Help identify this tap?

[Karbyde]

The only markings on the shank are the mfr. name/location and the pitch marking of 26 tpi. It's taper is similar to a pipe tap. The small end is chipped but looks like it was .250 diameter when new, the large end diameter is .500

I acquired this unique tap quite a few years ago, it was found in the bottom of dad's toolbox along with other rusty, banged up bits and taps. I never saw one like this during my tenure in a machine shop and don't know what application this tap would be used for other than thread repair of damaged 26 tpi threads. I spent some time looking online for info, and it appears 26 tpi is a BSC standard used for bicycles and on vintage motorcycles. I could find no info regarding the taper.

"British Standard Cycle (BSC or BSCy) is a British Imperial screw thread standard. Unlike other major British imperial thread standards (British Standard Whitworth and British Standard Fine) the thread runs at a 60 degrees rather than a 55 degrees angle. All sizes 1⁄4 inch and larger use 26 threads per inch (tpi), making them similar to 1 mm ISO threads, which are 25.4 per inch and also run at a 60 degrees angle. It was originally used with both bicycles and motorcycles.[1] However it is now believed[by whom?] to be obsolete in motorcycle manufacture. In the bicycle industry it is still found on virtually all bottom bracket threads and the wheel axles of low-end models manufactured in China,"

 

[SmithDoor]

The only markings on the shank are the mfr. name/location and the pitch marking of 26 tpi. It's taper is similar to a pipe tap. The small end is chipped but looks like it was .250 diameter when new, the large end diameter is .500

I acquired this unique tap quite a few years ago, it was found in the bottom of dad's toolbox along with other rusty, banged up bits and taps. I never saw one like this during my tenure in a machine shop and don't know what application this tap would be used for other than thread repair of damaged 26 tpi threads. I spent some time looking online for info, and it appears 26 tpi is a BSC standard used for bicycles and on vintage motorcycles. I could find no info regarding the taper.

"British Standard Cycle (BSC or BSCy) is a British Imperial screw thread standard. Unlike other major British imperial thread standards (British Standard Whitworth and British Standard Fine) the thread runs at a 60 degrees rather than a 55 degrees angle. All sizes 1⁄4 inch and larger use 26 threads per inch (tpi), making them similar to 1 mm ISO threads, which are 25.4 per inch and also run at a 60 degrees angle. It was originally used with both bicycles and motorcycles.[1] However it is now believed[by whom?] to be obsolete in motorcycle manufacture. In the bicycle industry it is still found on virtually all bottom bracket threads and the wheel axles of low-end models manufactured in China,"

It tap for fine adjusting.
I have only seen in books.

If I need adjustment I used a pipe tap and die a lot cheaper.

Dave

 

[djc]

If we speculate that it is cycle thread, we have to explain how it would be useful as a tapered item.

In the UK, we have another old 26 tpi thread standard, British Standard Brass (https://britishfasteners.com/threads-bsb).

That was used when decorative things were made: generally constructed from relatively thin walled tube.

But it still does not explain the taper.

 

[Drillrod]

The only markings on the shank are the mfr. name/location and the pitch marking of 26 tpi. It's taper is similar to a pipe tap. The small end is chipped but looks like it was .250 diameter when new, the large end diameter is .500

I acquired this unique tap quite a few years ago, it was found in the bottom of dad's toolbox along with other rusty, banged up bits and taps. I never saw one like this during my tenure in a machine shop and don't know what application this tap would be used for other than thread repair of damaged 26 tpi threads. I spent some time looking online for info, and it appears 26 tpi is a BSC standard used for bicycles and on vintage motorcycles. I could find no info regarding the taper.

"British Standard Cycle (BSC or BSCy) is a British Imperial screw thread standard. Unlike other major British imperial thread standards (British Standard Whitworth and British Standard Fine) the thread runs at a 60 degrees rather than a 55 degrees angle. All sizes 1⁄4 inch and larger use 26 threads per inch (tpi), making them similar to 1 mm ISO threads, which are 25.4 per inch and also run at a 60 degrees angle. It was originally used with both bicycles and motorcycles.[1] However it is now believed[by whom?] to be obsolete in motorcycle manufacture. In the bicycle industry it is still found on virtually all bottom bracket threads and the wheel axles of low-end models manufactured in China,"

Very interesting tap. So, who's the manufacturer and what's the location?

 

[Karbyde]

Reece Co., Greenfield, Mass.

 

[Drillrod]

That helped! There's info on the internet about the Reece Company, which specialized in taps and dies for the pipe industry. After merging with the Wells Tool Company, Reece was eventiually absorbed into the Cleveland Twist Drill Company. The tap in question was manufactured not only by Reece but other companies as well, and was referred to as a "taper tap", as per the attached catalog page from JM king and Co. 1888. In the book, Tool Making 1905 (Lost Technology Series--Lindsay reprint) these taps were used in "machine tapping" as opposed to "hand tapping."

 

[Karbyde]

"Tool Making 1905 (Lost Technology Series--Lindsay reprint) these taps were used in "machine tapping" as opposed to "hand tapping.""

In the book, Is there any info about the process of using a tapered tap and what it was used for? I did find some info about repairing cracks in cast iron using a tapered tap and threaded plug process. I dont think it is used much these days.

 

[Drillrod]

"Tool Making 1905 (Lost Technology Series--Lindsay reprint) these taps were used in "machine tapping" as opposed to "hand tapping.""

In the book, Is there any info about the process of using a tapered tap and what it was used for? I did find some info about repairing cracks in cast iron using a tapered tap and threaded plug process. I dont think it is used much these days.

I'll check later and post a scan of it if applicable.

 

[Drillrod]

Ok. These taps were apparently used in the mass-production of threaded nuts. The explanantion given in the book is not very technical but apparently the nuts were threaded and then manually removed from the shank of the tap where they collected.

 

[BaronJ]

Hi Guys,

All the automatic nut threading taps that I've seen and used are curved, looking like a letter "J". The tapped nut slides down the shaft round the "J" bit and falls off the end into a bin. The tapping machine looks very similar to a lathe.

 

[Drillrod]

Hi Guys,

All the automatic nut threading taps that I've seen and used are curved, looking like a letter "J". The tapped nut slides down the shaft round the "J" bit and falls off the end into a bin. The tapping machine looks very similar to a lathe.

Out of curiosity, when was that?

 

[djc]

It is not a nut tap. Totally the wrong shape (short shank above the threaded part and the taper goes the full length of it).

A nut tap has an extended lead in but it also has some length of parallel threads and then a long shank that is smaller than the minor diameter of the thread, so the nuts can collect there. See:

https://threadingtoolsguide.com/en/blog/short-wiki-about-the-nut-tap/

The J-shaped taps are used on a one one-trick pony nut threading machines. The J-bit is normally removable/separate for when the cutting edges wear out:

https://scorta-taps.com/products/type-r/

I only came back here as I saw this today:

https://www.fondera.co.uk/irontite-crack-repair.html

It is a cast iron stitch repair product that uses a fine thread tapered plug. What sort of tap would it require?

 

[Karbyde]

I think cast iron stitching is what this tap was used for. My dad had an auto/tractor repair shop in the 60's, I bet he bought a set like this for a repair job.

 

[Drillrod]

After scrutinizing the relieved threads on the end of the tap in the Tool Making book and comparing them with yours, I agree that what you have there is for cast iron stitching.

 

[djc]

I think cast iron stitching is what this tap was used for.

Is there any easy way to determine what thread pitch is used on current or historical stitching screws?

That would either verify or further muddle up the 26 tpi written on the tap.