Intorduction and Taps, taps, taps.

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charlesfitton

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Joined
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I'm new to the forum and am in awe of the quality work of which the members are capable .

I had the good fortune and rare privilege just before Christmas to purchase much of the equipment I'd need to break into this hobby from a WW2 veteran who is moving across the country to live in British Columbia. Namely a 12 x 36 in Lathe, med sized mill drill, and an Atlas/craftsman horizontal mill. (Just couldn't resist that last one). It's all in the basement now, with some new tall workbenches, nearly enough lights, and extra receptacles.

In an act of self-denial I've started to get organized and sort through all the related treasures (junk) that I've gathered through the decades and came across a box of taps, most still in the wax/plastic dip that protects them.

With the help of a good magnifying glass they were laid out on the bechtop by size, form and pitch (a trace of OCD at it's most useful). Some were easy to identify - a few BSC, more Witworth, a surprising number of British pipe tap and BSF, but the problem came with these left without parentage that I could ascertain....:

w.4355-26
w.562-20
w.7475-20
w.7787-14
w1.062-20
w1.125-16
w1.185-16
(There are several of most examples)

These may have been Canadian Army surplus. There were "serviceable" tags from the early 1960's and NSN numbers, so they could have been WW2 vintage. I include this as they may have been special built for Brit equipment that was still in the mil system then..Centurian tanks and Lancasters comes to mind.

Can the collective wisdom enlighten me as to an application for these poor orphans, or must I on faith alone treasure them until someone chucks them into a bin after my demise?

( which I hope won't be for decades yet...)


f



 
I can't help with the ID of the taps Charles, but can offer a hearty welcome to the group. Sounds like you have acquired the basics you need to jump into the hobby. You will find all the help here you need as there is an enormous amount of collective wisdom available for the asking. By the way, if you haven't figured it out yet, we love pictures!!

Bill
 
charlesfitton

Let me welcome you to HMEM. It is nice to see someone local join up.

I'm in Kitchener so not far away at all. As far as the numbers on your taps go without having seen the taps I am wondering if the first part represents a diameter and the last part the threads per inch. You might try measuring them with a caliper and counting the threads or using a thread gauge to see if those numbers make sense that way. If that doesn't work try posting a picture of them with a scale or something for size reference. With members all around the world there will be a few differend answers I'm sure.

I look forward to hearing more from you.

Cheers :)

Don
 
Welcome to HMEM Charles.

Your taps are defiantly marked with Military Specs.
I recognize the first three as being,
7/16"-26 TPI
9/16"-20 TPI
3/4"-20 TPI

The remaining three I have never heard of.
They may be proprietary threads, unique to the manufacturer.
If there is any way to complicate anything, the military will
do it BEST! ;)

Nice cache of taps you have there.
If they were mine, I wouldn't use them.
They may not be much today, but as time passes they will certainly
achieve some collectors value based on nothing more than their markings.

Rick
 
I'll hazard a guess

w1.062-20 1 1/16"Whit
w1.125-16 1 1/8" Whit
w1.185-16 1 3/16"" Whit

And welcome Charles
 
Charles,

Welcome to our forum. wEc1

The tap markings you have shown may well have a Whitworth thread form but I don't think they belong to any of the British Standard series using this thread form, BSW, BSF, BSP, BSB, nor do they match BSC which has a 60 deg angle and they are all to big for BA, (max dia 6.0mm).

Maybe they are specials for some obscure WWII weapon etc.

Best Regards
Bob
 
Wow, run those tap sizes through Google and you get all kinds of ideas for their use.
 
Almost certainly specials Bob, and I'm pretty sure the W would indicate the Whitworth thread form.

About the closest 'standard' size I can come up with is UNEF, but there all three diameters are 18 tpi
 
charlesfitton said:
In an act of self-denial I've started to get organized and sort through all the related treasures (junk) that I've gathered through the decades and came across a box of taps, most still in the wax/plastic dip that protects them.

With the help of a good magnifying glass they were laid out on the bechtop by size, form and pitch (a trace of OCD at it's most useful). Some were easy to identify - a few BSC, more Witworth, a surprising number of British pipe tap and BSF, but the problem came with these left without parentage that I could ascertain....:

w.4355-26
w.562-20
w.7475-20
w.7787-14
w1.062-20
w1.125-16
w1.185-16
Armorers (military gunsmiths) use a number of taps not normally found in industry. I.E. w.4355-26 is almost certainly a "force fit" for a w.4375-26 screw. In point of fact, all of them look to be "force fit" taps (i.e. .5625 = 9/16, .562 would be a fairly light force fit for a 9/16 screw). Prior to 1967, Unified National (UN) threads had a different "class" identification than you find today as Americans were making the transition from the older American Standards Association (ASA) to the American National Standards Institute (ANSI). There was no small amount of confusion during that period (which was when I served my apprenticeship).

One of the things that everyone should be aware of is that the U.S. is in the process of "privatizing" all their old public domain standards. If you go to http://assist.daps.dla.mil/quicksearch/ and request FED-STD-H28, you can download all the knowledge of screwthreads that a century of taxpayer investment developed. It will become "private intellectual property" here in fairly short order. It would also be wise to grab a copy of MIL-HDBK-5 (properties of metals for aircraft and spacecraft) while you are at it.

Additionally, I have a fair amount of information on engineering topics (including thread and pilot holes for tapping) posted at http://www.scribd.com/Lew Merrick that you might find interesting. One of my (many) "back-burner projects" is to write a new mechanical design engineer's handbook and the postings on ScribD are part of that effort.
 
pretty sure I have used .4335-26 on some old rolls royce engine castings from the 50's and 60's.The RR Avon springs to mind.They were used as an interference fit for steel studs in light alloy castings such as magnesium gearboxes.

happy days
Regards Steve C
 
Thanks for the insights gents.

I'm considering a camera to do pics - maybe someday.

I'd considered the taps as special purpose - but Rolls Royce? - Now I can lord it over everyone on snob value alone.

When I put the taps into Google, All I get is directed back to my original message. What interesting things can be out there?

f
 
For Lew Merrick: Lew, I can not find Mil-HDBK-5 listed. Is that the
complete number? Got the one about the screw threads. Thanks a
lot.

John Burchett
in Byng OK
 
kc5ezc said:
For Lew Merrick: Lew, I can not find Mil-HDBK-5 listed. Is that the
complete number? Got the one about the screw threads. Thanks a
lot.

John Burchett
in Byng OK
Sorry about the delay in getting back to you. The last version (which may be "pulled" at anytime as this is information in the process of being "privatized") is MIL-HDBK-5J -- though you should be able to find it as MIL-HDBK-5. If it has disappeared, I will upload it to the files area here if people would like to see what their tax dollars have made possible.
 
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