Bigger Prints Warping



  • I have to say printing from the duet wifi has been so easy. Especially on smaller things. (3x3x3) they look magnificent. However I need to print some larger things, more specifically some flat rails 1x 1/2 x 6 1/2. Every time it prints, at layer 10 of 47, the corners of the print start to curl. I am using PLA+ settings are 210 hot end 60 bed temp. I am printing on kapton tape on glass. Cooling fan is set layer 1 +0 ; layer 3 25%; layer 4-75; layer 5 100%. Any ideas?



  • Have you tried playing with pressure advance settings? you can change them from the gcode console midprint to see which setting stops the curling.


  • administrators

    Warping of PLA prints is often caused by draughts. It helps to shield the printer from draughts. Also check that there is no backwash from either of the fans on the hot end, and fit backwash eliminators if there is.

    Switching from Kapton tape to PEI may also help, or using PLA+ filament instead of PLA.



  • I'd check that the edges of your bed are not a lot cooler than the centre. PLA does contract on cooling (although print some ABS and this problem is put into perspective). IR thermometers are not very accurate but if you put a sheet of black paper on your bed, the readings from the IR thermometer will at least be relatively accurate.

    Try more insulation under the bed, and perhaps print a tall skirt (5mm) which will keep heat near the edges of the parts and shield from draughts.

    The other really easy thing, is load the part in any old cad program like tinkercad and add circular pads (mouse-ears) 1mm thick and 10-15mm wide at any sharp corners on the first layer. Circular pads distribute the shrinkage stresses much better and therefore the corner is not a concentration of force and doesn't pull away, just cut them off after printing.



  • @DjDemonD:

    The other really easy thing, is load the part in any old cad program like tinkercad and add circular pads (mouse-ears) 1mm thick and 10-15mm wide at any sharp corners on the first layer. Circular pads distribute the shrinkage stresses much better and therefore the corner is not a concentration of force and doesn't pull away, just cut them off after printing.

    Interesting.

    I download some STL files from Thingiverse that had these and I did not know what they were for.

    Now I do.

    Thanks.

    Frederick



  • They are super useful I've tried to convince the makers of slic3r to auto generate them as a support option, maybe I'll ask on the prusa slic3r fork since they seem much more active and involved. They work better than brims, and are easier to remove, brims still have concentrations of shrinkage stress at their corners, if the part has sharp corners. If a brim could become much more circular anywhere where there are angles greater than 70 degrees on the part they would work much better.



  • i dont think he is talking curling from the bed. I have seen this with PLA (i dont have a fan though) it was solved with pressure advance. the curling is occurring by layer 10 according to the OP unless his PLA has some really bad shrinkage.

    +1 on the mouse ears… i am going to ask S3D if they will do the same this would be perfect when dealing with Acetal pom or large prints of Igus iglidur which start curling at layer 1 if a perfect first layer is not achieved.



  • I don't get any warping with PLA - even monstrously large prints. The best temperature for me, on my machine, with my hot end etc. is 195 deg C, bed at 50 deg C, no fan except on very small parts and bridge moves.



  • Have you printed 3d benchy? The bow is where i noticed it mostly. Also corners of a cube when pressure advance is not set correctly. The OP is using PLA+ which cant be printed at 195 (i dont get extrusion that low) though 205 should be fine unless he is printing fast.

    mind you i am talking about several layers into the print…. I dont get warping from the bed just curling on layer corners.

    I guess well have to wait and see what the OP says if he means corner curling or warping from the bed



  • I was also experiencing this (IIUC) and the culprit was an uneven heat spread on the bed. I had the bed temperature set to 73°C for the first layer and 55°C for the rest. At around the fourth layer corners would begin to curl up. I felt the temperature at different points on the bed with my fingers and found out that there were stark contrasts in temperature between points only 2cm apart.

    A workaround for me was to heat the bed to 90°C, and start printing when it cooled down to about 80°C. I figured this would help the bed area further from the center to contain heat better and thus prevent larger temperature differences per distance from occurring. During printing of the first layer of a larger print the temperature would set to 73°C. After repeating the routine before each print, three 1.5h print jobs completed neatly with good bed adhesion and no detaching.


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