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Recycled 'Bot — Parallax Forums

Recycled 'Bot

ajwardajward Posts: 1,130
edited 2011-04-22 18:30 in Robotics
Hi all...

I've always had liking of tracked vehicles so I decided to try building a Basic Stamp tracked bot. There are quite a few options out there, but I wanted to recycle a bunch jun... er, resources I had laying around. I had a couple of Tamiya tracked chassis and recently got a Basic Stamp Homework board. So...
attachment.php?attachmentid=80287

My plan is to mount the homework board on this Tamiya construction chassis.

attachment.php?attachmentid=80286

The board is wider that the chassis, so some kludges are needed for a convenient fit.

attachment.php?attachmentid=80288

Here I'm in the process of cutting and finishing some of the unused stuff from the crawler kit. A bit of hacksawing, razor knifing and filing produced just what I needed.

attachment.php?attachmentid=80290

Here, the homework board fits nicely on the forward section of the crawler. This is just a test fit and might be altered down the road. The chassis still has the Tamiya dual motor widget. but the Futaba servos will just fit. Chassis to drive axle distance will be real close as will sprocket to sprocket spacing. The drive sprocket to idler wheel distance will be a bit shorter, but I can make up the distance pretty easily.

attachment.php?attachmentid=80289

There is space behind the logic board for a 4-cell AA battery pack. I could mount the board vertically and free up more deck space, but right now I don't know how far I want to go with this experiment. To the right is a servo using Tamiya right angle brackets. The servo =is= a standard servo... kind of a 'stand-in" while I await some continuous models.
The Tamiya brackets work and they're solid, but I've ordered aluminum replacements.

Well anyhow, that's my current project. Yeah... probably too much time on my hands! :lol:

Amanda

Comments

  • Martin_HMartin_H Posts: 4,051
    edited 2011-04-17 12:02
    Tracked robots are cool, so good luck with your project. Curiosity question. Under the track closest to the servo are two red things, but they are not under the other track as shown in the top photo. What are they?
  • ajwardajward Posts: 1,130
    edited 2011-04-17 13:27
    Martin_H wrote: »
    Tracked robots are cool, so good luck with your project. Curiosity question. Under the track closest to the servo are two red things, but they are not under the other track as shown in the top photo. What are they?

    Hmm... 'Looks' like they're in both pictures. Anyhow the red bits under the chassis are the standoffs used to mount the road-wheel brackets.
  • Martin_HMartin_H Posts: 4,051
    edited 2011-04-17 15:01
    Ah I get it, they're under the deck. So in the top photo you can only see the screw heads on the other side.
  • ercoerco Posts: 20,256
    edited 2011-04-17 17:45
    Very nice. It's a good day for junk... oops... Recycled Bots! Looks like you have some nice parts to start with. See PJ's post on Cypherbot for "Best use of Peanut Butter Jar Lids".
  • Tony B.Tony B. Posts: 356
    edited 2011-04-17 18:21
    Amanda,

    Great project! Thanks for sharing. Keep us updated with your progress. You do very nice work:smile:
  • ajwardajward Posts: 1,130
    edited 2011-04-17 19:28
    @Erco Thanks! I did look at PJ's bot. Are those lids from creamy or crunchy peanut butter? It could make a difference. ;-)

    @Tony B. Thank you! In a pinch, I can jury rig with the best, but if someone else might be looking I really, really, really want to create something that looks like I knew what I was doing! :-)

    I've finished mod'ing the Tamiya drive sprockets to mate with a (to be) modified servo horn. However... I'm tired and lost interest in trimming the horns tonight and besides I have to vacuum up a bunch of orange colored curly residue =someone= tracked in on the carpet. <grumble>

    @
  • ajwardajward Posts: 1,130
    edited 2011-04-17 19:31
    Martin_H wrote: »
    Ah I get it, they're under the deck. So in the top photo you can only see the screw heads on the other side.

    Ya got it! :-)

    @
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2011-04-17 19:35
    If you use a Futaba or Futaba-style servo, the small round horn will *exactly* fit into the large drive sprocket. Use a pair of nippy cutters to trim off the hub on the outside of the large Taimya drive sprocket, then drill that out with a 1/4" bit. Use a 1/8" bit (and a pair of pliers to hold it) to drill out two holes opposite one another in the small horn. You can then fasten the horn to the sprocket using a 4-40 x 1/2" screw and nut.

    I don't think the Parallax servos, which use Futaba splines, come with the small horns, but you can get them aftermarket.

    I'm interested in the red servo bracket. Is that something you made or bought?

    Anyway, remember that with tracked vehicles the wider the stance, the easier the steering. There's no need to keep the track base what it was when using the Tamiya Dual motor. You may also want to put less of the track on the ground. Use three idlers, closer together, rather than four. Make the angle to the front and back of the track steeper. For these rubber tracks the greater the contact area to the ground the more chance of the track popping off in a turn.
  • ajwardajward Posts: 1,130
    edited 2011-04-17 20:10
    Hey Gordon...
    GordonMcComb wrote: »
    If you use a Futaba or Futaba-style servo, the small round horn will *exactly* fit into the large drive sprocket. Use a pair of nippy cutters to trim off the hub on the outside of the large Taimya drive sprocket, then drill that out with a 1/4" bit. Use a 1/8" bit (and a pair of pliers to hold it) to drill out two holes opposite one another in the small horn. You can then fasten the horn to the sprocket using a 4-40 x 1/2" screw and nut.

    I don't think the Parallax servos, which use Futaba splines, come with the small horns, but you can get them aftermarket.

    I'm interested in the red servo bracket. Is that something you made or bought?

    Anyway, remember that with tracked vehicles the wider the stance, the easier the steering. There's no need to keep the track base what it was when using the Tamiya Dual motor. You may also want to put less of the track on the ground. Use three idlers, closer together, rather than four. Make the angle to the front and back of the track steeper. For these rubber tracks the greater the contact area to the ground the more chance of the track popping off in a turn.

    Thanks for the heads up on the round servo horns! I'm doing this with as much "recycled" stuff as I can, I have a couple of "X" style horns and I'm a glutton for punishment! ;-)
    Mod'ing the sprockets was, mostly, an experiment using a Ryobi hand drill, a Dremel tool and two handfuls of bits! Tedious, but satisfying.

    The red brackets on the servo came from the unused flotsam and jetsom of the Tamiya construction crawler... which never got fully built.

    The main reason I didn't change the track base, though I =did= think of doing so, was to use parts on hand. Also swapping the servos for the Tamiya twin motor gear thingy becomes =almost= a bolt in replacement. (fingers crossed!!!) I do agree with fewer road wheels. The Tamiya tracked vehicle chassis has three road wheels and a greater gap between the drive axles and road wheel axles. That lets it traverse rougher terrain than the crawler.
    This is just a 'proof of concept' vehicle and when I get it to work, I'll look at changing the track configuration.

    Thanks a ton for your input!!!!

    @
  • WhitWhit Posts: 4,191
    edited 2011-04-17 20:20
    Hey ajward,

    Just saw this! Great robot. How about a little demo video?

    I saw the tank tread kit the other day and almost bought it. Ummm? Maybe I need to go shopping...
  • ajwardajward Posts: 1,130
    edited 2011-04-20 08:47
    I started the semi-final assembly of my 'lil tank bot this morning and... surprise, surprise, a bit of twiddling in going to be needed. A couple of screws need to be used where it doesn't seem possible to get a nut on them. The servos and road wheel brackets want to occupy the same coordinates in the space-time continuum. The spacing of mounting holes of the servos and Tamiya chassis are off just enough to be annoying!!! And lastly... what is the one drill bit missing from my tool-box? Yeah, that one, the one I need most.

    Ah well off to the hardware store.

    Amanda
  • ajwardajward Posts: 1,130
    edited 2011-04-20 13:37
    Heya...

    Got the mechanical work on Ted completed with a minimum of harsh language! :innocent:

    The layout changed a little but not dramatically. I had to replace the 4 small road wheels with 3 larger ones. Of course the original track became too long, but another Tamiya set came to the rescue. Had to change the mounting brackets for the Homework board from 4 point to 3 point, but that shouldn't be a problem.

    My Boe Bot, Bob, let me use his continuous servos. Swears he remembers nothing of signing the donor card!

    Anyhow a couple of pics...

    attachment.php?attachmentid=80398

    attachment.php?attachmentid=80397

    attachment.php?attachmentid=80396

    Clearing all the tools off my desk and I should be getting the programming started shortly. Film soon!

    Amanda
  • LaserLinesLaserLines Posts: 14
    edited 2011-04-20 15:21
    Nice job. Looks cleaner, and more durable, than my attempt at a similar project.
    http://www.instructables.com/id/Inexpensive-Robot-Chassis/
    I like that you have used the Tamyia drive gear. My home made version works, but I suspect it will be my first part to fail. Please keep posting as you add sensors etc.
  • LaserLinesLaserLines Posts: 14
    edited 2011-04-20 15:30
    GordonMcComb wrote: »
    If you use a Futaba or Futaba-style servo, the small round horn will *exactly* fit into the large drive sprocket. Use a pair of nippy cutters to trim off the hub on the outside of the large Taimya drive sprocket, then drill that out with a 1/4" bit. Use a 1/8" bit (and a pair of pliers to hold it) to drill out two holes opposite one another in the small horn. You can then fasten the horn to the sprocket using a 4-40 x 1/2" screw and nut.




    Anyway, remember that with tracked vehicles the wider the stance, the easier the steering. There's no need to keep the track base what it was when using the Tamiya Dual motor. You may also want to put less of the track on the ground. Use three idlers, closer together, rather than four. Make the angle to the front and back of the track steeper. For these rubber tracks the greater the contact area to the ground the more chance of the track popping off in a turn.

    I wish I had read this post before I started cutting on a similar project. ...maybe for version 2.0. Thanks! (even though this isn't my thread)
  • ajwardajward Posts: 1,130
    edited 2011-04-20 15:50
    Just finished uploading a video of Ted's first steps.
  • WhitWhit Posts: 4,191
    edited 2011-04-22 18:30
    ajward wrote: »
    Just finished uploading a video of Ted's first steps.

    Might we have a link? I like the new design and especially the shorter wheel/tread base. Looks more sturdy. And may I assume you have a new drill bit? Robotics is a great way to collect new tools.
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