peirof last edited by
i have find this web, with useful information:
I have find it, why i am search info for tunining first layer, and in these web have an interesting reading, point 9
If you read the article, in point 9, he says that he extrudes until he can extrude soft at 50 mm / s. For an E3D extruder. Is it an adequate speed?
I'm thinking I'm either miss understanding (edit: more thank likely given I've woken up short on sleep again! ) or there is a typo.
Extruding 50mm of filament at 50mm/s would normally suck a large quantity of heat out of the hot end probably resulting in a stalling, chattering extruder.
I'm thinking bad phrasing as 50mm/s would be equivalent to 800mm/s nozzle print speed with 1.75mm filament, 0.5mm extrusion width and 0.3mm layer!
50mm3/sec would be around 333mm/sec. Not likely that was the intention either.
May be they mean extrude 50mm of filament at the extrusion rate that would be used to print at a speed of 50mm/sec. That gives a more reasonable real linear extrusion rate, but leaves the actual extrusion rate very dependant on your chosen slicer settings.
([extrusion width] * [layer thickness] * [print speed]) = [volumetric extrusion rate]
...so for me this would be:
(0.5[mm] * 0.3[mm] * 50[mm/sec]) = 7.5[mm^3/sec]
This still needs to be converted to a linear rate for the extruder:
[volumetric rate] / [cross sectional area of filament] = [linear extrusion rate]
[cross sectional area of filament] = pi * [filament radius]^2
7.5[mm3/sec] / (3.14 * (1.75[mm]/2)^2) = 3.12[mm/sec]
...and convert from mm/sec to mm/min:
3.12[mm/sec] * 60 = 187.2[mm/min]
So my G1 command would look like:
G1 E50 F187.2
Some soft TPUs don't like being extruded at much more than 1.5mm3/sec through my old work set up with 0.4mm nozzle (E3D V6, first Titan - crap with TPU - then Bondtech BMG). While guides are very useful to help learn from others experiences specific set points rarely translate well machine to machine and likewise bullet point set up guides often don't translate well material to material. Plastics are weird!
The process of calibrating the hot end is useful within your own work and as a sanity check but not necessarily useful for comparing results across machines.
Different hot ends have different geometric designs, materials, finishes, and coatings which results in different thermal capacities and heat transfer rates between the polymer and hot end.
There is the old adage that goes something like the man with two watches never knows the time.
I've considered how to calibrate my hot ends in the past but not got far with it as I wasn't sure how to deal with getting a good contact between the additional thermocouple and the first and how to compare values that are read from the interior of the hot end heat block (connected to the Duet/controller) and a thermocouple taped/held on the outside surface of the block.
I plan to move to PT100 sensors when time/money allow. Two sensors in the block would give a little more confidence in reported values but is also likely to reduce reliability.
Gold standard is measuring and controlling melt temperature and pressure, but that is no easy feat given the tiny volume of melt and dynamics of the head.
Maybe @mhackney could clarify himself?