Who out there has experience with printing knobs? As mentioned in another topic I have a device missing a couple of odd knobs
where to reach the recessed pot shafts (knurled ones) the center part extends below the skirt. I haven’t found any similar knobs for sale.
I thought about trying to print new knobs. Then I had another idea, maybe just print the extension? And then use a couple MF-A01s with them. That’d provide a better match than anything I could likely print (especially since at the moment I only have orange filament 
).
I’m thinking a cylinder with a hole to fit on the knurled pot shaft, about 1 cm long and 9 mm diameter, then reducing to a solid 6 mm diameter the MF-A01 would fit over.
Anything wrong with that idea? And do you have any knob designs intended for knurled/spline pot shafts? What sort of hole is needed?
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I have printed both of the customizable knobs linked to below. You just need OpenSCAD to create the files.They work quite well. There is limited customization as far as shaft type, but the regular splined design works well. I have ended up doing further customization in other CAD software, since I’m not really familiar with OpenSCAD. You might be able to take the splined part of the knob and cut it out and print that or customize the knob design to more or less replicate the bottom part of the knobs you are trying to replace.
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I’ve never used OpenSCAD and it looks … like a lot. What’s involved in getting a splined design into a STP file or something?
Yeah, it’s not a clear process. I’ve had to export as an STL and open it in FreeCAD and save it as a STEP file that way. Here is a ZIP with three of the STEP files I have made. I think they are just surfaces though.
https://drive.google.com/file/d/1xw6g6M4XSioabqBBegXGkbAgoE0ikaSd/view?usp=sharing
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Yeah, seem to be surfaces so getting the knurled hole into a cylinder is not obvious…
Try this one. It is a solid. Just a single knob with the knurling.
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I use OpenSCAD for my knobs (and for many other things), it’s really easy to learn and you can parametrise everything 
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Just take care of things like layer orientation and adhesion. If you print “on axis” with a knob you will get the prettiest result but you will also get the weakest in shear if you turn it a bit roughly it will snap along the layer line leaving a stub in the recess which will be a paint to get out.
I still would print on axis, because it will look nicest, but I’d probably start by making sure my temperature was enough to get good layer adhesion.
Not appropriate here as they are too chunky but you can also get brass inserts which give a much nicer result to a pure 3d print imo. DIY knob insert – Thonk – DIY Synthesizer Kits & Components
They are for 6.35mm shafts, but you can use the shims they sell if needed. I’ve used them to make some 1470AQ style knobs in a custom colour using a resin printer.
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