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Print head not following path and over extruding

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blob:https%3A//drive.google.com/eade3e6e-d6d4-472b-9bd0-8f205f03bffc

I have been trying to print the zonda print on thingiverse for quite some time now. My ultimaker 2 was stopping the extrusion mid print but that issue seems to have been fixed. The last print I attempted failed completely. It seemed to over extrude and not follow its defined print path. The link above should show the picture I took of the Cura file compared to the print.

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Lol - that's to a drive on your computer. I don't know how to access your personal computer. Start a new post. Click the right most icon that shows a mountain and a blue plus symbol. Click the "upload image" tab and then drag and drop your picture onto that, then choose full image (not thumbnail).

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I've seen this before when the part doesn't stick to the bed and gets dragged around by the nozzle. Is that what happened?

There are several ways to improve this. Here's my standard answer pasted in - you can probably skip brim step as this part (car) should be relatively easy to get it to stick:

lifting corners, curling corners, part not sticking to glass

1) Make sure the glass is clean if you haven't cleaned it for a few weeks. You want a very thin coat of PVA glue which is found in hairspray, glue stick, wood glue. If you use glue stick or wood glue you need to dilute it with water - about 5 to 10 parts water to 1 part glue. So for example if you use glue stick, apply only to the outer edge of your model then add a tablespoon of water and spread with a tissue such that you thin it so much you can't see it anymore. wood glue is better. hairspray doesn't need to be diluted. When it dries it should be invisible. This glue works well for most plastics.

2) Heat the bed. This helps the plastic fill in completely (no air pockets) so you have better contact with the glass. For PLA any temp above 40C is safe. I often print at 60C bed.

3) heat the bed (didn't I already say that?). Keeping the bottom layers above the glass temp of the material makes it so the bottom layers can flex a bit (very very tiny amount) and relieve the tension/stress. For PLA 60C is better than 50C. 70C is even better but then you get other "warping" like issues at the corners where they move inward but if you are desperate it's worth it. For ABS you want 110C (100C is good enough).

4) rounded corners - having square corners puts all the lifting force on a tiny spot. Rounding the corner spreads the force out more. This is optional if you use brim.

5) Brim - this is the most important of all. Turn on the brim feature in cura and do 10 passes of brim. This is awesome.

6) Squish - make sure the bottom layer is squishing onto the glass with no gaps in the brim. The first trace going down should be flat like a pancake, not rounded like string. don't run the leveling procedure if it is off, just turn the 3 screws the same amount while it is printing the skirt or brim. Counter clockwise from below gets the bed closer to the nozzle. Don't panic, take a breath, think about which way to move the glass, think about how the screw works, then twist. This may take 30 seconds but it's worth it to not rush it. You can always restart the print.

If you do all this you will then ask me "how the hell do I get my part off the glass?". Well first let it cool completely. Or even put it in the freezer. Then use a sharp putty knife under a corner and it should pop off.

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Alternatively your X and Y pulleys could be loose allowing the head to move the wrong path. But this is very unlikely to happen in *both* axes at once. But if the part stuck well to the glass and you watched this happening and the part wasn't dragging around - then plan B is to tighten the hell out of ALL SIX (not just 4) pulleys on each axis - usually the pulleys on the motor. Tighten the hell out of those - the hex wrench should twist a little.

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I wasn't able to watch the part print all the way through as it was around a 13 hour print. What I was able to watch was the beginning of the print, which most definitely showed the print sticking to the glass. On any previous print and any print since I haven't had an issue with the print not sticking. However, on some prints the machine seems to stop following the path very closely or it seems to start to over-extrude. I lowered the temp at which the material comes through the print head and this seems to help, but it didn't completely fix the problem.

I don't want to lower the temp of the head any more because it is already at the melting point of the plastic.

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Again I was having trouble inserting a picture into the post, so here is a link to an upload on imgur again. http://m.imgur.com/TNSDCBs

In the picture I have the same part printed two times. The first one, on the left, was using settings that I had no issue with before. Obviously these did not work and the print didn't turn out. On the second attempt, on the right, I lowered the temp and slowed the printing of the base layers. The part had no trouble sticking in either print but as you can see it did not turn out correct at the top of the print.

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This print has NO RESEMBLANCE to the other print. I'm pretty sure any issues are unrelated.

Clearly the print did not move. So that was not an issue with these 2 turkeys. Are these turkeys 13 hour prints? they look small like they are maybe 5cm (2 inches) across? They shouldn't take more than an hour I would think. Are they solid? I don't understand why this small part would take so long. I guess you need to post your settings. Please open the turkey gcode file using "load profile from gcode" then save your settings to a text file with "save profile...". Then post all the settings here - the entire file please.

the top of the turkey on the right looks like it had cooling issues. Did you have the side fans on? They are critical to getting good prints.

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By the way, since the turkey on the right came out nicer, I think lowering the temp helped. Consider going down to 190C if you aren't there yet. I suspect you are printing very slow volume rate. Very very slow. So you should be able to go down to 170c no problem if it weren't for that Marlin feature. If the temp drops below 170C though the extruder will stop turning on purpose. That's a Marlin feature.

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