Dual extruder pin valves

[merkur]

I think this is being way over thought... Putting moving parts in the extrusion path sounds good but with the added clearances needed for this to work, there will be a path for the molten plastic to gum up the path and then when it freezes on cool down will it ever become unstuck?

Now, remember I don't even have my M2 yet but, what would it take to mount the print heads separately, on the same rail ( Just another linear bearing block ) and park the print heads off to the side when not in use. There is G-code in the RAMBO for tool changes, all it would take is a tapered pin (servo driven? ) to connect the print head to the block on the belt clamp. Small magnets could keep the heads in place when not in use. simple G_code call for the desired print head, head gets parked, servo pulls pin, belt clamp block moves to the other print head servo engages pin, a simple wipe and off and running... Too simple?

[Tim]

This released by E3D today, maybe the "Cyclops" does something like you were describing?

The "Carmina Burana" score behind the video was a nice touch, as is their sense of humor at E3D.

It does nothing like I was thinking of. It's a better solution! Looks like they made a nozzle with two channels going down to a "V" connection near the tip. When one filament retracts, the other goes down, effectively blocking it from dripping.

I would think that the filament that has been retracted would continue to bleed into the filament that is extruding, but I also think that the main reason for dripping is the low pressure on the open nozzle; block the opening in any way, including another strand of filament, and you remove the low pressure.

The "Chimera" model looks very similar to the MakerGear dual extruder setup. Which means that it's a nice design, but still subject to drippiness. It's not clear to me why anyone would buy the Chimera when the Cyclops clearly represents a new generation. The "limited time only while supplies last" offer is very tempting.

[Tim]

what would it take to mount the print heads separately, on the same rail

There are some dual-extruder designs just like you suggest. But the solution requires that the frame design make room for the parked extruders---it would use up a lot of the X dimension on the M2 to do it that way. It doesn't get rid of the drip, and you'd want to be able to wipe each extruder after it comes out of parking mode. It all can be done, but the E3D solution is much cleverer.

I can see another problem with the E3D solution, though, which is that it would be difficult to impossible to use two completely different filaments, especially ones that melt at different temperatures. It's fine if you want to do two-color designs, but using one side for, say, making support structures would be tricky at best.

[merkur]

If there is room for a dual print head, why would cutting it in half take up more room? I really don't know... just asking. If the head is parked off to one side, it wouldn't be dripping on the part. Also two different colors coming out of one nozzle is going to mix the colors...

[Levi8than]

I don't have much faith in the cyclops design either. It's clever, but I think independent paths can do better. Parking and wiping is a good solution. But then you need another motor and belt or a clutch.

Keep thinking.

[MG_MLS]

Yeah, at first I was tempted, but really, I don't at this time see the need for duals in what I do. I did order the E3Dv6, and a few nozzle sizes, I've got some Taulman filament coming, (bridge and T-glase) and will be wanting to get some of their Tritan filament. Also ordered the MG v4 PTFE, I will have to figure out how to easily go between the two since I'll keep the v6 for the higher temp stuff.

now to figure out what all this PID and firmware stuff I've got to modify is!

[jimc]

let me know if you get bridge to work for you. i have tried a few times with the e3dv6 and can get it to extrude. to be honest though i dont feel i gave it my best shot so im going to give it a try again sometime soon. i rarely need nylon but when i do taulman's is really the only choice. other than 1 roll of it a year i refuse to buy any of taulman's filaments because the extrusion is so piss poor.

[Dale Reed]

MG_MLS,

Many folks here have posted information on the PID autotune sequence (I have a few times), and also on the PID_MAX #define parameter in the firmware build. Just search the Forum for "PID" and/or "autotune". A quick summary of the procedure (and a link to a more comprehensive document) can be found in viewtopic.php?f=7&t=1435&p=4658&hilit=PID#p4583 ...

Many of the posts are from two periods earlier this year --- the first was when a number of people converted their older M2s from 12V / 19V dual power supplies to a single 24V power supply, changing the voltage at (and heat generated by) the hot end, and the second was when several of us got to beta a dual extruder setup with all-metal ("V4 beta") hot ends, which have a different thermal mass and nozzle, resulting in a different heat load. Both these changes (and jimc's change to the E3Dv6) required retuning the PID parameters to account for changes in heating and/or heat loss (to filament or ambient).

Dale

[MG_MLS]

Thanks Dale, I had found those a while ago so knew they were on here somewhere but now to actually go through the process, thanks for the link since I don't think I had read that one.

jimc- yeah will do. first impression is that the size of the filament is not consistent and that probably won't help things out. I don't think I have a way around the nylon- for certain replacement parts on equipment. Or the real kicker is stuff I make for the lab- So far one part (from PLA) I made has held up, but it doesn't look the best since it has been washed with methanol and caused some of the black dye to come out (MakerGear filament). Nylon would be great since the part is used above a vat of acetone/alcohol mixture...

~Michael

[insta]

I still say HDPE. It was one of the original filaments used in RepRaps, and its only real problem is warp. It's kind of telling about its chemical resistance that acetone and alcohol are both shipped commercially in HDPE bottles.