How do I attach something to a square shaft???

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Forum topic by DrTebi posted 10-18-2013 09:47 AM 2995 views 0 times favorited 36 replies Add to Favorites Watch
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242 posts in 2687 days

10-18-2013 09:47 AM

Topic tags/keywords: screw wheel crank shaft box joint jig question


I recently acquired a nice 20” linear slide which I thought would be perfect for a screw-advanced type box joint jig. Everything is well, and I will start to build it soon, but I just cannot figure out how to attach a handwheel, or just anything, to that 1/4” square end of the lead screw?

If you look at the picture you can see that the lead screw was milled to a solid 1/2” round shaft to go into the ball bearings, and then the very end was milled flat on four sides. It’s 1/4” square. I was able to fit a 1/4” socket on it and play around with it, but eventually I would really like to attach a hand wheel, or make my own hand-crank.

I googled, searched through the entire “square” results of McMaster-Carr but just cannot find anything that would allow any type of mounting to this 1/4” end.

I am desperate; but I know there is a solution… What’s the trick?

36 replies so far

View REO's profile


883 posts in 1494 days

#1 posted 10-18-2013 10:29 AM

set screw, roll pin, small screw in from the end. the trouble may be the square hole.

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3979 posts in 2391 days

#2 posted 10-18-2013 12:42 PM

Easy with a matching square hole and a set screw.
Use a deep well socket for the hole (which track you were already on) and match the O.D. of the socket to the round hole in what you want to attach.
If you want to drill and tap a set screw hole in the socket you will need to heat it with a torch to anneal it first.
Otherwise you might also just drill a hole for a roll pin to attach it, but this would require a hole in your shaft.

-- Michael: Hillary has a long list of accomplishments, though most DAs would refer to them as felonies.

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Steve Peterson

317 posts in 2503 days

#3 posted 10-18-2013 06:01 PM

You could still put a normal round hole hand wheel on it. Just buy one with a hole slightly larger than 1/4”. Or buy a 1/4” hole and drill it out to the exact size that will slip over the square.

-- Steve

View Bluepine38's profile


3336 posts in 2506 days

#4 posted 10-18-2013 07:00 PM has some handwheels with and without holes in them. You can get one with a 1/4” hole, or
drill a hole and use a good small triangular file to make the hole square and fit over the shaft. Reid
also has quite a bit of interesting hardware.

-- As ever, Gus-the 77 yr young apprentice carpenter

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3256 posts in 2096 days

#5 posted 10-18-2013 07:16 PM

This isn’t a wheel or crank but the A/C business used a wrench that had a square hole in it to open valves for many years. It has a ratchet mechanism in the end. Turn it over to reverse.

View Loren's profile


8159 posts in 3068 days

#6 posted 10-18-2013 07:54 PM

View crank49's profile


3979 posts in 2391 days

#7 posted 10-18-2013 08:19 PM

Yes Loren, I was just about to suggest valve wheels, but you beat me to it.
The McMaster Carr folks have these as well; for more money of course.

-- Michael: Hillary has a long list of accomplishments, though most DAs would refer to them as felonies.

View HorizontalMike's profile


7064 posts in 2334 days

#8 posted 10-18-2013 08:55 PM

Crank has the idea. Just use a Square Hole drill bit and problem solved!

-- HorizontalMike -- "Woodpeckers understand..."

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418 posts in 1148 days

#9 posted 10-18-2013 09:31 PM

You might be able to find something here
I have used this company a few times with good results, they have lots of good stuff.

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7369 posts in 1427 days

#10 posted 10-18-2013 11:01 PM

Find one of these in the size you need and weld what ever handle you want on it.

-- Perform A Random Act Of Kindness Today ... Pay It Forward

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1222 posts in 1857 days

#11 posted 10-19-2013 03:29 AM

Maybe one of these will work.

-- Tom Finnigan - Measures? We don't need no stinking measures! - Hmm, maybe thats why my project pieces don't fit.

View DrTebi's profile


242 posts in 2687 days

#12 posted 10-19-2013 11:03 AM

Thank you for all the suggestions!

Well, Reids and McMaster don’t have hand wheels with 1/4” square holes, only with round holes. I could get one with a slightly smaller round hole and file it straight. Sounds like a work-around in a way though… there must be a better solution.

Drilling a square hole—that video was great, I don’t quite understand how it works, but if a square-hole-drill really exists, I will go for it (could even make mortises with it??).

Then again, using a 1/4” square socket and welding something on it, that sounds like the most reasonable solution. I just don’t have a welder… maybe I could ask my old teacher to help me do that.

I have looked at valve wheels, but I really would prefer something that’s larger and easier to turn.

I sent an email to Carrlane, who make handwheels with optional custom holes… no 1/4” square is listed officially as an option, but they may just do it for me.

Ideally I would prefer a hand-wheel that just fits, as opposed to mocking something up. $20-30 is not the end of the world for a custom fit hand-wheel that will sit tight as opposed to some mocked up version that may not sit well….

View REO's profile


883 posts in 1494 days

#13 posted 10-19-2013 01:41 PM

the square hole drill does exist lol but it would be quite an investment in tooling for one hole. get a blank handwheel from any one of several suppliers drill a 1/4” hole. take a piece of 1/4” keystock and round an short section of one end for a pilot. heat it up hot enough to melt the material you are working with and push it through the hole. drill and thread the handwheel for a set screw. how big

View casual1carpenter's profile


354 posts in 1896 days

#14 posted 10-19-2013 03:30 PM

I wonder if there is another line of logic you can follow here. Just how much cranking force is required to move your linear slide? Is your box joint jig going to require that much force to advance? I assume, perhaps wrongly, that the forces acting on the handle would not be that great as to require a steel handle. Would not a crank made of a good hardwood carry the necessary forces? You could incorporate the quarter drive socket easily or a mortise combined with an opening saw kerf and a couple of counter bored nut and bolt sets. A carriage head bolt and nut set towards the business edge of the crank which is fitted with a knob or handle would be a nice addition for ease of turning as well as a rough visual marker as to the crank turn amount.

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3256 posts in 2096 days

#15 posted 10-19-2013 03:36 PM

Talk to a machine shop about what you want. If you have a well equipped shop in your area they might be able to broach that 1/4 inch hole for a reasonable amount. If you can’t get a shop with a broach, have a socket modified and welded to the wheel. When you buy the wheel make sure it is something they can easily weld and want to weld. If the socket were shortened and drilled before the weld procedure it would probably be easier. by shortening the socket it would make the wheel more stable. If you can get Carrlane to make it then it would probably be the cheapest.

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