Is this an insane way to mount extruders? June 07, 2016 02:44PM |
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Re: Is this an insane way to mount extruders? June 07, 2016 02:52PM |
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Re: Is this an insane way to mount extruders? June 07, 2016 03:34PM |
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Re: Is this an insane way to mount extruders? June 07, 2016 03:51PM |
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Re: Is this an insane way to mount extruders? June 07, 2016 04:23PM |
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Re: Is this an insane way to mount extruders? June 07, 2016 05:33PM |
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Re: Is this an insane way to mount extruders? June 07, 2016 07:07PM |
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Re: Is this an insane way to mount extruders? June 07, 2016 08:32PM |
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deckingman
I'm a bit concerned about what happens to the tubes when the hot end is directly under the extruders. They'll need buckle and bend a lot when the distance to the hot end reduces by 150mm to 200mm. That might induce some twisting forces to the carriage, although it's riding on 2 linear guides and should be well constrained. It's still a bit of a concern though. Now if only the extruders could move...............
Re: Is this an insane way to mount extruders? June 08, 2016 04:02AM |
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Re: Is this an insane way to mount extruders? June 08, 2016 04:19AM |
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maso
It seems to me that you're basically looking to implement the flying extruder that's popular in delta printers.
I recently outfitted my delta with one: picture in case you don't know what I'm talking about
...and the spring mounted suspension might keep your issues at bay. The extruders are free to twist and change height based on head position, but don't have to be moved around laterally at all.
I've been thinking about trying something similar with my core xy variant.
Re: Is this an insane way to mount extruders? June 08, 2016 04:40AM |
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Re: Is this an insane way to mount extruders? June 08, 2016 07:25AM |
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realthor
The Delta style flying extruder approach is the best for this and I can't really see a way around it. You will have to place the extruders in the center of the -supposedly- square bed and have the bowden length set to a value that would allow printing on the whole bed in one go -imagine a cube encompassing the whole bed- and for that you need a radius of the circumscribed circle to your bed's corners.
This basically means to have the vertical members of the frame high enough to allow a flying extruder.
If you make the extruders a sort of sliding extruders (I have imagined this with the extruder attached to a scara arm that swivers around one of the members) and have them shorter than a value that would allow a full circumscribed circle to your bed then if you print big you will get at some point the printhead to have to pull the whole weight of the extruders and that will affect the print. Even if you make a sort of counterweight system where the pull will be easier on the printhead, the difference from running free and then all of a sudden having to pull the extruders will be significant.
Re: Is this an insane way to mount extruders? June 08, 2016 07:53AM |
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Re: Is this an insane way to mount extruders? June 08, 2016 08:15AM |
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realthor
The bowden loop has to maintain the largest radius possible to keep low friction between tube and filament. So best approach I see is having the extruder suspended from the bar, just like with a Delta flying extruder so it can swing in all directions, then somehow spring loading the extruder so that when the printhead approaches the position under it, it will rotate around its X axis bringing the bowden loop up... I will make a sketch later if this is too confusing of an explanation
Re: Is this an insane way to mount extruders? June 08, 2016 08:29AM |
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deckingman
The thing is, I need to mount the extruders somewhere so if I can figure out a way that will keep the bowden tubes as short as possible, it'll be a bonus.
Re: Is this an insane way to mount extruders? June 08, 2016 08:35AM |
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Re: Is this an insane way to mount extruders? June 08, 2016 12:30PM |
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the_digital_dentist
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deckingman
The thing is, I need to mount the extruders somewhere so if I can figure out a way that will keep the bowden tubes as short as possible, it'll be a bonus.
The shorter the tubes get, the stiffer they get. With 3 of them connecting the extruder gantry to the hot end carriage they'll be pulling the extruder gantry around as if it is all one piece. Unless you make those tubes very long (making them more flexible) and the printer very tall (to accomodate the long tubes), the moving mass will be higher than if you mount the extruders on the X axis carriage and use direct extrusion. That's why it's usually done with the tube(s) making a big loop at the top. Flexing a big loop keeps the load on the hot-end carriage pretty low, but then you have the extrusion problems associated with long bowden tubes to deal with.
Re: Is this an insane way to mount extruders? June 08, 2016 06:51PM |
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Re: Is this an insane way to mount extruders? June 09, 2016 02:38AM |
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aussiephil
I have some thoughts on this based on my flying extruder setup on the delta that should work if your prepared to have some vertical height above the printer.
I have around 200mm of Bowden length with 580mm diameter coverage withe the extruder suspended centrally about 300mm below the central retaining point 500mm above the hot end. The central point is then pulley counterweighted to take up the vertical motion on the delta an this could be used to manage the small amount you need across the XY movement
This keeps the Bowden tubes short at the expensive of some central vertical height.
I'd mount the 3 extruders in a triangle arrangement with the motor drives facing the centre giving a balanced flying arrangement, I've even mentally designed the flying extruder mount
Re: Is this an insane way to mount extruders? June 09, 2016 09:04PM |
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Re: Is this an insane way to mount extruders? June 10, 2016 02:51PM |
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Re: Is this an insane way to mount extruders? June 17, 2016 05:11AM |
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deckingman
Man, you are a star! Don't suppose you have that as an stl do you? No worries if you don't - I can cobble something together in OpenScad. Thanks for taking the time. I really think this, or something very like it, is going to work. Compared to my existing Mendel, my planned printer could end with 60% bigger X and Y, 500% bigger Z but with 30 to 50% shorter bowden tubes. Brill !!
Re: Is this an insane way to mount extruders? June 17, 2016 06:19AM |
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Re: Is this an insane way to mount extruders? June 17, 2016 07:20AM |
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Re: Is this an insane way to mount extruders? June 17, 2016 08:11AM |
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deckingman
Man you are a star! I've never played with S3D or Fusion 360, only Open Scad (and I'm not very good at that) but I should be able to import your stl into OpenScad and play with it if I need to but it looks fine as it is. The other thing that struck me is that I need to get wires to the hot end and of course these could follow the same route as the bowden tubes which would be quite neat and tidy. So that's another problem solved before I even thought about it. Thanks again.
Re: Is this an insane way to mount extruders? June 17, 2016 11:43AM |
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Re: Is this an insane way to mount extruders? June 18, 2016 01:51AM |
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Re: Is this an insane way to mount extruders? June 18, 2016 04:33AM |
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Re: Is this an insane way to mount extruders? June 19, 2016 02:18AM |
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deckingman
That's looking really neat. And small too, I imagined it was going to be bigger. I'll probably end up using short motors.
Re: Is this an insane way to mount extruders? September 02, 2016 06:23AM |
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