Printing a roller for wife’s pottery experiments. Also just designed a stamp based on a photo she found, queued up to print next. Learned a few new OnShape tricks doing that. This is the most CAD I’ve done in 25 years.
Gear design and printing accomplished! Sub-thread on further adventures there. Been a while since I updated this thread so you'll notice my newer prints are red rather than black. Bought the red filament to print stuff for my rover and is now default.
Figured out how to make gears in OnShape today using their featurescript. I am now officially unstoppable. 3d printing them now. This is just a hacky test job (those spokes on the largest gear are bad... I made them with a pattern of holes rather than an equal width spoke)
Next adventure being cued up: TPU filament was on sale on Prime Day so bought some (0.5kg for ~$8). It prints soft, rubbery parts. Goal is to see if I can print my own tire designs for rover. Stretch goal though.
My Monoprice Mini doesn't print TPU out of the box, it needs a small mod (a feeder widget) that can be 3d printed out of PLA. Obviously others have already figured out how.
A video on TPU printing... he's using the same printer as mine, so I'm hoping I can do it too, though he seems much better at the finicky stuff than I am. I get impatient. 3d printing is like the Potions class at Hogwarts.
Nope. Support adhesion failed near end of print. I think I need a raft for this. And/or design in my own supports. The two pillars at horn tips got ripped up. Wonder why? Up-tension from horn curve?
Recently remembered one of my earliest introductions to engineering thinking: my dad (a mechanical engineer) posing a classic CAD brainteaser to me when I was a teenager: what object looks like a circle in the top view, a triangle in the front view, and a square in the side view?
Later in freshman engineering school, our engineering drawing instructor posed the same brainteaser, before proceeding to demonstrate the answer by shaping a piece of chalk into the answer (whittling a piece of chalk by rubbing it on a board is legit machining btw)
The answer, which I just made in OnShape using the loft feature, is a thing which may have a name, I don't know, but is kinda like an oddly shaped cone frustum. Here is the drawing:
Ignore weird lines. They are an artifact of how OnShape does lofts geometrically. A loft is when you smoothly transform one face of an object into another. In this case, the 2nd surface should actually be a 1-d edge, but OnShape needs a face, so I made a very narrow rectangle.
Another way to pose the brainteaser is to ask: what object can plug a square, circular, or triangular hole, depending on how you orient it? So just for fun, I made a stencil of that too.
I actually don't know if this is the "only" correct answer. Afaict, a 3-projection view completely determines a solid model, but maybe complex surfaces have indeterminacy. I think I'll have to sand off some edges to make it the right answer.
Doh. Of course the solution is not unique. This one is skew symmetric. Any set of contours that fits within the 3 contours will do. I could have added a halfway loft plane with an ellipse cross section and that would have forced symmetry.
Anything contour that stays within the bounding box defined by square and triangle projection lines will work. Blue is what OnShape generated. Red is what I’d force if I wanted.
Also reprinting the horns from yesterday. Scaled down 50% with raft. Dunno what all that wispy stray fiber is. Too dry? From supports being printed coarse? PLA spool being not as good? Drip during travel?
Done. Messed up a bit tried to make the triangle equilateral and the rectangle a square at the same time. Doh. No way to satisfy this template. If you have a square, triangle will be isosceles.
Fingers crossed. Seems to be printing fine. Shiny with some stringing. Used Cura generic presets for TPU-95, whatever that is. Higher nozzle temperature (228F) but lower bed temperature (45) than PLA (205/65)
Decent compliance, rather stiff at normal resolution printing with 60% infill. I bet I could get much wider range by messing with infill density. But clearly settings need work. But unlike PETG this feels different enough as a material, it’s worth mastering.