Small Combo Square Needs Knurled Nut and Spring

  • Advertise with us

« back to Hand Tools forum

Forum topic by Mattyboy posted 07-10-2015 04:58 AM 2080 views 0 times favorited 11 replies Add to Favorites Watch
View Mattyboy's profile


50 posts in 2325 days

07-10-2015 04:58 AM

Topic tags/keywords: question combination square

Some months ago I found this 6” Brown & Sharpe combo square at a garage sale, but it did not have the knurled nut and spring to use with the clamp screw that holds the blade to the stock. I tried finding the right size nut at McMaster and at specialty fastener stores with no luck. The threads have an outer (major) diameter of 0.208” and I’m pretty sure there are 28 threads per inch. Apparently not a standard size. Finally I called Brown & Sharpe and they said they would send me a new clamp screw assembly (which includes clamp screw, nut and spring). They never did, so I bought one myself.

You can see the problem in the picture – the clamp screw I bought is a lot bigger than the original and will not fit in the stock. I guess this square was made before B&S standardized all their squares with one size clamp screw assembly.

Can anybody suggest a way to get this square working again? I’m not a machinist, so making my own is not a solution for me.

Thanks for helping.

-- Matt, Northern CA

11 replies so far

View Mattyboy's profile


50 posts in 2325 days

#1 posted 07-12-2015 07:25 PM

Anyone? ...... Anyone? (nudge)

-- Matt, Northern CA

View upchuck's profile


540 posts in 2912 days

#2 posted 07-12-2015 09:34 PM

Just so you won’t feel like you’re wandering around lost in the woods.
Good luck. Keep you eyes open for broken combo squares. Save all of the parts. Continue to use the ruler while you wait.

View Ripthorn's profile


1459 posts in 4232 days

#3 posted 07-12-2015 09:47 PM

The OD you describe is very close to #12 (like, a few thousandths off). #12-24 is a standard size, you could see if that is what it is by going to the hardware store or something. If it really is a non-standard size, you have a couple options. One is to try to source a new nut from another unit, another is to go to a machinist and have them make you a new one, the last is make friends with someone who can make one. However, note that having one made you will not get the same knurling pattern as the original. The originals had this great decorative knurling that simply is not made any more (and finding vintage knurls to make them is incredibly expensive).

-- Brian T. - Exact science is not an exact science

View bandit571's profile


29742 posts in 3931 days

#4 posted 07-12-2015 09:48 PM

Go out to Menards/Lowes/whatever. Pick up a small combo square that looks like the right size hardware on board. Take the head of your square along, and test it out.

-- A Planer? I'M the planer, this is what I use

View TheFridge's profile


10863 posts in 2733 days

#5 posted 07-12-2015 10:05 PM

Sounds like a #12-28 (fine thread).

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View JoeinGa's profile


7741 posts in 3254 days

#6 posted 07-12-2015 11:07 PM

I’d carry that clamp-screw in my pocket EVERYWHERE I went. You never know when a hardware store, big box or even a flea market might just have something to fit. And it doesn’t necessarily have to be an oversized knurled knob type. Even if you found a hex nut the right size you could JB Weld a larger hex nut to it for the grip.

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

View Ghidrah's profile


667 posts in 2470 days

#7 posted 07-13-2015 12:32 AM

If you could find a standard/metric bolt that fits the hole diameter, with some time, a hacksaw and a couple files you could reproduce the original close enough to work.

-- I meant to do that!

View Tim's profile


3859 posts in 3209 days

#8 posted 07-13-2015 01:16 AM

Fridge is probably right. #12-28 is a UNF standard size and #12 is .2160 major diameter. It doesn’t seem too surprising to be 62 thousandths smaller than the standard, but I’m no expert. It would be easier to buy and test a #12-28 than it would be to find a caliper designed to measure the minor diameter so try finding the screw first like Brian said.

View Mattyboy's profile


50 posts in 2325 days

#9 posted 07-13-2015 03:34 AM

Some great suggestions, all. Thanks a lot for that. I don’t need this to be perfect – just good enough to work.

Thanks again.

-- Matt, Northern CA

View Mattyboy's profile


50 posts in 2325 days

#10 posted 07-13-2015 11:01 PM

Well, thanks to some advise from the people above, I now have a working square. I was able to find a plastic knurled knob, a metric M-6×1.0 nut and a spring to get this thing functional again.

The M-6 doesn’t fit the clamp screw quite right, but it’s close enough for me to lock the blade to the stock of the combo square.

The knurled knob was made to fit a cap head machine screw, so it had a “housing” that would fit the spring, much like the brass knurled nuts for combo squares do. I drilled out the knurled knob (already drilled out in photo above) and filed until the M-6 nut fit, then epoxied it in place.

Cut a short length of the spring to provide back pressure to keep it together when adjusting the square.

Just a few bucks spent and a great result. And because the knurled knob is black like the stock, it doesn’t look too bad. Thanks to all for your suggestions.

-- Matt, Northern CA

View Tim's profile


3859 posts in 3209 days

#11 posted 07-14-2015 12:08 AM

I have to say I’m a little shocked the metric threads worked, but I’m glad you got it fixed up so you have a working square again. Nicely done.

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics