How do you find the gears you need in motors?

[ramonegumpert]

Dear Experts

I have this problem for a long time. I always cannot get my project done because parts are not available.

I need gears, eg. Pinion gears of certain size of certain number of teeths and the hole in the middle of the gear need to be of certain size.

How do you normally get the gears you need? eg. Metal or Plastic type.

How to fit such things into the spindle or shaft?

By force?

I have many projects I want to do but always, I do not have the parts.

To order from the net would be very costly.

Please advise.

Thanks very much.

Regards
Ramone

 

[Simon Bridge]

You go to an engineering workshop and ask them to make them for you.
Most people start with the standard gears they know they can get and build the project to suit.
Sometimes a standard bit of kit can be modified.

 

[Baluncore]

Gears come in many shapes and sizes. What sizes do you want? What is your motor power in watts or horsepower?

Start by looking for old photocopiers, they often have gears in them.
If you have one gear and you want more you can make a silicon rubber mold and cast more in resin.

There are places that sell kits of gears for hobyists...
http://www.hobbyparts.com.au/store/categories/gears/

There will be an RS Components in most countries.
http://australia.rs-online.com/web/...-power-transmission/power-transmission-gears/

Or cheap dead stock such as...
http://www.allelectronics.com/make-a-store/category/253/Gears/1.html

Let us know what you are building and we can help you to find the best way to do it and the bits.

 

[ramonegumpert]

Thank you Simon and Baluncore.

I have approached a RC hobby shop, no cigars. It has different size gears.
Mine is a straight pinion gear. About 10mm in diameter and having 12 teeth. It has a hole in the middle for the axle which is almost 2mm in diameter.

I will search in the websites provided also. I am repairing a children's electric ride-on car.

Looks like I have to get a 3d Printer. haha.

But before that, I will go with Baluncore's idea of DIY. I intend to make a mold using clay and then fill it with resin or some metal-bonding glue.

For resin, not sure which is recommended?

Thanks !

Regards
Ramone

 

[Simon Bridge]

Cheap 3D printer :)
http://reprap.org/wiki/Main_Page

How close did the hobby shop get - a 10mm diameter, 12 teeth, but wrong diameter hole?

 

[Baluncore]

I would make a one-off mould from plasticine. If I wanted to reuse the mould I would use an auto-grade silicon sealant. You will have to work out how to mould the hole for the shaft.

The resin can be 5 minute epoxy. If it needs to be stronger then you can sample a few strands of Kevlar from the cut end of a roll as available from a fibreglass supplier. Chop the strands into very short lengths then mix them into one part of the epoxy, before mixing the two parts. Epoxy bonds chemically to Kevlar fibres so it will be very strong if the resin is well loaded. You could use carbon or glass fibre but probably not as good as Kevlar in this application. There are special lubricants available for plastic gears. There is probably enough lube in an old VCR's mechanical actuator for your epoxy gear.