Shop OBEX P1 Docs P2 Docs Learn Events
Large Wheels — Parallax Forums

Large Wheels

jsmasterkingjsmasterking Posts: 35
edited 2006-02-27 17:49 in Robotics
Any one know where I can get large wheels that fit on the Parallax·Continuous Rotation Servos?confused.gif

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
·on····· plane··········································, when catching ducks

"In this house, we obey the laws of thermodynamics!"
··············································································^
http://profiles.yahoo.com/jsmasterking

Post Edited (jsmasterking) : 6/21/2006 12:45:36 PM GMT

Comments

  • WhelzornWhelzorn Posts: 256
    edited 2006-02-22 00:04
    you could always screw a servo horn onto a larger wheel...
  • Steve JoblinSteve Joblin Posts: 784
    edited 2006-02-22 01:02
    how large are you looking for?

    Parallax has a nice pair... http://www.parallax.com/detail.asp?product_id=721-00001-721-00002
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2006-02-22 14:57
    Plastic training wheels for a bicycle come in a package of two. Quite cheap and quite sturdy.

    But, I have doubts that servos will really support the leverage of lateral loads created by larger wheels. It would be better to have the wheels on there own weight bearing axel and then have the servo drive the wheel by a gear, a chain, or a small rubber wheel pushing the larger one.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    "When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

    ······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
  • jsmasterkingjsmasterking Posts: 35
    edited 2006-02-22 20:56
    I need thin wheels with very good grip. Parallax carry nice wheels but I need someing about one and a half of the radius of Parallax's.

    I like the idea of using the servo horns. If I wanted to make the wheels, what should I use?

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    ·on····· plane··········································, when catching ducks

    "In this house, we obey the laws of thermodynamics!"
    ··············································································^
    http://profiles.yahoo.com/jsmasterking

    Post Edited (jsmasterking) : 6/21/2006 12:45:35 PM GMT
  • Robert KubichekRobert Kubichek Posts: 343
    edited 2006-02-22 21:18
    jsmasterking said...
    I need thin wheels with very good grip. Parallax carry nice wheels but I need someing about one and a half of the radius of Parallax's.

    I like the idea of using the servo horns. If I wanted to make the wheels, what should I use?

    Try white nylon sheeting or aluminum, both soft enough, but aluminum is stronger. then slit a rubber hose to fit the circumferance of
    the aluminum hub, and weld ends using super glue for a nice rubber wheel look.

    Bob N9LVU scool.gif
  • WhelzornWhelzorn Posts: 256
    edited 2006-02-22 23:48
    here's a pic of how most people use the servo horn idea (me included):
    wheel_f6.jpg
    but depending on the power of your servo and the size of the wheel, you might want to use aluminum servo horns for strength.
  • TigerTiger Posts: 105
    edited 2006-02-23 05:40
    Why not skip the wimpy servo horn in favor of using the Parallax wheel against the larger wheel. It's much stronger than any servo horn and easy to work with.

    Just a thought... Tiger
  • Russ FergusonRuss Ferguson Posts: 206
    edited 2006-02-23 06:17
    An old CD could be used to make a big wheel. Do you want one this big?
    Servos often come with an assortment of servo horns and one of them is usually round. The round one is almost the same diameter as the slight ridge at the center of CDs. The round horns that I have need to be turned down by about 1/16 of an inch to fit snug inside of the ridge. If you work carefully you will be able to make the horn and CD be perfectly concentric without a whole lot of trouble because the ridge will guide the horn into place. Bolt them together after you are happy with the fit.
    Now for some traction -
    Get some 1/2 inch wide rubber bands from your favorite office supply, the ones that are the 3 1/2 inch size (or a little bigger). They will fit around the circumference of the CD (yes it can be done!) and give some nice traction.
    CD_Wheel.jpg
    688 x 532 - 40K
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2006-02-23 16:38
    You can add rubber to the CD by getting a motorcycle inner tube and slicing it into bands.
    Fortunately, in Taiwan these inner tubes are availble for free in used condition.

    If you want, I can send you a hunk.

    Alternatively, you can use two CDs with a spacer between to make one wheel.· Then you might be able to locate some large O-ring seals in your local area [noparse][[/noparse]try food containers]

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    "When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

    ······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
  • Steve JoblinSteve Joblin Posts: 784
    edited 2006-02-23 18:00
    I was in a hardware store one day and stumbled across 4 inch sink drainers.· I used some large rubber O rings from McMaster-Carr.
    attachment.php?attachmentid=40582
    bmp
    bmp
    dishstrainerwheels.bmp
    795K
  • jsmasterkingjsmasterking Posts: 35
    edited 2006-02-23 21:05
    I really like the sink drainer, but what I need is something with grip on the edge. Because I am slanting my wheels, I don't think a CD will be strong enough. I will try gluing a couple of CDs together and see how they turn out!

    Whats the best way to cut aluminum sheets?

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    ·on····· plane··········································, when catching ducks

    "In this house, we obey the laws of thermodynamics!"
    ··············································································^
    http://profiles.yahoo.com/jsmasterking

    Post Edited (jsmasterking) : 6/21/2006 12:45:28 PM GMT
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2006-02-25 15:12
    Are you cutting circles or straight edges in aluminum?
    Also, there are different kinds of aluminum - very soft and more structural.

    I suspect cutting circles in larger diameters would best be done by rotating around a center and using a saber saw or other fine toothed blade. Cutting on a lathe would be better.

    Sheets can best be cut on metal shears found in Heating and Ventalation shops.

    Incidentally, Aluminum's molecular weight is near to exactly 50% of Iron. Still Aluminum is about 5 pounds/cubit foot heavier that concrete.

    Mutiple CDs should be strong and lighter. Neoprene glue might work best [noparse][[/noparse]a.k.a. contact cement] Try using the water based version if you have trouble with the solvent melting the CDs.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    "When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

    ······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
  • jsmasterkingjsmasterking Posts: 35
    edited 2006-02-26 16:51
    I glued a couple of CDs together but I couldn't find out how to put the servo horns on with such a thick wheel. I tried using hot glue gun but, it keeps coming off. I was going to use some super glue but I want to make sure that will work before I permanently disfigure my servo horns. Does anyone know if superglue is safe on servo horns. The ones from parallax servos.

    For anyone who is interested, I am building a two-wheel, auto-balancing, robot based on andromotion from Androbot. If anyone wants the plans for the body, I have some CAD files. I need larger wheels because the parallax wheels are too small and the whole thing tips over when I go at full speed.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    ·on····· plane··········································, when catching ducks

    "In this house, we obey the laws of thermodynamics!"
    ··············································································^
    http://profiles.yahoo.com/jsmasterking

    Post Edited (jsmasterking) : 6/21/2006 12:44:52 PM GMT
  • Robert KubichekRobert Kubichek Posts: 343
    edited 2006-02-26 18:31
    jsmasterking said...
    I glued a couple of CDs together but I couldn't find out how to put the servo horns on with such a thick wheel. I tried using hot glue gun but, it keeps coming off. I was going to use some super glue but I want to make sure that will work before I permanently disfigure my servo horns. Does anyone know if superglue is safe on servo horns. The ones from parallax servos.


    For anyone who is interested, I am building a two-wheel, auto-balancing, robot based on andromotion from Androbot. If anyone wants the plans for the body, I have some CAD files. I need larger wheels because the parallax wheels are too small and the whole thing tips over when I go at full speed.

    idea.gif

    Hold the horn against the CDS, and mark with a fine tip black marker where the holes will be.
    Then use a SMALL drill to drill pilot holes, or just melt the holes using a very fine iron...
    You should have no problem, and then you keep from mucking up the servo horn...


    Bob N9LVU scool.gif
  • bobledouxbobledoux Posts: 187
    edited 2006-02-27 13:47
    Try this robot that uses CD's for wheels:

    http://home.earthlink.net/~botronics/index/robots.html
  • XNORXNOR Posts: 74
    edited 2006-02-27 16:42
    Here are some big wheels:

    www.bgmicro.com/prodinfo.asp?sid=03975462962962961441711371&prodid=ACS1480&page=1&cri=wheel&stype=3

    www.bgmicro.com/prodinfo.asp?sid=03975462962962961441711371&prodid=ACS1481&page=1&cri=wheel&stype=3

    ACS1480.jpg
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-02-27 17:49
    Whoa!· B.G. Micro had a site overhaul.· Last time I was there it was completely different.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
Sign In or Register to comment.