It just occured to me that if RepRapFirmware doesn't support M900, then any results I get by printing K Factor Test.gcode are invalid! The gcode simply draws lines back and forth, with each new parallel line increasing the K value… except using M900 instead of M572. Would it be wise to adjust the gcode for RRF, replacing M900 K10 with M572 S0.10 for example? Or does M900 work?

[[gcode]]
M900 K10
G1 X80 Y30 E0.37418 F1200 ;Travel to next testline
G1 X60 Y30 E0.74835 F1200 ;Slow part
G1 X30 Y30 E1.12253 F4200 ;Accelerate - cruise - decelerate
G1 X10 Y30 E0.74835 F1200 ;Slow part
M900 K20
G1 X10 Y40 E0.37418 F1200 ;Travel to next testline
G1 X30 Y40 E0.74835 F1200 ;Slow part
G1 X60 Y40 E1.12253 F4200 ;Accelerate - cruise - decelerate
G1 X80 Y40 E0.74835 F1200 ;Slow part

Full source: https://gist.github.com/anonymous/988a04f4454cbcdec78ae7342894fdd6

@dc42:

The difference is this. RepRapFirmware calculates:
So the connection should be:

marlin_K = extruder_steps_per_mm * rrf_K

[[math]]
25 = 98.75 * rrf_K


25 / 98.75 = 0.253164557

OK, so according to my K Factor Test.gcode results, somewhere between 20-30 appears to be ideal with this PLA filament. Applying dc42's formula, I rounded my K value to 0.25. I have added the following code to my slicer's starting script.

[[gcode]]
M572 D0 S0.25

As I write this my printer is 75% through my test cube and it is looking just as good as the previous print done at 0.15. I feel like this has have given 3D Printing an evolutionary step forward! Finally we have a way to get rid of those disappointing line change blobs!

P.S. For my current printer – since my extruder's steps per mm is nearly 100 -- the math ends up being as simple as moving the decimal point. For anyone that happens upon this post in the future though, please calibrate your extruder's steps per minute before attempting this math.

Thank you for the replies! Obviously I cannot use the exact same settings between my direct drive Prusa and my bowden Hypercube. But, I did want to use the K Factor Test.gcode described on Matt's Hub as a guide to calibrate my S code. I will do some experiments when I get time and report back in a few days.

Source: https://mattshub.com/2017/10/02/linear-advance/

Prusa Research just released a new Release Candidate firmware that includes Linear Advance. Long story short, I am getting incredible results on my Prusa MK2S with my K value set to 25 or 30, retraction set to 0.8 at 40mm/sec.

Before that I spent much of last week experimenting with Pressure Advance on my Hypercube with my Duet Wifi. I have gotten some good results with my S value set to 0.6. But what I want to know is, how do Pressure Advance S values relate to Linear Advance K values? Is an S value of 0.25 equal to a K value of 25?

Also, Prusa recommends changing the K value based on the type of filament used. So, I have placed that GCode in my slicer's Starting Script. Can we also add the M572 command to our slicer's Starting Script?

According to my K Factor test print, my Hypercube's K value would be similar to Prusa's recommended 25, which is why I'd like to know how to convert between K and S.

OK. While the above code does upload a file to duet, it does something to the file that leaves it unprintable. I have experimented with it and discovered the following works. This may not be the optimal method still, but it does yield a printable GCode file.

curl  -F "file=@[output_filepath]" "http://hypercube.local/rr_upload?name=gcodes/[output_filename].gcode"

The reason I say it is not optimal is that is places some HTTP data at the top of the file. But, Duet appears to ignore this code and happily prints anyway. So, for now it will do.

--------------------------16eea21da68ae83e
Content-Disposition: form-data; name="file"; filename="curl_test.gcode"
Content-Type: application/octet-stream

Thank you for this. I have fine tuned the code for Simplify3D a little, and it works great!

curl -d "@[output_filepath]" -X POST http://hypercube.local/rr_upload?name=gcodes/[output_filename].gcode

Thank you. I seem to be getting along fine without that fan. I used the code to trick the slicers into using Fan 2 instead and it is working fine.

The only thing I am missing out on is a fan to blow across the drivers. But, maybe that is unnecessary?

United States

After some initial confusion about why my part fan wouldn't turn on, I read that I needed to switch the connectors for my Hotend fan (F0) and my Part fan (F1). So, like an idiot I was holding a pair of wire cutters while I was unplugging the fan connectors, and I touched across the two F0 connectors.

The document "How to destroy your Duet Wifi or Duet Ethernet" gave me some hope that this may be able to be resolved by adding an external fuse. But somehow I don't think I will be that lucky.

For now I am disconnecting the blower fan that was blowing across the driver chips, so I can have a parts fan. Will that cause me a big problem?

What weird week I am having. First someone plows into my car, now I one small mistake ruined an almost $200 board. Is there a repair service for these boards? Or for a small fee can I trade mine in for a refurbished one?