Is this Tap and Die set UNF?

[DVD3500]

Hi All,

My Mom is cleaning out stuff from my Dad's toolbox sent me a picture of this tap and die set.

If I understand the standard correctly the 1/4" 24, 5/16" 24 etc are in line with the UNF standard....

Am I correct?

Thanks!

[Ian Foster]

1/4" 28 (TPI=threads per inch), 5/16" 24, 3/8" 24, 7/16" 20 and 1/2" 20 would be UNF.

The coarser TPIs would equate to UNC. Not sure what the 1/8" NPT is.

So you have a mixed set.

Very useful.

Ian

[GrahamB]

 

I agree, UNF and UNC plus 1/8" NPT.  NTP is very similar to BSP but not not the same.  Do not mistakenly force a NTP thread into a BSP tapping !

[Morgana]

NPT is National Pipe Taper - American. Also NPS (National Pipe Straight). American air tools (Chicago Pneumatic for instance) have NPS or NPT female threads, and people often insert BSP hose tails with a large spanner as GrahamB says. Not a good idea, and most inelegant.

UNF and UNC is very useful for your Triumph, if it's 1960s onwards. The smaller sizes (10-32 etc.) are also used on things like front grille screws.

[johny]

15 hours ago, Morgana said:

UNF and UNC is very useful for your Triumph, if it's 1960s onwards.

Out of interest, what threads were used on older Triumphs before 1960s?

[Pete Lewis]

in steves  online  vangaurd1 2 and renown  there are few clues but cam sprocket and dizzy say 5/16" +1/2" AF spanner 

and 1/4" +7/16"AF spanner     so engine looks predominantly unified 

[GrahamB]

My understanding was that prior to adopting the American Unified system after the war to simplify exports, the threads used were mainly Whitworth, a coarse thread, and British Standard Fine (BSF).  Whitworth have different hex sizes to UNF.  (I have a 1/2" hex drive Whitworth socket set inherited from my grandfather). These sizes would have been used on pre 1950 cars rather than pre 1960.  For comparison:

[DVD3500]

Many thanks all.

The more I use my Dad's tools the more the project becomes mine.

I will be getting all the suspension parts back and we will be mating the body and chassis back together so I will need to chase the threads as every thing has been powder coated/galvanized/painted.

Thanks for the input!

 

[PeteH]

In HEAVY industry and shipbuilding, the move to unified came somewhat later. I was working with a mixture of BSW/BSF and Unified from about 1960 onwards, apart from when working on some German war reparations plant, which where, as you would expect, entirely metric. And coincidently still bore the scars from Allied bombing!! The move to A-F post war was at at first largely confined to the Motor Industry, primarly cars, then gradually rolled out across the Motor industry, I think you will find. I have a sneaky suspicion that fathers 1946 build Hilman had a substantial numbers of BSW & BSF fasteners still. But it was pretty much a rewind of a pre-war design.

Pete

[Morgana]

On 06/12/2023 at 08:42, johny said:

Out of interest, what threads were used on older Triumphs before 1960s?

I've never worked on anything automotive that old, but I understand that as mentioned above, tooling from BSW/BSF plant was still around, especially in the somewhat hidebound UK motor industry. There's one story that some Morris engines had metric threads with Whitworth heads on as the company took over a French factory and didn't want the expense of either changing their British spanners, or the French machines! It may be that Triumph always used Unified post-War, but in a general sense when working on pre-1960 objects, tooling of the period could possibly have a variety of thread types that weren't completely converted. I think by the '60s it would have changed over completely in the motor industry.

The only reason for the change I'm aware of was the huge influx of American machine tooling and vehicles during WWII, and the need for associated maintenance equipment. Their 'National' series of threads (NF, NC, NS, NP etc.) ended up being chosen as the new standard post-War, renamed to Unified National, hence UNF, UNC etc.

British Association (BA - perhaps the mathematically most satisfying thread form) continued for a long time as the standard for instrumentation and electronics, rather than the smaller UNF sizes - I think it's still not completely unusual to have 4BA screws in pattress boxes.

Of course, there's the added fun that Whitworth has the original head size (BS190) and then the smaller hexes from BS1083 in which the head size matches the BSF example of the same fastening size, so for some spanners you may find yourself using the size below that which it's stamped with...

A big Whitworth spanner is a lovely thing - remember the size refers to the major diameter of the thread, rather than the measurement of the head as in AF spanner sizes. When I would need to use my 1.1/8"BSW one unless I were building an icebreaker, I don't know!

[Stratton Jimmer]

12 hours ago, Morgana said:

When I would need to use my 1.1/8"BSW one unless I were building an icebreaker, I don't know!

I work on a heritage railway and most of our locomotives have all Whitworth threaded bolts, set screws, studs and nuts.

[Pete Lewis]

for many years until more recently  the bolt of the battery terminal clamp were 5/16bsf  as a std fit 

a carry over  of times past .

any mechanic worth his salt carried a 5/16bsf - 1/4whit spanner at the ready to disconnect a battery 

Pete

[PeteH]

I`ve played with a lot of "Big Nuts" in my life, (Should I re-phrase that?) In excess of 150mm/6" A-F was not at all unusual. On older ships all nut`s where inveriably "flogged" tight, using a short (and still very heavy) spanner, and a 28lb Hammer. It was only by the later 60`s that more sophisticated hydraulic tightening systems became the norm.

Pete

[DVD3500]

BTW they arrive safe and sound and now the parts are back from the power coaters so I can finally start the rebuild!