Custom Grip

I'm doing some fiddly work trying to get some tiny spacers that will fit between my pulleys for my Core XY printer build. I finally decided I could use a nice hand vise with a form fitting grip for positive control.

One lump of Play Doh formed and squished between my thumb and fingers and a few scans later and I have the combined and cleaned .stl file generated:

It turns out, though, that the .stl files generated by the Matter and Form software are hollow shells (which isn't unreasonable since all it saw was the outside :-).

Unfortunately, these hollow .stl file seem to upset openscad when I import them and try to slice and dice them. I always get the "no top level object" error when I try to compile and render.

Fortunately, meshmixer has a tool to convert hollow objects into solid objects. Once I've done that, as long as I'm in meshmixer anyway, I can also use the smoothing tools to get rid of the cracks and creases from the original Play Doh lump which were scanned in. Exporting the fixed up .stl from meshmixer, I can then import it into meshlab and do some more cleanup, like decimation to simplify the model and make it easier for openscad to handle. Then finally run it through the online netfabb repair just to make sure everything is kosher in the modified file. That gives me my final fixed up scan:

Now I use openscad to import the file, rotate and translate it to a good printable orientation, slice off the top and bottom, and punch a 10mm hole through it where I'll eventually figure out how to attach things (as yet undesigned).

I print a copy:

And it fits in my hand perfectly, exactly the way the original Play Doh was squashed:

I've tried this out now, creating a part to wedge a brass M3 washer into the grip and actually managed to drill a 5mm hole in the washer, but I discovered lots of flaws in the process. The main one being that the hole is a simple cylinder, so the part rotates too easily when I need to apply force. I'm making a new one with a slot added so I can wedge things into the hole that won't be able to rotate.

...and here's the new grip along with a new wedge to hold a washer for drilling:

Here's what it looks like assembled with the washer held in the two halves of the wedge:

And here you see how the M3 bolt is used to pull the wedge down into the slot:

And even more incredible, as long as I work my way up through a series of larger drill bits, I can actually drill a 5mm hole in the brass M3 washer to allow me to use it as a spacer between the idler pulleys in my core XY printer design.

Go back to my main scanner page.