My multi-color/-material printers

[spegelius]

My other printer that I modified for multi-material printing is a Tronxy X5S-2E that I bought mostly because I wanted a corexy-machine and a printer project to build on. Didn't want a fully working machine, more like a base to build on. Still the printer printed suprisingly well without any mods, but there were some real problems:
- the X5S-2E model has a E3D Cyclops clone which is a 2-in 1-out mixing hotend. The hotend kinda works, but out of the box it leaked from multiple places and didn't feed too well with PLA, I had to beef up the default extruders with planetary gearboxes. I managed to block the leaks mostly, but switched to E3D V6 in the end, but I did some mixing prints. Might revisit the hotend some day...
- the belts weren't aligned which caused the print dimensions to get skewed going to the edges. That's a known problem with the earlier versions of the X5S and there are custom parts available to fix that.
- Z-axis implemented with two separate stepper motors that can move independently when not powered, what could go wrong... had to do manual adjustment quite a lot, until I designed a single Z-motor mod: https://www.thingiverse.com/thing:3612257 based on other similar mods
- some other minor issues that I've fixed along the way. I have replaced quite a lot of the original parts with mod parts and now the printer prints quite nicely.
- replaced the original board with Duet Maestro and 7" PanelDue
IMG_20200723_212337.jpgIMG_20200723_212403.jpgIMG_20200723_212346.jpgIMG_20200723_212357.jpgIMG_20200723_212408.jpg

Currently the printer has 6 extruders (https://www.thingiverse.com/thing:3813628) beefed up with belted reduction (https://www.thingiverse.com/thing:3091980). The extruders use Bondtech gears (ahem Aliexpress Bondtech gears). They do seem to work ok, although the gears might be bit better quality if they were original Bondtech gears (more on these later). They are a lot cheaper though so there's that.

Wiring needs to be taken care of. I need to redo the wiring from Duet to the relay, currently there's a resistor hack to get the Duet signal levels to work with the relay. I need to replace that with a decoder chip. Also general wire cleanup has been due for a while.

The extruders are mounted on a extra frame I did using Dollo3D extrusion parts. The reason for this is that it reduces the bowden length a bit and mounting all those extruders to the frame might have been cumbersome.

The relay board I'm using with this printer is a Sainsmart 16-port relay. With that I could control 9-extruders and taking the Maestro's second extruder driver, total of 10 extruders.

The feeder part for 6 filaments works, but it is a bit bulky and I don't like how it bends the PTFE-tube going to the hotend. Might change that at some point.

More pictures here: https://drive.google.com/open?id=1Ay...uEHLzl5vQdy5H_

[spegelius]

I'm currently battling some jamming issues with the Tronxy. I had to reprint some of the idler levers of the extruders and suddenly the tool changes are very finicky. Part of the problem is some small clearance issues on the levers due to the clone Bondtech gears not being equal, some of them have deeper grooves where the teeth are thus requiring the idler to close more. Also since the Bondtech gears are geared, the gearing itself doesn't allow the gears to close enough for good grip if the groove is too deep. Should have bought real Bendtech gears... not sure if I should just order the real gears. Couple of the filament change failure seemed to be due to lack of grip from the extruder so definitely can't rely on these. They do work ok for normal printing, but the filament change movements do require dome extra grip and torque, especially if the filament tips aren't perfect.

Another part of the failing tool changes might be the elevated temperature in the room during summer. The filament tips are more stringy, which eventually clogs the feeder part. I hope I can get that sorted out with tweaking the tool change gcode. Swapping filament to hotend isn't simply pulling one out and feeding another, the filament tends to stretch and have those wispy strings. Also the tip swells a bit when cooling so it might be simply too big to fit to the throat. And all this is quite random, a print could go well for an hour and then there's one single failed tool change which either fails the print by jamming in the feeder or leaves a gap due to missed layer.

Here's a couple tips that could be better, but usually feed ok. Also a picture of print that has parts missing due to failed tool changes. MMU2S apparently has a feature to detect failed filament changes which is a good feature. OTOH if the failures happen at this rate, it basically means babysitting the machine quite long, for example this print with 6 colors would probably taken 2 days or so, multicolor printing is slow.
Attachment 14891Attachment 14892Attachment 14893