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All Springer/NP/PCP Air Gun Discussion General > 3D printing and files

Part surface cooling between layers

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WhatUPSbox?:
Bob has collected a lot of data on Z axis strength. I was curious what the surface temperature was between layers. I was printing some cable clips in PETG and took some thermal pictures. Printing was at 240C with 70 C bed. The first picture was with 50% fan. The video was without fan cooling. I was surprised how low the surface temperature was for printing the subsequent layer and how quickly it cooled even without a fan. In hindsight, I was only painting a .2 mm layer and the thermal mass of the printed part can pull the temperature down pretty quickly apparently.

TorqueMaster:
This is interesting.  I couldn't really tell from the video -- with no fan, roughly how long does it take for the fresh 0.20mm layer to go from 240 down to 70C? 

I always figured the sooner the printhead got back to an area for the next layer, the more residual heat would be there, and somewhat better layer bonding.  If it's cooled in mere seconds, then layer bonding should be more about nozzle temperature (of course) and layer thickness -- thicker new layers should hold more heat than thinner ones, to better melt and fuse to the layer below them -- up to a point. 

WhatUPSbox?:
For the video, I printed 2 clips a few inches apart so that one would be visible between layers. I started the video as soon as the print head moved to the other clip. The video is real time (25 sec). I never saw 240C. The video starts at about 90C and drops down to 64 C within that time. If the part was taller, I'm pretty sure it would be below bed temperature. Short of having an enclosure, I don't think the head revisits in time for most of prints. Maybe if you are printing a thin wall tube.

TorqueMaster:
I watched a few other videos, and I think you're right -- I never saw filament above 140ish, and it was down to 80-90ish almost immediately.  Within 8-10 seconds, it was closing in on bed temperature.  That correlates well with typical "minimum layer times" which are usually around 10 seconds.

rsterne:
The only time I saw distortion from too much heat was in the test section of Nylon coupons at 270C+.... The sides were bulged and twisted with no fan....

I am currently printing some Z coupons in CF-PA6 Nylon, and the test section after breaking shows no layers, it is completely fused.... Unfortunately the coupons are failing through the eye, so no valid data.... yet....

Bob

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