Extending a Hex Shaft?

Does anyone know of a simple (cheap) way to extend a hex shaft? We have a need to couple the end of a Versaplanetary to a longer hex shaft but haven’t been able to find a cheap 1/2" hex shaft collar.

Any suggestions for teams without a lathe or a mill?

Know a local team with a hex broach?

It might not be pretty, but you could probably use a modified AM Hex Hub (http://www.andymark.com/product-p/am-0096.htm).


Maybe one of these?
The issue would be you would need to tap the end of the output shaft, and you would need that to be in line with the axis of the shaft.

Not that I know of, but probably. With all the hex stuff now we should probably get one soon, but we would have to buy a bigger arbor press for that as well.

That was my first thought and was hoping there was another way to do it.

What diameter clearance do you have? you could get quite creative with bolting some hex hubs together with standoffs.

possibly take a tube with a close enough inner diameter and shoot two pins through it to retain the shafts?

The VersaPlanetary 1/2" hex output also has a 1/4-20 hole in the end, you could possibly tap the end of the other piece of hex shaft, take a short piece of threaded rod, twist the two together then take a 1/2" Hex shaft collar on the outside to overlap the two which would transfer the torque.

Just spitballin here

I did not realize that versa planetary gearboxes came with a hole on the end.
Just use the male end half inch hex standoffs from mcmaster I posted the link earlier.

You can always throw away the shaft that came with the gearbox and make you own longer shaft out of some hex stock. We have done this a few times with planetary gearboxes. It will probably involve turning one end round, adding a snap ring groove, and milling some flats. This is very doable with a manual mill and lathe.


Is there a team nearby with a lathe or mill that would be willing to make you a coupler (or a longer output shaft)?

For future years, I highly, highly suggest getting a small benchtop lathe and mill – all told they’ll run you close to $2K, and problems like these just evaporate.

VersaPlanetary gearboxes have a spline on the output shaft with much higher torque carrying capability than the flats of other gearbox shafts.
Making your own spline would require a lot of effort

It’s not a money issue we have extremely limited space. I know your mobile cart solution and if we even had a closet I would do that but we don’t. We also don’t have anyone who knows how to use a lathe or a mill (outside of my extremely limited experience).

Wow. The table’s about the area of two-and-a-half FIRST totes put end-to-end, and holds most of our hardware in addition to the machines (which I’m certain someone would help you learn how to use!) I can’t imagine even trying to build a robot without enough space to store something like that.

Maybe if it’s that small, but we share space with other things in the school. So we have space but we have to clean up most nights.

I hadn’t bothered to look at the inner workings of the VersaPlanetary until now. That is quite a spline. Since we a) never use planetaries for high torque applications and b) like to customize the output shaft I don’t see us investing in these any time soon.

So as a follow up to my original suggestion, first buy a Banebots P60 and then DIY the output shaft.

We have to clean up every night (except Fridays), too. That’s one of the things that makes the cart so nice… EVERYTHING has to be taken out (from our closet on the second floor) and brought down to the tech shop (in the sub-first floor, 1.5 stories down), and EVERYTHING has to be put back. The cart goes everywhere with us: to off-season events, to regionals, to and from our work space…

You should reconsider. In industry, planetary gearboxes are the go to gear boxes for high torque applications. The versaplanetary’s load carrying capability is only limited by the aluminum hex shafts ultimate strength. It is stronger than its spur gear counterparts.

It has larger output bearings and a 28 tooth 0.5 module spline that has incredible load carrying capability.

Two AndyMark or VexPro hex hubs and six 10-32 screws.

I’m sorry if this is off topic, but what is this magic cart you speak of?