So I’m printing some small parts on my Simple Metal and the results are pretty good overall. The one thing I can’t seem to figure out is how to stop small corners from curling up. It usually flattens itself out over the course of the build but more times than not I’ve had it run into the nozzle and pull off the bed because the corner curled. I watched it print and found that it looks like the plastic is sticking to the nozzle a little bit and when it moves away it goes with it a little. I tried incorporating a Z hop, slowing speed, speeding up, more flow, less flow.
heated bed using hair spray. Let me clarify, I read back my original post and it is a little confusing. I’m not having adhesion issues I’m having curing on each layer after it prints. Instead of the top layer that was just printed being completely flat, it curls a little bit on corners on small parts. I think it is because the plastic doesn’t have enough time to cool before moving on to the next layer.
Under-extrude a bit for lighter flow. Single wall should also help minimize buildup. Might need multiple walls on top and bottom… And might need to play with the infill too, depending on needs. A healthy brim will help too. The smaller, more intricate… The slower. I’ve seen super tiny, detailed prints go down to 10mm/sec.
How big is your nozzle? If it’s less than 0.4 I suspect the layer height might be too big, which can lead to it curling up (not adhereing) to the lower layers well.
On very small parts the layers don’t have enough time to cool down. Printing slower typically doesn’t help because the radiated heat and contact keeps it hot. My own solution to this was custom gcode where the extruder would park off at the corner of the bed and wait until it cooled before printing the next layer.
You can also try lowering the extrusion temperature or using a fan.
Hmmm Cura has a function that will park the hot end if the layer time is under a certain amount of time and then start back up once the predetermined time is reached. Maybe that will help. I’m concerned about stringing though so I’ll have to see how that works. Thanks!
I have tried almost everything to stop corners and overhangs curl up and then be deformed with hot end again (mainly PLA, Simple Metal Rev. F). From thin walls to infill, from lower flow or min. layer time to temperatures (icl. printing on cold surface with PrintInZ plate), from Cura via Slic3r to 3DPrinterOS etc. Nothing works for me with ceramic Ubis. (And E3D V6 hot end was a jamming failure for the 1st attempt, but it is out of topic. And all metal Ubis is round the corner.)
@Brook_Drumm I have tried extra 120mm fan from different angle, but with no extra effect to curls. My best possible results to solve at least 35° overhangs are with minimum printing temperature (lowest then manufacturer suggest), lower flow (between 0.9 to 0.95 according to fillament), low infill and number of walls. But these settings are not handy for prototypes with vertical walls and demand of full strength.
It is not problem of bridges, but these curls up destroyed by nozzle from upper layers.
PS: Some printers can do 60° angles without leaks from overhangs.
Corners curling up usually are an indication that you are printing with too little cooling. You are laying down the next layer while the previous one has not cooled enough. PLA usually cools so fast it stays amorphous. The longer it takes to solidify, the more time it has to form crystals, which pack denser and doing so causes some shrinkage. Once you get to that stage, the previous layer does hold down the next one a little less, allowing the corners to curl up.
The solution is pretty simple: more cooling air. If you have a fanduct: throw it away unless it restricts the outflow to no less than 75% of the inflow area. Get a radial fan if you need more pressure, but even there you should not restrict it too much. A fan blowing from two sides seems to work too, counter-intuitive as it sounds though.
@Jelle_B I have tried 6 fan shroud variants, very noisy (super) fan, additional 120mm fan from different side. Maybe the last chance is to not only prolong time for small layers from 10 seconds to 20 seconds, but also return to lift nozzle away during these pauses between layers. But there is a problem of oozy Ubis hot end, so each return of the nozzle will be with some piece of fillament.
If you need more than 10 seconds you really need to improve cooling, make sure there is a nice flow parallel to the XY plane. You do not want a Z-hop, as that pulls material out of the XY-plane, making a bump the next time the hotend runs into it. An UM1 can print very fast with just one 50mm fan, so it all is a matter of aiming where your air goes. (and no, do not use any duct that has an outflow area smaller than 75 of the fan area).
Incidentally, if you print small/tiny parts, it really helps if you print 2 instead of having a hotend radiating heat on it all the time.
