Print issue - Warping?

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KeithA
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Print issue - Warping?

Post by KeithA » Sun Apr 20, 2014 3:32 pm

I have been having ,the same problem on multiple prints. I am not sure what it is being caused from. Can anyone give some advice on what I can try to improve it? It was printed from Simplify3D with the default profile. It seems to always happen in the back away from the fan. The bed temp is 70 and the hotend is at 215.

Thanks

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jimc
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Re: Print issue - Warping?

Post by jimc » Sun Apr 20, 2014 3:42 pm

its getting too hot and heat soaked back there. you can print this model along with some other items so each layer will have more cooling time.

KeithA
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Re: Print issue - Warping?

Post by KeithA » Sun Apr 20, 2014 3:48 pm

Thanks for your reply. I printed this with 2 other items but this one was the tallest.

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jimc
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Re: Print issue - Warping?

Post by jimc » Sun Apr 20, 2014 3:50 pm

when its printing down low like that time you layers. 25-30 sec per layer should be fine for cooling. make sure your fan is on and also turn the bed down a little. try 60.

KeithA
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Re: Print issue - Warping?

Post by KeithA » Sun Apr 20, 2014 4:07 pm

jimc wrote:when its printing down low like that time you layers. 25-30 sec per layer should be fine for cooling. make sure your fan is on and also turn the bed down a little. try 60.
Do I adjust that setting here?
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jimc
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Re: Print issue - Warping?

Post by jimc » Sun Apr 20, 2014 4:17 pm

Well i was just saying to add more objects to give 20-30 sec per layer. The speed reduction setting im a little iffy on. It reduces the speed but that also just keeps the nozzle next to the plastic longer. Im not really sure how effective that is. Lower temp to 60 and add enough items to get you some longer layer times then see what happens

Toby
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Re: Print issue - Warping?

Post by Toby » Sun Apr 20, 2014 4:41 pm

I had something like that when I printed the Abe Lincoln model. A small patch in the back about 10mm up from the bottom that was distorted like yours. This had plenty of time between layers.

I think it was caused by the pitch of the model in that area. The perimeters don't have enough to bond to from layer to layer and get a little distorted. That would correspond to your picture as well (assuming that's the bottom of the print we're looking at.)

I didn't test it but my thought for a solution was to increase the number of perimeters.

If insufficient cooling away from the fan turns out to be the problem, you can rig up a desk fan on the back side. I have a small one (about 5") that I got at walmart and leave on the desk behind the printer.

jsc
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Re: Print issue - Warping?

Post by jsc » Sun Apr 20, 2014 4:57 pm

Previous responses have covered the main salient points: PLA tends to curl up on overhangs when not cooled sufficiently, use an extra fan for the back if it's happening there, etc. People have also designed swooshy fan ducts that try to direct the fan cooling in a circle directed at the nozzle (like this one: http://www.thingiverse.com/thing:154907; designed for the older extruder, sadly). It would be swell to have one for a v3b (any 3D modeling wizards, hint hint), but the v4 is "coming soon".

I don't know if it helps, but I also like to set perimeters to print inside to outside for overhangs like that, the theory being it will give the outer perimeters something to hang onto.

Toby
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Re: Print issue - Warping?

Post by Toby » Sun Apr 20, 2014 5:28 pm

jsc wrote:I don't know if it helps, but I also like to set perimeters to print inside to outside for overhangs like that, the theory being it will give the outer perimeters something to hang onto.
Yes. And you need to make sure your perimeters are touching each other with a high enough extrusion multiplier.

Given the other thread about manually adjusting the multiplier during print, it occurs to me you could sit by the print and when it comes to the problem perimeter bump it up manually then bring it back down to avoid over-extrusion elsewhere. But I don't know how fast the firmware responds to commands like that.

Toby
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Re: Print issue - Warping?

Post by Toby » Sun Apr 20, 2014 5:36 pm

And theoretically it should help to reduce the layer height, since then the width of the perimeter is the same but the overhang is less per layer.

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