OT - Question about measuring threads

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Model T Ford Forum: Forum 2017: OT - Question about measuring threads
Top of pagePrevious messageNext messageBottom of page Link to this message  By Erik Johnson on Saturday, June 03, 2017 - 11:16 pm:

I recently picked up some Craftsman stackable tool chests filled with tools at an estate sale.

Included were the three drill press handles below.

Before tossing them into the scrap metal bin for recycling, I thought I would try to sell them on eBay to recoup some dollars.

I'm posting here because I know folks are knowledgeable usually quick to respond.

The thread diameter is 31/64" according to my drill gauge.

The pitch is 12 TPI according to my thread pitch gauge.

Is the above considered 1/2" x 12 TPI, even though the diameter is 1/64" shy of 1/2"?

I know the threads are not metric because I have a metric micrometer and metric thread pitch gauge - the diameter is not an even number of millimeters and none of the metric pitch gauges fit.

Thanks for your help.

1

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Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Schedler, Sacramento on Sunday, June 04, 2017 - 12:52 am:

See if the thread coincidentally matches metric. A lot of the drill presses are/were made in Taiwan.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Schedler, Sacramento on Sunday, June 04, 2017 - 12:53 am:

Sorry, I didn't read close enough


Top of pagePrevious messageNext messageBottom of page Link to this message  By George Mills_Cherry Hill NJ on Sunday, June 04, 2017 - 01:14 am:

Depends on how old...

They are not metric based on the imperial size given.

My guess? They are to original 1/2" x 12 USS with a twist that was very common years ago. Their handles fit everyone else's...but real to size thread by others would not fit into their units female threads!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Erik Johnson on Sunday, June 04, 2017 - 01:26 am:

That's okay.

1/2" x 13 TPI is standard in the U.S. today. (1/2" x 12 TPI was common approximately 100 years ago in the U.S.)

In my Google searches, I found the following info:

- 1/2" x 12 TPI is British Standard Whitworth thread and was very common in the UK prior to their conversion to the metric system.

- 1/2" x 12 TPI bolt threads are common in Chinese manufactured power tools.

- It was also suggested that some higher-end U.S. power tool companies like to use uncommon thread sizes in order to keep replacement parts proprietary and discourage the manufacture of aftermarket replacement parts.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Sunday, June 04, 2017 - 04:09 am:

M12x2 exists, even though M12x1.75 is standard. Would probably have showed 15/32" on the drill gauge though, since 12mm is about 0,472". 2mm pitch would be 12.7 tpi while 1.75 mm would be 14.5 tpi.


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Menzies on Sunday, June 04, 2017 - 04:15 am:

I have a Taiwan(previously Formosa) drill press with 1/2" - 12 TPI handles with a very sloppy fit
probably as you have determined 1/64th under. I bought this drill press in the 70s and it was used then, therefore it could be 60 years old.

In the KBC Tool and Machinery catalog they list a
1/2" - 12 TPI in the special tap section.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Allan Bennett - Australia on Sunday, June 04, 2017 - 04:29 am:

Whitworth and UNC are interchangeable, except for 1/2".This is the one size where the number of threads/" differs. UNC is 13 tpi and whitworth 12 tpi.
I have it from a reliable source the difference between the two is the angle of the thread, 55 degrees rather than 60 degrees. I have no reason to remember which is which.

Allan from down under.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Humphrey on Monday, June 05, 2017 - 09:40 am:

Maybe an ACME thread AKA(power screw threads)
I have ran across some of these before. I am sure some of our machinist here will be able to help...


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