Where to buy gears...and whats this one thing called?

[NJFAIL]

Where do you guys recommend going to buy cheap plastic gears?
And I need some flat gears, sort of like a timing belt cut and laid out straight...what is this called? I've been reading up on gears trying to learn about them, and they said these are called 'rack gears', but when I type this into google or ebay nothing useful comes up... Is there another name for them? Or am I better off just cutting a timing belt in half and gluing it to a piece of wood :\

I'm looking to buy relatively small gears, maybe an inch or two, size isn't much of a concern, I need a bunch of them, so I don't think I could find enough in old VCR's around my house.

 

[Reloadron]

Rack and Pinion is what you are looking for. They look like this. The example is steel but I think that is what you want. Also Spur gears. Google Rack and Pinion as well as Spur Gears.

Ron

 

[cr0sh]

Rack Gears is correct; I don't know of another name for them - maybe someone will educate both of us?

If you need one that matches a specific timing belt pulley profile, though - it would either have to be custom machined ($$$), or doing as you say and cutting/gluing a timing belt could work OK too (you could also try to mold your own from a mold made using a cut-up timing belt - they show a method to do this to create your own pulleys on the RepRap machine; a rack would be similar in scope).

As far as buying small gears, you might try Grainger or similar suppliers; also, go to google and type in "small gears" - you'll find supplier listings and such - not much online, but plenty of places to call and request catalogs from (many of these places aren't online - check your yellow pages if you are in a large city; here in Phoenix, AZ we have several places like this - one of the better ones that sells to the public is call "Bearing, Belt and Chain" - they once gave me free bushings for some small gearmotors I had!).

You might also check in Tamiya kits; they have a kit that is just "gears"; not the best gears, mind you, but OK for small load projects. Then there are gears for RC cars and planes and such...so check out hobby stores.

 

[framerotblues]

You could also try **broken link removed**, they have a good selection of gears.

 

[Brevor]

There is a company called "Small Parts" that sells such stuff, Search for them on Google.

 

[bryan]

Google Robotic stores. Should find plenty of online stores that sell gears etc.

 

[NJFAIL]

Am I correct in thinking that these 2 gears will work together? 1 is a small gear and 1 is a large gear, Right? What should I look for in a to work with these gears?





Also, what should I use to connect to the gear's center?

A person will turn the large gear, the large gear will turn the small gear, which will raise the panel that the belt is glued to (belt will be cut in half to make a 'rack'). This will make it so a small turn of the large gear moves a large amount of the panel.

 

[framerotblues]

What you're looking for is called a Gilmer belt. Gilmer belts and Gilmer pulleys are special, and not the same as spur gears, the pitch is much coarser. They're really designed to transfer large amounts of power as long as the belt has contact with a certain number of degrees of arc on the drive/driven pulley. If I correctly understand what you're asking, you plan to try to transfer power to the belt by applying power on a tangent... and I don't think that's going to work with a Gilmer belt. The pitch is too coarse to do that properly. As you're raising the belt, I'm afraid the top tooth will let go before the bottom tooth catches. It might work if the pulley is large enough, but if I gauge the size of the belt you need by the size of the gears you want to use, it's not going to. (It might work if you were to use materials the size of automotive timing belts and pulleys.)

Why won't a steel/brass/nylon rack work in your situation?

 

[NJFAIL]

What I'm going to do is have a dial, attached to the dial will be a bar of some sort that is then attached to the large gear. so it looks like a cylinder |-|
The small gear will be moved by the large gear. They will meet perpendicularly, ie, at a right angle. The small gear will then move the 'rack' up or down, depending on which way the person turns the dial. The rack is glued to a flap (cover, panel, door, whatever you want to call it) that prevents air from blowing into the tube/pipe.

I really would love to have a steel/brass/nylon/any material rack, but I honestly haven't been able to find any!

 

[framerotblues]

Check out page 1054, 1055, and 1056 of the McMaster-Carr catalog. McMaster-Carr

If you're going to have gears meshing at right angles to each other, you're going to want miter gears. Look to page 1057 for those. Good Luck!

Edit: I see Reloadron provided the same link I did. There's a wealth of knowledge to be gained by perusing the McMaster-Carr catalog in your free time.

 

[NJFAIL]

Check out page 1054, 1055, and 1056 of the McMaster-Carr catalog. McMaster-Carr

If you're going to have gears meshing at right angles to each other, you're going to want miter gears. Look to page 1057 for those. Good Luck!

Edit: I see Reloadron provided the same link I did. There's a wealth of knowledge to be gained by perusing the McMaster-Carr catalog in your free time.

Is there any other way to change the direction of work? It says miter gears need to be the exact same pitch/# of teeth/size. I wanted 1 gear to be larger and 1 to be smaller. Any ideas on what I should do?
Imagine a panel. On that panel there is a dial, and below the dial is a raising door/gate. You turn the dial one way to raise the gate, you turn it the other way to lower the gate. The gate is actually deeper, ie, its on a panel before the panel with the dial. so its below it but behind it as well.

 

[jbeng]

Try Sterling Instruments

 

[framerotblues]

That can be interpreted a lot of different ways. Pictures (or at least crudely-drawn MS Paint diagrams) are worth a thousand words.

 

[NJFAIL]

Sorry about that, here we go:

**broken link removed**
The "dial gear" is a dial with a gear attached behind it.
The Flap is behind the dial gear. There is no particular measurement, as I haven't made any of this yet.

How do you think I should get the dial gear to raise the rack gear?

 

[NJFAIL]

Anyone know what I should do to attached the 2 gears? Or would a different assembly work better? I was thinking back to my lego set from years ago, and I thought 2 gears could mesh together at a right angle.

 

[cr0sh]

Anyone know what I should do to attached the 2 gears? Or would a different assembly work better? I was thinking back to my lego set from years ago, and I thought 2 gears could mesh together at a right angle.

You're probably thinking of the crown gear in the older technic/expert system LEGO sets; you could have such a crown gear under the dial, but you would still likely need an intermediate pinion/spur gear between the crown gear and the rack on the gate.

Alternatively, you could build a right-angle drive in other ways; instead of a crown gear, you could use two 45 degree bevel gears. You could also mount a worm on the shaft of the dial, and use that to drive a "worm gear" which would then (using another gear) drive the rack (this arrangement would be useful in that it can't be backdriven by the weight of the gate).

 

[framerotblues]

hmmmm

What about something like this?

**broken link removed**

Similar to a drum on a winch. The rope/string/cable attaches to the gate at some point. The gate could have a spring on the bottom, pulling it back down. The amount you'd turn the dial would depend on the drum size. Super simple but needs more real estate for the drum.