Attaching gear to shaft

I have a steel shaft and a steel gear. The gear does not have a grub screw and I dont have access to welding equipment.

Any ideas on how I can attach the gear to the shaft?

Keyway

Whats that?

Wikipedia definition http://en.wikipedia.org/wiki/Keyway_(engineering)here.

How big is the gear and shaft? What sort of power has it got to take?

I havent got the tools to cut a groove in the shaft for a keyway :sad:

The shaft is 6mm diameter, the gear has a 6mm bore. I havent bought the gear yet but it is available in a few different sizes. Most likely be 25mm diameter.

It is for the drive to connect the driving wheels with the rear wheels for 4 wheel drive. The only ones I can find with a grub screw are plastic ones.

What I usually do is drill a hole through the boss of the gear/ sprocket and through the shaft. Tap it then add a bolt with a nylon lock nut on the other end.
Dont know if thats a good idea but I have never had any dramatic failures. Just the bolt coming undone due to not tightening it every now and then.

just tack weld it on i think that is what mario did with the speed 900s

whoops reading one post whilst posting in another, note to self, only have one window open at a time :)

(Message edited by typhoon_driver on December 08, 2008)

I think the shaft is too thin to drill a hole through, and I dont have access to any kind of welding equipment.

Hmmm. Perhaps I could glue the sprocket to the wheel hub.

Tom: BAD IDEA!

Glue shouldnt really be used in robots other than antweights

if you want to attach the gear directly to the wheel, then put 4 bolts through the gear and into the wheel hub. Just make sure they are lined up before you do so

As David said, glue isnt gonna cut it in featherweights for that sort of application. You need something more robust.

If the shaft is too thin to drill through (and by the sounds of it, it is) then you can still put a grub screw through the boss of the gear/sprocket. Id use two (at 90 to each other) to help lock it in place. You could also continue drilling through to the shaft, but only far enough to make a little dimple in the shaft, which would give the grub screws an extra bit of grip.

Cant guarantee that itll be devoid of slipping, especially if the forces going through the drive system are large, but it should do the job. Its how I will be attaching the pulleys to my 6mm weapon motor shafts.

Ok :) Glue was a last resort!

If I drill through the boss for a grub screw, how do I thread the hole?

use a tap

http://en.wikipedia.org/wiki/Tap_and_diehttp://en.wikipedia.org/wiki/Tap_and_die

How good a fit on the shaft is the gear? and how much torque is going through it.
Green loctite actually works VERY well for attaching pinions to a shaft, just leave it 24hours to set and you should be fine for most featherweights.

Ah ok. The bore is 6mm, same as the shaft, so its not loose or tight.

I suppose the loctite is worth a try at least! :)

Thanks for everybodys help.

Ive recently done that on a much smaller motor and tried to remove the gear (which was a loose fit before). I had to cut the gear in half to get it off:proud:

Loctite 603

Trev

put a ball bearing over your hole in gear hit it with a hammer which will make it smaller then press it on with loctite as well better to weld it tho

Ah good idea! Ill have to find a ball bearing though. Probably got one somewhere.

Now, Loctite 603 or Green Loctite? :)

im sure if you went to any welding company they would tack it up for you for free

Thats the thing though, I dont know of any welding company near here/cant find one!

yellow pages and the internet

If you€™re going to take up roboting seriously, buy a welder off ebay or something. Then learn:)