Securing gears on shafts
 

Hello,

I was wondering if there were any ways to secure gears on shafts. I don't mean along the axis of rotation (that is easily solved by hex/keyway broaching gears or carefully welding). How would I keep a gear from sliding along a hex shaft if it was already broached to the correct size?

I have thought of tack welding, roll pins, spacers, and set screws in the place of roll pins.

I ruled out tack welding because it would be nice to be able to reuse the gears in a case of emergency, and I don't have the clearance in some parts for spacers.

I am probably going to resort to using set screws but I was wondering how some other teams secured their gears on shafts.

thank you, Vivek

Re: Securing gears on shafts
 

Get gears with hubs. Drill a hole in the hub, tap it, and setscrew the gear to the shaft. It's probably a good idea to locktite the setscrew, just to be sure :)

Re: Securing gears on shafts
 

unfortunately, I already got gears without hubs. I was wondering if there was anything like an e-clip for hex shaft?

thanks, Vivek

Re: Securing gears on shafts
 

You could still machine a snap ring or e-clip/retaining ring groove on a hex shaft.

You could also try one of those push-on style self locking rings.




Lastly, they sell clamping collars with hex bores which may work.

Re: Securing gears on shafts
 

seconded on the collars. A round bore collar would also probably work okay.

Re: Securing gears on shafts
 

We use McMaster.com, go to their site and type in "aluminum collar". Click on About aluminum collar and there you go, the best method, we used 20 aluminum collars this year on our robot for multiple purposes.

Re: Securing gears on shafts
 

eclips would probably be a good solution. I haven't used them before. I still don't think I have enough clearance for the locking collars.

What do you think about gorilla glue? It is a gearbox so there should be no side load on the gears. Wouldn't a few dabs of gorilla glue work?

thanks, Vivek

Re: Securing gears on shafts
 

For most purposes, a decent Epoxy will hold better than gorilla glue. In either case, if you choose to do so, make sure all parts are completely grease-free before application.

you could also use a small roll pin, if you have the machining capabilities to do so (which you probably do, if you are custom making a gearbox) as the Tough box did this year.


How much clearance do you have?

If there is not enough clearance between the gears for shaft collars, but more than 1/16 of an inch, small spacers (cut from tube stock, or from the IGUS bag) have worked well for us in the past, with either shaft collars where there is more clearance, or the gearbox walls to hold all the parts together.

Re: Securing gears on shafts
 

By clearance I mean a gear from another shaft in the gearbox comes too close to the hex shaft which would need a collar/spacer. Sorry if that doesn't make sense. It makes sense to me but I have the gearbox memorized.

After talking to Chris lyddiatt from 1114, I've decided to go with roll pins. Although, more ideas would be appreciated if teams have found any creative ways to secure gears.

thanks, Vivek

Re: Securing gears on shafts
 

Oh, I thought you meant that two gears on the same shaft needed to be very close together.

Roll pins should work fine.

Re: Securing gears on shafts
 

set collars work very nice, but they are heavy. one solution that is a little more cheap is zip ties. it doesn't necessarily look nice, and its not the most affective, but it works in most situations...

Re: Securing gears on shafts
 

Snap rings would be good. You could also just use tubular spacer sleeves or thrust washers, depending on your setup. (One year the kit of parts contained a right-angle gearbox and required sleeves to locate the pinion over the larger helical gear.)

Re: Securing gears on shafts
 

I don't know if it has been mentioned already (possibly by a different name) but I have often seen circlips function well to keep things on shafts in place. Nylon spacers also work alright (assuming they don't grind on anything). If you have the space, a custom shaft can often be designed to have a high spot that secures the side of one or two gears too. I like circlips though because they are easily removable and take up little space on a shaft.

Re: Securing gears on shafts
 

How do you machine the groove needed for a circlip(snap ring, e-clip, etc)? Do you need a special lathe bit or will a triangular insert dealie suffice?

thanks, Vivek

Re: Securing gears on shafts
 

Special bit is a requirement sad to say