Saturday, February 13, 2010

Measurements Continued

Last post I mentioned having some trouble getting a good measurement on the internal splines of the secondary sheave. I put it out to my readers for help and suggestions, and thanks to the powers of the interwebs, somebody suggested making a casting or imprint of the inside of the secondary (thanks Pascal).

I debated for a while what to use to do this: plaster, gorilla glue, expanding foam, potting flower foam. Then it hit me, wax! It's cheap, I have some in the kitchen, should be tough enough to get a good imprint and it's easy to do. This is the wax you'd normally use for baking and making somekind of weird candies or something. I've never made any food with it but apparently it's edible.

So I did, made a real mess with wax everywhere, I spilled some and spent more time cleaning and scraping wax than I did actually preparing. First, I cleaned the inside to get the grease, rust and junk out of the hole. Then I sealed one end with masking tape, sprayed WD-40 down the hole to act as a release agent for the wax and I was ready to pour molten wax down the hole.

A small side note on heating wax do not simply put wax block in your metal pot and put in on a heat source. This doesn't work, don't ask me how I found out. The proper way to do this is to place a smaller pot for the wax inside a larger pot filled with water, which you then bring to a boil...

The end result looks promising:

It took a while to cool, which is good because it allowed for plenty of cleanup time.
For those worried about dimensional accuracy, it was a very tight fit, so I think it will be good enough. Now I can use the proper spline measurement tools.


  1. Too bad we can't just make a jackshaft the same way. Maybe replacing wax with JBWeld ;)

  2. We could sand cast a jackshaft using the wax as a template...
    If there weren't such high loads a polymer shaped using the same method as the wax with reinforcements could probably perform quite well and be really light.