Retraction Speed

I've just finished my tantillus running LCD-less with a sanguinololu. I've gone thru the marlin firmware and commented out associated LCD lines. Everything is working well I just cant seem to up my retraction speed. I have it set to 55mm/s in firmware as the max speed, and I have the 'speed' setting under 'destring' in KISS set to 55mm/s as well but it still seems awfully slow.

The head is pausing for about 1/2 second during each retraction/extrude cycle which is leading to melted blobs on the printed object. Is there something I'm missing? My retraction distance is about 5.2mm right now which to me seems like it should only take 1/10th of a second at the most to complete.

No skips, motor and drive are nice and cool, gears are firm and not slipping...I'm kind of stumped on this one. Other then that everything is working perfectly. I can print most objects fine (blobbing is on the inner most perimeters so its usually hidden on larger parts). I'm printing the calibration triangle right now which is a lumpy mess as I try to dial in my settings.

Here's a bit of g-code I've extracted from an earlier test...as far as I can tell KISS is telling the extruder to move at 3300mm/min or 55mm/s.

; 'Wipe (and De-string)', 0.0 [feed mm/s], 54.0 [head mm/s]
G1 X49.28 Y44.18 E0 F4800
G1 E-5 F3300
G1 X48.57 Y43.46 E0 F3240
G1 X48.39 Y42.78 E0
G1 X49.97 Y44.35 E0
G1 X50.44 Y44.31 E0
G1 X50.03 Y43.9 E0
; fan on
M106

The reason why the retraction speed is so slow is the maximum step rate is being exceeded which makes it go really slow.

In the retraction calibration setting section it tells you how to set it up [www.tantillus.org] but requires the LCD. You can do it using a host program by typing M203 Ennn where nnn is the required mm/s in place of where the instructions tell you to change the retract speed via the LCD. Then do everything else the same as the instructions say.

Edited 1 time(s). Last edit at 06/24/2013 01:43AM by Sublime.

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
Tantillus.org	Mini Printable Lathe	How NOT to install a Pololu driver

Wow what a speedy reply!

So if I got this right I can start the pyramid with : M203 E40 injected into the start of the g-code, run it and see what I get. Then stop the print, change the E value up by one and play again (as per instructions), find my max step rate, drop by one, then hardcode into firmware.

I'm assuming M203 is going to set the maximum feed for the entire g-code cycle so it matters not where I inject the code?

Thanks for the help, a terrific little printer you have designed.

You should be able to enter the M203 Ennn while it is printing and change the setting on the fly. The actual speed you are setting is only the extruders maximum "E" so it will only effect the retraction speeds since we can not actually print at that speed. The changes will only stay in effect until you reset the electronics so be sure to follow the part about changing it in Marlin and re-uploading.

Also be sure to use Capitals for the M and the E because at least for me using an old version of Pronterface the commands only work with the capitals.

Edited 1 time(s). Last edit at 06/24/2013 03:50AM by Sublime.

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
Tantillus.org	Mini Printable Lathe	How NOT to install a Pololu driver

Cool,
I didn't know pronterface let you insert g-code on the fly. That greatly simplifies my calibration procedure. Thanks again master Sublime .