Hand machined mechanical pencils

Cheap bevel/mitre gears (14/09/11)

So.....one day I needed some right-angle bevel gears. They needed to be steel, and around 30mm dia or so. Proper steel bevel gears are rather expensive (£15-20 or so), so I spent some time looking round to see if there were any alternatives. Then, totally by accident, I saw a post on Hackaday where a guy had made an outboard motor using an electric hand drill. I wasn't too amazed with the outboard as a whole, but I was struck by what he was using for the right-angle drive; a "right-angle drilling attachment". I checked up EBay and, sure enough, they are all over the place for extremely low prices. The ones I eventually went for were from http://stores.ebay.co.uk/tkstores494 (search for "right angle drill attachment") for all of £5! I got three of them.

They have a 9.5mm input shaft and a drill chuck on the output (actually, probably quite an impractical thing to use). Inside the housing there are two sintered steel bevel gears, which appear to be hardened. The bearings are plain bushes. I was originally going to try and use the existing shafts, but it was impossible to remove the drill chuck (it says it's threaded 3/8"-24, but there is an additional cross-headed screw holding it on, which I couldn't get to budge). When I was attacking it, the gear came off the end, so I decided to make arbors for the gears themselves. The gears have a "D"-shaped hole in the middle which is 8mm diameter and 7mm thick from the flat to the opposite side. I managed to make arbors which were nearly a press-fit, and a little bit of superglue did the rest.

They're a bit clunky - 12 teeth, about 26mm diameter - but did just fine for what I wanted them. It was a pretty low-torque application anyway. Main thing is - they are dirt cheap! And you even get a drill chuck for your money.

My new toy

Case removed

Closeup of gear

Gears removed (the shaft whacks out)

Gear with an arbor

Pressed on to arbor with some superglue

Pair of gears