Subject:
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Re: caster wheel design
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 30 Mar 2005 19:27:21 GMT
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Viewed:
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821 times
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In lugnet.robotics, Patrick Levy wrote:
> Hi,
>
> I´m tring to build a robot that may use a caster wheel, But i am running
> some serious problemes in it design. If I use an axle or pin for the caster,
> it will bend. (the robot is quite heavy). So i tried to use a turntable as a
> caster axle, but for some reason, it also did not work (the caster does not
> turn somootly.).
>
> Does anybody have some tips for good caster design?
>
> Thanks
>
> Patrick
Move the other wheels or the CG so that the caster doesn't support much weight.
No matter what your design, a caster that carries a lot of weight will not work
well. The large turntables will have a lot of friction when carrying a lot of
load. Also, a caster reqires an offset between the pivot axis and the wheel
axis. The offset is what makes the caster self steer. Unfortunately the offset
produces a torque that the turntable will have to react, making even more
friction. If it is to hard to change the load carried by the caster, how about
using two?
When you say "axle or pin for the caster" what component are you referring too?
Is it the axle for the caster wheel, or the pivot? If its the axle for the
caster wheel you should modify your design to support the wheel on both sides.
If you are talking about the pivot, you should use an axle, not a pin. The axle
should be long and supported at two points that are far apart. This will
minimize the friction between the pivot supports and the pivot axle. The lower
the friction the better the performance.
I like making my casters using the medium pulley wheels. Depending on how the
spacing works out I may or may not use a tire. Sometimes I even build casters
using the small bevel gears as a wheel. These don't work well on carpet, but
are great on a smooth surface. Using smaller sized wheels makes it easier to
build a stiff caster, because it is easier to have a shorter horn (offset
between the wheel axle and caster pivot). The horn is a cantilever, and
cantilevers are usually bad things. I would use larger wheels only if there is
some sort of obstacle that the robot must traverse, and if that's the case, then
caster wheels are probably a poor choice anyway.
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Message has 1 Reply:
 | | Re: caster wheel design
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| (...) Another "microcaster" is the style used in "ERBIE the Robocar" discussed here (URL) made with a 2x2 turntable, a 2x3 plate, and a single wheel (URL) works surprisingly well, so long as 1) The weight isn't huge and 2) the surface isn't too (...) (19 years ago, 30-Mar-05, to lugnet.robotics)
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Message is in Reply To:
| | caster wheel design
|
| Hi, I´m tring to build a robot that may use a caster wheel, But i am running some serious problemes in it design. If I use an axle or pin for the caster, it will bend. (the robot is quite heavy). So i tried to use a turntable as a caster axle, but (...) (19 years ago, 30-Mar-05, to lugnet.robotics)
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