The Files: unfortunately discourse does not allow much filetypes beside images, so you can download the files from this gitlab repo i just created. this is not something I am currently actively working on, this is just a place to drop the files. the .tar.gz in that repo contains all the rest of it.
the bottom part needed to be split and we got rid of the sidewalls of the inserting piece so that the picam-cable does not kink (it is basically as wide as the slot in the OFM). the center-pieces exist in 2 variants, one has a larger cavity to easier insert the z-motor-cable halfway in the chain.
Please feel free to use it however you like, we of course would love to see it incorporated into the official builds, i deliberately have choosen the same opensource-license.
However, in it’s current state, all the pieces have to be printed with tree supports and the printer must be able to print quite steep overhangs. We printed the parts on a Prusa CoreOne on PLA. This version is basically “for the looks”, but I am sure, the printability can be improved quite substantially.
i just noticed, that while inspecting the regular upright low-res microscope, that the drag-chain most likely would work on that one, too. maybe minor modifications are necessary, but the camera-cover is fully open on both sides, so I think it “should” also work on the low res version. the drag chain cannot stretch to a fully horizontal arrangement because of the “scale-tip”, but in the other direction it can easily bend to 90°, so a tighter radius itself should not be a dealbreaker.
@zeus I don’t know why I only ‘liked’ this before and did not comment, it is so cool.
When you first posted it we were in the middle of looking into changing the orientation of the Upright camera. We thought that the x and y axes would have to be the same for Upright and the standard inverted in order to work with our new scanning and stitching process. That would have made it harder to use this chain.
However, software changes have made the rotation unnecessary, and I have also started using my own Upright again. So I looked at your repository, rather than just the great photos here. It is very helpful that you have used OpenSCAD, which is not the easiest to use for design. The code looks to be very compatible with the main Microscope repository.
You’re welcome. My wife and I usually use OpenSCAD for 3D-Designs, well before first hearing about the OFM the first time, because when you are familar with coding, it feels like the natural choice, even if many things that are typical for CAD-Design are very hard to pull off in OpenSCAD, while others are laughable trivial instead.
However, the problem or rather hurdles with the dragchain is, that you have two very intricate angles (at the start- and end-piece), and you cannot overdo it, because a flatflex-pcb only can handle so much kinking in the sideways direction (which is a deflection of preferably zero…). Beside that you have to somehow work around other moving parts. Because of that the dragchain has more aesthetic elements than purely necessary from a technical standpoint, because it was “not a very technical part” in the end anyways. Nevertheless, even though it is primarily not designed for printability, but for coolness-factor, i think it absolutely nailed it. The state in which the code is now is totally useable, however, for a solid integration to the main repo there may be some tweaks needed for more robust handling of geometry changes at the OFM itself and for scriptability. We however would absolutely love to see this integrated, because when looking at the pictures, in my opinion the drag chain feels absolutely natrual to the OFM and looks just awesome
…just before I forgot: meanwhile we also have a version of the top-part for the high-res-upright-OFM for the HQ-Camera. As expected it does also fit with some minor modifications of the top-piece…
I forgot how much I dislike removing supports. The finish quality over supports on my Prusa Mk4 is also disappointing. Anyway all printed. As suggested, I used tree supports. I did supports only on build plate.
There is now a cover over the z-cable tidies for Upright. I modified that, but got the angle of the channel wrong, so I just hacked it.
Looks good so far. Now that you have most of the cabling covered, it is interesting, how much the colored motor-cabled stick out. therefore we “painted” our cables with spray-rubber, but white heat-shrink-tubing, electrical tape or sleeving (as seen in gamery computer cables) would also cover it up.
However now you see the problem with the “angles” i mentioned, and what the maximum angle is, that the flexcable can kink. ideally you want to tilt every chain-link by the smallest amount (~0.5°) for a gradual slope, but that would be really hard to nail perfectly i think (and you would have to iterate a lot until this fits)…
btw: if you want a gradular curve over the links, and they end up a little too loose, you can insert a stiff cable on the inside as bendable stabilizer or something like that.
I really like this drag chain. One niggle is that the angles on the microscope mean that the flat camera cable needs to start from the camera at one angle and then needs to end at the cable channel at a different angle, and also displaced slightly, which gives kinks.
So I started thinking about how to do this smoothly using out of plane bends. This is where I have got to. The red part gives the two bends calculated to make the angle change and sideways translation to meet the position and angle of the chain. The white cover over the top makes it look a bit neater.
you should’ve added the image from the merge request, as it makes the intent much clearer.
(edit: he’s done that …)
anyhow, this is a really interesting solution to solve that problem without kinks at all.
our design for the drag chain was based on a very gradual curve over the whole length. this is not ideal, but i don’t think it stresses the cable toooo much. however, this here is a very interesting take on displacing and flipping the cable basically at will.
Your images only show this section from above, but it does not seem to be a problem for you. In your build it looks as though you have folded the cable quite tightly back on itself at the camera, I have left mine in more of a curve. This might be making a sufficiently different angle of entry into the top piece? Or should I have tried to wiggle that kink down into the first green link?
yeah, also on our scope it is certainly not “kink-free”, but i don’t worry too much about that, because there is not much movement in the chain during normal use. the reason you normally want to have a 100% kink-free chain is because drag-chains/energy-chains usually travel together with one of the axis, which is not the case here.
anyways, every “proper” solution, like yours, is certainly more favorable than just bending it around the curve. the bend was a neccessary evil to make the chain happen in the first place, however i did not even thought about rolling it around two cylinders to achieve free angular placement…
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