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The Visible 'Bot — Parallax Forums

The Visible 'Bot

ajwardajward Posts: 1,129
edited 2013-08-03 01:29 in Robotics
Since I got my stepper motors, I've wanted to use them in something kinda neat (neat to me anyhow). I'm working on a sun following solar panel, but I really like things than move around under their own power. This week I went to Tap Plastics and scored some cool scrap/cutoff pieces. I started assembling Clyde this morning.
IMAG0603.jpg

The deck is clear 3/16" acrylic sheet. Each main wheel is two discs of 1/8" clear acrylic with about half the thickness milled away around the circumference. Bolted together they make a nice groove for an o-ring tire (If I can find the right size!). The "tail wheel" is a 1" acrylic ball just glued to the bottom of the deck. Of course, it doesn't move but he's just going to be an indoor critter so it doesn't matter too much.
Each stepper mounted with a couple of Parallax L shaped brackets. I got the hubs from eBay in a convenient 5-pack! Setting up a Homework Board to drive everything.

Time for dinner, then back to the lab! ;-)

Amanda
IMAG0603.jpg
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Comments

  • WhitWhit Posts: 4,191
    edited 2013-06-29 17:25
    What robot?

    Looks like another great project Amanda!
  • Martin_HMartin_H Posts: 4,051
    edited 2013-06-29 17:57
    Amanda, you are on a roll lately. I will definitely be curious how well those steppers work for you.

    Btw how did you mill the acrylic wheels and find the center? My plywood experiments with a Dremel circle cutting jig haven't turned out as nicely.
  • BrainStrainBrainStrain Posts: 30
    edited 2013-06-29 19:39
    Cutting circles or any other shape can be challenging without the tools that make it easy. If you are successful at cutting circles with a Dremel, even if they are not as nice as you would like, you can clean them up very well on a drill press. Make sure you use a compass to draw the circles so that you know you have good centers marked. Small drill presses don't cost much and you will never regret buying one. You can never get the drilling precision you would like to have if you only have a hand-held drill. I would cut the circles out on my band saw, but whatever you use, after they are cut you can spin them in your drill press and use it kinda like a vertical lathe. You can mount the circles in the drill press with the needed size bolt, nut, and a couple of washers. Then spin the disks and round them off almost to perfect circles with a file. In this case the circles are thin enough that you might be able to spin them all together on the same bolt. If that works they will all be the same size, or close enough when you finish. Then you can use a file again to cut a groove in the edge of each disk for an O-ring. You might want to play around and make a couple of jigs as tool rests to help hold the file. Good luck.
  • BrainStrainBrainStrain Posts: 30
    edited 2013-06-29 20:01
    One more thing. I could not sleep tonight if I failed to mention safety. Power tools are dangerous, even small cute ones. If you are not experienced with power tools, make sure you are aware of the primary hazards they present. Maybe you can find some safety videos on You Tube. For example. You can find circle cutters for drill presses at any hardware store, but they are not really good for large circles. You may find that there is a style of circle cutter with a drill at the center and an adjustable arm that swings at the radius to cut any size circle you would like. Those circle cutters will break your fingers and otherwise mangle your hand before you have time to blink. Oh, and you can't hand hold the piece while you are cutting it. You'll have to clamp it down on two sides. Don't want to scare anyone, but I nicked a couple fingers on a table saw once. It is something you never forget.
  • ercoerco Posts: 20,255
    edited 2013-06-29 20:16
    Clear Clyde is clever!
  • GenetixGenetix Posts: 1,748
    edited 2013-06-29 21:56
    Nice looking bot but the name Clyde was the orangutan with Clint Eastwood in the early 80's.
  • ajwardajward Posts: 1,129
    edited 2013-06-30 01:32
    Martin_H wrote: »
    Amanda, you are on a roll lately. I will definitely be curious how well those steppers work for you.

    Btw how did you mill the acrylic wheels and find the center? My plywood experiments with a Dremel circle cutting jig haven't turned out as nicely.

    The discs were just some pieces I found in the scrap bin at Tap. Half a dozen of them and I thought if I didn't grab them for something I'd regret it. The edges were already milled so all I needed to do was find the center and drill the mounting holes.
    Finding the center was pretty easy using this gadget. (Thanks to PJ for the tip!!)
    cf.jpg

    Got it for $4.99 at the local ACE Hardware.
    cf.jpg
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  • ajwardajward Posts: 1,129
    edited 2013-06-30 01:48
    Genetix wrote: »
    Nice looking bot but the name Clyde was the orangutan with Clint Eastwood in the early 80's.[/QUOTE

    I'm sure he won't mind me using it! ;-)]
  • ercoerco Posts: 20,255
    edited 2013-06-30 11:52
    erco wrote: »
    Clear Clyde is clever!

    Also might have been Visible Vic/Vince or Transparent Tran/Travis...
  • ercoerco Posts: 20,255
    edited 2013-06-30 11:54
    CLEARLY Clyde needs one of these transparent breadboards: http://www.ebay.com/itm/180758250443?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
  • ajwardajward Posts: 1,129
    edited 2013-06-30 12:05
    I finished up the mechanical stuff with Clyde this morning and went on to wiring up everything.
    IMAG0604.jpg
    IMAG0605.jpg
    IMAG0606.jpg


    Power comes from a 6xAA battery pack under the deck, mounted as far forward as possible to gain traction. Tho' as I feared, the plain wheel doesn't have enough traction to move very effectively. Then I noticed the old tires from Sid... the Scribbler wheels are about .020" bigger than Clyde's wheels. A bit of a struggle getting them to slip on but, they do fit nicely and give him a bit of grip.
    IMAG0607.jpg


    Um... yeah, some cable management is called for here. ;-)
    IMAG0604.jpg
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    IMAG0605.jpg
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    IMAG0606.jpg
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    IMAG0607.jpg
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  • mindrobotsmindrobots Posts: 6,506
    edited 2013-06-30 14:08
    Clyde has some really Hot Wheels!!

    (no offense, erco! :smile:)

    I'll have to go hub shopping on ebay.

    EDIT: I didn't realize we were playing name games: Ivan the Invisible
  • GenetixGenetix Posts: 1,748
    edited 2013-06-30 14:19
    Looks good! What are those 2 square boards in the back?
  • ajwardajward Posts: 1,129
    edited 2013-06-30 14:45
    Genetix wrote: »
    Looks good! What are those 2 square boards in the back?

    That's the front actually. Think BoeBot Layout. Those are the driver boards for the stepper motors. Probably a better way of mounting them, but this is just one of my many projects to occupy way too much free time! :-)

    @
  • ercoerco Posts: 20,255
    edited 2013-06-30 16:46
    ajward wrote: »
    Genetix wrote: »
    Nice looking bot but the name Clyde was the orangutan with Clint Eastwood in the early 80's.[/QUOTE

    I'm sure he won't mind me using it! ;-)]

    Heaven forbid you use a Pololu Orangutan controller and voice control for navigation on this bot, in which case you could simply say...?

    Ahem, in which case you could simply say...?
  • ercoerco Posts: 20,255
    edited 2013-06-30 17:08
    Amanda: You can lose those two controller boards, just get a ULN2803, which can handle 8 lines. Here's my Boebot on steppers. Trust me, you want to keep the weight balanced over the drive wheels, like almost no weight on the skid. You'll see why in testing.

    Clarence would be a good name too.
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  • WhitWhit Posts: 4,191
    edited 2013-06-30 20:35
    ajward wrote: »
    The discs were just some pieces I found in the scrap bin at Tap. Half a dozen of them and I thought if I didn't grab them for something I'd regret it. The edges were already milled so all I needed to do was find the center and drill the mounting holes.
    Finding the center was pretty easy using this gadget. (Thanks to PJ for the tip!!)
    cf.jpg

    Got it for $4.99 at the local ACE Hardware.

    I remember that post of P.J.'s - I will have to go look at my ACE too.
  • GenetixGenetix Posts: 1,748
    edited 2013-06-30 21:17
    erco wrote: »
    Amanda: You can lose those two controller boards, just get a ULN2803, which can handle 8 lines. Here's my Boebot on steppers. Trust me, you want to keep the weight balanced over the drive wheels, like almost no weight on the skid. You'll see why in testing.

    Clarence would be a good name too.

    Cap screws also.
  • ercoerco Posts: 20,255
    edited 2013-07-02 10:23
    Amanda: I forgot to mention, I used two 18650 Li-Ion batteries in my steppper Boebot with good results. That's just over 8V fully charged, going straight to the motor driver. A little extra voltage helps these "5V" steppers move faster more reliably. You can see the battery holder in my pics on the rear end of my bot, where it helps take some of the weight off of the ball roller.
  • ajwardajward Posts: 1,129
    edited 2013-07-02 13:01
    erco wrote: »
    Amanda: I forgot to mention, I used two 18650 Li-Ion batteries in my steppper Boebot with good results. That's just over 8V fully charged, going straight to the motor driver. A little extra voltage helps these "5V" steppers move faster more reliably. You can see the battery holder in my pics on the rear end of my bot, where it helps take some of the weight off of the ball roller.

    Yup! I'm powering the board with 9 volts (6xAA cells) and the driver boards from Vin. He's working pretty well. I'm starting to figure out some simple navigation... my first square closed only a couple inches off the mark! :-)
  • ercoerco Posts: 20,255
    edited 2013-07-02 13:45
    Ah yes... you never forget your first square: http://www.youtube.com/watch?v=hzNgYpJdfDs

    But sadly that trip is a dark, one-way road that leads to shadowy late nights and much harder.... maneuvers.

    Like figure eights! :)http://www.youtube.com/watch?v=9l32qYXJfTg
  • ajwardajward Posts: 1,129
    edited 2013-07-02 19:09
    The second attempt at a square. The first was off just a bit and the room was too dark. The aiming point is a piece of electrical tape on the sticky note.
    http://www.youtube.com/watch?v=RAzFl2v43FE&feature=youtu.be

    Got straight lines and angles figured out. Now to discover the secret of curves! The joys of exploration!

    Amanda
  • ercoerco Posts: 20,255
    edited 2013-07-02 20:04
    Sweet run! Your Bot's a real "square".
  • WhitWhit Posts: 4,191
    edited 2013-07-02 20:11
    Great job Amanda! Like a pro...
  • ajwardajward Posts: 1,129
    edited 2013-08-03 01:29
    erco wrote: »
    Amanda: You can lose those two controller boards, just get a ULN2803, which can handle 8 lines. Here's my Boebot on steppers. Trust me, you want to keep the weight balanced over the drive wheels, like almost no weight on the skid. You'll see why in testing.

    Thanks for the idea erco. I just got a 10 pack of the ICs from China. ($2.38)

    @
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