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I have a model I've been trying to print for the past month, another vertical wind turbine. The base is 10 inches in diameter, about 3/8 to 1/2" thick. The height is around 12.5 inches. The problem is after printing 8 to 12 layers, the print head will slow way down, and then starts printing at an angle. Something is causing one of the towers to lose steps. I've tried slicing with different programs, regenerated the model to a lower resolution stl file, tried different sd cards, printed from the pc in "dry run" mode. It still happens. Time wise, its around 2 to 3 hours into the print. Always while its printing infill.

I had assumed it was the stepper drivers getting hot, but according to my IR thermometer, they are below 50C. The stepper motors are also below 50C.
During this time I've printed some long prints, 18 hours or so, with no problems. It is just this one model so far that seems possessed.

Thoughts?

You've tried printing from SD and it doesn't matter, same result?

Stock arms? Is an end hanging up on the effector or carriage mount?

Umbilical swinging to extreme during a fast infill move, and getting caught on arm or fan?

Yep, tried different SD cards, and nope, no mechanical hangups. I'll have to try to download the section of dropcam video where it fails, and post it.

If your printing at the edge of your build area, you might want to slow down your travel moves, as the arms get closer to horizontal they have to move much faster to meet the required movement speed of the effector, and the limit is on the platform movement, not the carriage movement. So a requested 200mm/s might require a carriage to move at closer to 400, at the center of the build plate it's not an issue.

I believe max speed for infill was set for 100 mm sec. As I posted earlier,,, you get a warning its about to fail when the print head slowly moves to the center,,, the last print was sliced with Craftware, using triangle infill at 10 percent.

Polygon brings up a very good point. Travel speed and infill speed are separate, but even so 100mm/s is a lot near the perimeter.

Consider the worst case - the effector is extremely far from one of the towers, and that arm is nearly horizontal. If the printer tried to move the effector back to the middle at 100mm/s, how fast must the tower skate move to make the effector move at 100mm/s immediately? Extremely fast - probably faster than it can handle.

I bet Polygon nailed it.

Lets see if this works,,, https://www.dropcam.com/c/8818242dbd544 ... 3644e7.mp4 Two minute clip, and the fail happens right after it lays down the two outer perimeters.

Weird! Your Rambo cooling fan is working?

Mac The Knife wrote:Yep, tried different SD cards, and nope, no mechanical hangups. I'll have to try to download the section of dropcam video where it fails, and post it.

Good point! When I was print the spiral speakers, they went way out between the towers and the arms were very flat. The dithering motion of fill between parallel lines was just too much and the print would fail by losing steps. Had to slow to 30mm/sec via the over ride until past this stage.

Worked fine after discovering this.

That is exactly the failure behavior that I had with the speakers. Same pause, return to center and then wandering off. I thought that the problem was just overflowing the processor queue and the processor resetting.

After losing a lot of steps the motion is fairly random. I solved mine by slowing way down.

nitewatchman wrote:That is exactly the failure behavior that I had with the speakers. Same pause, return to center and then wandering off. I thought that the problem was just overflowing the processor queue and the processor resetting.

After losing a lot of steps the motion is fairly random. I solved mine by slowing way down.

That's why I figured it was processor related, not mechanical. Oh well, I cut the flange down from 10 inch diameter, to 9 inch diameter. The rapid travels prolly didn't help much either. I'll have to give it another go tomorrow evening.

Reducing the diameter to 9 inches did the trick, all other settings were left the same. I'll blame it on constipated buffers.