Question here: Is it a must to have this 150 degc hotend temperature? When I print ABS every things expand while heating up and the zero setting is'nt good anymore. Then I have to play with fine settings until I get a good first layer. Annoying
Thanks.
Francis
Full Disclosure: I'm no expert on anything related to 3D Printing.
I was having trouble getting consistent first layer squish, so I did a little test. After running Ellis' squish tuning procedure, I printed a file with (9) 30x30x0.25mm patches, once with hot end at 150C, then again with hot end around 45C.
Trial 1: Bed 110C, Hotend 150C, Chamber 44C, 30 minute heat soak. Results: Good first Layer.
I let things cool down over night.
Trial 2: Bed 110C, Hotend 45C, Chamber 44C, 30 minute heat soak. Results: Gaps between lines.
I did NOT run this test multiple times and I'm sure there are a bunch of variables that I'm not measuring, but just based on the little that I did do, it seems that hot end temperature matters. So I did a little research (aka googling) and I did a little math.
Length of V6 nozzle is 12.5mm. Rate of thermal expansion for brass is 0.0000188 per degree celsius. Delta Temp on Nozzle 150-45=105C
Delta Nozzle length: 12.5mm * 105 * 0.0000188 = 0.024675mm
This is not huge difference in length, but with my very limited experience, I think it's enough for a noticeable difference in first layer appearance. It seems to me that being consistent with hot end temperature when Z-Homing / QGL / Bed Mesh, is relatively important. I'm guessing if you always run with hot end off, you'll be ok. Likewise, if you always run with hot end at 150c (or some other consistent temperature), you'll also be ok. But I think it's important to always do it the same way.
I'll appreciate any feedback I can get on my (probably over simplified and maybe just plain wrong) logic. Keep on tappin'!