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Thread Pitches

G Willikers

Subscriber
Last Subscription Date
06/03/2020
This might be something worth talking about in this new forum. Does anyone have expertise in the area of thread pitches?
All I know is that I have different lots of old square nuts and bolts because there were different thread pitches used over the years.
Some companies seemed to use their own pitches.
British threads were different.
Then of course, there is metric!
Any thoughts?
 

uglyblue66

Subscriber
Last Subscription Date
11/07/2018
I aint real smart on this subject for sure.But my dad was on a crew that built the large power line towers and the bolts were galvanized.The threads were slightly different as the nut had to screw over the coating or something.Maby someone else can understand what I mean but I know those nuts won't work on a standard bolt and a standard nut won't thread right on the galvanized bolt.
And on the Model T Ford,there is 4 bolts, 1/4 in size that hold the bendix cover on the transmission hog head. Those bolts have a unique thread and if you loose them you have to get some thru the suppliers. Henry had a squabble with the company making bolts .
 

David Hoover

Subscriber
Good question, prior to WW1 a 12 tpi, 60 degree thread was pretty popular, Sawyer Massey and a lot of the Ontario steam company’s used it. Along with a lot of nuts fitted to bolts makes for fun reassembly some times. Standardized threads were a deffinate improvement! Didn’t George White buy a screw company at one point?
 

Pat Barrett

Subscriber
Age
71
Last Subscription Date
01/02/2020
Ugly blue, The 1/4" funny thread pitch you mentioned was probably 1/4-24. It was common after the turn of the century. Harley and Indian also used it.
 

David Hoover

Subscriber
Here’s a good breakdown of the screws development. I think one of the biggest variables would have been the people making them. Accurate and consistent measuring tools along with the people to properly use them would determine the consistency of a good product. I found when working on the early Sawyer gas tractors that if you had 3 nuts and three bolts you better keep them paired together, because there wasn’t two the same. https://www.nord-lock.com/insights/knowledge/2017/the-history-of-the-bolt/
 

Pat Barrett

Subscriber
Age
71
Last Subscription Date
01/02/2020
David, back in the 70's I helped a friend, here in town who some how had gone to Lousiania and leased a narrow gauge steam Locomotive to restore. Her name was Stephanie and she was a 36" Gauge Dickson. Some of the drive arm bolts were missing, so we took a good one out and had it duplicated, Wouldn't fit. They made a hole, then made a bolt to fit the hole, nothing standard.
 

G Willikers

Subscriber
Last Subscription Date
06/03/2020
I have an early newspaper account, buried here somewhere, of two companies, Goold Shapley & Muir and the Waterous Engine Works Co. opening a joint facility for making nuts, bolts, etc.. I forget the date but maybe pre-1910.
I know from working on both company's products, that they seemed to use an obsolete thread pitch, or even their own thread pitch. It is what it is when you are restoring this stuff.
 

DSRemodel

Registered
Last Subscription Date
01/20/2016
my dad was an engineer for a fastener mfg. co. I recall him getting a government job done for a magneto rebuilder. it was a short flat head brass screw with 1/4-27 threads. I still have the roll thread dies
 

Frank DeWitt

Subscriber
Last Subscription Date
12/17/2019
As a mechanical designer I run into odd threads on a regular bases. Just some examples.
Davenport screw machines have there own thread about the same size as a #10

miniature toggle switches are 1/4-40

The optics industry has many odd threads. A microscope thread MAY be .8 x 36 Whitworth form

Then there is the "standard" C mount lens thread (1.0-32)

Because of my optics work I know where to buy taps for 1/4-80 3/16-100 and 1.035-40 among others.

BTW as far as I can tell there is no standard for plastic bottle threads such as coke or water bottles.

“The wonderful thing about “standards” is that there are so many to choose from!"
 

David Hoover

Subscriber
I worked in a place 20 years ago that had a bunch of Davenport screw machines, what an amazing thing to watch, with great potential to be mind boggling. A couple of them were making GM brake bleed screws, with about a 10 second cycle time...
 

Jake Jacobs

Registered
I worked in a place 20 years ago that had a bunch of Davenport screw machines, what an amazing thing to watch, with great potential to be mind boggling. A couple of them were making GM brake bleed screws, with about a 10 second cycle time...
schwinn bikes and Singer had their own threads.
 

Frank DeWitt

Subscriber
Last Subscription Date
12/17/2019
I worked in a place 20 years ago that had a bunch of Davenport screw machines, what an amazing thing to watch, with great potential to be mind boggling. A couple of them were making GM brake bleed screws, with about a 10 second cycle time...
Agree. A amazing machine. They can make a schrader valve. or a BNC connector body with continuously rotating stock. Seems impossible.
 

Rob Charles

Sponsor
Last Subscription Date
04/05/2017
There are a whole bunch of brass work threads. 3/4"-27 etc.27TPI is pretty common Lunkenheimer used a lot of weird threads. The thread on the larger Crowns and royals is like 9-32" 27 Makes for a pita to make replacement parts . Years ago I had to make an adapter to fit onto the pull out spout on a 5 gal pail. Its a weird buttress thread. Rob
 

Ronald E. McClellan

Subscriber
Last Subscription Date
01/05/2020
Several years ago I had to buy a gear for my lathe to make a 11/16 - 30 to repair one of my electrical machines. It seams that no one can make a 30 ! This spring I made a 7/16 - 20 For an oil cap that was missing on my C & C dynamo. Ron
 
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