Good rubber/latex material for small wheels?

Discussion in 'The Projects Forum' started by indeedisuper, Nov 16, 2015.

  1. indeedisuper

    Thread Starter New Member

    Oct 14, 2015
    21
    1
    Hello,

    I am making wheels for my robot that moves along a metal rail. It needs to be able to move up and down the rail so traction is important. I've tried different materials and found that these work pretty well with the exception that it wears out pretty quickly.

    Does anyone have suggestions on other materials that are more durable but also has good traction? I found that stiff materials result in the wheels slipping on the rail...
     
    Last edited: Dec 14, 2015
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,542
    2,369
    Is this the only function? UP/DWN?
    As miniature rack and pinion would do it.
    More mechanical details are needed.
    Max.
     
  3. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,770
    970
    You linked to tubing?

    Frankly sounds like you should redesign how the system moves up/down a rail..
    From the sounds of the current design any dust/dirt/moisture,etc will drastically change the coefficient of friction causing your robot to lose traction..

    More surface area may allow you to use a harder material (note the "Shore" values of those parts you linked to).. Higher = Harder = more wear resistant

    But yes try a rack/pinion or timing belt or something.. Relying on friction is not the smart move..
     
  4. indeedisuper

    Thread Starter New Member

    Oct 14, 2015
    21
    1
    And the robot is basically a cart moving along the rail with the rail not being flat but more like a roller coaster. I linked to tubing because those are my wheels when I cut them down. Those tubes fit nicely onto the shaft of the motors.
     
    Last edited: Dec 14, 2015
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,542
    2,369
    If the track travels convoluted as you say, you can use the rack and pinion principle using endless timing belt as supplied by Breco Belts etc, the wheels would be timing pulleys that match the belt pitch, no slip there!
    Max.
     
  6. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,770
    970
    need more details.....

    sketch/picture of this robot?
    motor shaft size?
    dimensions,etc...?
    rail material?
    environmental conditions?
    potential chemical exposure?
    robot speeds?
    expected wheel lifespan?
    allowed slippage?

    as I said before..in general, the harder the material the longer the wear life (lasts longer)..
    of course the harder the material the lower the coefficient of friction (slips easier)..

    rubber tubing is obviously not a good "wheel" choice and not something I'd expect to take km's of abuse..
     
  7. Sinus23

    Member

    Sep 7, 2013
    160
    408
    "the timing belt will have to be the length of the rail (few km in length)" Are you sure that it wasn't a bit less than that?
     
  8. GopherT

    AAC Fanatic!

    Nov 23, 2012
    6,043
    3,806
    Latex has very little strength. Remember that from when you were dating? That was latex. Thermoplastic polyurethane (TPU) is very, very abrasion resistant good but kind of slippery. Then PVC tubing is also good.

    If you need the material to be elastic, TPU is very stretchy - Eventhough it is stiff. Do not use the fiber-reinforced tubing if you need flexibility.

    tPU is used in high pressure air hoses, water hoses and packaging for high-value medical instrument packaging.

    McMaster/Carr calls TPU "polyurethane" tubing.
     
    shortbus likes this.
  9. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,770
    970
    use wheels not tubing :confused:
     
  10. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,797
    1,103
    Silicone rubber sealant can be moulded to make very grippy wheels, or treads for wheels.
     
  11. indeedisuper

    Thread Starter New Member

    Oct 14, 2015
    21
    1
    Actually I just realized polyurethane is used in skateboad/rollerskate wheels...I think they might be promising!
     
  12. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,797
    1,103
    No, but I guess they'd survive pretty well. Have you ever tried removing cured silicone? :)
     
  13. shortbus

    AAC Fanatic!

    Sep 30, 2009
    4,010
    1,530
    The adhesion to the substrate is good with RTV/silicon seal, but there is little tear resistance to it. Meaning that build up above the "joint" interface,(thickness) will tear but leave a small layer bonded to the base.
     
  14. indeedisuper

    Thread Starter New Member

    Oct 14, 2015
    21
    1
    Are you saying that silicone sealant isn't the way to go?
     
  15. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,542
    2,369
    Does this only occur on the driven wheels or do you need to stop free wheels slipping?
    Max.
     
  16. indeedisuper

    Thread Starter New Member

    Oct 14, 2015
    21
    1
    It would only occur on the driven wheels.
     
  17. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,770
    970
    I'm so wondering the function of this robot...
    Something for a coal mine?
    Pipeline inspection?

    But I'm astonished that you want something to travel km's on steel rails at 2m/s and you just slapped tubing over the motor shaft..
    Sounds like you should find a decent mechanical person to offer better drive mechanisms..

    The second you hit "grime" your wheel/friction solution falls apart.. Not that I know what grime means to you..
     
  18. GopherT

    AAC Fanatic!

    Nov 23, 2012
    6,043
    3,806
    Silicone is not abrasion resistant. Use polyurethane elastomer, polyurethane thermoplastic (tpu) or a vulcanized rubber.

    http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXMSY3&P=ML
     
    Last edited: Nov 17, 2015
    shortbus likes this.
  19. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,542
    2,369
Loading...