Hardware sources

I'm new to this group, and although I'm quite sure this question has been asked a hundred times before, I can't get to archives that go back more than
a few weeks. My question... Are there any sources of low-cost gears? I need a few 28-pitch gears, aluminum, brass or stainless, from 0.75" to 1.5" diameter, with 0.25" bore, and a collar with set screw(s) for mounting. I have found a couple companies that will sell them for $12-$20 each, but I can't afford that price for a dozen or so gears. These are for an experimental project that I have in mind, but would like to keep the cost as low as possible.
Can anyone can point me in the direction of a low-cost supplier of gears, magnetic clutches, fractional hp drives, etc.?
Many thanks for the help!
--
Dave M

Good judgment comes from experience, and a lot of that comes from bad
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Google groups has deep archives.
$12.00 to $20.00 is the new price. Your other options seem to be surplus.
Mike

than
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as
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been
diameter,
but
cost
gears,
Yep, I've been to all of the surplus stores that I can find on the web, and some have a few gears in their listings, but not have exactly what I need. Guess I'll have to bite a big bullet and pay through my nose to get what I need.
Thanks for the reply.
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Dave M
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    --Not as good as they once were, but check out candhsurplus.com
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Hacking the Trailing Edge! : big Elevator of Life...
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Many thanks.. But I had already visited their web site. Nothing in the way of gears that I can use there, but I do buy odds & ends from them occassionally.
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Dave M
MasonDG44 at comcast dot net (Just subsitute the appropriate characters in
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The problem is that 28 pitch isn't all that standard. It would be better if you could use "even" pitch: 12, 24, 32, 48, etc. Otherwise, 28 pitch is pretty much going to be a "specialty" size, and you'll pay specialty prices.
And because you are needing a fractional pitch, stamped metal is probably not an option (not worth the dies needed for a progressive stamper), so anything you get will be machined. You're talking money here.
A fairly nice source of *standard* pitches and components is Stock Drive -- https://sdp-si.com/eStore /. Their online store now includes prices.
-- Gordon Author: Constructing Robot Bases, Robot Builder's Sourcebook, Robot Builder's Bonanza
Tweetldee wrote:

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On Tue, 15 Jun 2004 15:05:06 -0700, Gordon McComb
That explains why I didn't see 28 pitch in the Small Parts catalog.
I looked for the OP's specs in the catalog and didn't quite find what he wanted, and Small Parts' prices were barely better than what he said was too high. But just FYI, their website is:
http://www.smallparts.com
I've yet to order from them. They look to be comparable to digikey, but for mechanical parts, in that they're probably not the cheapest for what they have, but they do seem to have a lot of stuff.

What's a progressive stamper? (I think I could guess, but I's rather know for sure)

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Thanks for that info. I didn't know that 28-pitch wasn't a standard size, because most of what I have seen on the shelves in RC hobby shops is 28-pitch. Only problem is that they're mostly in plastic or nylon... not suitable for my purpose; and the rarely have a mounting collar. I've looked at Small Parts Inc catalog, and have bought a few things from them, but they are a bit on the pricey side for most items. Maybe I can change my gearing to a "standard" size like 24-pitch if that will get me a better price. BTW, what is a "progressive stamper"? I assume that it's a machine that can stamp out a large number of gears in various sizes without having to retool for each size. Am I close?
Thanks for the advice.. and the url
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Dave M
MasonDG44 at comcast dot net (Just subsitute the appropriate characters in
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"Progressive stamping" is a high-volume production technique most often used for things made from wire, like connector pins. Continuous wire or strip stock goes in and is bent or punched by the first die. The stock advances one notch, and the next die performs the next operation. Two to ten steps are typical. The last step is often a cutoff, so that the finished part is cut from the strip.
Typical tooling costs are around $20,000 for a die set, but the parts come out at speeds faster than a machine gun shoots.
This isn't usually used for gears, unless they're stamped from sheet stock.
The usual sources for gears are Stock Drive Products, Small Part, Inc, Berg, and for larger gears, Boston Gear. Boston Gear has a little online course in gears at
http://bostongear.com/training/gearology.asp
This covers the basics of power transmission, and how to use gears properly.
                John Nagle                 Team Overbot
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Rapid have added a Robotics section which is rather fun, they have muscle wire
http://www.rapidelectronics.co.uk
Pick "Projects For Education"
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Tweetldee wrote:

They may not actually be 28-pitch, but rather something in metric that is pretty close to 28-pitch. This is just my suspicion. I buy a lot of Traxxas replacement parts as components for my robots, and they seem to come in the "standard" size.

John Nagle pretty much answered this one, but I'll add that the "progressive" comes from the way the part is formed into shape. Each die in the line makes the part a little bit into the final shape. They don't try to make a part into the final shape with one die and a single BAM stamping, as it would likely crack either the material or the die.
For cheap gears they may use a die or set of dies, but the gears would be fairly thin, like for a wall clock or something. The larger, thicker metal gears are commonly machined out, which takes time even with CNC, and uses up tooling. This is why this stuff is so expensive new.
-- Gordon Author: Constructing Robot Bases, Robot Builder's Sourcebook, Robot Builder's Bonanza
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size,
not
can
retool
Thanks for the additional info. You're right about a lot of the gears in RC shope being metric.. but many of the gears in those stores are in fact labeled as "28 pitch", which leads me to believe that they are indeed, 28-pitch. All for naught, however... none of them are the right material.
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Dave M
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Tweetldee wrote:

No doubt they are 28 pitch, but the pitch is basically a measurement of the number of teeth dividded by the diameter (it's a little more complex than this, but it's good for ballparking). It's sorta like 6mm being kida sorta 0.250"...not quite, but close.
As I noted, some imported parts are based on imperial dimensions. I note that just about everything I get in the Traxxas line is this way. I have favorite 48 pitch gears I often use in designs, and they match a lot of surplus gears I pick up here and there.
-- Gordon Author: Constructing Robot Bases, Robot Builder's Sourcebook, Robot Builder's Bonanza
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