by cdsteinkuehler » Thu May 01, 2014 1:56 am
I've been reviewing the design files and ordering parts. Now it's question and random thought time:
Bearing support:
* Do you think the design is OK as-is or do you think additional support for the bearing bolts is mandatory (ie: would you build another one just like what you've got)?
* If you feel more support is needed, what about just cutting another face plate and extending the sides to make more of a box frame? This seems pretty easy, although likely wastes material (and makes it harder to string). I'm not that worried about either of those issues right now, but they are important for a cheap printer for the masses.
Locking when powered off:
* It seems like what you want for locking is something like an elevator brake that fails safe (locked). You could put teeth (or rubber, or whatever) on the pulleys and have a magnet that pulled a locking wedge into place when no power was applied. If you wrap some wire around the ferrous material the magnet is pulling towards, you could pass some current through it to generate an opposite field and push the magnet away when power is applied. This should be cheap in bulk (or if you make your own windings), but could be expensive in low volume unless you find a good pre-wound coil.
* You could apply the same principle to clamping the string instead of the pulleys, but then you don't get a positive mechanical lock. I'm not sure if you really need that, but it seems better if it actually keys mechanically rather than just relying on pressure to keep things from moving.
Keep thinking outside the box!