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External Servo Pinion — Parallax Forums

External Servo Pinion

ercoerco Posts: 20,259
edited 2011-10-13 16:34 in General Discussion
http://photoshipone.com/shop/index.php?main_page=popup_image&pID=94

Just found this, I had been wondering if anyone sold these, which would allow people to to bigger & better things with servos, after doing the CR mod. Make a monster servo or multiturn sail winch servo.

A tad pricey, but useful if you need it.
servogear.jpg
288 x 213 - 15K

Comments

  • W9GFOW9GFO Posts: 4,010
    edited 2011-10-12 18:07
    ServoCity.com has pinions that fit Futaba and HiTech servo splines.
  • ercoerco Posts: 20,259
    edited 2011-10-12 19:37
    MUCH cheaper! Thanks Rich...
  • Duane DegnDuane Degn Posts: 10,588
    edited 2011-10-12 19:49
    JR servos with metal gears use a 3mm machine screw to hold the horn in place. This makes it easier to add your own horns/gears.

    Here's one using a Lego gear.

    attachment.php?attachmentid=85924&d=1318473673

    I use this type of setup to drive heavy loads. It keeps a lot of the strain off the servos.

    I've also used a RC heli pinion to drive a large gear. Being able to use long screws (3mm) with the metal geared JR servos makes these type of hacks a lot easier.

    Duane
    ServoGear111012a.png
    344 x 412 - 286K
  • W9GFOW9GFO Posts: 4,010
    edited 2011-10-12 23:07
    What do you suppose ServoCity hasPatented.jpgregarding those gears?

    http://www.servocity.com/html/48_pitch_hitec_servo_gears.html
  • Duane DegnDuane Degn Posts: 10,588
    edited 2011-10-13 07:00
    W9GFO wrote: »
    What do you suppose ServoCity hasPatented.jpgregarding those gears?

    http://www.servocity.com/html/48_pitch_hitec_servo_gears.html

    I was wondering the same thing. What the heck is there to patent about attaching one more gear to a gearbox?
  • ercoerco Posts: 20,259
    edited 2011-10-13 08:31
    It's probably the spline pattern. There's a one-spline difference between Futaba and HiTec, and they defend their turf with great zeal and fervor...
  • PublisonPublison Posts: 12,366
    edited 2011-10-13 08:39
    W9GFO wrote: »
    What do you suppose ServoCity hasPatented.jpgregarding those gears?

    http://www.servocity.com/html/48_pitch_hitec_servo_gears.html
    Our patented 48 pitch gears are designed to attach directly to the output spline of a servo.

    Maybe they invented the number 48? :)
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2011-10-13 09:29
    He has a number of patents along these lines. I looked at them once and several are obtuse for what they're protecting. The actual invention is not always clear from the list of claims. You can do a search for them on the uspto.gov site; the inventor name is Pettey; Brian.

    I've always thought patenting these things was an exercise in overzealousness, as any infringers are likely to be the Chinese, and it's very hard to combat. The hobby market is sufficiently small that a windfall from an infringement case would be rare . More common is to get a summary judgement and no collection. You're out attorney fees with nothing to show for it.

    This in no way says anything about Brian's products. They're well made, and well thought out. I'm just not sure they need to be patented, given the size of the market. That said, should he ever sell his business his portfolio of patents would hike the selling price, and make it attractive for someone like Hitec or Futaba.

    -- Gordon
  • W9GFOW9GFO Posts: 4,010
    edited 2011-10-13 13:11
    I am completely amazed that a patent such as this can get approved.

    He has essentially taken a gear with an internal spline sized to fit a hobby servo and called it his "invention".

    Here is a list of his "inventions".

    It looks like for his last 10 patents he is taking common ideas and calling them his inventions.
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2011-10-13 13:47
    W9GFO wrote: »
    I am completely amazed that a patent such as this can get approved.

    He has essentially taken a gear with an internal spline sized to fit a hobby servo and called it his "invention".

    In reading the first few claims it's more than just a gear as a servo horn, but a complete mechanism that fits outside the servo and incorporates gears and other components.

    The "art" of writing patents is so that you can't easily follow what they're talking about, yet still meets the requirements of disclosure. You're required to be specific, but you can obfuscate, too, which then widens the interpretation of what you're claiming. Whoever wrote this patent is a master at obfuscation.

    -- Gordon
  • ercoerco Posts: 20,259
    edited 2011-10-13 13:52
    Eschew obfuscation at every opportunity!
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2011-10-13 13:54
    Ever since I discovered that my laser cutter could cut the fine servo splines, I've made my own servo gears. They're two-piece affairs, with the top piece having a hole for the retaining screw, the bottom piece having the splined hole, and both having matched involute gear teeth on the outer edge. The two pieces, made of acetal (Delrin) are held together with tiny sheet-metal screws. This construction (unless I wanted to gllue them instead) puts a limit on the gear's minimum size.

    -Phil
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2011-10-13 16:30
    erco wrote: »
    Eschew obfuscation at every opportunity!

    True for most things, but patent writing isn't one of them. It shouldn't be that way, but it is.

    -- Gordon
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2011-10-13 16:34
    Phil Pilgrim (PhiPi) wrote: »
    the top piece having a hole for the retaining screw, the bottom piece having the splined hole

    Could you simplify using a small metal washer on the outside of the gear face? If you have power settings on your laser, you could probably "engrave" a divot that fits the profile of the washer, for a more flush appearance.

    I recall there was a guy (Bruce Filner, I think) that used reduced power modes to do limited depth cutting for the splines, effectively keeping them from piercing all the way. Always seemed like an interesting approach, but I have no idea how effective it was. I never saw an example of a finished product.

    -- Gordon
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