Re: Tek Knob Project - scan and make
I might send you my miraculously unbroken FG504 freq stop knob. It's mechanical design is obviously flawed. What saved it is probably the fact that the motion stop, which normally puts pressure on the knob's weak points, has rounded over and ceases to function. So the varistor reaches the end of it's travel instead.toggle quoted messageShow quoted text
On Tuesday, December 19, 2017, 1:41:07 PM CST, Kuba Ober <email@example.com> wrote:
A polycarbonate or graphene-infused PLA insert would probably work, and instead of a clearance fit a tighter friction fit would be called for. I’m of the mind that given the low cost of replacements, a friction fit is all that’s needed. A drop of ABS juice/glue is all that’s needed to retain a knob worn out from multiple removals. Or just print a new one, they would be a few bucks each from a print service, or a dime or two when printed on your own printer.
Another idea that I’ve tried and was working OK is to have a locking sleeve where the knob has two parts, top part having a tapered slotted sleeve that fits the shaft, and the bottom part having a conical seat that compresses the sleeve. A snap latch interlocks these two, unfortunately for small knobs it’d be a single use part that has to be destroyed for servicing.
Another option is, instead of a permanent latch, to have the bottom part do a twist-lock on the top part. This would allow for a few reassembles before it wears out to require replacement. That may be hard on the smallest of knobs. Probably the smallest knob this would work on is something like the 7000 plugin freestanding adjust knobs like hor/vert offset, trigger level, etc. It’d also need a slow print at 0.1mm or even 0.05mm layer height with a 0.1 or 0.2 nozzle. Regular friction fit knobs work OK printed with a 0.4 nozzle.
The biggest deal would be to have the 3D models of existing parts and then the design of replacements is a separate and a much more limited task and can be easily applied to all the parts of a given class at once.