1/2 inch by 11 thread bolt ????

[werowance]

someone asked me if I had a 1/2 inch by 11 thread die that I could make a new bolt for an antique grist mill. I have not seen the bolt but I cant find that is even a normal thread. I cant imagine they would have custom made the threads for a weird count in a piece of farm machiniery.

so guess my question is am I wrong that its not a normal thread if it really is 1/2 x 11?

and I'm not about to single point thread cut it on my lathe as I am terrible at that. usually just start a thread enough to make it easier to run the die on it.

 

[werowance]

and the more I think about it, he said the head was a 3/4. I'm wondering if it would be 5/8 x 11 with a 3/4 head?

 

[BaronJ]

If its antique then it could possibly be, or 9/16 unc.

 

[Charles Lamont]

5/8" x 11 TPI is a Whitworth size. Heads went smaller after a while so unless it is really old it would likely fit a spanner marked 9/16 W 5/8 BSF.

 

[mortimer]

hi the head of bolts in the UK went down a size during the second world war to save metal

 

[chrsbrbnk]

some of the antiques have fasteners that were before the unified standards always sorta throw you for a loop . where I used to work we had a customer that made grain sorting machinery , designs that were pre WW1 and alot of their production tooling had bolts that were pre unified !!! (this was just 2 years ago) have to rebore the head reliefs and stuff like that to use new bolts

 

[William May]

If you have a Machinery's Handbook" you can look under screw threads and find the wide variety that are actually in the tables.
I do a lot of work on antique cars (Before 1916, NOT used cars like 1965 Mustangs!) When I run across an odd thread, I usually order a tap and a die for whatever work I am doing. If you use one (the tap.) you will eventually need the die)
My 1/2" taps and dies currently range: 11, 12, 13, 18, 20, 24, 32 tpi. Also, I have the L/H taps and dies for most of those.
If you are working on old equipment, you need to be VERY careful to identify the thread you are working with. Use a caliper to determine the actual major diameter, and then a thread gauge to determine the actual thread.
A lot of people say "Oh, there was no thread standard in the old days, so they are all odd!" This is NOT true. The U.S. 60 degree thread was well-established BEFORE the Civil War. Virtually all U.S. manufactured equipment since the Civil War uses the 60 degree thread. It is just the pitch that can be odd. Although some manufacturers picked odd pitches for technical reasons, or to make their equipment less tamper-prone.
The ONLY place I have seen REALLY odd threads is in antique magical equipment. Magician Machinists used nearly all special threads, made with screw plates, instead of dies. Why they did this, I do not know. It may be because they were typically using the same threads as watchmakers. (I found this out from a club member who is renowned for his magical equipment. He also restores antique magical equipment as well, and he has a HUGE collection of screw plates and is always buying more.)
A good example of an odd thread that was commonly used is 1/4-24. This was known as the "Harley ******* Thread". But actually, it was a common standard thread in the early part of the century. If you look at a Harley part number, there are 2 digits that tell you the year the part was first used on a Harley. The oldest part I have found on my 1961 Pan Head is the clutch operating shaft, which shows it was put in production in 1903

 

[Bessemer20]

Some manufacturers used proprietary threads so you had to go back to them for replacement parts. Quite common in the early 1900s.

 

[Wizard69]

This has already been covered well but it is worth pointing out that Unified Threads came about after WW2 due to the need for compatibility with US and British standards. There where standards before that but lets put it this way far too many standards. What isn't also well known is that not all of those standards where of English measurement, very small watch and instrument screws where metric. Before WW2 in the US the most common standard was the Sellers thread which evolved into USS. It would take over 34 years from the advent of the Sellers standard until the first standard metric thread form was established in 1898.

When I mention most common in the USA it liteerally meand just that. The Sellers thread became the standard by adoption by the US government, Pennsylvania Railroad and the Locomotive manufactures. This highlights just how much power and influence the railroads had at the time as they where instrumental in Sellers thread rise in acceptance. That doesn't mean there where not dozens of other thread forms floating about from the mid 1800's on.

I did a lot of reseaarch on threads a few years back because I was considering buidling a app for the iphone. The app never really happened because frankly a better solution beat me to it. However it is fascinating to look at the history of screw threads and realize how long it took for industry to see the value in standard threads. It took WW2 to get the English based countries to knock heads together on a common standard. If it wasn't for the railroads we would have an even bigger mess these days.

 

[SmithDoor]

I have only seen one 1/2" 11 bolt and nut
I do not know why it was made but it was a odd ball for bolt and nut
I try find out and used books on threads dating back to 1910 and was not listed

Dave

someone asked me if I had a 1/2 inch by 11 thread die that I could make a new bolt for an antique grist mill. I have not seen the bolt but I cant find that is even a normal thread. I cant imagine they would have custom made the threads for a weird count in a piece of farm machiniery.

so guess my question is am I wrong that its not a normal thread if it really is 1/2 x 11?

and I'm not about to single point thread cut it on my lathe as I am terrible at that. usually just start a thread enough to make it easier to run the die on it.

 

[William May]

Have them send a drawing to me, and I can make if for them. No problem. I have that die in my tapping desk.

 

[werowance]

Have them send a drawing to me, and I can make if for them. No problem. I have that die in my tapping desk.

Thanks William, I will ask them if they still need it, they probably do. it about 1.5 inches long and 3/4 inch head.

where did you come up with a 1/2 x 11 die if you don't mind me asking?

 

[William May]

I have been ordering special taps and dies for the last 30 years or so. If I see one, and the price is reasonable, I will buy it. Like some people have a toolbox, I have a tapping desk, with a "Universal Pillartool" mounted on top for tapping, and then drawers below for all the taps and dies, in sets.
As I said, I do a lot of work on antique cars, and I also do a lot of work on scale steam locomotives.
Taps and dies are kind of like mice. When you aren't looking, they seem to multiply. So I had to do something to keep them organized.
If you google the "Universal Pillartool" you will see a tool very similar to an industrial "hand tapper" but much more useful and with many more applications. It was designed by the late George Thomas.

 

[werowance]

I have been ordering special taps and dies for the last 30 years or so. If I see one, and the price is reasonable, I will buy it. Like some people have a toolbox, I have a tapping desk, with a "Universal Pillartool" mounted on top for tapping, and then drawers below for all the taps and dies, in sets.
As I said, I do a lot of work on antique cars, and I also do a lot of work on scale steam locomotives.
Taps and dies are kind of like mice. When you aren't looking, they seem to multiply. So I had to do something to keep them organized.
If you google the "Universal Pillartool" you will see a tool very similar to an industrial "hand tapper" but much more useful and with many more applications. It was designed by the late George Thomas.

William, I spoke with the gentleman who wanted the bolt last night and he is interested, would it be ok if I pm you some information and ask about cost etc?

 

[William May]

William, I spoke with the gentleman who wanted the bolt last night and he is interested, would it be ok if I pm you some information and ask about cost etc?

Soitenly!

 

[William May]

Has he seriously thought about just running a 1/2" -12 tap through, and calling it a day? Much cheaper, and the problem is over with.
It it's just one bolt, it would probably be about $10 total. I need a drawing with all the dimensions. Also, what kind of material? if this is an old bolt (which I would think it IS, based on the obscure thread) then probably mild steel would be fine. But it is hardened? or made of some special steel, as far as he knows?

 

[werowance]

pm sent William, I appreciate it.

 

[Wizard69]

Has he seriously thought about just running a 1/2" -12 tap through, and calling it a day? Much cheaper, and the problem is over with.
It it's just one bolt, it would probably be about $10 total. I need a drawing with all the dimensions. Also, what kind of material? if this is an old bolt (which I would think it IS, based on the obscure thread) then probably mild steel would be fine. But it is hardened? or made of some special steel, as far as he knows?

Please no. This likely an old iron casting that might not take kindly to thread abuse. With a little gogglig you can find a vendor like: High Speed Steel Special Pitch Taps | HSS Special Thread Taps which lists at least one tap.

 

[William May]

Please no. This likely an old iron casting that might not take kindly to thread abuse. With a little gogglig you can find a vendor like: High Speed Steel Special Pitch Taps | HSS Special Thread Taps which lists at least one tap.

NAH! If this thing is as beat-up as he says, it will probably not even notice a 1/2-12 tap going through it, much less stress over it. I'd be amazed if he even gets any real tapping action out of it, other than removing a few high spots. This idea was slanted towards him minimizing the money and future trouble this little detail is going to cost him.

 

[goldstar31]

William


Is your UPT to Geo Thomas's design please? I'm having to unearth the mine to stamp the numbers on the Worden tool grinder. Apparently George had a hand in the machine design - or perhaps it was it the earlier Kennet?