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Faster BoeBot — Parallax Forums

Faster BoeBot

Matt GillilandMatt Gilliland Posts: 1,406
edited 2012-10-29 08:04 in Robotics
Just testing an idea...

Same power, same servos, same code...

[video=youtube_share;9PAzqughSuM]
-MattG

Comments

  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2012-10-25 10:45
    Same power, same servos, same code... external gearing. Nice!

    -Phil
  • Duane DegnDuane Degn Posts: 10,588
    edited 2012-10-25 11:28
    Let's see, use servo to gear down a motor and then add external gears to gear it up? Do I have that right?
  • Martin_HMartin_H Posts: 4,051
    edited 2012-10-25 11:51
    Matt, neat.
    Duane Degn wrote: »
    Let's see, use servo to gear down a motor and then add external gears to gear it up? Do I have that right?

    Efficiency wise it's not the best, but I imagine that you could create a new internal gear set with the same effective gear ratio.
  • Matt GillilandMatt Gilliland Posts: 1,406
    edited 2012-10-25 11:51
    Let's see, use servo to gear down a motor and then add external gears to gear it up? Do I have that right?
    Let's see, look at a really quick, proof of concept prototype and poke fun at it? Do I have that right? :lol:
    :tongue:
    -MattG
  • Duane DegnDuane Degn Posts: 10,588
    edited 2012-10-25 12:15
    Matt Gilliland wrote: »
    Let's see, look at a really quick, proof of concept prototype and poke fun at it? Do I have that right? :lol:
    :tongue:
    -MattG

    Dead right!

    I'm trying to figure out how to attach the BOE-Bot wheels to one of the servos' internal gears to make this concept more efficient.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2012-10-25 12:37
    Duane Degn wrote:
    I'm trying to figure out how to attach the BOE-Bot wheels to one of the servos' internal gears to make this concept more efficient.
    Or ... you could just use bigger wheels. :)

    -Phil
  • Matt GillilandMatt Gilliland Posts: 1,406
    edited 2012-10-25 12:40
    I'm trying to figure out how to attach the BOE-Bot wheels to one of the servos' internal gears
    You know what's really cool - I've got all you amazing guru's to do the "heavy lifting" for me...you come up with great ideas, I then delete your post, and then I take the idea as my own. :tongue:

    I mean, think about it. Is Phil really that bright? There just may be some under-world connection between Phil and Browser - and Browser shows no mercy - he has super-user privileges here -

    Ok, now I scared myself...he's a cat, and he's lurking...I can feel it. :lol:

    -MattG
  • Matt GillilandMatt Gilliland Posts: 1,406
    edited 2012-10-25 12:51
    Close ups...

    -MattG
  • W9GFOW9GFO Posts: 4,010
    edited 2012-10-25 13:11
    Phil Pilgrim (PhiPi) wrote: »
    Or ... you could just use bigger wheels. :)

    Yeah, I like that idea. Wanna race?

    BigBOE01.jpg
    BigBOE01.jpg
    1024 x 765 - 124K
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2012-10-25 13:21
    Matt,

    I get how the servo splines are laser-cut in the spur gear, but how did you make the shaft that connects to the wheel?

    Rich,

    Now those are big wheels! What did you use for tires?

    -Phil
  • W9GFOW9GFO Posts: 4,010
    edited 2012-10-25 13:25
    I use the same "tires" that are used on the standard wheels, I'm surprised that they stay on so well. I do plan to make a groove and use an o-ring in the future.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2012-10-25 13:42
    W9GFO wrote:
    I use the same "tires" that are used on the standard wheels, I'm surprised that they stay on so well.
    I'm more surprised that they stretch that far!

    -Phil
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2012-10-27 08:41
    Looks like magic to me.

    The vacuum cleaner belt replacement department at Walmart or other discount store will have you swimming in larger circumference rubber orings and belts. They're actually better than the standard buna rubber orings you might buy as they have an additive that resists breakdown from oils (skin oil, oil in carpet, whatever). How many of youse guys still have the original orings from the original Parallax BOEBot wheels? Mine disintegrated years ago -- the oring tires, not the wheels.

    Anywho, from a frictional efficiency standpoint, the larger diameter wheel is more efficient than spur gears. However, the spur gears allow the use of existing Parallax plastic injected wheels.

    -- Gordon
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2012-10-27 08:50
    Phil Pilgrim (PhiPi) wrote: »
    Matt,

    I get how the servo splines are laser-cut in the spur gear, but how did you make the shaft that connects to the wheel?

    Looks like a 4-40 machine screw. There's a lock nut against the inner gear (the white one, which seems to be used as a spacer); the end of the screw goes through a hole in the BOE chassis to support it on that side. The wheels are held in position with a laser cut pillow block, that in turn is mounted to some undercarriage. At least that's what the 2.5 second shot of it in the video seems to suggest.

    -- Gordon
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2012-10-27 19:55
    Gordon,

    You got all of that from 2 1/2 seconds? Impressive! :)

    -Phil
  • ercoerco Posts: 20,256
    edited 2012-10-28 11:07
    Matt Gilliland wrote: »
    Let's see, look at a really quick, proof of concept prototype and poke fun at it? Do I have that right? :lol:
    :tongue:
    -MattG

    I'm sorry I was on vacation and missed the opportunity to poke fun at it. Was it a contest?
  • Matt GillilandMatt Gilliland Posts: 1,406
    edited 2012-10-29 07:58
    I get how the servo splines are laser-cut in the spur gear, but how did you make the shaft that connects to the wheel?
    It's tough to show, but this was truly a "guerilla-get-it done-quickly prototype".

    What I did was cannibalize two other servos and took out the final gear (that had a bearing cavity on one side). So I used that as a "detached" shaft extension - essentially the device requires the drive shaft to be aligned very closely to this final gear's shaft receiving hole - it wobbles a bit (because of slight shaft mis-allignments, but it worked well enough to prove/disprove torque question-ability.

    un-reliable, simplistic, and cheap. my middle names.

    -MattG

    PS When Andy's finished with testing it, I'll shoot an exploded view pic - just as long as none of you laugh...
  • Matt GillilandMatt Gilliland Posts: 1,406
    edited 2012-10-29 08:03
    I'm sorry I was on vacation and missed the opportunity to poke fun at it. Was it a contest?
    Perfect timing :lol:
    -MattG
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2012-10-29 08:04
    Matt Gilliland wrote: »
    un-reliable, simplistic, and cheap. my middle names.

    Inexpensive maybe, but never cheap!

    -- Gordon
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