I have been agonizing over the extruder setup as of late. I have been waffling between 3 options: 1) Bowden, 2) Lightweight all-in-one unit, and 3) Flexible shaft driving a hobbed bolt on the effector.
Option 3 is not proven. I would like to get this flexible shaft. The one that is .187x20". It costs $130 and still the shaft will have an angular deflection while loaded of 5 degrees over the 20". The slope comes out to be .2mm of filament. Not too shabby. I have seen someone idea that uses a speedo cable. That brings the cost down to $15 or less if you go to the junk yard. The deflection has to be a lot more but you can go up to 30ish degrees and stay under 1mm of play. Slic3r can handle that no problem. My current opinion is that this has potential but the complexity is not worth the possible gain.
Option 2 is still on the table. I contact QU-BD and they are hooking me up with one of their small extruders before it hits the market. I haven't gotten it yet so I am not sure how it will fit into the design.
Option 1 is what I am going to do. Everything about Simpson screams symmetry and nothing says symmetry like bowden. Bowden tubes work and they are light. (It sounds like an easy decision but it wasn't.)
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Here is the design of the effector. There are some neat features. Every arms connection can rotate independent of the others. The bolts cause radial pressure on the bowden tube and the extruder. This unit should have zero play. It is also printable without any support structure. Check out the exploded assembly video below.
Extruder Assembly Video
Other news: I have most of the rest of Simpson CADed out but I am obsessing over small things. I am designing plastic arms but I am going to have to make another version with wooden arms for now. The arms are nothing special. I can just use flatstock with various holes arrayed along the central axis. I wish I had a big enough printer to do the plastic arms first.
Option 3 is not proven. I would like to get this flexible shaft. The one that is .187x20". It costs $130 and still the shaft will have an angular deflection while loaded of 5 degrees over the 20". The slope comes out to be .2mm of filament. Not too shabby. I have seen someone idea that uses a speedo cable. That brings the cost down to $15 or less if you go to the junk yard. The deflection has to be a lot more but you can go up to 30ish degrees and stay under 1mm of play. Slic3r can handle that no problem. My current opinion is that this has potential but the complexity is not worth the possible gain.
Option 2 is still on the table. I contact QU-BD and they are hooking me up with one of their small extruders before it hits the market. I haven't gotten it yet so I am not sure how it will fit into the design.
Option 1 is what I am going to do. Everything about Simpson screams symmetry and nothing says symmetry like bowden. Bowden tubes work and they are light. (It sounds like an easy decision but it wasn't.)
Here is the design of the effector. There are some neat features. Every arms connection can rotate independent of the others. The bolts cause radial pressure on the bowden tube and the extruder. This unit should have zero play. It is also printable without any support structure. Check out the exploded assembly video below.
Extruder Assembly Video
Other news: I have most of the rest of Simpson CADed out but I am obsessing over small things. I am designing plastic arms but I am going to have to make another version with wooden arms for now. The arms are nothing special. I can just use flatstock with various holes arrayed along the central axis. I wish I had a big enough printer to do the plastic arms first.