I apologize for wandering off into the world of brand X again, but I am working on an Aultman & Taylor steam engine at the moment.  I am making a steam chest bolt.  All of them seem to be 5/8" Whitworth threaded and it is definitely a different pitch diameter than a Unified National Coarse the same size.  I look for  Whitworth nuts for sale; their offerings get up to about 7/16" and then they are labeled UNC.  UNC definitely won't match the bolts.  If I thread to UNC, sure as the dawning daylight some future idiot will mess up the match, nuts to bolts, and then they will be short two bolts instead of just one!

Since I only need one Whitworth nut, I think but am not dead sure, I don't want to caugh up their considerable asking price for a box of 50, especially since I'm not dead sure.  I've found other threads on that machine that I so far haven't been able to identify.  Or maybe they cut them with a very dull threading die.  WAAAM has always reimbursed me for purchases, some quite considerable.  I don't want to take advantage of them.

So, does anybody know of a supplier that would sell one 5/8" Whitworth nut and mail it  to Oregon?  My thanks in advance for checking this out.  

Jack wrote:

I apologize for wandering off into the world of brand X again, but I am working on an Aultman & Taylor steam engine at the moment.  I am making a steam chest bolt.  All of them seem to be 5/8" Whitworth threaded and it is definitely a different pitch diameter than a Unified National Coarse the same size.  I look for  Whitworth nuts for sale; their offerings get up to about 7/16" and then they are labeled UNC.  UNC definitely won't match the bolts.  If I thread to UNC, sure as the dawning daylight some future idiot will mess up the match, nuts to bolts, and then they will be short two bolts instead of just one!

 

The only difference between a 5/8 UNC thread and a 5/8 whitworth thread is the thread angle. UNC threads are 60 degrees and British threads are 55 degrees. For most low torque application a BSW nut will work fine on a UNC bolt and verse visa with the exception of 1/2" which also has a different TPI.
Could it be a metric thread? M16?

Is British Standard Whitworth the same as used in USA 110 years ago? I considered trying some of my motorcycle contacts, but I've never seen a 5/8" Whitworth in a motorcycle so I had no sample. But maybe I should go of that answer. Thanks!.

UNC was adopted during or after World War 1 so I assume it would be the same BSW but the standards applied to BSW changed over the years. It may even be a special thread for that manufacturer. Not a lot was standardized in 1910. Do you have a vernier caliper and a thread pitch gauge?

Hi PhilC,
do you have any Landrover enthusiasts about, and if they have a series 1 you will be able to get one of the brake shaft that runs through the chassis and per the parts cataloge.

 
part 24
 

regards
 

The original bolts I will call Whitworth because they appear to be. I'll abbreviate that to just W.

W nut jambs on UNC bolt with less than one thread caught.
UNC nut fits sloppy loose on the W bolt.
Thread count is 11 tpi on both W and UNC.
O.D. on W bolt is slightly greater than on UNC bolt at grip, above the threaded portion.
W bolt thread appears to be slightly radiused in the bottom of the thread cut, but appears nearly sharp at the top. (?) Thread gauge sits just a little high on W bolt.
I have a 55 deg threading gauge that fits on the W thread, but just a little high because the gauge does not have the point radiused.
W nuts take a 1" wrench, close to or at the old W formula. I would like to have one of the old, large W nuts. I believe the UNC 5/8-11 nut is a 7/8 (?) wrench size.

It appears to me to probably be Whitworth but I won't say for sure until I try the fit. Thanks for input.

I think if you get a new nut for it you will have the same problem if all the other bolts are cut the same. Sounds to me like your original assumption that they used a blunt die is correct or they used an obscure standard for BSW. I think your only option moving forward if you want your new bolt to match is to get a die nut and run it up all the threads to finish the thread cutting and then replace all the nuts so they are the same.
15/16" spanner fits a 5/8 UN bolt either UNC or UNF.

Thanks, PhilC, you may be right. But I think instead that I will get a short piece of hex bar and grind a 55 degree tool on a small boring bar. It just seems like a quicker job to just make a nut, and still have the originals in service. The greatest attribute of this old tractor is it's relic value. For best fit for extreme service, I believe you are spot on. This is apparently more of a conundrum than I ever thought it could be. The bolts are special tee heads. I want to keep them and the thread fit is a thing of beauty, but somebody in the past must have lost one and stuck in a machine bolt.