Switching to 2.85mm Filament

[GoremanX 0]

I run an Ender 5 Pro with a whole lot of modifications (Duet 2 Maestro board, linear rails, different extruder, all-metal hotend, etc, etc). It's been running great for months and months and giving me beautiful results. Until recently, I was running it with a Micro Swiss hotend with 0.6mm nozzle fed with a BMG extruder through a bowden tube.

 

For my most recent project (huge print with many, many pieces), I ran out of the filament I was using and that filament is now discontinued. I couldn't find inventory for that filament in 1.75mm, but I was able to find a few reels in 2.85mm. So I decided to switch the printer to a 2.85mm setup. I went with a Titan extruder and V6 hotend with capricorn bowden tube. I also switched to a 0.9 degree motor to increase the accuracy since I figured I'd be extruding 2.7x slower than before. Everything is mounted and seems to function.

 

As far as I could tell, no firmware changes were required other than small changes to the thermistor settings and adjusting the e-steps to accommodate the 0.9 stepper. I doubled the e-steps, commanded 100mm of extrusion, and it was spot on (I guess the BMG and Titan have exactly the same reduction). I then auto-tuned the hotend heater and all seemed to work right.

 

Then in Cura, I went into my printer settings to change the extruder to 2.85mm... and that's where everything went downhill.

 

First, all my custom materials disappeared from within Cura. This isn't such a big deal since all my custom materials are 1.75mm anyways, but when I tried to add a new material, the "Create" button did nothing. There's no way to add anything to the list.

 

So I just entered my temperature settings manually into Cura, sent a print job to the printer... and the results were awful. At 0.1mm layer height (which was accidental, I wouldn't normally print that thin with an 0.6mm nozzle), the surface was full of blobs and zits and over-extrusion. I've done 0.1mm with an 0.6 nozzle before, and it never came out that ugly. During the entire print, the extruder was doing a bizarre kick-back every few seconds. Like the pressure in the tube was too high and forcing the extruder and stepper motor back. At first I thought it was just the retraction that was more audible (this extruder is way more noisy than the BMG was), but this kick-back was one-way only and happening right in the middle of straight lines.

 

I retried the print with 0.2mm height, and the exact opposite happened. It under-extruded massively and came out with all kinds of gaps. Though this may have been because I turned the hotend temperature down a little. Meanwhile, the kickbacks continued throughout the print.

 

I'm getting the impression that the extruder is pushing filament way too fast, and I'm not sure where I'm supposed to adjust that. Is this a firmware thing? A Cura thing? Why can't I add materials? I'm at a loss...

 

 

[gr5 2,265]

Quick answer is that the ratio of 2.85 to 1.75 squared is 2.64X or 1/2.65 is .377.  So try 38% flow for a quick fix.

 

For the proper fix, you need to tell Cura that your printer can accept 2.85mm filament.  It's in the machine settings somewhere I think?  I remember doing this once and it was a pain.  First you have to tell cura that your printer takes that size filament, then you have to choose the new sized filament.

 

Machine settings are usuall here:  go to left side of screen in PREPARE mode.  Click on your printer, then do "manage printers" then "machine settings", then "extruder 1".  Then modifiy material diameter.  I think you want to possibly save, exit and come back in?  Maybe not?  I don't know if I ever got this working.

[GoremanX 0]

15 minutes ago, gr5 said:

Machine settings are usuall here:  go to left side of screen in PREPARE mode.  Click on your printer, then do "manage printers" then "machine settings", then "extruder 1".  Then modifiy material diameter.  I think you want to possibly save, exit and come back in?  Maybe not?  I don't know if I ever got this working.

Thanks, I finally got it somewhat working. I tried Slic3r, and the kickbacks disappeared. Of course, the result was typical Slic3r (wide line spacing that looks awful), but at least it showed me that Cura was still generating code for 1.75mm filament.

 

I had already done the setting change you suggested, but it's not enough. I had to use the Printer Settings plugin to show me the hidden settings, and use that to tell it that my printer now uses 2.85mm diameter filament. Now everything works as expected, including adding new material to the list. Not sure why that setting isn't normally changeable within Cura... not cool.

[gr5 2,265]

On 8/14/2020 at 10:19 PM, gr5 said:

Machine settings are usuall here:  go to left side of screen in PREPARE mode.  Click on your printer, then do "manage printers" then "machine settings", then "extruder 1".  Then modifiy material diameter. 

But did you try the above suggestion?  That does the same thing as the printer settings plugin.

[GoremanX 0]

I couldn't, the setting didn't exist. My printer is an Ender 5 Pro, so when I set it up initially (long before I switched to a Duet board), I used the Ender 5 preset in Cura. This fills in a bunch of printer settings, but it also automatically hides some of the printer settings from the Machine Settings and Extruder tabs, including filament diameter. Near as I can tell, there's no obvious way to make those settings appear.

 

Since my last reply, I've created a new custom profile from scratch, and now that profile allows me to change the filament diameter for the extruder without needing the Printer Settings plugin.

[gr5 2,265]

Nice.  For other people following along, there is a 3rd way to change your printer settings and that is to edit the json file directly and restart cura:

The files are in a "definitions" folder *somewhere* on your computer (no idea how to find this folder on a PC - maybe in c:/program files/ultimaker/??  Here are 10 of the files out of about 106 different printer configuration files.  Find your printer.

geo@geo-Wild-Dog-Pro:~/cura/share/cura/resources/definitions$ 
geo@geo-Wild-Dog-Pro:~/cura/share/cura/resources/definitions$ 
geo@geo-Wild-Dog-Pro:~/cura/share/cura/resources/definitions$ grep -R -i material_diameter *
101Hero.def.json:        "material_diameter": { "default_value": 1.75 },
3dator.def.json:        "material_diameter": { "default_value": 1.75 },
abax_pri3.def.json:        "material_diameter": {
abax_pri5.def.json:        "material_diameter": {
abax_titan.def.json:        "material_diameter": {
anycubic_i3_mega.def.json:        "material_diameter":
bfb.def.json:        "material_diameter": { "default_value": 1.7 },
bq_hephestos_2.def.json:        "material_diameter": { "default_value": 1.75 },