Subject:
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Re: Motors: Please help! Going out of my mind...
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Tue, 27 May 1997 16:45:44 GMT
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Original-From:
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Chuck McManis <cmcmanis@freegate.NOSPAMnet>
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Reply-To:
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cmcmanis@*SayNoToSpam*freegate.net
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Viewed:
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1841 times
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Fred Cass wrote:
> I've been searching and hunting trying to find some motors to use
> for a new robot base.
Of all the things in a Robot, motors are in some ways the most
difficult to obtain.
> Does anyone have any suggestions for where to find motors with
> gearboxes that can carry a few pounds of load on the shafts?
> Actually, the best would be motors with gearboxes, and shaft
> encoders built in.
Both Brevel and Globe make such motors, they typically go for
anywhere been $175 each and $500 each.
> Does anyone have any suggestions perhaps for some household item, or
> tool that I could rape for it's motors?
[I'll assume that the above exceeds your budget :-) ]
> Currently I've been using modified R/C servos, but they are noisy,
> and cant really carry any load to speak of...
You've reached a spot where you get to delve a bit into the mechanical.
Basically what you are looking for isn't available 'surplus' because
it isn't a common set of requirements (whereas things like battery
operated, high torque, etc are) You will find that your motors will
take a decidedly uncomfortable jump in the proportional cost of your
robot at this point.
I tend to use modified toy cars a lot because they already have load
bearing shafts (ususally limited to < 3 lbs) but they don't have
encoders. However there are other options and I'll identify some
that I've used (clearly not an exhaustive list :-)
First, Hobby Shops ( like Tower Hobbies, etc) sell axles that are
designed for airplane 'landing gear'. This things have a shaft out
one side and a thick bolt out the other. You drill a bolt sized hole
in the side of your robot and bolt on the axle. The wheel is kept
on the axle using a 'keeper' which is a ring with a set screw that
prevents the wheel from sliding off. Now I've used these by first
screwing a Lego Dacta large gear to the wheel, then mounting it on
the axle. Next a motor with a small Lego Dacta gear glued to its
shaft was mounted next to the wheel with the gears meshing. This
combination supplied the load bearing shaft I needed on my Sumo
bot and easily carried 6 pounds (3 Kg).
Second there are a couple of places selling 12 volt motors that have
been 'liberated' from Child ride on toys. These motors are cheap,
noisy, and consume current like a teenager consumes soda, but they do
have a load bearing that can be used to carry about 30 lbs, (60 lbs
if you use a pair of them like the kid cars do). They don't have
encoders and they will need a pretty beefy motor driver circuit.
The third suggestion are some of the motor gearbox kits that Tamiya
sells (www.robotstore.com has them) Since these are kits they are
more easily modified. The dual gearbox motor can probably hold about
3 lbs, although I've not stressed mine yet. Their flexible mounting
scheme makes building something like the first example with the
gears perhaps a bit more practical. (you can adjust them to meet
the close tolerences of meshing gears)
Finally there are a couple of companies (StockDrive, Small Parts, etc)
that sell gears and linkages. A very popular motor power coupling
strategy has been using timing belts (toothed belts) connected
between a motor and a wheel. Sometimes the belt itself is used as
'tread'. Its not cheap of course but it can get you past the motor
selection criteria.
--Chuck
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Message has 1 Reply:
 | | servo motors
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| I was wondering how many RC servos can be easily controlled with the handy board. I have seen that people have sucessully used 2 at once, but have not seen any more than that. Is it possible or has no one ever had a need for it? It seems that to (...) (27 years ago, 27-May-97, to lugnet.robotics.handyboard)
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Message is in Reply To:
| | Motors: Please help! Going out of my mind...
|
| Please somebody help! Actually it's not quite that bad, but I've been searching and hunting trying to find some motors to use for a new robot base. Does anyone have any suggestions for where to find motors with gearboxes that can carry a few pounds (...) (27 years ago, 25-May-97, to lugnet.robotics.handyboard)
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