Thursday, March 19, 2009


The $1, no tools, pillow block bearing

Now that I have a linear bearing design that's inexpensive, and easy to build with hand tools, I've started on the other aspects of my repstrap. Today I built a pillow block bearing for supporting a lead screw.

The bearings used are standard 22mm skate bearings available for a few cents each online. I've used a 3/4 inch pipe hanger (they came 20 to a bag for about $2), and some JB weld. Steel-impregnated epoxy putty might work even better. I've laid everything out on some parchment paper, along with a $1 hobby clamp. Clever use of a weighty object might alleviate the need for the clamp.

I spread a generous amount of the JB weld on the inside of the pipe hanger, inserted the bearings, and clamped them in place, making sure that both the bottom egde of the bearing and the pipe hanger were flush with the tabletop. The parchment paper prevents excess epoxy from sticking to anything.

I've used a section of my lead screw to ensure that the two bearings are aligned.

The spacing of the mounting holes on this particular 3/4 inch pipe hanger happens to be 2 inches on center - perfect for attaching it to my 1 inch square gridbeam (which has one hole every inch).

This whole process took about 30 seconds, from mixing the epoxy to clamping the assembly and setting aside to cure.

A great find! Almost better than a printed part (almost), and much simpler for those just starting with a RepRap. Be sure to document it on the builders wiki. It tends to be overflowed by the huge amounts of posts to the builders wiki, so this knowledge should somehow be consolidated and categorized to be effective to more people.
Erik, I've since made a complete set - 8 - for my repstrap. I made my set with only one bearing per pipe hanger, and they work amazingly well - like professional parts. Additionally, with only one bearing, alignment is much less of an issue, so I didn't have to use the bolt section or the clamp. Simply insert bearing into epoxied pipe hanger, ensure both parts are flush with the tabletop, and let cure for a day or so. It takes about 5 minutes to make a dozen.
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