Only your friends steal your books.
--Voltaire

Library Stamp

I love to lend out my books, but I hate to lose them. I wanted to make a stamp this week that I could use to label all of my books, thus mitigating my misgivings of misplacing my monographs.

I took this week to learn Rhino, as I've been using SolidWorks all semester. The tradeoffs between surface modeling software and solids-based CAD were quite apparent, and I'm glad to have started learning to use Rhino. Some screenshots of my Rhino models for my library stamp:

Turning my designs into a mold took a lot more time than I expected. First, using the Modela Player software for Windows was an arduous process, but their software is pretty nice (once you know how to use it). I used this to make the stamp handle, through a rough pass then fine pass with a 1/8" ball-nosed end mill.

I decided to use the fab modules to mill the face of the stamp, because the toolpaths from Modela Player enforced milling a border around the entire piece, which took about an hour for a small part. I used a 1/16" ball-nosed end mill, and I made care in my Rhino design to ensure there would be enough clearance for the bit. This mill worked very well, but there was a slight bit of wax left that had to be trimmed by hand:

The final molds, after trimming with an X-acto knife:

The casting process was ridiculously simple, and only slightly messy. I used the PMC-121/30 Wet urethane rubber for the stamp face (with different colors of pigment) and the Smooth-Cast 325 urethane plastic with yellow pigment for the handle.

Here are my parts after pulling them out of the molds:

The letters of the face mold were stubborn - the casting material often didn't fill in some of the letters. So I tried a few times, using a different pigment every time. The red one turned out best:

mitigating my misgivings of misplacing my monographs

The 3D CAD files for the stamp are here:

Stamp Body: Rhino File (.3dm) | .STL file (binary)
Stamp Face: Rhino File (.3dm) | .STL file (binary)

Cello Body Accents

I originally planned on making accents for the body of my cello (final project) out of urethane plastic/rubber this week. We didn't seem to have an end mill deep enough to do the job, but I spent a good amount of time creating molds for the body accents I'd like. I'm still planning to mold/cast these for my final project - after finding an appropriate end mill for the Shopbot.

Full mold with matching-holes and parts for left and right of cello:

Banana Doorstops

Finally, Natalie and I inherited a mold from our group for a banana door-stop, so we made a few of them out of the PMC-121/30 urethane rubber.