Dual hotend, one motor possible?
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Hi guys
So my mad brain had an idea and before I waste any more time thinking about it, I wanted to make sure it's actually possible to realize from a firmware point of view.
Basically I want to have a direct dual drive with two hotends. But the motor stays the same and switches between the gears. Switching is done mechanically, be it a swinging or a linear motion to lift one nozzle and engage the other one. Like I said it's only an idea.
Now i want to make sure it's actually possible to realize in RRF. So two tools but they share the same motor, spinning cw for one and ccw for the other.
Is that even possible? Hopefully someone has already had some experience with this or a similar problem. It's hard to search someting without knowing what you're looking for
Thanks in advance.
Mind you it's not even a concept at this stage.
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We (at LOG hackerspace) designed such dual extruder using one motor. It is not driven by a Duet, but it should work.
Here is our design: https://wiki.logre.eu/index.php/DondoLOG based on this one: https://www.thingiverse.com/thing:673816 (we changed a lot of things, leading to a much more simple geometry).
Onshape designs are here: Mine¹: https://cad.onshape.com/documents/ab5e4a91e08de464a68c8fa9/w/d1a6bf327030002f2355aebe/e/4fc76c1855ace35a39166ba3 (using aluminium plates) and a derivated, made by a friend: https://cad.onshape.com/documents/44cc3aa0e2de59f4440a6e4b/w/58c86854d8b2aa8e76983bb9/e/82ef35419fb25e023c2c8b7d (using PMMA 6mm).
Feel free to ask if you want more details. Note that the second design is now working (see https://piwigo.logre.eu/picture.php?/1139, https://piwigo.logre.eu/picture.php?/1239 and https://piwigo.logre.eu/picture.php?/1286); I never tested mine...
¹ my design means to me, as it is my very first usage of Onshape (and first time I ever used a parametric CAD software).
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It should be possible to do this with a Duet. Just configure each tool (hotend) with the same extruder drive number in the config file. The only tricky part is reversing the drive direction. Once it is set in the config file you will need to change the direction in your tool change files.
If your extruder drive is 4 then you will need a M569 P4 S1 in the tool change file for tool 0 and then a M569 P4 S0 in the change file for tool 1.
Or they could be opposite depending on your dive setup but the idea is it changes the drive direction at the time of the tool change.
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I remember this talk:
https://reprap.org/forum/read.php?70,196591,196591#msg-196591There were few attempts IIRC to make the same thing without servo that rocks the extruders to select if you are using first or second by just reversing the motor, the direction change would select E0 or E1 but that setup does not allow for retraction so IIRC it was abandoned. If you search reprap.org you will surely find lot of info about it.
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@timcurtis67 said in Dual hotend, one motor possible?:
It should be possible to do this with a Duet. Just configure each tool (hotend) with the same extruder drive number in the config file. The only tricky part is reversing the drive direction. Once it is set in the config file you will need to change the direction in your tool change files.
If your extruder drive is 4 then you will need a M569 P4 S1 in the tool change file for tool 0 and then a M569 P4 S0 in the change file for tool 1.
Or they could be opposite depending on your dive setup but the idea is it changes the drive direction at the time of the tool change.
As Tim said.
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Perfect... I'll get going then
