Subject:
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Re: A query to GBC members, module builders, and technic model builders.
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 28 Jan 2005 01:35:44 GMT
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Original-From:
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Mr S <szinn_the1@yahoo.!Spamless!com>
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Viewed:
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3012 times
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This is getting a bit long, so you might have to read
previous posts to figure it all out....
--- Geoffrey Hyde <g.hyde@bigpond.net.au> wrote:
> Do you find any situations where you have to space
> the gears out so the
> chain fits tightly and snugly instead of slackening
> and introducing chain
> backlash? One problem I did encounter with chain
> elements in particular was
> their tendency to slacken off unless you found the
> right combination of
> distance and gearing to put them at.
At times, the chain slackening is a desirable effect,
and when it is not, an idler gear takes up the slack
giving the chain a firm fit for use in both directions
of travel, however, I have experienced what you are
talking about and eliminated it with simple redsigns.
> That sounds like a good start, of course by buying
> extra packs one could
> extend the treads as needed. As for the price range
> I agree fully, but it
> may come down in the end to what price LEGO can
> manufacture and sell them
> for.
Well, hopefully LEGO will see some value in producing
specialty parts/packs for AFOL. At least AFOL have the
money to spend!
> Well, I think if you just put an axle into the
> micromotor drive element, and
> join it together with the standard chain and gear
> elements, you can already
> achieve that effect. I don't see any need for 3rd
> party manufacturing yet.
> As for the servo motors, yes that would be a nice
> idea, perhaps LEGO can
> build their own design up, or adapt a pre-existing
> design to suit their
> needs.
>
> The difficulty with servo motors, though, is that
> they're going to need a
> whole lot of on/off pulses as servo motors by their
> definition do tend to
> move one step or part of rotational cycle at a time.
> I also understand
> there are models out there that come with inbuilt
> position and rotational
> sensors.
The reason for using a servo is that it adds
positional accuracy and strength that would take huge
amounts of LEGO pieces to immitate, not to mention the
size/space it would require. 44 oz/in of torque is
alot for a LEGO creation, and you can't beat the small
size of a servo motor. Yes, servo motors require
continuous stream of pulses, but then turning a
regular LEGO motor requires continuous output as well.
Mindsensors.com has an add-on that gives this
capability but then the servo is not easily compatible
with LEGO parts. I would like to see LEGO servos.
> I know one can with the proper ratio of chain links
> to gears, introduce gear
> reduction with chain elements, by making them drive
> different sized gears.
> I'm not sure of the exact ratios, but I think one
> could drive a 24-tooth to
> a 40-tooth gear without much trouble. However, I do
> believe there is a
> limit to what gear reduction is possible, as the
> chain will always drive the
> same amount of gear ratio based on the size
> differences.
The chain only eliminates the need for the gears to
mesh with one another. The gear ratio is the same as
if the gears were meshed together without the chain.
Cheers
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