1/2 hex shaft coupling

We have been looking around and we can’t find 1/2’’ hex shaft coupling.

Does anyone know where we could find a coupling to fit two 1/2’’ hex shaft together?

Rookie team Carnicas 4952

You could get two of these and bolt them together.

You can always make one by drilling a hole in a piece of bar stock so that the HEX will fit in tightly then add set screws or even pin the Hex in place.

Of course a lathe will really help. The picture is taking a square block and making it round for all the poly cord pulleys we need on this years bot.

How would you go about attaching the hubs to the shaft? Are you thinking tap a hole or two and use setscrews?

Small Parts used to have things like this, but I can’t find it anymore now that it’s become Amazon Supply.

You might be able to find a piece of C channel that fits snugly on one side of the hex shaft. Cut two lengths of it, place them on either side of the butted shafts, drill holes through the channels and shaft as a sandwich, bolt it all together.

If you can’t find the channel, then find a person with a brake and make some yourself. Use 60 degree bends.

How much torque / tension does it have to withstand? I’ve 3D printed hex “sleeve” that we plan to use as spacers - but it is incredibly strong - even when printed with a relatively low infill.

They’re available up to 2" long and super cheap, I’ve considered putting setscrews in them for couplings but never actually tried it.
It might not be strong enough for your application though.

One of our students suggested we cut the end off a deep wall 1/2inch socket and put some set screws in it. Should work.

If anyone near you has a 3D printer you can print one of these from
Thingiverse: http://www.thingiverse.com/thing:229161

Best to print with Nylon if they have an all metal hot end.

Very good idea only problem is the socket has been heat treated and will be very hard to drill and tap unless you are using carbide tooling.

Last year, we bought one of these: http://www.mcmaster.com/#2424k14/=qfauwg and ran a broach through it. I’m not entirely sure how well it will perform as a power transferring connection, but it connects two shafts just fine. Initially, we planned on running power through that coupling and then onto our climbing mechanism, but that never panned out, so instead, it just connected the two ‘stub’ shafts that our arm pivoted on.

In a pitch, I’ve also seen teams take a hex hub from AndyMark, drill two holes in it for set screws and use that to connect two shafts. Works just fine, but isn’t ‘pretty’ fix unless you take the bolting surface off.

We are using Hex-hole sleeves, purchased from SDP/SI; just search for part number “A 7C20-08”.

The shafts we are joining are captive, and the sleeve is constrained between hubs, so we aren’t bothering with set-screws, though it would be pretty easy to drill and tap for set screws if desired.

They are very solid and are a slip-fit on the VEXpro hex axles. They are not particularly cheap or light though. If you need them to be light, and you don’t mind spending for a hex broach, you may be better off broaching round shaft couplers as thefro526 describes.


  • Dean

You could use a lathe and drill the ends with a .251 drill and use a dowel pin and
and press it together or weld it



The WCP Colson Live hub has a 1.875" deep 1/2" HEX in it,
This and some pins may suffice.


I would recommend investing in a hex broach in both 3/8 and 1/2 inch sizes. You will not believe how much they will get used. We needed similar couplings last year and could not find any so we made them by broaching 1/2 inch round shaft couplings

We are using these this year, from Team 221 systems. They seem to be working out alright.


The problem with buying a hex broach is you have to buy an arbor press big enough to use it. I know we don’t have the space for that until next year when we get our new shop.

Nice find! This would be easier to drill and tap than the steel sleeves I posted. They wouldn’t work for us this year because we need something that can fit inside a 1⅛" diameter bore, but I will definitely keep this in mind for future years.


  • Dean

I prefer not to use set screws, generally. The only ones I’ve had decent luck with are the ones with knurled points to help prevent backing out.

If I were connecting two shafts together I would use a few spring pins, dowel pins, or cotter pins. Also consider axial shaft retainers. A little fancier, but they can work quite well.

Buy a 1/2 inch deep well socket and cut the square end off.

Easy and cheap.