Thinking out-loud about dual hotend

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Neotko
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Thinking out-loud about dual hotend

Post by Neotko »

I just got an idea for dual hotends that could make it actually work for a dual heads on the same pack.

The mayor problems of dual hotends (without changer) are:
- Drips
- Inactive hotend has dirt that pushes printed stuff
- Too slow to cooldown the inactive hotend.

Solutions / ideas

- Smarter slicers, s3d with some toolchange scripting could solve half the problem. But the firmware machine should help also.
- Static blower fan, on the machine, pointing to the hotends could cooldown the heads. Like a 'parking' area where the active hotend cools-down, wipes, moves a bit out of the blower fan area, then soon to be used hotend heats, primes, wipes.

Firmware side, the guys of BCN3D did an amazing job with his firmware to simplify the calibration. And since they released everything opensource and they use marlin, it shouldn't be too hard to port it.

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Re: Thinking out-loud about dual hotend

Post by Amedee »

Having 2 heads allows you to calibrate the height in software. You can't do that if they are together as the lowest one will hit the print...
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Re: Thinking out-loud about dual hotend

Post by Neotko »

Indeed. But firmware could allow you debug it with print tests. Ofc the best way to do it it's with a gauge feller (been there donethat) and it's a pain in the ass without print tests, and when you runs print test you need to do a lot of weird prints yo actually calibrate it.

One of the reasons I disassembled my magnetic head changer was because even the slightest change and I had to printa lot of test to recalibrate, and because the offset wasn't good enough by firmware I hadto use the caliper over and over until I was able to get something 'ok'. And even then, a small twist of a screw (and a nozzle change was unthinkable ofc) and was all over again.

With dual hotends the first problem I see on um2 it's that the whole hotend can rotate slightly shifting both hotends. Just because the black plastics of the hotend have slack allowing room for the full block to twist agood 1mm on both directions (this happens when you tight the nozzle for example).
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Re: Thinking out-loud about dual hotend

Post by drayson »

There is a German guy at the Ultimakerforum playing around with a dual head with active water chiller to uncouple the heat transition between the two heater blocks and the head - and active nozzle lift. Unfortunately in German language, but ...
https://ultimaker.com/en/community/1765 ... einstellen
seems promissing...
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Re: Thinking out-loud about dual hotend

Post by drayson »

Another solution I recently found was to implement a servo to move a whiper forward/back to clean the nozzle - maybe instead of the tower...
I already hooked up a servo thanks to amedee's FW addons but have not engineered something up to now...
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Re: Thinking out-loud about dual hotend

Post by Neotko »

Indeed the water cooling sure works, but it's also so heavy and it needs more hardware. I really think that with a good blower fan on a parkstation the hotend could get it's beauty, and I mean a parkstation because as soon as you get two hotends you need to be sure that the inactive hotend has been fully 100% clean, or any peace of material will hit the print. That's also one of the many reasons dualextrusion systems always advertise themselves with small objects that don't go beyond the distance between the two nozzles.

Indeed, a servo controlled by gcode would be the sollution. Because with that you get a fully clean nozzle. I did search a lot about how to use the extra connections on the um2.1 boards to try to PWM a system with 5v, and well, I failed because my firmware/soldering skills are close to zero. But indeed, a servo would fix a lot of troubles.
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Re: Thinking out-loud about dual hotend

Post by Amedee »

Neotko wrote:Indeed. But firmware could allow you debug it with print tests. Ofc the best way to do it it's with a gauge feller (been there donethat) and it's a pain in the ass without print tests, and when you runs print test you need to do a lot of weird prints yo actually calibrate it.
I have to admit their calibration process is really idiot proof -- even if the user mess with the sheet of paper, they allow to loop in the calibration phase until you reach the right point.
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Re: Thinking out-loud about dual hotend

Post by gudo »

Hi to all
Just my 2 cents
There are interesring ideas here : http://www.thingiverse.com/thing:1362557
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Re: Thinking out-loud about dual hotend

Post by Meduza »

Yeah, i do think that a tilting / lifting hotend like that would be a very reasonable way to go to get good performance out of a dual extrusion printer...

Me and johank was doing some sketches for a tilting hotend with a precision bearing and water cooling a few years ago, but we never got around to actually building it.
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Re: Thinking out-loud about dual hotend

Post by Blizz »

I personally still think that a sort of a filament slicer & assembler and only 1 head is way simpler to implement than get the 2 head thing working nicely.
It doesn't even have to melt the pieces of filament back together, the pressure of feeder on the piece behind it should be enough to drive it forward.
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Re: Thinking out-loud about dual hotend

Post by Neotko »

Guys an idea, but I don't know if this could work.

Endstops when closed makes a short circuit between 5v input right? Could that be reuse to not only it sends the 5v short, but a circuit takes that 5v?

I ask because this way it could be posible to activate the 'parking' area when some endstop it's activated, making the air + wipe zone alive, and turning it off when the endstop it's open.

I have zero circuit knowhow that's why I ask :D it could allow to have 2 zones, one for x enstop where it cools, then goes y (thinking outloud) and then the wipe + purges the nozzle. Then it goes back to print.
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Re: Thinking out-loud about dual hotend

Post by Meduza »

Just activating something from a switch being pressed? No problem whatsoever.

Or you could activate it with a pin from the controller board and custom firmware/gcode
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Re: Thinking out-loud about dual hotend

Post by gudo »

Meduza wrote:Yeah, i do think that a tilting / lifting hotend like that would be a very reasonable way to go to get good performance out of a dual extrusion printer...

Me and johank was doing some sketches for a tilting hotend with a precision bearing and water cooling a few years ago, but we never got around to actually building it.
Hi to all!

Meduza
A sketche for a compact mechanicaly workable UM2 TLS (Tilting/Lifting System), motion by servo motor
I'm not expert in sotfware , thinking it would be possible to manage a dual extrusion process for it

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