Sunday, March 28, 2010

Pendants are coming along, and mix-and-match servos

I have five more of the LED uranium-ball ring-circuit pendants finished and ready for sale. While my eventual goal is to have a dozen or so ready for the steampunk world's faire, I am aware that I had a backlog of people wanting theirs. Contact me if you were one of those.

I've been running the robot with HS-5645MG servos lately. I'm not happy with them. While they don't have the terrible problems with ringing and overshoot that the HX-12K servos had, they do have a weak gearbox design. The second-to-last gear in the gear chain is surprisingly thin. I've lost track of how many gears I've seen break on these servos, always in the exact same spot. The HX-12K servos had a much thicker gear in that same position, and I've never seen one fail that way. HX-12K servo failures I've seen tend to be electrical board or motor failures, or structural failures in the servo case.

I am experimenting with building a composite servos using the motors, potentiometers, and drive boards from the HS-5645MG servos and the gear train from the HX-12K servos. They have nearly the same gear ratio, and appear to have the same spacing between gears and same size shafting. There are some odd clearance issues. The HX-12K gears jam when installed in the HS-5645MG cases, although the HS-5645MG gears run fine in the HX-12K cases. I have installed the motors, drive boards, and potentiometer from a HS-5645MG in a HX-12K case with the HX-12K geartrain. The potentiometer is a tight fit and doesn't turn smoothly if I tighten the case screws tightly, but other than that the arrangement works.

The weak link is still the HX-12K case. The mounting tabs break off, the case itself cracks, and I've seen a few cases of total failure of the mounting boss for the small internal shafts inside the gearbox. Making my own cases from cast aluminum is out of the question in the condo, and having cases custom-machined would be unreasonably expensive. If I had that kind of budget, I would just buy higher-quality servos in the first place. Still looking for other options.

7 comments:

  1. I have been selling them in person for $75 each. I'd prefer to continue to sell them in person for that amount, but would be willing to arrange other payment and shipping options.

    ReplyDelete
  2. I Met you this weekend and wanted to buy teh pendant but was low on cash. Afterwards I was wondering if you could get your hands on the larger 1" uranium marbles and make a larger pendant, please reply back or send me a message. I'm on empire as CyberHedz. thanks!

    ReplyDelete
  3. I can do so. I don't have the material on hand at the moment, but next time I'm browsing Ebay for new supplies I'll get a few of the larger marbles.

    ReplyDelete
  4. great, please let me know asap, i'm definitely in for at least 1

    ReplyDelete
  5. Drew, I'd like to order one of the pendents. I didn't have the cash at the fair (and I was busy hawking my hand flamer behind you)
    How do I contact you through blogspot?
    Major Girth

    ReplyDelete
  6. I can be contacted at ellindsey@gmail.com

    ReplyDelete