Optical Table CNC Lathe - Bellows
I want bellows for the linear rails. In the past I used stainless steel way covers,
But that only worked for part of the rails and going forward I want to be able to convert the lathe to a mill, so I want something like this:
This is quite challenging. I only found one parameterizable bellows model:
And this guy had to try multiple print settings before his bellows came out acceptable. I tried that model as well, and had some initial success:
but the bellows really came out way too hard or fragile. I tried may different print settings and geometries, and also modeled some different style bellows in Fusion 360 to try.
But for the most part this did not work well. Here just a few failures:
So I tried to replicate the successful build on Thingiverse, and succeeded - at least at first. After some height, the layers would not bond properly because the model sagged under its own weight.
I compensated by increasing the extrusion width. I figured that in the areas where the model is close to the nozzle the wall would be thicker, and in the areas where the wall sagged, the extra material could compensate by building a higher wall. This seems to have worked.
Next, a major problem with the model is that it needs end-caps. So I modeled the profile for a LRX35 rail in Fusion 360, and them combined the two STL files in Simplify3D. The end cap was set to print solidly with 20% infil, and the bellows was set to run in vase mode, as before.
This also seems to work well, though the initial layer stayed stuck to the printer.
I then cut off the excess bellows to check against rail. The fit is pretty good:
But the bellows don't compress well after cutting off the bottom section. This is going to take some extra work.
So I recreated a bellows Fusion 360, since that made it much easier to model the top section. The initial result is promising:
The top part can't use support, as support is very hard to remove with this material. And without support, it has slowly change from thin wall to thick plate. I made the angle too shallow and the bottom looked a bit like spaghetti.
Still, other than that it works, so I fixed the angle and tried twice the bellow length. The print was done with Simplify3D. The bottom and top sections were separate models set to print solidly. The middle section was printed in vase mode.
This came out well.
Next, I made a small modification to the bellows to have a better skirt at the bottom of the rail.
That works well enough to try printing a longer version.
I am pleased with that. Up to this point all the test prints were for a LRX35 size rail. I need bellows for a LRX45, so its time to scale up the work.