Dual Direct Drive Extruders Concept

The more and more I look at this extruder, the more I like it. It's very compact, and would be very simple to adapt to my hotend mount. But apparently, the gears they use are proprietary made from pinion rods (no add. specs given). The bearings are 5x10x4mm I think, definitely a 5mm ID RC car bearing. I have a bunch of those, so I'll test fit out later this week. I really need to get this dual extruder thing going fast though. I have until mid-december to finish designing and print AND ship 100 almost life-size hands, along with 50 business cards which I still have to design and print. So important, guess these are going out to some big names in euro art scene, could be a career changer here.

 

I watched that the other day. Even forced my wife to watch it. She was kinda like "what?" before it grabbed the second nozzle then she was rightly shocked.

Really cool concept, though I worry about the repeatability of the grab when it changes nozzles. We'll see once they try to print on it.

 

I've been thinking about the possibility of using a pinch roller instead of a hobbed bolt for no more clogged hobb. The only problem I can think of at the moment is it slipping on the filament, especially if an oiler is used. Thoughts?

 

The principle makes sense but I feel like you'd need both pinch rollers to be gear driven and a way of adjusting the pressure it supplies.

I just kinda feel like that would be too obvious and that someone would have tried it before. Though maybe it was so obvious it go overlooked.

 

Here's the new design, pretty much complete. I've included height adjustment using screws and springs, uses the direct drive extruder I've linked to previously, cylinders on the x-carriage keep the mounting brackets in place, allows for direct drive and bowden drive hybridization of printer. The height adjustment works by assembling the two hotends seperately and mounting individually. The bowden side is cut out to fit half the screw perfectly, while the direct side is cut to allow for the screw to move up and down while still maintaining grip on the piece. I'd recommend using a washer on the side with the screw head to just help clamp the two hotend sides together, though the posts in the carriage should keep them aligned on their own. This is my first release candidate version, so any improvement advice would be appreciated. Included in the post is a .zip file containing all three .stl files if anyone would like to try. I'm printing the x-carriage out right now, and hope to have the full assembly installed within a few days.

 

Just a quick update, I've redone a few of the files to optimize for printing and some slight adjustments. I'm still having issues getting the model sliced properly in Cura. It seems that on both mount_b pieces, the entire portion above the screw hole is missing from the gcode, and nothing I do in 3ds Max is able to fix it. I tried slicing in CraftWare though, and everything seemed fine. So it seems to work on some programs, and not on others.

Any insights?

Included is a .stl file with all the most up to date models combined into one file.

Just wanted to add, I have some work to do for a client, but afterwards I plan on adding the dual heatsink fan ducts and nozzle fan ducts.

 

Okay, so I've gotten most of the mount pieces printed, and the hotend fits perfectly, like a glove, on both sides. The tolerences between pieces on each side is a little tight, so the tiny outside arms flare out a tiny bit, but nothing that should impact print quality. Thinking of adding a small M3x6mm hole in the sides to clamp those side arms down. Other than that, preliminary fitting seems a go, and its looking like it should work as of this iteration. Any additional updates I'll post here, and the thingiverse page is now active as "in progress". Link for any who'd like to follow:

http://www.thingiverse.com/thing:565616

Edit: Also, I've been printing at 25% infill, seems good for the 3 flat mount pieces, but the 4th with the extruder base on it seems to need 80-100% due to the thin walls, possibly 3 shells instead of 2, undecided yet. Could also be printed orientation, possibly printing it on it's side will help strengthen the part overall. The smaller of the walls broke while removing the support from the screw hole.

I'll post pics once I have the full assembly installed. Planning on printing with glow-in-the-dark ABS. Gonna look great since I have a shit ton of lights inside the case to charge it. Gonna make some nice time lapse.

Which makes me think, lots of people been doing upgrades in terms of print quality, but why no "bling" printers? Where's the "pimped out"-ness? Thinking when I install this, I'll re-redo all the wiring with new quality wires and nice bright white UV sheathing, should only have 3 sheaths visible once it's complete instead of the 3-4 small sheathes bundles together on each side (didn't really think it through my last run through). Approx. 8 blocks of 3x bright cool white LEDs throughout the case controlled by a dimmer pwm on the right front side of case. I have an extra glass bed as well with a replacement heater I need to install on it, will be reorienting the cables in a direction where my smooth rod mounts wont cut into the wires and they will slide through a hole underneath, totally out of visibility, I wanna scrape all that black paint off the bottom though (or use some kind of solvent, if anyone knows what kind is required, that'd be awesome information, it's pretty tough to scrape all that off with a razor blade) and possibly put 2x UV diodes I have lying around in there under the bed as well.

I got ideas, I got ideas!

Last question for this post. Anyone know if I picked up an additional 12v PSU and hooked the two in parallel to the bed heater, will that allow me to reach higher temps? Maybe around 110-120c? Or maybe a dedicated 24v specifically for bed heater a lights, with the rest of the printer running off the stock PSU? I figure if I went with 2 psu's, splitting the load between them would be ideal, but I could be wrong. I'm still teaching myself a lot of this stuff, so any advice is appreciate. I swear, I'm learning a lot from you guys.

 

People are having success with tapping aluminium foil to the underside of the bed to insulate it to decrease bed heating times and increase the achievable temp.

 

Interesting. I never thought of insulating the bed. Aluminium foil sounds like it would definitely work, but I'm wondering if I just coated the whole thing in ceramic insulation tape if that would do better. Idk, now I'm just having a stream of thought kind of thing, but would a very thin layer of thermal paste between the heater and the bed further help? I'm seeing layers now top to bottom: kapton tape, bed, arctic silver 5 high density polysynthetic silver thermal compound, heater, little bit additional silicone gasket maker (used this to reseal heater contacts and thermistor when they detached once, worked great for a long while) and then ceramic insulation tape. Thoughts?

edit: wow, thought about that for a bit, and the lack of sleep must be getting to me. I would definitely NOT want to use thermal compound as that would draw heat away from the heater and bed. I've been doing some research and found this:

http://www.amazon.com/DEI-010131-Titanium-Exhaust-Wrap/dp/B0039Z1UHA/ref=zg_bs_15726941_1

and this:

http://www.amazon.com/Heatshield-Pr...Insulating/dp/B0051USD80/ref=zg_bs_15726941_3

Both have fairly good reviews, and I can see using some heat tolerant adhesive to attach it to the underside of the bed, maybe a spray on silicone. From the reading on how well it works for automotive exausts and headers, I'd imagine it would perform as well or better than ceramic tape. Might reduce the power draw enough from maintaining temps to hit 120 with stock psu. (?maybe?)

 

Exhaust wrap is hardcore. You want to keep the weight down too to reduce the inertia for direction changes. I'm going to foil mine and see how it goes, just have to wait for my kapton tape to arrive. Foil is cheap too.

 

Very true. I've been thinking of how to increase accuracy and have been considering changing out all the steppers to geared for the torque gain and switch from belts to some other medium. I've seen and already discussed the fishing line tech, but I'm wondering if geared steppers with lead screws would be a better option. I'm not sure if I could just reuse the current belt system and switch out the belts for fishing line or if i'd have to create a whole new pully system. I know lead screws are more accurate and faster than belt drives, at least from what I've read online, and I'm thinking that will greatly help to compensate for any additional inertia, especially when combined with the geared steppers.

 

The countdown has finally started on the Cyclops: http://e3d-online.com/

If it doesn't support flexible materials (most likely) I'll be upgrading to the hybrid set-up too, the designs are really looking great! If i do, should i change to 3mm filament? I would think that the extra thickness is better for the bowden?

 

so, this chimera seems like it will solve a lot of issues> http://e3d-online.com/Chimera

Think it will work with the hybrid setup?

 

2 Cyclops. Yes please. The only down side I can see with the Cyclops is multi material prints.

 

Hm, so after printing out all the pieces, it seems I've run into a problem. The two screws meant to help level mount_a_direct have no way of being tightened or loosened. The only solution I have for this is to move them out more, and lose about 5-10mm on the x-axis, or redesign the extruder to move the horizontal screw that blocks the leveling screws from going through the mount, which will probably result in loss of x travel as well. Still working on it, hope to have an update by morning.

edit: also seems the holes for the bearings are a little too big, probably need to reduce diameter by 1.5-2mm or so.

Those two hotends look sexy, and having both seems like it would be ideal. I'd get one to test, but I'm pretty much out of funding at the moment.

 

The guys at E3d gave me the details for the Legends. They both have the same attachment for the X carriage so they should be interchangeable! I've attached the PDFs

 

Yup I've been working on the cyclops design myself:



Seems pretty tight to add in a direct feed nozzle, but I think it's possible. I ended up rotating it along the Y which is better for chimera setups.

 

Keep me updated on the design, if you manage to squeeze a direct feed in then that'll be awesome !