GearHeads Forum

works fine. :)

Hello. And Bye.

Excellent. Nice pattern.

Art

Finally completed my laser-cut acrylic take on 'Zinnia' after letting the plans and parts sit for almost five years...
Did some re-engineering, mostly to get all the parts to fit the 12"x16" limits of my laser. Wheels are 20", which is about as big as I can segment one up without a ton of waste.
Short video of it in operation here: https://www.dropbox.com/s/fgyz2qq84whfc ... 9.mp4?dl=0

FWIW, I tried a couple with mineral spirits: the problem is they seemed to gum up a week or so later...some kind of residue attracting cruft in my garage. (The stuff they sell here in SoCal doesn't look/smell like the stuff I remember from my youth.)

"Gunk" engine cleaner worked a lot better, except for the hassle of getting it out of the aerosol can so I could really soak the bearings.

Steve:

  Its all good to know. In future I know the way Ill go..

Art

ArtF wrote: >>24m 30s  shields removed and cleaned with Teflon dry lube added


Good god, thats way better than I figured on top of head. Thats a long time to degrade ..

Art

It was much longer than I expected as well, especially since they were random no-name bearings.

A pendulum degrading in 24 minutes only needs 1/3 as much restoring force as an 8 minute pendulum. I hope to post a video soon showing the complete results.

Steve

>>24m 30s  shields removed and cleaned with Teflon dry lube added


Good god, thats way better than I figured on top of head. Thats a long time to degrade ..

Art

I have been testing various bearing configurations for pendulum supports. It is not exactly the same setup as a kinetic sculpture, but I believe some of the same principles apply. Less friction is better.

The load is around 8 ounces. I measure the time that it takes for the swing to degrade from +/-8 degrees to +/-1 degree.

Here are the swing times of various 623 (3x10x4mm) ball bearing configurations:
    5m 50s  sealed with factory grease intact
    7m 40s  shielded with factory grease intact
  14m 00s  shields removed and cleaned - low end of range
  20m 50s  shields removed and cleaned - high end of range
  24m 30s  shields removed and cleaned with Teflon dry lube added

The bearings were generic eBay versions costing around $5 for 10 bearings. 3 of the 10 were slightly tighter than the others. The remaining 7 would probably all last around 20 minutes or better.

My clock with ball bearings for the pendulum support has been running non-stop for two years with no signs of wear. Running then dry seems OK when the load is significantly lower than the rated max loads.

Steve

I'd agree with that, so long as it isn't wobbly.. the least resistance as possible is
desirable..