18th c Screw Plate Use

[James Wilson Everett]

Guys,

The topic on making 18th c breech threads wandered off into the use of a screw plate.  It is great how one discussion leads to another.  Here is an introduction on how 18th c gunsmiths made the screws for the lockplate & other machine screws.  Making wood screws is in a seperate tutorial.

Here is a photo of a typical screw plate that would have been used by our 18th c gunsmith.  It makes 10 different sizes of machine screws and taps. You can see the paired holes, the lower holes make a thread that is identical to the upper holes but is a few thousanth of an inch larger.  The larger holes make the tap, the smaller holes make the screw.






The screws I use to make the hand made locks is a 0.174 - 30 thread and one can be seen in the second screw plate photo.  The screw plate swages or forms the threads, they are not cut as in modern dies.  To make these lock threads I form a pin using a screw grinder with a shaft diameter of 0.157.  The screw plate swages this out to the 0.174 thread.  The threads look a lot like lightbulb threads, and they are very smooth.



Jim Everett

[rich pierce]

Thanks, Jim.  So when threading the screw one simply screws the stock in, as opposed to the back and forth action one would use with a modern die?  And do you use any lubricant?

[James Wilson Everett]

Rich,

I normally hold the iron rod in a vise and turn the screw plate onto the rod.  The photos show a finished screw just for a show-n-tell.  Actually, the iron rod for that screw was a blacksmith tong handle originally.  I do not cut the screw from the rod until after the thread is completed and even after it is installed in the threaded hole.  Then I cut it from the rod and finish the head & slot.  You do not need the keep reversing the screw plate as you do with a modern die as there is no chip breaking required.  You actually can turn the screw plate onto the rod as quickly as you wish.  The tool is very easy to start and to keep square, unlike modern dies that seem to be nearly impossible to start square by hand (at least for me).  Of course a good lubricant helps I use any oil or grease or soap.  Thanks a lot for the question, I can tell that you have used a die a lot.

Jim Everett

[brobb]

Thank you for posting your excellent information and photos.  This is very interesting to me.  Have you ever used a screw plate with modern mild steels?  If so what was the result?

Bruce Robb

[Dr. Tim-Boone]

The $64.00 question:  Where can one purchase one of these screw plates?

[rich pierce]

I got 2 off evil-bay over the years.  But I search there weekly with several key words.

[James Wilson Everett]

Guys,

Here are some answers to your questions.  I am glad to see the inerest in actually using the old tools & techniques to make the guns.

Bruce,  Yes the screw plate works very well with modern mild steel.  Go to mcmaster.com for the McMaster-Carr supply company.  Order some 12L14 carbon steel rods to make the screws.  1/4 dia. works great for the lock screws and 1/2 dia. is for the hammer screw and for the sideplate screws.  I also use high carbon steel to make the taps and also the frizzen screw if the flashpan does not have the screw support arm.  You can get W-1 drill rod from McMaster Carr that acts very close to 1095 steel.

Dr. Tim, These are available and not too expensive on E-Bay.  I have bought several from E-Bay.  Sometimes they are listed by names other than screw plate - thread plate - threader, and others.  Try to get one with the two little side holes as these are usually very well made tools.  Here are photos of another screw plate.

Jim Everett

 

[AndyThomas]

The $64.00 question:  Where can one purchase one of these screw plates?

Jim, apparently feeling sorry for me since I had no shoes, gave me a screwplate after we met, three years ago! 

I've been putting that screwplate to good use too. Thanks Jim. 

All of these show-and-tell posts should go in the tutorial section. Looks like I'm not the only one trying to learn how to use the old tools.

Andy

[Glenn]

No, you're not the only person trying to learn how to use the old tools.  I'm following along in total bewilderment and awe.  I've always wondered how they made things like screws and such back in the old days before modern lathes and tools came along.  I really do appreciate all this information being so painstakingly shared here.   

[flintriflesmith]

A lot of what y'all are interested in in terms of using period tools to make screws, etc. is addressed in Volume I of The Journal of Historical Armsmaking Technology, NMLRA, 1985. Out of print but often available through EBay or used book stores on line for 25-40 dollars.

As a side note --- the screw plates with the two holes flanking the threaded hole are usually later in the 19th century. Those holes were added so a broken screw could be removed by splitting it with a jewler's saw. 

Gary

[FALout]

Would the gunsmith back then have bought these plates via a company making them here or were they imported?

[James Wilson Everett]

Guys,

My understanding is that such tools were imported from England, I believe Birmingham was the tool making center.  However, I am a tool user and not a collector.  Maybe someone who collects tools can have a more definitive input here.  Thanks for the interest and for the question.

Andy, Good to hear from you and I am glad that you are putting the screwplate to good use.

Jim Everett

[rich pierce]

Jim, were tapped holes done the same way, basically formed not cut, and how would that affect the size hole one needs to drill?

[JTR]

Interesting thread!
And I have a question too.
I have a hand forged/made screw plate, and tried to make a screw with it once, but with no luck. But, I used a slightly larger diameter piece of metal than the thread size in the screw plate, like you'd do when you cut threads. However you're saying you use a smaller diameter than the thread size to form the threads? I was thinking the plate would swedge the threads down to size, and you indicate that the plate will swedge the threads out to a larger size? In your example, a .157 blank out to a .174 screw.

John

[dannybb55]

To put some more light on the subject read this: One Good Turn: A Natural History of the Screwdriver and the Screw by Witold Rybczynski. The screwdriver was the only tool that was not around a thousand years ago. This book goes through the progression of everything that was made possible as screws got better.

[James Wilson Everett]

Guys,

During the swage process, either for machine screws in this posting, or for the wood screws in the tutorial section, the threads will expand outwards from the original shaft diameter.  A good approximation is the distance that the thread valley is pressed into the metal is the same distance that the thread crest grows outwards.  You have to arrive at the optimum diameter for the original shaft by trial & error.  For the lock screws that I make from the first posted photos - the final thread diameter is 0.174 - the original shaft diameter is 0.157 - the hole in the screw plate will pass a 0.136 drill but will not pass a 0.140 drill, so the plate hole diameter is about 0.138.  I know this sounds weird when compared to the way we use a modern die, but it is the way screws were made in the period.

Jim Everett

[dannylj]

I see a couple on ebay now. They are in England. They are listed as watch maker screw plates but the largest size is 2mm. Interesting.  Danny

[James Wilson Everett]

Danny,

Try for some larger sizes unless the plates would be for making those amazing miniature guns.  The sizes I normally use from my "working" screwplate is:

1.  0.156-30 for the thin screw used for a sling swivel.
2.  0.174-30 for the lock screws, the sideplate screws and for the tang screw.
3.  0.216-23 for the lock top jaw screw.
4.  0.268-19 for - I can't remember, but I did use it somewhere because I have the tap.  I guess my mind is like a collander - only lumpy things stay in.

I plan to post a topic on making and using the 18th c taps sometime soon.

Jim Everett

[Bill-52]

I've been reading this thread with great interest.  Thanks, Jim, for the information and pictures.  I continue to be impressed and intrigued with the tools used by 18th & 19th century gunsmiths.

Bill

[James Wilson Everett]

Guys,

Here are some photos of the taps that must be made from the screwplate.  Making the screws is only half of the job.  Since these screws predate the standard sizes we must also make the taps for the threaded holes.  The screw plate has two nearly identical holes. One hole being a few thousanth of an inch larger and is used to make the tap.  As I am sure you understand, the tap must be slightly larger than the screw for everything to go together.  These are made from W-1 tool steel and are heated to 1500F and brine quenched - yep fully hard.







These are the four taps described in the posting of this morning.  Bad news - the size of the hole in the lockplate is only determined by trial & error.  There is no reference to tell you this since every screw palte is different.  When you get it figured out - only tell your apprentice not to reveal it on pain of death!!

Jim Everett

[Glenn]

Guys,

Here are some photos of the taps that must be made from the screwplate.  Making the screws is only half of the job.  Since these screws predate the standard sizes we must also make the taps for the threaded holes.  The screw plate has two nearly identical holes. One hole being a few thousanth of an inch larger and is used to make the tap.  As I am sure you understand, the tap must be slightly larger than the screw for everything to go together.  These are made from W-1 tool steel and are heated to 1500F and brine quenched - yep fully hard.








These are the four taps described in the posting of this morning.  Bad news - the size of the hole in the lockplate is only determined by trial & error.  There is no reference to tell you this since every screw palte is different.  When you get it figured out - only tell your apprentice not to reveal it on pain of death!!Jim Everett

Just for clarification, the pieces used to be threaded as taps need to be softer at first than the screw plate, correct?  I'm thinking the stock that accepts the threads must first be annealed, then after threading re-hardened ...

[eddillon]

Back when I was flying FB-111s out of Plattburgh, NY in the '70s I bought an old farm in the Adirondacks.  Had several out buildings including a shop with all the equipment a blacksmith would need.  Too darn cold to retire there so I regretfully sold the place as is in the '80s.  Did take this screw plate with me, though.  It appears to be quite hard.  No holes for chip removal but I assume that one could use the plate as described in this discussion.  I have been hesitant to do so.  Should I start with brass rod to check it out?

[James Wilson Everett]

You can try brass rod, but be sure to anneal it first as usually brass rod is work hardened.  Heat it to a dull red and quench in water.  Yes, I know this sounds like it will harden the brass like it does with carbon steel, but this is the way to soften brass.  Actually leaded steel rod 12L14 rod will work better.  Use a good thick grease or soap as a lube.  Give the rod a little taper to help start the thread.

[coutios]

  Ya got to love it... 18th century roll taps... I keep telling people they wern't dumb..  Couple of great threads James.. Thanks much...

Regards
Dave

[James Wilson Everett]

Glen,

You are right!  I should have said that the taps were formed from annealed, soft W-1 tool steel first, and when completely formed and finished, then they were hardened.  I guess this does make more sense.

Jim