Ebay find, well, semi-find
I have a soft spot for tap and die sets, and nice old original sets with odd-ball sizes are even better. So here are some pics of a Little Giant set I recently scored off of the bay.
Last pic I was trying to show off the case hardening, but it doesn't show well. These are the smallest little giants I have ever seen. The sizes in this set are 1/4x20, 7/32x24, 3/16x24, 5/32x36, 1/8x40, 3/32x48, and the ever popular 1/16x64.
These will go well with the big set I picked up a couple years ago for the staggering sum of a C note. I couldn't tell it had ever been used.
You can still get little giant style dies and collets at McMaster. Bring yer wallet, though. Still, good if you need to complete a set.
Also, you can grind out individual teeth on a die and make it work. Something about that snaggle tooth that hangs everything up and makes the die burr over the thread.
Got a couple of LG sets. Both with 4" collets. One was USS fine thread and the other was NC thread. The NC set was complete and very close to not used. The NF set not so good.
Another treasure of mine is a Henry Hanson 1" round die set in a wooden box. Virtually unused. I almost want to go get a bunch of Chinese 1" round dies to use in it just to save it. Anything of this ilk made in America is worth keeping as a memento now.
Joe in NH
Very nice. I have the more common 1/4"-to-3/4" NC set and use it occasionally. I've never seen a small set like that for sale complete and in good shape.
thnx, jack vines
Speaking of odd taps, I just picked up a box of about 200 small assorted taps on ebay, obviously from some old machinist's box. Picking through them, they were mostly standard US sizes, but there were a couple of oddballs.
One I found in particular is a 1/2-12, which looks quite old.
There's also a 1/4-25, which looks to be a home made custom tap.
I also found a pair of 1/2-10 Acme taps, RH & LH
If any of you need to borrow one of these for a restoration project, let me know.
The 1/2-12 are common on older machines. This was a "standard" of sorts long before the concept of "vendor defined building standards" such as the 8 thread bolts that Westinghouse made famous on their large steam turbines - and which was a way to guarantee return business. 1/2-12 are available from places like MSC who do an active trade with someone on the pacific rim who can produce these sort of things on an "on demand" basis.
The 1/4-25 was a tap that was used on Ford Zenith Carburetors of various ilk. Main jet? Steve Pargeter has written up extensively on rebuilding the Ford Model A Zenith carb and mentions using a metric thread tap that is "close" (but not exact) to replace this.
It all starts with Little Giant. Pretty soon it will be variations on this to include Greenfield Tool & Die and their predecessors Wiley $ Russell. I think the Strelinger Tool Catalog Reprint (1896?) has quite a bit of information on the historical origins of systems of thread & die sets. They describe the three I've cited above.
It's amazing that so many of these started in Greenfield, MA. I spent a good amount of spare time at the Best Western Inn in Greenfield and toured externally the city(town) of Greenfield and these former industrial seats. Why an obscure turn of the Deerfield and Connecticut Rivers should become a worldwide industrial center of thread cutting machinery and tooling still defies logic.
The interrelationship between the cutlery and machine tool industries of that area is interesting also and bears your further reading. See "The Conservative Rebel: A Social History of Greenfield, Massachusetts" by Paul Jenkins which you may find at your local library or at www.abebooks.com.
Joe in NH
" The 1/2-12 are common on older machines. This was a "standard" of sorts long before the concept of "vendor defined building standards" such as the 8 thread bolts that Westinghouse made famous on their large steam turbines - and which was a way to guarantee return business. 1/2-12 are available from places like MSC who do an active trade with someone on the pacific rim who can produce these sort of things on an "on demand" basis."
It will be common all right.1/2" BSW or British Standard Whitworth.Still being made and used in large quantities right up to the 1970`s.
Careful to genericise BSW with USS. BSW is a 55 degree threadform and USS is 60. I have a woodworking lathe made in central Massachusetts in the mid-1850s and it utilizes BSW threads. (The tap & dies of which were perhaps more available in those early times.) A 3/8" NC USS bolt will thread into it (same TPI), but the engagement is "tight" and possibly with local deformation.
And ditto, the similarity is recognized. A square head jointer of my experience used 1/2-12 bolts 60 degree V thread pattern bolts to hold the two cutter blades in place. Considering the centrifugal force and the poor appearance of those original SQUARE headed bolts, (probably hand forged) I opted instead to go for high strength BSW bolts to replace the originals. These are equivalent to USS "grade 8" bolts and their use raised my confidence levels extremely. They were bought rather reasonably, as I remember it.
I'm an "equal opportunity" mechanic and if it works, I'll go with it. Hard to find BSW dies on this side of the pond. Mostly from Motorcycle specialty shops. Best price I've seen is about $24 American - but I may not be looking in the right place.
The fractional threads smaller than 1/4" are called Sellers Threads.
I learned this fact right here on PM when I posted about my Little Giant set which is identical to yours !
I'm missing all the Sellers taps, though.
1/4"(6.35mm) X 25 similar to a 6mm X 1mm (25.4 tpi) 60 degree threads. O BA 6mm X 1mm 55 degree thread.
More About Sellers' Threads
The ASME considers William Sellers' 1864 paper on thread standardization to be a milestone in mechanical engineering/
Note that since the man's name is Sellers, they should be refered to as Sellers' threads, not Seller's threads as I mistakenly wrote in a previous post.
Note also that the 1864 paper proposed a standard for 1/4" up to 6". so the sub-1/4" sizes in the Little Giant tap & die sets being discussed aren't in the original paper.
BTW: An obscure factoid is the the numbered thread series we use today, like #6-32 and #10-24, actually go up to #30, but I've never seen anything in real life in that series bigger than a #14-20.
For the record BA threads are 47 1/2 degree thread angle, not 55 degrees. No idea of the logic behind this choice of thread angle.