how to drive 1/2" hex shafts with a drill?


#1

I have seen many videos of teams trying out ideas for things like intakes using wheels mounted on shafts and spun using a drill. The team leadership wants to have new team members try building “really janky prototypes” at a Mock Kickoff we are doing on Sunday.

We have lots of 1/2" hex shaft but it is too big to fit in the chucks of the drills we have (3/8" and 1/2"). We don’t have access to a lathe at this time. We do have some hubs for the 1/2" hex. We don’t have any of the 3/8" hex shaft and hubs.

What sorts of things can we do to make such prototypes with what we have? Can we do it by putting 1/2" round shaft in a hub for the 1/2" hex and applying a lot of duct tape? Is that janky enough?


#2

In certain prototypes we have used a 1/2" nut driver or deep socket drill attachments just put in the drill chuck and slide over the hex. Not as robust as fixing something onto the shafts but it works in a pinch.


#3

Whenever I would make prototypes and needed to drive stuff with 1/2" hex I would just put a 1/4-20 self tapping bolt in it and then attach the drill(1/2" chuck) to the bolt head. There probably are better ways to do this, but hope this helps!


#4

Find a 1/2" hex socket or nut driver that you can chuck into your drills.

https://www.homedepot.com/p/Milwaukee-Shockwave-1-2-in-x-2-9-16-in-Steel-Magnetic-Nut-Driver-49-66-4537/203382256


#5

You use this thing.


#6

My first recommendation would be to find a nearby team with a lathe and get them to turn down the end of a handful of hex shafts for you. That would give you a fixed quantity of “prototyping materials” you would be able to use.

If that didn’t work, my second recommendation would be to utilize some pulleys and belts. It makes your prototypes a little more complex, but you could get a handful of pulleys mounted to hex hubs for your hex shaft, and some more mounted to round keyed hubs for the drill. Assuming your prototyping out of plywood, you would just need an extra hole at the proper spacing to support the other end of the round shaft - and you can probably get “good enough” by just stretching the belt between the two pulleys and drilling through the center of the round hub and then slopping the hole a little until everything works.

We’ve also done interesting things using polychord or surgical tubing as belts between two bare shafts, without pulleys. If it’s stretched tight enough it can transmit some torque, but you may also see some slipping. Usually good enough for a quick prototype that needs to run all of 30 seconds before you move on to the next one. It also lets you do things like a figure 8 configuration to get the shafts spinning in opposite directions for a shooter prototype.

Edit: Do’h! A hex driver would totally be easier and more reliable in many situations.


#7

yep, go to lowes/home depot/harbor freight, and find a set of hex sockets with a 1/2" one.

Sort of related: http://www.instructables.com/id/Handheld-Motor-Tester-for-FIRST-Robotics/


#8

So we use these. We used these shafts in 2017 to rotate our floor gear grabber using a seat motor, but due to the high torque and accidentally switching to 6061 aluminum, we have a large amount of shafts that are almost broken but work well for testing intakes. We did also try stainless at one point so we have a couple of those in the bunch, but I believe we went through a total of like 30 or something during season, most broke the end off before we could replace them.


#9

You should have one of these https://www.homedepot.com/p/Milwaukee-1-4-in-x-3-8-in-Steel-Square-Socket-Adapter-48-32-5031/202562858 and/or these https://www.homedepot.com/p/Milwaukee-1-4-in-x-1-4-in-Steel-Square-Socket-Adapter-48-32-5030/202562857?MERCH=REC--PIPHorizontal2_rr--202562858--202562857--N for use in your impact driver (you do have an impact driver don’t you) and the 1/2" socket you already have and chuck it in your drill to get the speed you need. To janky it up a bit you can add lots of duct tape to attach the socket to the hex shaft and the socket to the adapter.


#10

Wow! Thanks for all the fast answers.

I have some of these nutdrivers at home so I will bring them along on Sunday.

For the future, we can get some 1/2" hex turned down to fit a drill chuck.

I think we might have a few pieces of churro so we can try if that fits in a 1/2" drill chuck.

Thanks also for the reminder about the old drill. I had collected a bunch of dead drills from the assembly people at my last job.


#11

My students built one of these, and then let out the magic smoke with too high a duty cycle on the SLA robot battery.

To replace it I got my hands on a bunch of new 12v lion drills (on sale), and cut all the heads off. Benefits include this way our prototype mechanisms are power-limited until we drop them onto a chassis… implicit power-budgeting. https://www.amazon.com/Black-Decker-BDCDD12C-Lithium-Drill/dp/B0111N8L7I

(We held onto the heads for offseason activities.)


#12

i normally just cut the shaft like 1 or 2 inches longer, and from those 1 or 2 inches lathe off 0.25in or more from the diameter of the stock so that you can stick it in the drill chuck.

if you have some sort of milling machine, you could also probably shave off like a bit on each face of the hex shaft, that might work too.

best of luck :slight_smile:


#13

We didn’t like having to turn down every shaft we used, so we made a one-time tool for every time. It’s just a short hex shaft which has been turned down on the end with a 2” spacer in the hex end. We drilled through both the space and the hex shaft then screwed the two together. So far, it’s handled many seasons of abuse and is dead easy to use.


#14

That sounds cool. What spacer did you use? Do you have a photo you can share?


#15

I imagine they are referring to this spacer (217-3265) on this page: https://www.vexrobotics.com/acetalspacers-vexpro.html

Neat idea! this is however pretty just a home brewed nut driver. It’s advantage I could see would be a deeper socket


#16

I tried the Harbor Freight nutdrivers and found that the shaft wobbles a lot because the socket part is not very deep. I might try some of these.

I would worry about the plastic spacers shattering if there is some sort of shock load.


#17

I may be wrong, but I would suspect the wobbling would be more due to the fact that it wasn’t being driven by the driver close enough to a bearing or some other supporting feature. I would not be surprised if the deeper nut driver still produces a wobble.


#18

For those without access to a lathe, but want to secure a shaft, just buy a 1/2" nut driver that fits your drill, slot the socket by sawing parallel to the axis with a band saw or hack saw, and use a pipe clamp or appropriate-sized shaft collar to secure it.


#19

All of these will work, but my #1 goto is a 1/2" socket and a converter from the socket square to hex is what I use consistently