Saturday, February 02, 2008


Trying a new coupling idea

The Jameco stepper that I am using has a thin, o.08 inch (2 mm) drive shaft. Attaching such a thing to a threaded rod presents problems. I began by using duct tape for preliminary tests. I needed something a bit more permanent, however, and decided to try something new that leveraged the generally good reports that I've had from other people in the Reprap project about JB Weld epoxy's ability to handle mechanical stress.

I began by tapping one end of the #10-24 drive shaft with a 3/32 in bit in my Dremel hand tool. The 3/32 bit at 0.09375 inches in diameter is just a shade bigger than the 0.08 inch drive shaft diameter. For those of you who are not familiar with drilling metal you should know that you can burn drill bits out very quickly if you don't keep the hole wet with coolant. I make my own in a small squeeze bottle out of a teaspoon of peanut oil (actually any cooking or machine oil will do), a few drops of diswashing liquid and the rest of the small (usually no more than 6-8 oz size) squeeze bottle is filled with water. Shake that up and you have quite a decent drill coolant for effectively free.

You can see here that I've wrapped the threads of the rod in several folds of a paper towel so that the vise doesn't mar the threads. One other advantage with drilling with a coolant besides saving your bit is that the drilling goes a LOT faster. You will also notice that most drill bits tend to be slightly magnetised, so the metal swarf (bits of metal drilled out of the hole) stick to the bit.

(Read the whole story)

Comments: Post a Comment

Links to this post:

Create a Link

<< Home

This page is powered by Blogger. Isn't yours?

Subscribe to
Posts [Atom]