Marlin on Duet Wifi?
February 03, 2020 03:36AM
On Google I just found old comments, saying it is not possible to run Marlin on a Duet Wifi. Can anyone confirm there is no way?

I built my printer with a Duet Wifi including a Display and I like the Webinterface and the flexibility. But I keep having blobs at every start of a line and I assume, that it is a firmware issue. I think RepRap Firmware treats acceleration different than marlin. Since a friend updated his Ender 4 with a Duet Wifi, he has the same problems. He carefully transmitted all settings like acceleration etc. and uses the same slicer profile. Besides that we tried so many things and opened several threads in different forums in different languages. I may be wrong but I know nothing else to try, than changing the firmware. So ether I buy a new hardware or I can flash Marlin on the Duet Wifi. This would be much better, because I could easily go back if it does not help plus I would not have to buy new electronics.
Re: Marlin on Duet Wifi?
February 03, 2020 01:05PM
RRF treats acceleration in the same way as Marlin, so there should be no differences there.

The most common reason for getting different results with RepRapFirmware is that the thermistor settings are not correct for Marlin or for RepRapFirmware, so you are printing at different temperatures.

Do the blobs definitely occur at the start of lines, and not at the end of lines immediately before retraction? If they definitely occur at the start, check that you don't have an "Extra restart distance" configured in the retraction settings of your slicer.

HTH David



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Marlin on Duet Wifi?
February 10, 2020 09:53AM
I have blobs at both: Start and end of each line - no matter whether retraction occurs or just a travel move. The thermistor settings are the same and though I tried different settings for temperature, coasting and extra restart distance. Usually coasting and extra restart is deactivated.

If I set a high coasting value plus a negative restart distance, I run into unterextrusion at the beginning of a new line but though I have a blob because the hotend just waits too long before it starts to move so it has time to ooze. It feels like it was waiting for the extruder to accelerate. Like the extruder acceleration had a higher priority than YX movement.

Have you checked the source code of both firmwares? I did not but I am pretty sure, that there are differences. Just have a look the the "jerkpolicy" of RRF, which exists in Marlin not in that way.

As a result I noticed something, which I can only explain with different acceleration treatments:

When I set the coasting to 10 mm I expect the line to get thinner 10 mm before the next retraction, right? And that is what happens with marlin. With RRF the same thing happens but there is one difference: The XY movement seems to stop for a very short moment, resulting in a little blob at the point, wehre the coasting begins. The line gets thicker before the width decreases! So it seems like the RRF notices, that the extruder shall stop immediately 10 mm before the next retraction. But since this would require an infinite acceleration of the extruder, it slows the xy movement down in order not to make excessive demands of the extruder. At least that´s my explaination. The last idea to find out if I am right, is to thy marlin instead. So I still wonder if I can run Marlin on a Duet?
Re: Marlin on Duet Wifi?
February 10, 2020 04:18PM
Quote
Dysplaced
If I set a high coasting value plus a negative restart distance, I run into unterextrusion at the beginning of a new line but though I have a blob because the hotend just waits too long before it starts to move so it has time to ooze. It feels like it was waiting for the extruder to accelerate. Like the extruder acceleration had a higher priority than YX movement.

If you have set a low enough extruder acceleration, then of course it will take priority over the XY acceleration, because the acceleration of the move as a whole is chosen so that all acceleration limits are met, as well as any acceleration limits that you or the slicer has set using M204. Perhaps you have set the extruder acceleration too low? Also, pressure advance requires extruder jerk; so the combination of low extruder jerk setting and high pressure advance setting will also slow down acceleration, in order to respect the extruder jerk limit.

As to Marlin on Duet, I heard that Scott was working on it but I don't know what hit time scales are.

HTH David



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
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