Securing gears on shafts

[vivek16]

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

[tdlrali]

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

[vivek16]

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

thanks, Vivek

[Travis Covington]

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.

[Joe G.]

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

[R.C.]

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.

[vivek16]

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

[Joe G.]

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.

[vivek16]

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

[Joe G.]

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

Roll pins should work fine.

[thatmorman]

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...

[Tim Baird]

Originally Posted by tdlrali

It's probably a good idea to locktite the setscrew, just to be sure

If you are going to Loctite it (which I recommend) try to use the blue variety. It'll hold, but you can get it off later in the heat of battle without working too hard. The red will just cause unnecessary frustration.

Speaking of being "in the heat of battle", I'm a huge fan of pinning gears, hubs, etc to shafts. If you're trying to install one and someone says "you have 30 seconds to be on the field", a drill bit and a quick 'snap' can work wonders, if anything to get you through one more match.

[IKE]

"LOCTITE THREADLOCKER 222 LOW STRENGTH PURPLE, 6 ML. TUBE (38653)

E-mail this product to a friend





Low strength threadlocker. Designed for precision metal fasteners under 19mm. Protects threads from rust and corrosion. Removable with hand tools.

Applications: Set screws, adjustment screws, calibration screws, meters, gauges. "


Nobody ever seems to use Purple. Not sure why. Grant Imahara recommends it in his Battlebots book Kicking Bot.

[vivek16]

Originally Posted by Tim Baird

If you are going to Loctite it (which I recommend) try to use the blue variety. It'll hold, but you can get it off later in the heat of battle without working too hard. The red will just cause unnecessary frustration.

Speaking of being "in the heat of battle", I'm a huge fan of pinning gears, hubs, etc to shafts. If you're trying to install one and someone says "you have 30 seconds to be on the field", a drill bit and a quick 'snap' can work wonders, if anything to get you through one more match.

Speaking of that, get a bunch of 3/32" bits. they're only 52 cents here: http://www.buydrillbits.com/products...?c=JL-USA-FRAC

Just invest in 40 of them. they're only twice the price of spring pins.

I am slightly kidding but it does seem like a good idea in a hurry
It would probably be better to use a spring pin.

-Vivek

[Dick Linn]

You can get a 10-pack of 3/32" bits at Harbor Freight for $1.49, not that there very good ones. http://www.harborfreight.com/cpi/cta...emnumber=93077

One think I find useful around the shop is to have some drill rod in various sizes. In smaller sizes, it is very inexpensive. You can get a 3 ft. length of 3/32" drill rod for about a buck. Larger sizes can be used for axles, etc.

http://www.use-enco.com/CGI/INPDFF?PMPAGE=789&PMCTLG=00