First tower essentially complete! Getting there, slowly but surelyby Apsu - Look what I made!
This is very clever. Fixing up the CAD shouldn't be difficult at all, and definitely a very quick print. I bet if you sourced the switch from a specific vendor you could get the accuracy of the switching action from the datasheet and know for sure what the measurement *should* be, then tweak the model tolerances and calibration around that.by Apsu - Look what I made!
I did a live stream a bit ago to discuss the current Tripteron build I have and answer questions, walking through the construction, and showing lots of video of it in motion. The link is here if anyone is interested and not following my YT channelby Apsu - Look what I made!
Decided to try the outer arm links jointed on top of the inner, to lift them away from the build volume a bit more YouTube Link Gifv link for endless fun Sorry for the low quality, free license of Fusion doesn't let me render prebaked motion studies at higher res ;Pby Apsu - Look what I made!
Quotekayrangandhi I don't see why you couldn't do that (print on any surface) with the Delta version. Sorry, I should've quoted correctly ,what software do you use for cad and simulation? Oh! Hah, no problem. I'm using Fusion 360.by Apsu - Look what I made!
Quotekayrangandhi I don't see why you couldn't do that with the Delta version Not sure what you mean. This is the delta-like version. Did you mean why can't I simulate the orthogonal version -- the one I built and got printing? Because I did simulate it, I didn't post quite as much of the simulations but I simulated the hell out of a ton of arm designs. The difference is in the orthogonal versby Apsu - Look what I made!
And last check for good measure. Added a 1N lateral load to the effector, which is *ENORMOUS* acceleration for how much these parts weigh (effector is 50g as-modeled). This is equivalent to 20,000mm/s^2 acceleration (F=ma, 1N = 0.05kg * 20m/s^2, 20m/s^2 = 20000mm/s^2). Total: XY: Z: The last one is particularly interesting, because the effector deforms more than with gravity, as expected,by Apsu - Look what I made!
Did some offset platform simulations to compare, and looks like the behavior is the same with respect to effector deflection Total displacement Z displacement Looks like the isostatic behavior is excellent. Looking good!by Apsu - Look what I made!
Quoteo_lampe I don't want to rain on your parade, but I don't see huge advantages against a common delta or the cartesian tripteron? OK, you win headroom against a delta, but the elbows sticking out everywhere weights more against it. I see several advantages. For one, symmetric arm assemblies suspending the platform from above with no possibility of the arms impinging on the build volume is a dby Apsu - Look what I made!
Small update Trying out 20mm x 20mm arms with square cross-sections and hollow inside with 2mm shells, simulating just gravity to see balanced joint stresses. I chose 25deg arm angles to maximize the loads. Keep in mind if you've never seen something like this, the *huge* visual deformations are because the software amplifies small values so they're visible and you can see what's happening easieby Apsu - Look what I made!
Quotekayrangandhi What i meant with that draft assembly was to try another way to assemble one of the arms of the tripteron, using the same effector, but looking for more arm rigidity and less joint play/backlash. Of course the full design would have one assembly like that per tower. Correct me if I'm wrong, but I understand each arm defines a tilted circle that slides along the vertical tower aby Apsu - Look what I made!
Little more proper renderings of a mockup. And yes, I'm aware the rails are overlapping the corner brackets ;P I completed the forward kinematics as well, and have some code written up for Smoothieware that I will test after I build the prototype, and after testing, submit for inclusion upstream. The code is here, and the comments there describe the method I'm using to define the forward/inby Apsu - Look what I made!
Quotekayrangandhi QuoteApsu Quotekayrangandhi From the experience with bearing joints, do you think making a planar joint with a bearing joint+ a linear rail would be a good idea? I'm not 100% sure what you mean by planar joint or bearing joint + linear rail. I've got linear rails already, to which the shoulder bearing joints will attach. Do you mean a compliant laminar joint by "planar joint"?by Apsu - Look what I made!
Quotethe_digital_dentist I don't know if the sag in the arms would be linear and correctable by just tilting the print bed. It seems like the motion might define a pretty complex, unflat surface. (assuming your talking about the delta-like configuration) Well given the offset angles of the arm joint plane, it would depend on what's sagging and where, I suppose. Of course the goal is to mechanicby Apsu - Look what I made!
Quotethe_digital_dentist It would be interesting to see what a dial gauge clamped to the extruder carriage reads when you move it around the bed surface. I thought about it, but figured the IR probe would give me a good indication of tramming since the accuracy is around 0.02mmby Apsu - Look what I made!
Quotekayrangandhi From the experience with bearing joints, do you think making a planar joint with a bearing joint+ a linear rail would be a good idea? I'm not 100% sure what you mean by planar joint or bearing joint + linear rail. I've got linear rails already, to which the shoulder bearing joints will attach. Do you mean a compliant laminar joint by "planar joint"?by Apsu - Look what I made!
Alrighty, time for an update. Overall, this was a huge success, I'd say. Managed to build something that makes reasonable prints and can be improved further. It also seems to be the first machine of its kind ever actually built, so that's pretty cool too There are some challenges left to solve with the orthogonal Tripteron which are particularly difficult, and I think I'm going to pivot slightby Apsu - Look what I made!
Quoteo_lampe Good job, Sir! I've seen worse test cubes. In the side view I see some regular wobble every 5-6 layers. Makes me wonder if the z-stepper would need a gearbox or just a lead screw drive? ..now back to watching this video again Oh there's all kinds of stuff wrong here, haha. The Z axis is absolutely jumping a little due to being belted and having 200 micron resolution. It also slipby Apsu - Look what I made!
SHE PRINTS!! YouTube Link Plenty left to work on, but I got the rest of the bits necessary to mount everything and got it printing successfully. Here's the result: Bottom Top Side I forgot to add some smarter ending gcode and it squatted on the corner on top a bit, and I was testing different accelerations along the way... But all of that is improvable, the fundamental behavior worksby Apsu - Look what I made!
Well Christmas came early, my E3D extruder and hotend are here, got a 200x300mm boro glass bed, and the extruder motor will be arriving later today. Looks like I might actually be printing tonight with any luck. Just need to design a groovemount that can attach to my effector and we're basically there. Maybe bed-mounting clips if I'm feeling really enterprising, but I have a differential IR Z prby Apsu - Look what I made!
Quoteo_lampe With a little longer extrusion, you could win a bit print room,too. The MGN12 rails are sold in fixed length, but 2020 extrusion sells tailored to your needs. See blue circles in the attached pic. Yep, you are indeed correct. I had a bunch of 305mm extrusion and 300mm rails, so I just went with what I had, but absolutely I could expand the frame so the rails don't run the full lengtby Apsu - Look what I made!
Small update, decided to try moving the shoulder joints out a bit more to increase the build volume and give the wrists a bit more breathing room. Looks like it'll work and is an easy tweak/print! I like how relatively easy it is to hack on this platformby Apsu - Look what I made!
Quoteo_lampe Awesome! That looks better than the first layer of my delta ATM BTW: I linked your Tripteron thread to this vacuum bed one, because they would be a perfect match. Maybe I can lure you into building a conveyor belt bed haha. I managed to get in touch with Nicholas Seward the other day to talk about my Tripteron, and we were talking about the fact this design could actually print oby Apsu - Look what I made!
Huzzah! Looks like we're on the right track. I made it draw on a non-flat board on a non-float box on a squishy table cover, using a dry-erase marker, and yet it did a decent enough job I think I'm ready to move onto pushing plastic. Here's a video: YouTube Link And the result itself: Obviously these are not ideal conditions, and it doesn't tell me exactly what a print would look like, andby Apsu - Look what I made!
At last, the time for printing has arrived! Got one of the new shoulders done, looks pretty great! Two more new models to test, then I'll set up an overnight plate full of joint brackets to print.by Apsu - Look what I made!
Small update, pic and turntable of latest effector design. And no, the center circle is not misaligned It's equidistant from each axis using a particular method. Might change to a different one, we'll see. YouTube Linkby Apsu - Look what I made!
Quoteo_lampe I love the looks of it, but maybe the center platform needs an redesign? It seems to be pretty tight to mount a hotend. Looked that way, but that was a 22mm cutout for a 608 bearing. When cut down to 12mm (J-Head groove mount diameter) there's tons of room. In fact, I've been redesigning the effector/platform a fair bit. I made a ThingiVerse page for the project, so STLs are more eby Apsu - Look what I made!
Added a couple more frame pieces and framing brackets, more like I originally intended to do. Here's a few 1080p renders to illustrateby Apsu - Look what I made!
Alright, I finished up the bulk of the remaining CAD and assembled it for some motion testing. Here's a video of manual manipulation, looks like it'll work well enough to proceed! YouTube Linkby Apsu - Look what I made!