What I have learned about dual extrusion

[ivanhandler]

I finally completed my first successful dual extrusion print. I made tons of mistakes so I thought I would recount what it took (as embarrassing as it is) to recount the mistakes I made and how I corrected them.

• 1. My mistake was recompiling and uploading the new firmware using Arduino 1.8+. I downloaded 1.6 and uploaded the recompiled firmware but that failed as well. That is because I forgot to clear the firmware first. Once I did that the dual extrusion portion started to work.
  2. Since there are over 100mm of the Y connector and bowden tube to the HE280 I set my tool change retraction to 150mm to start. Turns out all you need is 3mm. This is because the firmware is smart enough to know about the Y connector. That made it easier on my spools that can start to unwind and get tangled when a long retraction comes in. I still have this problem with some spools, it appears to be related to how springy the filament is.
  3 Use a dust filter. I use the one at thingiverse: https://www.thingiverse.com/thing:190118. This is important I discovered since otherwise my extruder starts to grind on the filament after a few hours. I think the reason for this is that small bits of filament build up in the path from extruder to HE280 (watch a filament change and you may see what I am saying) which probably doesn't block anything but with a long path small tugs and pulls can add up enough to slow the filament down so that in an area of enough retractions (they can get more numerous as you approach the end of a print) the filament can get stuck in the extruder. I use a bit of mineral oil but apparently vegetable oil can work just as well.

[elliot m]

Hi All,
first time poster - long time reader...This is a longer post so I figured breaking it up a bit would make it easier. This first section is about the hardware install on a V2 with HE280 and dual extrusion.

So I just completed upgrading my V2 to the new HE280 and Dual extruder. I am having a few issues. I am interested in PLA/PVA mixtures to allow good surfaces and support for complex parts for printing.

So here's where I'm at:
All the hardware is installed, I re-made the upper tower side boards to fit the second ez-struder on the top, and added a dual filament rack that allows easy feeding to the struders. I have the HE280 hooked up and powered up (but I do have some errors - more on that later.)

Images of build:

The image of the drill bit was my way of performing the chambered edge on the bowden. I can make the wall thinner longer into the pfte tube, as well I can still make the 45 degree cambered easier than with a utility knife. I used several bits of larger diameter as I stepped the wall thickness down .

[elliot m]

I did have some issues I will document here - hopefully it helps someone.

1. I needed to make new top side panels for the NEMA motors to fit in since the V2 vs V3 with dual extruders has shorter panels - in the V3 this wouldn't be necessary as the mount for the ezstruder is already on the side - and all electronics are moved upstairs. I used 1/4" MDF board and cut the proper slices out and installed - you can see them in the previous post. If I were doing over again I think someone has a motor mount on here for the V2 - but I didn't notice this until it was too late. I'll probably go back and re-do. If I find them or someone else does please link.

2. I had issues with the HE280 and truthfully we are still getting used to one another:
a. I had calibration issues which were eventually tracked down to a loose 22ga red and 22 ga blue wire in the 8 pin connector - this was a pre assembled unit from SeemeCNC and the wires were under the shrink-wrap.

b. This video was a help and may be indicitive of HF leads on the head if anyone else is having calibration issues. They mentioned they have a post on this forum but since I found their video through google first I figured I would link it again. https://www.youtube.com/watch?v=DxGT18rDKUM&t=11s

c. I am still getting weird issues with heating up through PID function. It seemed to be going fine up until I wanted to re-do for higher temperatures than I originally programmed. Now sometimes the PID does not take, or it fails with a time-out error. Maybe I will Clear and re-install or just reboot again and see if that can help. It also does seem to be taking an awful long time to heat up. In fact as I write this, I am trying to print PET - the probe tops out at 217-218 - just below where it should be. This algo is killing me. I've done the set-up 8x now and run the algo up to 280 (though it never gets there and times out

Any help is appreciated.

[IMBoring25]

The image of the drill bit was my way of performing the chambered edge on the bowden. I can make the wall thinner longer into the pfte tube, as well I can still make the 45 degree cambered easier than with a utility knife. I used several bits of larger diameter as I stepped the wall thickness down .

The chamfer should be on the outside diameter, not the inside. The inside is the filament path, which you want to be continuously seated at its interface with the hot end to prevent a thick spot in the filament path. Chamfering the outside edge helps ensure that imperfections on the outside edge don't hold the inside edge off of the interface. Chamfering the inside guarantees a thick spot in the filament path.

[elliot m]

Hmmm - I'll have to take a look at that from the image on the instructions page, it looked like the chamfer was on the inside and it states that it goes into the single end of the Y adapter.

I made the assumption this was to help guide the filaments as they would be changed often - and possibly need a little persuasion if they were trying to run down the side of the tube. If this is correct, wouldn't all edges of the pfte tubing be rounded?! I've not see the push connect fittings need this in the past. I can see your point if the edge was not 90 degrees or someone used a pair of side cutters. Thanks!

[IMBoring25]

Hmmm - I'll have to take a look at that from the image on the instructions page, it looked like the chamfer was on the inside and it states that it goes into the single end of the Y adapter.

I made the assumption this was to help guide the filaments as they would be changed often - and possibly need a little persuasion if they were trying to run down the side of the tube. If this is correct, wouldn't all edges of the pfte tubing be rounded?! I've not see the push connect fittings need this in the past. I can see your point if the edge was not 90 degrees or someone used a pair of side cutters. Thanks!

Forgot to follow up with this, sorry.

I can't say I've done anything with the Y adapter. My experience with critical PTFE/hot-end interfaces is predominantly with the E3D v6. The fundamental difference with the interface at the hot end is that you are more likely to be dealing with potentially-soft/molten filament. The thing you're trying to keep from happening is having a soft section of filament retracted into that interface and then squeezing it out into a thick spot at an imperfect interface that can then cool and soften just a little and cause a jam.

[ivanhandler]

I am having trouble when switching filaments. It appears that the y-connector can jam even when there does not appear to be anything in the way. I have chamfered the outside of the bowden tubes but I still get resistance when pushing the filament down through the y-connector. Anyone else noticing this problem. Even better, anyone have a solution??