Prints come out lumpy

General LulzBot TAZ
1

Hello folks,

I’m printing on a TAZ 5 standard setup with Hexagon head. I have recently run into the problem that items I am printing are coming out lumpy and distorted. I’m not really sure how to describe it, so I’ve included pictures. The mystery here is that these exact parts, with the same material and settings, printed cleanly in the past. The only change I can think of is that a couple weeks ago I moved the printer from one desk to another desk right next to it (total distance moved ~5 feet.) I’m thinking this could have messed something up, but I’ve had clean prints since the move.

The material here is PLA/PHA, printing at 225/70. Layer height .14, Speed 50mm/s. There’s no problems with bed adhesion. I’ve looked around for existing threads on this issue, but as I’m not really sure how to describe it, I’m not sure what to look for. I had wondered if it was a cooling issue. There’s no enclosure on the printer, and if I leave a door open there can be a draft. But this was never a problem in the past, and I still get these issues if I close the doors and eliminate the draft.

Any ideas?

UPDATE:
Upon further examination, I can see that the problem is areas curling up during the print. When the print head passes over, it pushes them back down again, but then they curl back up. It’s especially bad on areas with slight overhang, as they are thinner. No problems with adhesion to the bed though.
IMG_20160621_240000929[1].jpg
IMG_20160621_240012598[1].jpg

2

That looks like mainly a cooling fan issue. Check that your cooling fan is operating at the correct speed and is enabled.

3

It is. However, it is very hot in my area at the moment. We’re in a heat wave and are getting over 100degrees the last couple days. Could that be interfering?

4

It depends on if you have air conditioning and what your ambient temperature is. If your room where the printer is located is much hotter than normal, that would definitly mess with your results. Those little 40mm fans can’t handle a 30 degree temperature swing.

5

It’s certainly that much hotter in here than usual. I do have other fans running, but they don’t seem to help much. Is there anything else I can do to deal with this?

6

Switch filaments is about your option at the moment. Something like abs that likes heat would work.

7

You could also try lowering your printing and bed temperature a bit and lower your print speed as well. Try 195c and 50c and something like 30mm/s speed and see if that helps.

8

Hard to tell by the photos, but your object looks a little on the small side. Have you tried printing multiples at once, which would allow more time for it to cool?

9

Thanks everyone. It is cooler the last couple of days, and my results have improved. However, I still can’t get a clean print. I have tried:

  • Lowering print speed
  • Thinner and thicker layer heights
  • ABS
  • With and without extra fans
  • Lowering head/bed temp

None of these seem to make any meaningful difference. I’m getting better results, but couldn’t notice an improvement from any of these changes. The area that’s still having trouble now is a ~20deg overhang. The layers curl up, and aren’t sufficiently pushed down by subsequent layers.

10

Can you post the STL and / or GCODE?

11

I’m afraid I can’t as it’s a piece for a client. I do seem to be having this problem on multiple pieces though. Maybe I can dig up a file where I can recreate it that I could share, but it won’t really tell us anything.

12

No problem. Might be worthwhile to run through netfabb to check for any errors in the mesh.