New rotating multi extruder concept, no X or Y offset. Let me know what you think.

I've been an amateur product designer for a while now and while working on one of my pet projects, I went browsing for a new 3D printer (I have 2 now but a 3rd wont hurt riiight? ).. Anyway one thing let to another and I had this idea to potentially squeeze 3-7 nozzles into a small package with only 2 motors used.



Oops I need to state that the 2nd diagram is a top-down view

(another short writeup on my blog)

So what do you guys think of this design?

Edited 1 time(s). Last edit at 08/12/2013 05:46PM by Fetish.

Oh come on, at least tell me my drawings suck or something?

How with only TWO motors?
Don't you need an extruder feed motor for each filament handled?
Are you just showing hotends and this is a Bowden 5 shooter?
How are you switching from extruder to extruder --- hotend power --- extruder power? Hot end heat up?
If you keep all HOT how do you prevent drooling?

Old style pen plotter used 6 pens in rotating mount I think it used a solenoid to click pen into write position?

??????

I think my drawings must have *really* sucked. LOL

I made a fast model on sketchup, hope I can get the idea across more clearly now.






This is just a concept at the moment. Of course there's still the filament cooling issues etc that have to be ironed out...

But it'll be cool if some guru here can make this into something real or even take it to the next level.

Edited 1 time(s). Last edit at 08/27/2013 02:21AM by Fetish.

The "drool guard" is unsupported of course...

I can't quite see how that work, because the guard needs to be lower than the hot end tip. Otherwise it will just dig into the side of the hot end. Of course the guard can't be lower because it would hit the print.

Perhaps the hot end can be lifted by a similar mechanism on the heater block?

Hi Bobc,

The drool guard can be held in position by any conventional means. I didnt draw the support in cuz I thought it'll clutter up the already quite cluttered inner spacce.

The hot ends (and the respective feeding mechs.) will be individually spring loaded to hold the active tip just below the drool guard, and when rotated to the retracted position, the tip will slide up the ramps located on both sides of the opening on the drool guard.

Due to the meshing angle of the feed gears and the feed motor, when the tip gets 'retracted', it will cause the filament to be retracted slightly, and when a tip is rotated and lowered into the active position, the initial meshing of the gears will cause the filament to extrude a little. Coding for a wipe piller like the one in kisslicer will be needed to keep drools in control in this case.

I'm going to assume you've already thought of this but here it is anyway:

You could have your extruders angled, like this microscope has it's lenses angled
[earth2geologists.net]

This should give you plenty of room for a drip guard, without springs.

Edited 2 time(s). Last edit at 09/12/2013 06:42PM by dudesom.

Check this out: [www.youtube.com]

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You could use some variation on the geneva wheel and a little DC motor to index the multi-head. Less expense/weight than a stepper and it would have a mechanical hold with power off.
[www.youtube.com]

Also, you shouldn't have to spring-load the nozzles like that. If they're free to slide up and down (which is a non-trivial part of the design) then they'll just slide up the ramp and as soon as the extruder motor tries to jam the filament into the chamber it will force the nozzle down.

It looks like you're not leaving enough space in there for tensioning mechanisms. Each one of those filaments will need its own tensioner. If you want to guesstimate how much space the whole thing will take up I suggest using actual extruders in you model, or at least get the dimensions of actual extruders.

I'm not sure that eliminating the extruder offset is all that valuable. It's an easy thing to account for in software. Since you still take up the same amount of space with all those extruders, and they weigh the same, the only thing you're doing is using one stepper to drive the filament on all of them instead of one stepper each. Assuming someone needs a half-dozen extruders loaded and ready to go at a moment's notice, that would be a significant savings, not to mention allowing the use of pre-existing electronics/firmware.

However, the value of this approach would be directly related to how many extruders are available. Not only would the mass/size increase but using a half-dozen-or-more extruders more or less simultaneously implies an equal number of rolls of filament stacked somewhere near the printer. So the only applications this would make sense for would be larger. It wouldn't be a hobby-level thing. That conclusion is supported by the amount of rigidity you'll need in the multi-extruder structure itself to allow the nozzles to slide vertically without deflecting while still holding all of those parts far enough apart so they don't interfere with each other. Probably a custom metal machining job.

dudesom> Having angled hotends wont solve the drool problem....

makeme> Awesome idea that geneva wheel!

I'm afraid without the (very light) springs, there might still be some dribble coming out of them nozzles sitting on the drool guard. The sudden extention as the hotend is lowered by the spring when it comes down the ramp might give the nozzle a little 'retraction' effect which might keep the goo from bursting forth, esp with rotating to a nozzle 2 units away.

Not sure about filament tensioning tho..

I think this might be a deadend design for the moment, according to points brought up.. :-/

Thanksss!

Actually I think angling the hot ends would help with the drool problem. You'd use a guard, as your original shows, but because the nozzles don't need to individually elevate (because of the angle), the springs wouldn't be needed. You could also attach the guard tightly so that it would flex slightly, providing s decent seal (in my mind).

I'm just trying to make it easier for you to build the thing

I really like this idea! I think there should be a way to use 1 main motor for extruding and a few other motors for aligning the different nozzles in place so I am happy other people are thinking about this problem.

I wanted to make sure I understood a potential issue in your design. When you switch out a color the gears are at a certain spot. When the next color comes in the gears need to match the motors gears perfectly. In theory once you set the gear positions for all the colors they should stay put since they are leaving the motor properly lined up, but what happens if you get a little bit of drift in the color gears when not in use. How can you ensure that the gears mesh with the motor perfectly every time? I sort of imagine like a clutch not being engaged type problem.


For what it is worth, I was thinking about a different approach using solenoids. Imagine if you have the maxtruder shown here:
[store.makerstoolworks.com]
But you have a second gear coming out from the motor and then a second pinch wheel and hot end. You then control which extruder is working by a solenoid activating 1 pinch wheel or the other. The solenoid would take the place of the spring in that case. I was getting stuck on finding a solenoid that is strong enough I think the spring exerts like 66 N of force which is like 6 kg of force. That estimate is based on the max force that your fore finger and thumb can exert which I think is about how strong that spring is on the maxstruder. You may be able to get away with a weaker solenoid. I think this one puts out about half the force:
[www.sparkfun.com]
Anyone with more experience in solenoids care to chime in?