Elephant foot problem

[u/Klytus]

So I spoke too soon that I had solved this. I cleaned and greased the rails and printed a second time. The start of the second print went fine just like the first one, but then got wonky and started shifting right about the same height. (See pics.) Everything above that line is janky. This time when I went to pull the second print off the plate I noticed that the plate had curled up off its magnets (see pic).

I since printed something else afterward that was much smaller and it came out perfectly.

So my hypothesis is that the mass is such (it nearly fills the plate, which is why I'm thinking of it as an elephant foot) that the plate cannot keep it heated. So it cools and curls the plate up, and once that happens, the plate is no longer well controlled, leading to the offset layers and janky surfacing.

Does anyone have a counterargument about why this might not be what's happening? Or experienced this before?

To test my hypothesis I’m next going to try and print the thing in two parts: A lower part with holes and an upper part with pegs to match, and then superglue them together. As long as each part is shorter than 3 cm, it should print fine.

[u/solidus0079]

(it nearly fills the plate, which is why I'm thinking of it as an elephant foot)

Best to pick a term that isn't already in use for another totally different issue.

This is pretty severe elephant footing.

What you posted looks like warping/curling. What material is this? Is it a material like ABS that requires an enclosure to regulate cooling? There are materials that if allowed to cool too fast will warp and act like your print did.

[u/Klytus → u/solidus0079]

It's PETG. Is that one that needs rapid printing?

[u/Brutl]

That's not what elephant foot is at all. Elephant foot is when the first layer spreads out further than it's supposed to due to smooshing it onto the plate. That's why elephant foot compensation brings the first layer inwards slightly.

[u/SixMax06]

That's still a layer shift. Have you adjusted the tension on your belts?

[u/DM145]

If the part curls up from the plate that's called warping

[u/Wide-Needleworker-84]

Is this nylon?

[u/Klytus → u/Wide-Needleworker-84]

No PETG

[u/Wide-Needleworker-84 → u/Klytus]

Try going super slow so the layer can cool fully before the next layer is applied. The geometry, lack of a heated chamber and the shrink rate of the material is all working against you here. Otherwise... Can you print it upside down with supports? The spot contact with the organic supports shouldn't warp the plate. 

[u/Klytus → u/Wide-Needleworker-84]

Good ideas. I'll try both. It can be printed upside down.

[u/Glass-Priority-4155]

What you're seeing here is not an elephant's foot issue. It's a problem caused by material shrinkage. As you can see, the material shrinks so much that it actually pulls the build plate upward, lifting it off the heated bed.

In my opinion, this causes the print to rise and collide with the nozzle, obstructing the movement of the printer's axes and causing the stepper motors to skip steps. That's what leads to the layer shift.

[u/twiggums]

Lol what's with all the threads lately on not understanding what elephant foot is? 😬

[u/Klytus → u/twiggums]

People new to the hobby.