vintage threads Square Nut

[bolensboneyard]

I have restored several vintage 1910/1930 or there about machines and found that the bolts used with original square nuts do not seem to have an identifiable thread. Machine thread recuts slightly different when chased with a die or tap and pipe thread it's not. Is there a name/type of thread that covers these? What is it? What would I look for to find the right tool to chase the thread on those I have separated with much heat, much oil, and much work? thanks Bobby Ps.please contact me [email protected] if you have tool to sell for this purpose

 

[Schurkey]

I'm thinking that there were no/fewer thread "standards" back then. You might find threads having different threads-per-inch than what is now typical. I suspect that different manufacturers used different threads-per-inch based on their own "engineering" standards.

For example, a 1/2" bolt now might be the standard coarse-thread, 13 threads per inch. I've seen a die for 1/2", 12 threads per inch in an ancient tap and die set. Clearly, enough folks were using 1/2-12 to make it worthwhile to supply taps 'n' dies to match.

[Edit]Unless someone else has specific info to offer, I'd suggest buying a thread gauge, and hoping they used what has become the standard thread profile.

Depending on where things were made, you could even be looking at Whitworth thread profiles. I have Z-E-R-O experience with Whitworth.[/Edit]

 

[woody 73]

Schurkey I like your explanation very good; many is the time when I was stumped as to what thread pitch was on old machines.

 

[neophyte]

I'm thinking that there were no/fewer thread "standards" back then. You might find threads having different threads-per-inch than what is now typical. I suspect that different manufacturers used different threads-per-inch based on their own "engineering" standards.

For example, a 1/2" bolt now might be the standard coarse-thread, 13 threads per inch. I've seen a die for 1/2", 12 threads per inch in an ancient tap and die set. Clearly, enough folks were using 1/2-12 to make it worthwhile to supply taps 'n' dies to match.

1/2" 12tpi is a standard Whitworth thread size. I actually have a small Makita bench grinder that has 1/2" Whitworth threads on the arbor and I doubt it's more than three decades old. I've heard some other Asian made grinders may also use Whitworth 1/2" threads, as well as possibly some other sizes.

Back in the Early 1900s Britain was one of the major tool and machinery producing countries and Whitworth was one of the standardized thread systems used. The Whitworth thread system was also used in other regions including the USA. The pitch on most Whitworth bolts is the same as the UNC thread standards used now with the exception of 1/2" which is 13tpi in UNC and 12tpi in BSW. The other difference between Whitworth and UNC is the shape and angle of the threads. Whitworth used a 55 degree angle with rounded peaks and gullets, whereas UNC uses a 60 degree angle with flattened peaks. If you run into Whitworth threads they may just seem to be poorly machined UNC bolts since the sizes are similar.

The flats on Whitworth bolts and nuts were also specifically sized for the whitworth thread standard and mostly won't match up to current SAE or Metric wrenches.

More on British Standard Whitworth.

https://en.wikipedia.org/wiki/British_Standard_Whitworth

And on the wrench sizes.

http://www.sat.dundee.ac.uk/~psc/spanner_jaw.html

 

[F124C]

^^^ Great answer and great links!

Yeah, Whitworth, that'll sort out the men from the boys!

I wonder how many modern vehicle/equipment 'technicians' have even heard of the Whitworth thread system or BSF or it's little brother, BA ?

AL.

 

[MadeinCanada]

The following link is the best site I have found for thread types and measurements.

http://www.oldengine.org/members/diesel/Tables/Mech1.htm

Ray

 

[Fretters]

Over your side of the pond, if it appears to be a Whitworth thread, it could also be UNC or UNF if on something produced over there.

 

[MShaw]

"I wonder how many modern vehicle/equipment 'technicians' have even heard of the Whitworth thread system or BSF or it's little brother, BA ?"

Or, as in my case, have 1/4" , 3/8" , and 1/2" drive square sockets. I used them extensively years ago on farm implements.

 

[JZiggy]

I restored a Record vise recently that had jaw screws which are 5/16"-26 BSC (British Standard Cycle). Talk about esoteric. I think it was used only in the mid 50's and 60's, maybe someone can confirm. These screws are aaalllmost M8x1.0 (read -25.4 pitch).

 

[F124C]

"I wonder how many modern vehicle/equipment 'technicians' have even heard of the Whitworth thread system or BSF or it's little brother, BA ?"

Or, as in my case, have 1/4" , 3/8" , and 1/2" drive square sockets. I used them extensively years ago on farm implements.

You, Sir, are obviously a 'Connoisseur' of tools.

AL.

 

[F124C]

I restored a Record vise recently that had jaw screws which are 5/16"-26 BSC (British Standard Cycle). Talk about esoteric. I think it was used only in the mid 50's and 60's, maybe someone can confirm. These screws are aaalllmost M8x1.0 (read -25.4 pitch).

Probably goes back even further to when that particular model of Record vise was designed. British manufacturing companies were loathe to change designs even fastener types/threads/tooling/machinery. Their philosophy seemed to be 'why change something if it's still selling'.

This is why e.g. British cars/motorcycles had such long production runs - think Morris Minor, Mini,MG's,Triumphs etc. They basically woundn't invest (=waste money) in new machinery or models until they really had to due to rapidly falling sales.

If you work on old British motorcycles, you'll often encounter British Cycle threads.
There was a story doing the rounds that the last (Meriden?) Triumphs M/cycles had many components produced on old secondhand ex-shipyard machinery, so you had great machinist guys trying to produce small precision parts on worn, totally unsuitable ginormous ex-shipyard lathes!

AL.

 

[larry_g]

If you do a google image search on thread restorer tool you will see many different types of thread restoration tools. Note the ones that wrap around the screw and only have one or two 'fingers' that clean out the thread. There are also thread files that can be used to fix up damaged threads. If just removing crud a wire wheel will do wonders.

lg
no neat sig line

 

[spongerich]

First thing's first.

You need to accurately measure the threads

Check the major and minor diameter as well as the thread pitch.

If they're in good condition, use a thread pitch gage and see if you can tell if the thread angle is 60 degrees or something less. (Whitworth threads are 55 degrees... if they're in poor condition, you might not be able to see the difference)

Once you have accurate measurements, you can look up those dimensions in Machinery's Handbook... you do have Machinery's Handbook don't you? Every garage should come with a copy. If you don't, post your findings here.

 

[MShaw]

"You, Sir, are obviously a 'Connoisseur' of tools.

AL."

Not so much. For years I repaired part time on the road. If I didn't have a wrench I was beyond borrowing from a fellow employee or getting from the tool crib. Hence a rather large assortment of tools.

 

[dutchgray]

I restored a Record vise recently that had jaw screws which are 5/16"-26 BSC (British Standard Cycle). Talk about esoteric. I think it was used only in the mid 50's and 60's, maybe someone can confirm. These screws are aaalllmost M8x1.0 (read -25.4 pitch).

Its called Cycle because its from the bicycle industry, so goes back much more than the 50's. Its use on motorbikes, is due to many of the companies being bicycle builders before engines got added.

 

[Dave455]

Well, contrary to some of the info here there WERE established standards for threads in 1910, and in fact way before that!

To find out which, if any, applies to your machine, the easiest way is to see if you can work out where the machine was made! If it's a British machine the threads will probably be BSW (British Standard Whitworth) or BSF (British Standard Fine).

If it's a US machine they will be National Coarse or National Fine.

Bear in mind though, that standards change, and some formerly popular forms become less used. Back then different thread pitches were often used for 'heavy' nuts or square nuts, which don't get used in that size of nut now.

Bear in mind also, that the U.S. adopted Unified threads in the 1950's. Although they are 'similar' to the old National series, there are some changes. The 'Numbered' threads on the old series included a far greater range than on the new, and these often cause confusion if found by the unwary!

The only way to be sure is to get a selection of bolts, and keep trying till you get a fit! You'll probably get the right size easily, but will need a bit of a fiddle to find the correct pitch!

Once you've discovered the correct thread, the only way to re cut it, is to use a Tap in a tap wrench. You can get both for little money from firms such as MSC.

 

[MShaw]

One of the most noteworthy odd thread systems was he Brown & Sharpe thread system. At one point I asked a factory man from B & S why they used a mongrel thread system.

The answer was that they had their system firmly established and in production before some upstarts came along and created a different US standard.

 

[bigjake22]

I restored a Record vise recently that had jaw screws which are 5/16"-26 BSC (British Standard Cycle). Talk about esoteric. I think it was used only in the mid 50's and 60's, maybe someone can confirm. These screws are aaalllmost M8x1.0 (read -25.4 pitch).

Probably goes back even further to when that particular model of Record vise was designed. British manufacturing companies were loathe to change designs even fastener types/threads/tooling/machinery. Their philosophy seemed to be 'why change something if it's still selling'.

This is why e.g. British cars/motorcycles had such long production runs - think Morris Minor, Mini,MG's,Triumphs etc. They basically woundn't invest (=waste money) in new machinery or models until they really had to due to rapidly falling sales.

If you work on old British motorcycles, you'll often encounter British Cycle threads.
There was a story doing the rounds that the last (Meriden?) Triumphs M/cycles had many components produced on old secondhand ex-shipyard machinery, so you had great machinist guys trying to produce small precision parts on worn, totally unsuitable ginormous ex-shipyard lathes!

AL.

The 5/16 x 26T is still used today on front wheel axles on many cheapo bikes like what is sold at your local Sprawl-Mart. I'm not too sure when it was first used, but I would imagine it probably goes back to the advent of the safety bicycle.

Also, traditionally on bicycle hubs with thread on axle nuts, US made hubs were 24 tpi and "imports" were 26 tpi.

 

[JZiggy]

Interesting stuff! Thanks for sharing.

 

[Fretters]

I restored a Record vise recently that had jaw screws which are 5/16"-26 BSC (British Standard Cycle). Talk about esoteric. I think it was used only in the mid 50's and 60's, maybe someone can confirm. These screws are aaalllmost M8x1.0 (read -25.4 pitch).

26TPI could also place a thread in the BSB camp. It's always 26TPI, regardless of diameter.