Monday, 11 October 2010

Secret Tapes Revealed

I'm happy and relieved to report that my wobbly ball bearing problem has been solved. I can't say that I'm greatly proud of the solution, but at my target budget, it was the best I could come up with..

It turns out that the movement of the ball bearing comes indeed from the small space between the bearing and the threaded rod. That's surprising, because for the larger bearing, there is almost no movement. It just shows the relative level of precision required for these sorts of constructions, even at a hobby level.

The options to create a tight fit were
  1. Get the threaded rod machined. Expensive and I would need new, smaller-size bearings. Once I start spending money to machine things, I might as well buy a proper solution.
  2. "Slim down" the threaded rod an find a small metal or plastic sleeve that could fit over it, making it just the right size for the bearing. Probably possible, but not easy with no machining tools at home.
  3. Fit something thin, for example, paper, adhesive tape, etc between rod and bearing. Cheap, but not exactly professional.
Well, I had a go with adhesive tape and it worked. The bearing now sits steady and there is no wobble and no modulation of the linear movement. The main worry is if the tape will give way over time, eg, due to heat or ageing.

I'd like to figure out a better method, but for now I find it acceptable enough to move on to Y and X axis and to the more detailed prorgamming challenges.

Any alternative suggestions would be welcome.


Anonymous said...

Heat sleeve wrap?

Thomas said...

Nice idea, but the ones I know are a bit too thick for that.