Ye Olde Screwplate

[vtsteam]

I bought this screwplate at the Bernardston engine meet, tossed together on a table with a bunch of other newer tools. It has a double series of die holes with gauge numbers that don't match current U.S. screw gauges (numbers of the screwplate decrease with increase in diameter) and don't match drill gauge numbers either. The pitches are 28, 32, 37-1/3, and 42-2/3. The first two are pretty familiar, the last definitely not!

[vtsteam]

I think this is the maker:

[Fergus OMore]

I have a homemade one. Mine has a range of BSW dies but around the edge are a number of 'notches' to take many various thicknesses of square tap ends.

Very useful - and came with the word 'stolen' I paid for it- not guilty me lud!

Norman

[vtsteam]

Naturally being the curious type, I had to see if it still worked. I had a piece of 3/16" galvanized rod that fit the 7 hole and a piece of 1/8" brazing rod that seemed to fit the 12 hole.

And, yes indeed, it still works:



I didn't have the screwplate level for the steel 3/16" rod so the thread is somewhat canted. But it did check out at 32 tpi with a screw gauge. Actually, it's easy to hold the screwplate level, by eye, as I discovered on the second piece -- the broad surface makes it pretty apparent when you're off when you start the thread. If you bother to check, that is! 

The second piece mated well with the 38 tpi screw gauge for the full length of the thread. I naturally don't have anything 37-1/3 tpi to test with!

[S. Heslop]

I've seen pictures of those before but never knew they cut screws. I thought they were just for checking sizes.

Was there any rationale behind having them all on the same plate though? The limitations seem obvious.

[vtsteam]

Norman:
I like the tap wrench function. Wonder why it said "stolen" Maker's name?

Simon:
Saving on high grade steel?
Easy to find the right size?
No need for a die holder (or several)?
Lower cost?
Easier to make?
One tool does it all?

[vtsteam]

It is quite polished (not apparent in pics) and also has a warm brown tinge -- at first I wondered if it had been silver plated. Then realized that was probably the tempered color -- a dark straw. Polished before tempering.

It is beautifully tapered in two directions. The center of the blade is thicker than the edges and the blade tapers in width down its length. the larger die holes are thicker (more threads) than the fine gauges.

[Fergus OMore]

Norman:
I like the tap wrench function. Wonder why it said "stolen" Maker's name?

Simon:
Saving on high grade steel?
Easy to find the right size?
No need for a die holder (or several)?
Lower cost?
Easier to make?
One tool does it all?

Steve
My impression was that this was probably an apprentice's piece made from gauge plate because the 'Stolen' word was done with a pointed punch rather than with proper letter stamps.

Simon- It is a very useful one tool does all thing when all that people tapped were probably Coarse Whitworth( BSW) things.

You know it is not that far into history when the Brits actually were fairly standard.  True, there were BA and BSF but not much more in the run of the mill production. Today, I have drawers full of all sorts of taps dies -and still dont have the one that I want. Damned nuisance. Easier to go Metric and be damned

Regards

Norman

[vtsteam]

If you mark all your tools "stolen" it might get them returned when borrowed! And if they were stolen, harder to sell.

Of course it doesnt look too good if your shop is filled with tools marked stolen! 

[vtsteam]

Anybody got an idea what system or period (or country) these gauges and pitches relate to?

1 through 5 gauge are 28 tpi pitch
6 through 9 gauge are 32 tpi pitch
10 through 12 gauge are 37-1/3 pitch
13 and 14 gauge are 42-2/3 pitch

1 gauge seems to measure about .260" ID
5 gauge seems to measure about  .202" ID
10 gauge seems to measure about .136 ID
14 gauge seems to measure about .107" ID

The above die hole ID's would be approximately the minor diameter, so the actual gauge diameter would be larger.

[Bluechip]

Anybody got an idea what system or period (or country) these gauges and pitches relate to?

1 through 5 gauge are 28 tpi pitch
6 through 9 gauge are 32 tpi pitch
10 through 12 gauge are 37-1/3 pitch
13 and 14 gauge are 42-2/3 pitch

1 gauge seems to measure about .260" ID
5 gauge seems to measure about  .202" ID
10 gauge seems to measure about .136 ID
14 gauge seems to measure about .107" ID

The above die hole ID's would be approximately the minor diameter, so the actual gauge diameter would be larger.

This is Standard Wire Gauge

http://www.clag.org.uk/swg.html

Some of it 'sort-of' fits if it's the minor diameter, bearing in mind there are several other UK wire gauges. I'll see if I  can find a table. have it somewhere.

Birmingham Wire Gauge, Stubs, etc ... no wonder we poor Limeys are always baffled ... 

Dave

Edit

OK. So I have :

Imperial Standard Wire Gauge
Instrument Wire Gauge
Twist Drill Wire Gauge
Warrington Wire Gauge
Whitworth's Wire Gauge
Stub's Steel Wire Gauge
Birmingham or Stub's Iron Wire Gauge
Birmingham Gauge for Sheets and Hoops
Birmingham Wire Gauge for Silver and Gold
English Music Wire Gauge

.... and Uncle Tom Cobley and all ....  your choice ... as I'm skint I suggest we can drop the Silver & Gold Gauge ...

Also have AWG but I suppose you've tried that one  ??



Dave

[vtsteam]

Dave, thanks for all the references. My eyes are going buggy after looking through various charts and sources tonight. This chart seems pretty good:

http://www.dave-cushman.net/elect/wiregauge.html

I'm thinking the closest match seems to be Washburn & Moen gage -- especially at the low number end of the scale. The highest number on the plate, 14, doesn't seem to fit any of them, since the minor diameter I measured is larger. However I could easiy be off in measurement, as all I have is a caliper, and the jaws don't even fit in the hole. Even then, the W&M gauge is closer than some of the others.

I looked up Washburn and Moen: https://en.wikipedia.org/wiki/Washburn_and_Moen_North_Works_District

and they were located only 85 miles away from here in Worcester, MA, and the vendors at the Bernardston, MA show might even have come from Worcester. Coincidentally, my father-in-law graduated from Worcester Polytech, which was founded by Ichabod Washburn.

So it seems at least a good possibility that this was a Washburn and Moen Screwplate, possibly even originating in Worcester, MA where the wire company was located.

pitch:

I do still wonder about the two weird fractional pitches -- why in the world were they chosen?

re. usefulness:

It might be fun to make a few taps to match, by running some turned drill rod through the screwplate in some useful small sizes, and then fluting and hardening --  as I did for the acme tap I made.

[Fergus OMore]

I'm unable to dig into my records because of having imminent medical checks away from home!

However, I suspect that the odd pitches are metric.  Very old metric weird stuff out of Europe or possibly Europe émigré out of Europe. Anyway, with luck, I shall try to dig out my old copy of Machinery( 1942 edition) to see what it contains.

My hasty view is that they are probably watchmaking and clock stuff- which came out of places like Besancon which is next door to- would you believe- Ornans where Vernier lived! Been to both, my son studied there.

Cheers

Norman

[RussellT]

why in the world were they chosen?

So that future users will curse :bang:when they've lost the screw and can't find a replacement. If you want to be remembered fondly don't give into the temptation to actually use them. 

Russell

[Fergus OMore]

why in the world were they chosen?

So that future users will curse :bang:when they've lost the screw and can't find a replacement. If you want to be remembered fondly don't give into the temptation to actually use them. 

Russell

But this is exactly what  people do. Myford has a spindle nose which is a standard UNF or UNC size but this thread is BSW i.e. 55 degrees not 60!

Then there are  BA's which are- dammit- Metric/Imperials.

As I said to Simon- let's go metric and-- head for the little men with white coats and a straitjacket.

Then- if history is to be quoted( not again, Norm) Lord Nelson's navy had bloody big heads on bolts- 'cos the matelots twisted the heads off anything smaller.

Seriously, screw threads were struck and made by hand and eye and the world had to wait until our Mr Maudsley came along. Not Mr Whitworth as written by the other Norman Atkinson.

Yea, yea

Norm

[Fergus OMore]

The answer now to the Funny threads s that these are Lowenherz threads for German optical etc stuff.

I now recall GHT writing about making a 42.5MM thread on his Leica camera.

Now we have it- easy( if you have a 1942 copy of Machinery 's Handbook and GHT's equally pedantic prose.)

N

[vtsteam]

I probably will use the screwplate and threads, just because I enjoy doing stuff that other people aren't doing, and because I like to connect with people who made things in the past. And because I like to see old tools being used and not just sitting on shelves in a museum, or at the bottom of a pile on a sale table.

Whether or not people will curse me in the future because I didn't make replacement screws easier to come by, I can't say -- personally, I doubt they will remember me for any reason at all. 

And iIf it causes them to have to do historical research, and then develop an older skill to replace them, I'll feel I've contributed something to the world, after all.

[Ned Ludd]

Hi Guys.
Just to add another line of thought, let us not forget wheel spokes can have gauge size threads.
Ned

[wgw]

I have one of these screw plates, marked "the weiss" and Warrington (a town in N England ). There are 12 pairs of holes but no size markings, range from aprox 5/16" to aprox 1/8", look like whitworth threads . I think each pair is a starter and finish die, but have never tried them. I always understood that they were used by blacksmiths and mechanics to make a thread for repair work.

[Rick O Shea]

Clockmakers use these screw plates and they are fairly common in clockmakers workshops today I have a lot of them which I regularly use.  They may have been made by Stubbs but were sold all over Europe  certainly Stubbs made them for the french clockmaking industry and I suspect they were exported to the USA at the end of the 19-early 20 cent. They are really good for matching old threads found in clocks and other mechanical devices with non standard  pre Whitworth form thread pitches.

[howsitwork?]

Have a look in Tubal Cain's model engineers  handbook. Holtzapfel threads were a curious tpi .. Just a thought...