RepRap vs. Marlin Firmware

[AutoWiz]

That is incredible. I never would have made it that far. But now i might try it. You are awesome, man. I let myself get discouraged by failures and so I never got a raspberry pi connected to any of my printers with octoprint up and running. And i spent $150 on S3D a year or more back now and never got it to work. I have only used repetier host with slic3r and then prusa slicer since it came out because i understood it to be the continuation of slic3r. Since early 2016. I need to spend more time in the areas i am weak. So last night i got my very first print out of S3D. on my geetech i3 printer and just a benchy. But i got the damn slicer to work. Finally. So now i am going to get more used to using S3D. And i have a pi zero, a pi 3, and a pi 4. I will take another stab at getting octopi up and going. I am lost at what gcode commands are needed to get the mmu2s to load its initial filament. or to change filaments? I like using as little start gcode as possible. I think my start Gcode for my Geeetech i3 with the TMC2209 drivers and the SKR 1.4 turbo and the proximity switch for Z is just 2 lines. G28 and something else. I dont want all these prime lines and a purge tower. I just want to make it so the nozzle goes off the bed and purges what it needs to get to the next filament and get back to printing. This would be easier for me if i had experience with an MMU2S in its correct environment, i guess.

[spegelius]

I work in IT (software development/DevOps) so I spend quite a lot of time with problems somewhat similar to these issues so my problem resolving abilities (and tolerance of stuff shitting itself) is quite high at this point . But yeah, there are moments now and then when something just doesn't work and it does get discouraging at some point.

I have S3D, but don use it much nowadays. My main slicer is KISSlicer, but occasionally I use PrusaSlicer, mostly for prints that I know KISS has problems with. Also supports are better on PrusaSlicer and of course S3D's custom supports is the best solution. Although I've gotten into habit of modeling my own supports when needed and also generally modeling in a way that the need for supports is minimal. I've also tried soluble supports with one multi-material machine and it does work quite nicely in general.
For multi-material printing I use all those slicers. To add the tool change gcode, I wrote a post-processing tool to add the extra commands around the tool change commands because at the time when I got into multi-material printing, none of the slicers supported a single-nozzle/multi-extruder setups. The post-processing tool supports PrusaSlicer, S3D, KISSlicer and Cura at the moment. There's also MMU2S support in it, although I haven't tested it myself, the profile is from a user. The tool: https://github.com/spegelius/filaswitch

About MMU2S: I assume that to change filament, all you need is to issue the tool command: T0, T1 etc.? I sliced a multi-color print on PrusaSlicer for MMU2S a while ago just to see how the gcode looks and I didn't see any extra commands so I'm assuming that the Marlin handles the MMU2S-stuff when it sees a tool change command. But as I haven't actually seen or used a MMU2S-unit this is just speculation. That's how I would do it anyways... Getting bit impatient waiting for my unit to arrive, luckily there are other stuff like this to keep me occupied
Edit: tool change command won't move the nozzle to purge bucket/purge tower, that usually comes from slicer. Although maybe there's support for that in Marlin? In RRF that could be done with a macro that is executed with tool change command, but RRF doesn't support MMU2S AFAIK.

RRF progress: I tested the fan frequency and with 500Hz, only 100% speed spins properly. After testing few frequencies, it seems that below 50Hz is good, so settled for 25Hz. With that the fans starts to spin at 45%, although it really doesn't move any air at that point. BTW, I did all that on my phone using the web UI to edit config files, control the fan etc. Can't get that with Marlin, even though through Octoprint quite a lot is possible.
I printed a benchy, but it seems I need to get a better part cooling fan and shroud because there were obvious issues with cooling. I'll probably redesign something to better work with the Volcano. Still the print finished and apart from cooling and stringing issues it looks fine.
I calibrated Pressure advance and compared to Marlin Linear advance there values aren't comparable. The PLA I used isn't the same as when I calibrated Marlin, but the difference is quite big. With Marlin, the LA value was 0.28 and with RRF a comparable value is around 0.7. I also calibrated retractions so I'll print another benchy to see if the stringing is better. Also maybe try another filament, current one is cheap PLA from Poland.
RRF in general: the limitation of LPC1768 based boards is that it has less memory than Duet boards which means there can be only only HTTP session at a time. So connecting with my phone to DWC while I was also connected to it on my PC resulted in connection errors and the board even did a reset few times. The connection limit can be probably worked around by setting up a HTTP reverse proxy on some PC/raspi so only thing directly connected to the DWC is the proxy -> only one session. The random board resets just show that the FW is still experimental, as it says on the github page.

[AutoWiz]

There are better chips now for the same or comparable money. BigTreeTech has the SKR PRO and the BTT002 mainboards that use a STM32F407 chip. It is cortex-M4 cpu @ 168mhz over the 100mhz of the lpc1768 or the 120mhz of the lpc1769. And both of those are only cortex-M3 anyways. I have one of each of those mainboards on the way. I already have one SKR pro and that is what is going to drive the Diamond Hotend 3 into 1 mixing printer. They just released a new revision of it. The 1.2. I do not know what the difference is. they look the same but mine says 1.1. Either way it is under $50 for 168mhz cortex-M4 cpu: https://www.biqu.equipment/products/...cf1aa7f4&_ss=r . The BTT002 mainboard is designed to be a direct replacement for the Prusa MK3S and brags on supporting multifarious screens and all sorts of other junk and i thought with that i might be able to have both the MMU2S and a touchscreen at the same time. It is here: https://www.biqu.equipment/products/...dcb79d56&_ss=r

[AutoWiz]

If you wanted to do something really crazy, BTT has this awesome looking board with an expansion board that holds a total of 11 stepper drivers. This is also driven with the 168mhz cortex-M4 cpu. But i am telling you this could drive 3 Chameleons feeding into a Diamond Hotend. I am just saying 11 or 12 color mixing if we can find a few pins to dedicate to one more stepper driver. I would and very well might take on such a project after i understand how to use the MMU2S and the diamond hotend seperately. Here is that 11 axis board: https://www.biqu.equipment/collectio...31261892280418 . These are great and wild days for tech and we are only limited by our imagination and skills.

[AutoWiz]

Hey buddy when you do get your MMU2S, this video is a good walkthru of the important adjustments to check to get things up and running smoothly. software aside of course. https://www.youtube.com/watch?v=XH-F8h7Y1tM&t=

[spegelius]

Thanks, those tips should come in handly. The MMU2S seems quite technical with custom controller and all. Not necessarily a bad thing, it'll just take some time to get used to it. My current multicolor machines are lot simpler, more in line with the first MMU. I'll do a forum post about them and the MMU2 journey later. BTW, it seems the MMU2S is again out of stock in Prusa shop, seems there's shortage of parts again. Hoping my kit shipping isn't affected too much.

I ordered SKR Pro and TMC2209 drivers, figured it's time to upgrade. Maybe I'll swap it on the custom Prusa machine. Not sure I'll ever need 11 stepper drivers, but who knows where this multi-material thing is going . I have a cyclops-clone from a X5S-2E machine, it's not very good but does color mixing so MMU2S + cyclops would be interesting. Just thinking about the amount SW tuning is needed... . I do have 6-color machine with 6 extruders, but I'm only using one stepper driver to control them all. I use a custom relay setup to switch the active extruder when switching filaments.

RRF woes: setting the fan speeds lower than 500Hz has an interesting side-effect: setting fan speed to 100% doesn't work if it hasn't been set to something else before. I.e. right after starting the printer, issuing M106 S255 does nothing. But if the frequency is set to 500Hz, it starts to spin as its supposed.
On reprap forums one of the dev thinks there's a bug in the FW and hopefully there's a fix coming. Not a big problem because I need to swap the fan in any case as its axial and not powerfull enough.

Also having some quality issues with low layer heights (0.15). I use adaptive layer heights in KISS and that seems to cause inconsistent quality with RRF. It might be due to Pressure Advance, but haven't had time to test it properly. Also might be due to bad cooling so better fan duct is in order pronto. Might switch back to Marlin to get a reference Benchy done, luckily switchin back and forth is quite simple.

[spegelius]

So there was a new version of the RRF firmware (3.1.1-14) and that seems to fix the issue with the fan not starting properly. I also went back to Marlin for a while to get a comparinso benchy done:
IMG_20200719_141234.jpgIMG_20200719_141305.jpg

Quite ugly, not sure what's going on. Obviously cooling is an issue, but not sure if that causes the layer artifacts. Need to investigate more, but the main thing is that it happens on both Marlin and RRF so I can continue using RRF.
Easier prints that don't have layer problems:
IMG_20200719_141151.jpg
I'll continue debugging the quality issues in Dollo3D thread.

I tried the mesh bed leveling in RRF and it works quite well. I don't have a probe so the process is manual; you start the leveling process by issuing G29 after homing all axes. The web UI then shows a dialog where you can manually jog the Z height in 0.05mm incerements until it's good. After going through all the measurement points the results are saved to /sys/heightmap.csv. To use the saved file, issue G29 S1 in start gcode or before starting a print.
Compared to Marlin the process is quite similar, on Marlin I used the 12864 display and leveling menu to do it. Maybe bit more faster way, but usually there's no need to do the leveling process very often so not a big deal.
The nice thing about RRF is that the result file is a basic csv file on the sdcard which you can edit directly in the web UI or on your PC. On Marlin, you need to use gcode console to do the editing and the data is stored in EEPROM and can't be restored if you need to reset the EEPROM.

So far it seems that I'll be continuing to use RRF, since it seems to work quite well. Stability hasn't been an issue in use as long as I don't try to connect to web UI from multiple browers.
Pros:
- configuration stored in files on sdcard, easy to modify, easy to backup, easy to restore
- no need to compile FW
- general flexibility of the FW, about everything can be configured with the gcode
- web UI built in, no need for Octoprint
- ethernet/wifi support
- better driver timings it seems, printed movements seem 'cleaner', no resonating that happens on Marlin.

Cons:
- no backlash compensation support. Nice to have, especially with Dollo printer
- apparently no support for display on Sbase due to low memory. Not a big problem, web UI through phone/tablet works fine and does more
- experimental status of the FW. Seems stable but still

[AutoWiz]

How old is the filament you are using? Maybe it is just bad or old filament? Maybe try printing it with the nozzle 5c cooler? Either way it is very encouraging you saying there is a newer version released. Nothing better than FW that gets updated. Can you elaborate on 'backlash compensation"? I don't know what that is. And I have to watch some Youtube videos today on RRF's web UI and also KISS slicer.

[AutoWiz]

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We'll let you know when an instance of marlin or RRF gets corrupted by malware, buddy. and thank you for your meaningful input.

[spegelius]

Uhh, the idea of installing a crappy antivirus software to a 3D printer... nope.

Yeah nice to see that the development is going on and the devs are listening to bug reports.

The filament should be fine, it's not that old and prints fine on my other printers. I modified the fan shroud a bit, but no with much success, I'll post more details on the Dollo thread.