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peter-parnes

Warping on UM2 heated bed

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I have now made about 10 prints on my UM2 and almost all have warping. Way more warping than on my UM1. I thought the heated bed would reduce the warping, not increase it? Any suggestions on what the best temperature of the heated bed is?

Ps. For those wondering I can say that printing directly without having to fiddle with the blue tape is wonderful!!!!

 

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Would be good to know more details...

Room temperature? (almost never reported but very important that it is not too cold)

Filament type?

Settings used?

Object shape and size?

Pictures would be good, video even better... :)

We print PLA-based filament with 60C and copolyester/PET (Colorfabb XT) with 75C bed.

The glue stick helps against warping although we haven't had any warping problems.

/Daniel

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I have now made about 10 prints on my UM2

Yay!!! :)

 

and almost all have warping.

:sad:

Warping/shrinking is very complicated. If all you care about is the bottom layers this is very easy to fix. Assuming the part is the robot or larger and you are using the blue PLA that came with the UM2 then 70C bed temp is great. This will keep the lower layers of the robot hot enough that it never becomes solid and so it will be soft. It is also important to keep the fans off for the first 10mm or so. That way the entire lower portion of the robot stays above 55C and 55C is about where that ultimaker blue PLA turns from mush to solid. You can do this in cura advanced "cool" settings. It would be helpful to keep the air also hot so I would consider closing the front of the UM and covering the top with a box but this shouldn't be necessary.

In addition, the "brim" feature in cura helps immensely. Also cleaning the glass (with soap and water or alcohol or windex or dish washing soap) and then a thin coat of glue stick.

Make sure the glass plate cools to at least 50C before trying to remove the robot because at 55C or warmer you may destroy the robot (distort it).

For ABS you need the glass MUCH hotter - I think around 110C maybe?

 

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Hi again.... after some more printing and testing I have made good progress on some smaller object but I still get a lot of warping on bigger objects. Objects that printed fine on a blue-tape-UM1. I am printing in room temperature 75 degrees on the print bed. I do increase the flow to 115% on most prints. I have tried leveling the bed several times. The wrench in the first three images is printed on a washed glass bed with a fresh layer of glue.

Here are some pictures:

IMG 0082

IMG 0081

IMG 0080

IMG 0079

IMG 0078

IMG 0077

 

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I noticed a pretty big difference in warpage between the blue PLA I got with the printer and black PLA from Faberdashery that I've had for a long time. The blue PLA showed pretty much zero warp on a print I did, only a teensy tiny bit lifted in one corner with the bed at 50C. However, with the black PLA I had massive warp.

The latest prints I've done have been with white PLA from faberdashery and it seems to have a tougher time sticking to the bed during the first layer (it bubbled up immediately) so I had to put a bit of glue on there. I only put very very light pressure on the glue stick to get a very thin and uniform coat under the print. Made a big difference. The other prints were done with a clean bed.

So it does seem to vary quite a bit depending on brand.

edit. Three Swedes in the same thread, that has to be some kind of record :p

 

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1) Yes, first layer too high

2) Use the brim feature. I see you used it for the pencil case but not the wrench.

3) Please do the following experiment:

Get a thin piece of pla - maybe from a failed print that is only a few layers thick. Thicker than 3mm is too thick. In fact if you can get 5 or 10 or 20 that is better.

Place it(them) on the heated bed and heat to 60C. After 5 minutes go back to the printer and remove the PLA part from the glass. Try bending it quickly before it cools down. Repeat at 70C and 80C. Try to find the temperature where the PLA is very soft. You want the bed hot enough to achieve this - you want the PLA soft enough so that even if it does warp a little at least it won't pull of the bed - it will just self adjust.

Also you want the fan on a low setting for quite a few layers so the PLA doesn't cool below this "glass transition" temp.

My blue PLA seems to transition around 55C.

 

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