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Dual extruder concept

Posted by unromeo21 
Dual extruder concept
November 10, 2016 03:03AM
Hi everybody,

I found some time ago a really nice concept for implementing a dual hotend extrusion system which I find really clever and compact. It's a variation of the tilting extruder some users experimented with, but I never saw this particular system implemented anywhere.
I made a quick 3d model and a short animation, based on the original design, so I take no credit for it and I don't know the "inventor".

Youtube

What do you think ? Could it be successfully implemented if the construction is solid and play free ?
Re: Dual extruder concept
November 10, 2016 06:43AM
That looks pretty good. Stratasys does something similar in some of their printers. The trick is going to be getting the nozzle heights matched and repeatable. It would be pretty easy to do it cheaply for a one-off but if you're thinking of semi-mass production, it may be expensive.

For a one-off I'd probably make all the pivots using bearings from HDDs. You could try a printed linkage, but cutting it from aluminum would be more rigid/stable.


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Re: Dual extruder concept
November 10, 2016 06:50AM
Looks OK to me. But given that you only need to raise the non-printing nozzle about 1mm higher than the printing one, I think you could use a much simpler arrangement, base on tilting or rotating the entire print head by a few degrees.


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Re: Dual extruder concept
November 10, 2016 09:33AM
Quote
dc42
Looks OK to me. But given that you only need to raise the non-printing nozzle about 1mm higher than the printing one, I think you could use a much simpler arrangement, base on tilting or rotating the entire print head by a few degrees.

Yes David, that's true. But that does not solve issues that this design or the IDEX design solves, like stopping oozing, keeping the hotend at the working temperature all the time, keeping pressure inside the melting zone, wiping the nozzle before using it. It has the advantage over an IDEX solution that it's compact, no extra carriage and motor needed, simpler to configure.
Re: Dual extruder concept
November 10, 2016 10:46AM
Quote
unromeo21
Quote
dc42
Looks OK to me. But given that you only need to raise the non-printing nozzle about 1mm higher than the printing one, I think you could use a much simpler arrangement, base on tilting or rotating the entire print head by a few degrees.

Yes David, that's true. But that does not solve issues that this design or the IDEX design solves, like stopping oozing, keeping the hotend at the working temperature all the time, keeping pressure inside the melting zone, wiping the nozzle before using it. It has the advantage over an IDEX solution that it's compact, no extra carriage and motor needed, simpler to configure.

Hmm... That's not quite true. Tilting mechanisms can just implement small blades that cover the inactive nozzle to stop oozing. Or set firmware to have a standby temperature. Or both!

I do however like the idea that it is raising the nozzle at the same time, where as tilting mechanisms have a chance of flicking the print as it moves. Could your mechanism move quick enough to stop all oozing? Tilting a nozzle a few degrees is very fast.
Re: Dual extruder concept
November 11, 2016 04:02AM
Quote
Origamib

Hmm... That's not quite true. Tilting mechanisms can just implement small blades that cover the inactive nozzle to stop oozing. Or set firmware to have a standby temperature. Or both!

I do however like the idea that it is raising the nozzle at the same time, where as tilting mechanisms have a chance of flicking the print as it moves. Could your mechanism move quick enough to stop all oozing? Tilting a nozzle a few degrees is very fast.

I know that about the tilting nozzles, I was just saying in my first post:

Quote
unromeo21
It's a variation of the tilting extruder some users experimented with, but I never saw this particular system implemented anywhere."

But David was talking about the simpler tilting mechanism, where the inactive nozzle is being lifted by no more than 1 mm, without the blades and stuff.

It should be quite fast, the animation is just slow. Planning on building a prototype soon, just to prove the concept. I was thinking about the best method to drive it.. Servo would be the most simple, but not that accurate. Another option would be to use a really small Nema 11 I have lying around to drive the mechanics, an attiny85 and an endstop made by electrical contact between the two blue plates for maximum precision.
Re: Dual extruder concept
November 23, 2016 10:54AM
you could move to an offset position away from the print for any movement needed to go through the tool change operation


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Re: Dual extruder concept
June 08, 2017 06:34AM
Would it not be advantageous to have only one hotend moving though? You could still use the same mechanism, but only one hotend would suffer from the imprecision in the mechanics, so you would essentially end up with a main hotend that is accurate, and a supporting hotend that is not quite as accurate, but can be deployed and retracted ...
Re: Dual extruder concept
June 18, 2017 03:23PM
I'm just gonna do a little shameless self promotion:
[www.thingiverse.com]
I would love if some people would implement it on their printers. It's worked super well so far.
Re: Dual extruder concept
June 23, 2017 06:18AM
Quote
galaxyman7
I'm just gonna do a little shameless self promotion:
[www.thingiverse.com]
I would love if some people would implement it on their printers. It's worked super well so far.

Very interesting.... do normal retractions not affect the position of the nozzle ? I have had a similar idea where a motor would tug on a Bowden instead to move the hotend. Extra wiring of course, but it can be kept off the gantry.
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