UNS threads

[Great War Truck]

Working on our Peerless truck rebuild we find that the threads seem to be UNS. Was this a common thread size in 1918? We thought that UNC would be more likely?

Thanks

Tim

[edinmass]

Tim......my 1917 White uses USS which was more common back then, but virtually non existent today You need to figure out exactly what you have.......there were multiple options back in the day. I have no answer for you....as I am in a hole right now with the same problem myself. 

[Great War Truck]

Thanks Ed. We thought that we had every thread covered and are now on the search for UNS taps and dies. We will see what we can find.

Cheers

[padgett]

Number of threads in the early 20th was the same as the number of settings on a thread cutting lathe, near infinite.

[edinmass]

1 hour ago, Great War Truck said:

Thanks Ed. We thought that we had every thread covered and are now on the search for UNS taps and dies. We will see what we can find.

Cheers

 

 

If you find USS taps and dies during your search, I would like to purchase them...........👍

[Frank DuVal]

Adding to the confusion, USS is United States Standard. And it is what UNC is based upon:

 

A Unified Thread Standard UNC thread is mechanically interchangeable with a USS thread of the same diameter. However, there are tolerance and other differences between a thread compliant with the USS thread and a Unified Thread Standard UNC thread.

 

Read about USS fasteners here:

 

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

 

Or, of course, Machinery's Handbook. No shop should be without one! No need to buy a new one, as used ones are available, and those thread standards have not changed much in 50 years.

 

There was also small changes in fasteners because of WWII, so our stuff was interchangeable with British standard fasteners, since we were in the Lend Lease Program with them. This led to:

 

https://communities.theiet.org/discussions/viewtopic/807/22803

 

Ed, what have you found different from the 1917 USS and current UNC?

[Great War Truck]

Thanks chaps.

I see that you are in Fredericksburg Frank. I was there a couple of years ago. What a lovely town it is. I ate in the Bavarian chef. Small world.

Tim 

[edinmass]

Frank......EVERYTHING is different.......we have not found a single bolt or nut that works......and we have a bunch of weird stuff on hand..........it looks like the set will get us everything we need............let’s keep our fingers crossed. Right now every fastener on the car is original........we are missing seven pieces, and all the hardware.....and there is a fair amount of it, that held the splash aprons on was used as “stock” for spares. The splash aprons will have modern hardware holding them on.

[padgett]

Now that you know the diameter, TPI, and the formula a good machinist should be able to cut anything you need. Do you have a thread cutting lathe ?

[Ivan Saxton]

On 11/14/2020 at 6:32 AM, edinmass said:

 

 

If you find USS taps and dies during your search, I would like to purchase them...........👍

If you tell me the bolt diameters and the respective pitches I will see what I can come up with.   Thread angle will invariably be 60 degrees.   Perversely, thread angle for Whitworth and British Standard Fine are 55 degrees.    I have never had problem getting whatever taps/dies from local manufacturers.  Patience & Nicholson at Castlemaine,  (who also had capacity for large work for the goldmines in the region), would often make special sizes when they were needed.    The most odd thread I had to cut recently was the taper thread for the water inlet from the pump into the cylinder block of the Roamer Duesenberg.   I also had to do a Metco  thermospray rebuild up of the water pump shaft because that was badly rusted.  I managed to save enough of the rusted stub inlet pipe to get the OD, the pitch, and approximate angle and taper  length.  I made the new stub out of a free- machining stainless with slight sulphur content, I cheated by cutting a parallel thread, and used a thread file of the correct pitch so the tapered thread would just seal correctly in the block.    I wonder how many of these cars and engines were destroyed because this component had such a short finite life.        Ivan Saxton

[edinmass]

Here is the set I was gifted. Seems that vehicles and machinery made in Cleveland Ohio pre 1919 were usually USS. White, Peerless, and Stearns Knight seems to all have used USS. Getting someone to cut threads is now very difficult........you basically need to find a someone who is a hobbiest that is willing to work with you. In southern Florida I have not found that person yet. Up in New England, you can find plenty of machines that will easily do the job.......but the skills to run them are now almost non existent. I have not found a single commercial machine shop in Florida that want to take on the task regardless of willingness to pay. I think I will get by fine now with this set. We need very few pieces. With strange fasteners, you think there would be one speciality company in the world that would take up the slack and make and sell the hardware. Once set up, making multiple pieces is fast and inexpensive. One would expect that customers would gladly pay five to ten times the normal cost of hardware.........I know I would. Making what I need by hand will be acceptable.......but time consuming and not as well done as something made on a lathe.

Edited November 17, 2020 by edinmass (see edit history)

[1950panhead]

1/4-26  https://www.fastenal.com/product/fasteners/bolts/hex-cap-screws-and-hex-bolts/600003?categoryId=600003&level=3&query=1%2F4-26%2Bbolt&isExpanded=true&productFamilyId=25661
5/16-20 = M8 x 1.25 https://www.mcmaster.com/screws/hex-head-screws/thread-size~m8/jis-medium-strength-steel-hex-head-screws/
3/8-18
7/16-18 https://britishfasteners.com/search.php?search_query="7%2F16-18"&section=product
1/2-18

 

[padgett]

Interesting. After graduation from GMI with a dual ME/EE degree I used to think best with a lathe and mill. Later it became a DVM and an O'scope. Was handy because wife wanted a BMW so got a 2000A that had a very low hanging AC compressor (Texas - the other state I'll live in). When she pulled too close to a parking bumper, there went the clutch and I'd need to remove & come to the shop after hours and beat straight then chuck on the lathe to make the V true. Always considered "just another tool" with many atachments.

 

Why when someone mentions an odd thread my first thought is a thread cutting lathe. Never occurred to me it was a lost art.

[Great War Truck]

18 hours ago, 1950panhead said:

1/4-26  https://www.fastenal.com/product/fasteners/bolts/hex-cap-screws-and-hex-bolts/600003?categoryId=600003&level=3&query=1%2F4-26%2Bbolt&isExpanded=true&productFamilyId=25661
5/16-20 = M8 x 1.25 https://www.mcmaster.com/screws/hex-head-screws/thread-size~m8/jis-medium-strength-steel-hex-head-screws/
3/8-18
7/16-18 https://britishfasteners.com/search.php?search_query="7%2F16-18"&section=product
1/2-18

 

Thanks. I will give them a try.

[Restorer32]

Years ago we did a '46 T&C. The front bumper brackets were held to the frame with bolts with a thread we never could identify. We finally decided they must have been war surplus. The bolts were damaged so we resorted to helicoils and regular bolts.

[edinmass]

3 hours ago, Great War Truck said:

Thanks. I will give them a try.

Many of the modern taps are still not the same, as the angle of the thread is cut to 60 degrees and not to the 50(or is it 55. There isn’t a lot of agreement on what was done.) of the WWI era. When installed the bolts just don’t grab correctly. After a few unsuccessful results, I decided to only try for a set of 100 year old tap and dies. I think there was a lot of “in house” fasteners being used. Also, some different applications on the same vehicle. The lug nuts on the rim clamps are regular standard thread. We are taking each fastener one at a time.........if the car wasn’t so original, I would probably go at it from a different approach.

Edited November 16, 2020 by edinmass (see edit history)

[Gary_Ash]

Part of the issue with pre-WWI (and even later) screws and bolts is that the U.S.S. sizes for numbered screws extended beyond what we normally see as 6-32, 8-32, 10-24, etc., and sometimes #12 and #14 screws, plus thread/inch counts that are not common today.  Older cars may not have used 3/8" or 5/16" bolts even if they measure close to those dimensions.  They do have 60° thread angles with flattened tops and bottoms, as do current threads.  Here is a chart of U.S.S. numbered sizes from the Mechanical Engineers' Handbook in 1919:

 

Ed was lucky to obtain a set of taps and dies for some of these.  Note that the current standards for some numbered screws are #6=.138", #8=.164", and #10=.190" body diameter.  We are unlikely to find any 6-36 or 10-30 screws at the hardware store.  You can find 14-24 screws and taps if you look hard, but normally a 1/4-24 or 1/4-20 screw would do the same job.

[JV Puleo]

Perhaps not surprisingly, I consider single-point threading to be about the most useful skill I've learned. I don't think it's a lost art so much as one that simply isn't needed very much any more so fewer people do it...but it isn't hard and with practice anyone with the proper lathe can do it. I probably can't make the tiny sizes...my lathe is simply too big but if one comes along I'd like to get a small tool-room lathe, something like a Rivett, to make small parts. The Rivett was built in Waltham, Massachusetts and it's the lathe that Henry Royce kept at home.

[JACK M]

1 hour ago, Gary_Ash said:

but normally a 1/4-24 or 1/4-20 screw would do the same job.

 

I ran into this on an old Dodge I was working on.

Close but a stale cigar.

I just couldn't force myself to force it.

But I do have the 14-24 tap. And I found the screws.

[padgett]

Glad to see there are still some practitioners in the woodwork who still have the capability to turn oddball threads. BTW my '75 edition of Macinery's Handbook includes UNS  (Unified Special) threads 3/8-18, 7/16-18, and 1/2-18 with all relevant dimensions.

[edinmass]

20 hours ago, Gary_Ash said:

Part of the issue with pre-WWI (and even later) screws and bolts is that the U.S.S. sizes for numbered screws extended beyond what we normally see as 6-32, 8-32, 10-24, etc., and sometimes #12 and #14 screws, plus thread/inch counts that are not common today.  Older cars may not have used 3/8" or 5/16" bolts even if they measure close to those dimensions.  They do have 60° thread angles with flattened tops and bottoms, as do current threads.  Here is a chart of U.S.S. numbered sizes from the Mechanical Engineers' Handbook in 1919:

 

Ed was lucky to obtain a set of taps and dies for some of these.  Note that the current standards for some numbered screws are #6=.138", #8=.164", and #10=.190" body diameter.  We are unlikely to find any 6-36 or 10-30 screws at the hardware store.  You can find 14-24 screws and taps if you look hard, but normally a 1/4-24 or 1/4-20 screw would do the same job.

Thanks Gary.......the Peerless car tap set I have has 26 threads per inch.......and nowhere on the above chart has the 26 tip listed. Basically I think it’s all a crap shoot........now I need to locate an antique thread guage.....my modern snap on guage doesn’t have a 26 in it.......among others that seem to be no longer in use. I have found a handful of other USS taps and dies, but none of them are the correct thread per inch that the White uses. I think it’s a case where I got very lucky on finding the Peerless kit.......which has two broken taps......that can be ground and used again. I’m hoping to get away with what we now have on hand. Many of the bolts I need are for the firewall which has cast sections and I don’t want to retap them to something different.

Edited November 17, 2020 by edinmass (see edit history)

[padgett]

Even HF has a small one: https://www.harborfreight.com/7-inch-x-12-inch-precision-mini-lathe-93799.html. Along with a mill to create a head the proper size, you can get started with an assortment of tools and a mill vise for about $2k.

 

Several careers ago I needed a mill and lathe to think about how to design things properly.

 

 

 

Edited November 17, 2020 by padgett (see edit history)

[JV Puleo]

3 hours ago, edinmass said:

Thanks Gary.......the Peerless car tap set I have has 26 threads per inch.......and nowhere on the above chart has the 26 tip listed. Basically I think it’s all a crap shoot........now I need to locate an antique thread guage.....my modern snap on guage doesn’t have a 26 in it.......among others that seem to be no longer in use. I have found a handful of other USS taps and dies, but none of them are the correct thread per inch that the White uses. I think it’s a case where I got very lucky on finding the Peerless kit.......which has two broken taps......that can be ground and used again. I’m hoping to get away with what we now have on hand. Many of the bolts I need are for the firewall which has cast sections and I don’t want to retap them to something different.

 

See if you can find one for "British Standard Cycle" - 26 tpi was used for most of the smaller sizes.

Also, if you need a special tap made I'd try Victor Machine — I think they are in Brooklyn.

[padgett]

Its all out there, just a different hobby, guess schools no longer teach "machine shop". Sometimes I wonder if the car hobby is becoming too specialized. Remember working at Tracor in Austin in the 70's (back when was mostly ME). and having to make the tools to make the tools...

[edinmass]

On 11/16/2020 at 3:37 AM, Great War Truck said:

Thanks. I will give them a try.

 

They don't fit correctly because of the thread angle...........it seems 55 is not correct......we tried Whitworth as we stock it here in out shop for Rolls Royce cars..........it just damages the threads and will not tighten. I used the Peerless set to make some bolts today, and it worked fine. 

[padgett]

Synapse fired that the thread was originally developed by the ALAM which may explain things.

[Gary_Ash]

1 hour ago, padgett said:

Even HF has a small one: https://www.harborfreight.com/7-inch-x-12-inch-precision-mini-lathe-93799.html. Along with a mill to create a head the proper size, you can get started with an assortment of tools and a mill vise for about $2k.

 

Several careers ago I needed a mill and lathe to think about how to design things properly.

 

 

 

 

I bought the Harbor Freight 7x10 mini lathe, found the bed was not really long enough to put a 1/2" drill bit in the tailstock chuck with work in the lathe chuck.  Also, the 3" 3-jaw chuck can't really grab anything very big so the 7" nominal swing can't normally be used.  I went to the Little Machine Shop web site and bought a 16" bed with leadscrew and moved the motor, gearbox, cross slide, and tailstock to the new bed.  I also bought a 5" lathe chuck.  Now I can put some decent sized stuff, but not large items, into the lathe.  The biggest limitation is that the motor doesn't have enough torque to take a deep cut, so 0.010" per pass is about the limit in cold-rolled steel.  The current price of the HF 7x12 lathe is about $700, the 16" bed from Little Machine Shop is about $200, and the 5" chuck is $154.  For the money, the Little Machine Shop HiTorque 7x16 lathe with 4" chuck is a better deal at $1100, has about 3 times the low speed torque of the HF unit.  Both the HF and LMS machines will cut nearly all of the USS/UNS/UNC/UNF and metric threads, including non-standard ones.  But, these are still "toy" lathes compared to the real industrial stuff.  I have turned 2" steel bar stock, cut threads, and done many other jobs in my lathe - it just takes time.

 

HF 7x10 lathe with 3" chuck upgraded to 7x16 bed with 5" chuck.

 

Edited November 17, 2020 by Gary_Ash (see edit history)

[edinmass]

Gary......I agree for a garage project that set up is fine.....only one problem........I don't have the talent or experience to do good work. I would need to make 20 bolts to get five decent ones..........maybe we can get you into the 3 D printing, casting, and custom bolt business............help pay for the Stude!👍

 

Having a classicial engineering background such as you have, and all of it's practical applications is a HUGE advantage for fabrication and design. When we were racing, we always had guys who couldn't tune a carb or ignition, but they could fabricate anything needed out of scrap and make it look like NASA made it. This hobby just has so many unusual skill sets it boggles the mind.

[Amestryyz]

Tim......my 1917 White uses USS which was more common back then, but virtually non existent today You need to figure out exactly what you have I am currently doing research on it will come back and give you depth detail on this...thank 

[edinmass]

1 hour ago, Amestryyz said:

Tim......my 1917 White uses USS which was more common back then, but virtually non existent today You need to figure out exactly what you have I am currently doing research on it will come back and give you depth detail on this...thank 

What do you have for a 1917.....car or truck? 

[padgett]

I agree, learned mainly on Cincinnati Milacron machines, just pointing out that a small thread cutting lathe for a starter is not very expensive. Add in a small mill to shape the head and have all you need to learn what you really want for a minimal initial outlay. May also find larger machines on CraigsList.

[A. Ballard 35R]

 

Ed, I have several sets plus miscellaneous thread gauges. I don't think the BluePoint metric one is of much use to you but the Craftsman set has a 26. There are also a number of S. W. Card, Mansfield, Mass gauges with everything but a 26. In addition there are many taps and dies. Are there any of them you need to replace the broken ones you have?

 

PM me your address and I'll send the Craftsman set off to you.

[Gary_Ash]

Yes, Ed, you might have to make 20 bolts to get 5 good ones in the beginning, but then you would have learned new skills and the next job would go easier.  For jobs like making USS bolts, the driving force is frequently time:  I need it now, not in 3 weeks when the local machine shop can do it for me.  It also doesn't take many outside jobs to cost more than a machine you own.  As Padgett says, a small mill/drill complements the small lathe.  I picked up a very used Rong Fu RF-25 mill/drill with a 28"x8" table for $500 (now $2000-$2500 new), built a stand for it out of angle iron to support its 440 lbs.  It would do your bolt heads easily enough, though an added rotary table might help if you can't buy hex stock the right size.  To avoid further hijacking this thread, maybe we should have a new thread on shop tools for car restoration.

 

Rong Fu RF-25 mill/drill with 28"x8" table, manual X-Y motion.

[padgett]

Agree, precision (at least automotive precision) machining is not hard to learn with the proper tools. Can have a good start for less than the price of a lift.

 

Is that part of an inline 6 exhaust manifold ?

[Gary_Ash]

Padgett:  The manifold is for a straight 8.  See thread in Speedsters, about half way down Page 3.

 

[edinmass]

Success with the new tap and die kit from Peerless..........made two bolts for the horn. Need to get some bolts with a correct parkerized finish to work with. Two of my taps are broken.....and need to be ground. Since they are made of unobtainum I will ask Joe P to grind them for me. 

Edited November 18, 2020 by edinmass (see edit history)

[Gary_Ash]

Ed, see the Wikipedia article on Parkerizing.  Your 1917 White may have used an iron phosphate process on the bolts but later manganese or zinc phosphate processes may give you the same black in an easier process.  You just need the chemicals, a beaker, and a hot plate to turn the bolts gray or black, easy and cheap to buy.   Don't do this on the kitchen stove at home!

[edinmass]

Gary....I have a Walmart hot plate that provides all sorts of heat for the restoration process. We often will place a 3/8 thick piece of steel on it and use it as a surface  heater for components that are difficult to get apart. Just raising the temperature up to 300 degrees will most often make things come apart. Also keeps peace in the home as we are not working in the kitchen. We also have an old oven at the shop to heat up the larger items. 

[edinmass]

UPDATE:

 

Thanks to my personal machinest and super talented Joe P, knower of everything from the 17th to the 20th century, I have found a source for most of the obscure taps and dies that are modern, and affordable. Joe.....your the BEST!

[JV Puleo]

And...as a general "heads up" for membership of this forum , the source is the Victor Machine Company. They are in Brooklyn, NY and carry an enormous line of taps and dies in obscure sizes. We found all but one that Ed needed in their on-line listing...and the odd one, 1/8-40, is available on Amazon. The first thing I bought  from them (they were recommended by one of my antique machinery friends) was an odd tap to make a big knurled nut for a Brown & Sharpe milling machine built around 1900-1902. (This was before I learned to thread.) Victor does have a $25 minimum order but if you are doing this sort of work it's hard not to spend that much!