 30 seconds and they were all identical – with the current feedrate, approximately 11 revolutions.

To further confuse, one thing I noticed was that even without a load there was buzzing from the extruder stepper – the pot was initially set at 12 o’clock, and an increase to 1 and then 2 increased the volume of the buzz. Turning the pot down to 11 and then 10 reduced the volume, but the buzz remained. The stepper did not buzz when it was new.

Amazon link to the stepper that is currently on the extruder:

I switched to this larger stepper some time ago when the original stepper begain clicking. Thinking it may be underpowered, I swapped it for the larger one above. clicking still occurs after the machine has been running for an extended periods. Any thoughts on the cause, or if it might be related?

I’ll be swapping back to the previous stepper today, and I think I can run the suggested test with both steppers over the next 2 days. Link to the original stepper which I’ll be switching back to today. It is identical to those on all of the other axis:

https://www.inventables.com/technologies/stepper-motor-nema-17

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.

Thanks cmcgrath5035.

I’ve ruled out a viscosity shift as the source of the problem because in my process, the ‘droplets’ are created by one pump cycle, which is one complete revolution of the stepper controlling the pump. When the trouble arises, the amount of droplets per linear distance approximately doubles. Meaning that it is not simply an increase in flow but rather an increase in pump cycles.

I’m sending the code with CoolTerm – and recently began sending the code from a Raspberry Pi 3 with CoolTerm Linux (which I prefer because it frees up my laptop). There are no signs of trouble, but I have to admit that I rarely understand what is being spit out in the CoolTerm status scroll. I suppose it would be interesting to try sending it from my windows PC.

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

Thanks for the reply yawstick. I’ll try to get a real time video but it will be a couple of days.

The tank is big enough for an entire print – I had the same thought about the viscosity changing from settling so I recently built an agitator for the tank. But the trouble remains.

The pump is iterative and squeezes out droplets – the droplets per linear distance nearly double at the point of ‘trouble’. So the pump appears to be cycling (nearly) twice as much as I’m asking it to.

Thanks – to further clarify: G2 is successfully tracing the intended circle but the pump (A) is not running as expected. I’ll try your suggestions out tonight. I’m also going to update my firmware (still running 0.96). Here’s a link to my settings on dropbox:

https://www.dropbox.com/sh/0qlkbw80ikkxzzv/AADLUKhE0X0z8FUEshyixIlCa?dl=0