12 point box wrench size.

[egnorant]

I just discovered that a 3/8th square head bolt is not compatible with a 3/8ths 12 point wrench or socket! Open end 3/8ths fits fine. Found the 7/16ths 12 point is a good fit.

After wrapping my brain around it I understood why, but is this something well known and I just missed it?

Bruce

 

[PelicanPines]

We should make a table of the square sizes=12pt sizes...

 

[nbpt100]

This is where an 8 PT 3/8 comes in. More commonly now are the spline wrenches. They are suppose to cleanly fit square fasteners but I never have confirmed it. I rarely come across square nuts and when I do i use an open end. Good observation!

 

[four.cycle]

^ This is why they made/make 8-point sockets. Most all the older 1/4" drive socket sets contained 8-point sockets in 1/4", 5/16", and 3/8".
You can find 8-point sockets up to (and exceeding) 1 inch easily on Ebay - most commonly in older Craftsman. Matched sets will be spendy.
A few oddball onsie-twosies in 1/4", 5/16", and 3/8" might set you back a whole ten bucks (including shipping.)

Or there's probably several guys here who have extra oddball 8-points they'd probably give away if you paid the shipping. I think I might have a few in Giller or Thorsen, but I have no clue where anything is here anymore.

Or just use the open-end wrench, provided you can get to it that way.

I rarely come across square nuts

^ That's because they pretty much have gone by the wayside in favor of 6-sided hex nuts.
If you're working on a 1930's toaster or radio, however, 8-points are indispensable.

 

[egnorant]

I had just gone my whole life knowing a 12 point can be used on a square nut. I never had the occasion to check this difference.

Dealt with a few squares and just used the 8 point or open end that fit.

I was just sitting playing with a couple of new estate sale tools (Craftsman 943796 tri-wing ratchet and a Bonney 1161 7/16th wrench) and noticed the box end fit the 3/8ths perfect and the open end was too big!

Took a moment to wrap my head around the math and geometry of the situation and I was just wondering if this was well known and just bypassed me or just a rarely used oddity.

If I ever used a 12 point on a square I am sure I just tried one and grabbed until I got one that fit.

Bruce

 

[gdocktor3]

This is where an 8 PT 3/8 comes in. More commonly now are the spline wrenches. They are suppose to cleanly fit square fasteners but I never have confirmed it. I rarely come across square nuts and when I do i use an open end. Good observation!

I've come to really like spline sockets and wrenches. They just work really well and if you're going to buy something with 12 point, you may as well get the spline because of the versatility with different style fasteners, as well as the ability to removed stripped or rounded off fasteners.

 

[bobcatdan]

While a 12 point can be used on a square head, technically not the right tool.

 

[franzdom]

Opposite edges on a hex are 15% larger than flat to flat (wrench size).

Opposite edges on a square are 41% larger than the flat to flat (open end wrench size). This is why you need a larger wrench when you use the 12 point for a square bolt or nut compared to a hex.

 

[gungatim]

when in the oil change business, we always used a box end 12pt. on stubborn square trans/diffy plugs. and for the recessed ones, a 3/8 ratchet with a 1" extention works perfect.

 

[nbpt100]

Opposite edges on a hex are 15% larger than flat to flat (wrench size).

Opposite edges on a square are 41% larger than the flat to flat (open end wrench size). This is why you need a larger wrench when you use the 12 point for a square bolt or nut compared to a hex.

I get what you are saying.
I think you mean to say the diagonal across the corners. Not opposite edges.

 

[gigamel]

Yes, the corners of the square takes up a bit more space than the corners of the same size hex.
The factor is roughly 1.18 to 1.22 dependent on the actual size and shape of your 12 pt socket/wrench and how much the corners of the square are rounded:

Sq. 12pt
1/4" 19/64"
5/16" 3/8"
3/8" 11mm, 7/16"
1/2" 15mm
5/8" 19mm, 3/4"
3/4" 22mm, 7/8"
7/8" 26mm
1" 30mm

 

[Dave455]

Never considered using a 12 point wrench on a square nut! I can see why you might think it would work, but as you've found 'bi-hexagonal' is different from 'tri-square', even though they both have '12 points'

Perhaps this is a terminology issue! The terms '6 point' and '12 point' are peculiarly American! I'd gone all my life without encountering either, until I opened a Snap On catalogue!

The British terms would be 'hexagonal' or 'single hex' and 'bihexagonal' or 'bihex', which say exactly what the tools are!

For square nuts, or shafts, you would need a 'square' or 'bisquare' socket! The word 'bisquare' implies two superimposed square recesses, each with 90 degree corners, which '8 point' does not'!

 

[franzdom]

I get what you are saying.
I think you mean to say the diagonal across the corners. Not opposite edges.

I meant to say opposite edges because how else can you measure it? You are trying to engage flats near engagement edges. Do you measure to points? It's a lot easier to measure to edges.

I see how you could consider those to be corners, but to me they are edges, while corners are points.

 

[BDT/NWMN]

In short words; a twelve point box end wrench or socket may "sort of grab" a square plug, but it is not the proper tool to be using. Hats off for the Members who went into detail to explain why this is so.

 

[four.cycle]

Perhaps this is a terminology issue! The terms '6 point' and '12 point' are peculiarly American! I'd gone all my life without encountering either, until I opened a Snap On catalogue!

The British terms would be 'hexagonal' or 'single hex' and 'bihexagonal' or 'bihex', which say exactly what the tools are!

Early on, they were referred to as "Single Hex" (for 6-point) and "Double Hex" (for 8-point), and "Double Square" (for 8-point), as shown in this 1944 Stevens Walden (Walden Worcester) ad for their 1/4" drive "Migit" socket set advertised in Motor Service magazine:

1944 Motor Service Magazine Walden Worcester "Migit" socket set ad by four.cycle, on Flickr

 

[Empty Pockets]

I have a bunch of 8 point (or if you prefer bisquare) sockets, somewhere...... I can't remember the last time I used any of them.

 

[four.cycle]

egnorant: did you check the "Free Socket" thread yet?

 

[egnorant]

egnorant: did you check the "Free Socket" thread yet?

The last thing I need is more sockets. I do have many square sockets. Just found this odd and kinda pushed up against my logic.

I actually have that Walden box and a bunch of Walden square stuff!

Bruce

 

[wolf_from_wv]

^ That's because they pretty much have gone by the wayside in favor of 6-sided hex nuts.
If you're working on a 1930's toaster or radio, however, 8-points are indispensable.

Or Meccano building sets...