625 / 625zz bearing using 7½ shot

This is a simple "625ZZ"-sized bearing, using "7½" size shot pellets from an extra shotgun shell I had on hand. Such pellets measure a hair over 2.5mm diameter. Nominal size is 5mm ID, 16mm OD, 5mm thick, as with a standard 625 bearing, though it'll be slightly thicker (for me, 5.2mm) once assembled.

Internal tolerances are pretty close, so you better dial your printer in well before giving it a try. The outer part of the shell is a bit on the thin side, so you'll need very good bed adhesion.

Inspired by blecheimer's airsoft-based bearing, http://www.thingiverse.com/thing:56298 , except this one is press-fit. For best results, use a tiny amount of superglue to fuse the "inner" pieces together, and dab some good grease into the slit.

You'll want to flip the "inner-2" piece upside down for printing.

These are of course intended to be temporary; I used a pair of them in my extruder until I could replace them with real 625ZZ bearings. Judging by the level of wear when I tore them apart after a bit over two weeks, I'd guess I could have gotten two full spool's worth of extruder operation out of them with a little coaxing. Most of the wear appeared to cast-off "dust" from the shot pellets mixed with the 3-in-1 oil I was using. The printed parts had the beginnings of a split around the middle of the outer shell.

Print instructions

Licence: Creative Commons - Attribution Category: DIY Print Settings

Printer Brand: RepRap

Printer: Prusa i3

Rafts: No

Supports: No

Resolution: 0.1 mm

Infill: 100%

Notes:

Use your best filament for this, and print slowly. Print as hot as you can (without stringing/hairs becoming a problem), as good layer bonding is especially important for the outer shell.