Author Topic: making screws with a screw plate (Read 10482 times)

rich pierce · « **on:** October 29, 2012, 04:53:50 AM »

I found and bought 3 screw plates on ebay. The holes run from 1/16" (one of the plates was a jewler's or clockmaker's plate I think) on up to about 5/16". I am trying to figure out some things. I'll go back and read Jamed Everett's stuff and mine that for a bit.

I find that on the screw plate that spans what today would be a #4 to a #12, many of the holes (dies) employ the same pitch. Seems I can start threading a rod on one hole then take it to the next smaller one. My experience with a 16d nail: .161 is the body diameter. After threading it in the smallest hole possible the threads external diameter is .169. So material was displaced, like threads on a bicycle wheel spoke. The pitch seems about 32. The threads do not seem so deep.

Questions:
How does one determine the correct diameter rod for a hole in the screw plate, and know when threads are full height and depth?

I assume if I want to make a tap to correspond, I simply thread a rod, file tapered flats on it, and harden it?

Dave B · « **Reply #1 on:** October 29, 2012, 06:22:20 AM »

Rich Iam interested in your project here. I picked one my self and have played with it a little. I like the Idea of being able to make screws to fit original llocks when conventional threads are not working. I would do as you are talking about with threading the softened tool steel then harden it to use.

Acer Saccharum · « **Reply #2 on:** October 29, 2012, 05:07:41 PM »

I envision you would have to make 'taps' in successive sizes, to form or cut the thread in a hole. I imagine you would want to practice on scraps before working on the real deal.

Realize that the threading tools were high carbon steel, and the parts to be threaded were most often iron. If you try to thread one of today's cast plates, you may run into difficulty. Anneal any old plates/parts you may be threading.

James · « **Reply #3 on:** October 29, 2012, 07:07:24 PM »

Rich, what size were yours described as? I have been looking and saw some listed as watchmaker type and sizes given in mm, and I thought were to small for gun use.

rich pierce · « **Reply #4 on:** October 29, 2012, 07:35:07 PM »

Hi, one is very small, about 6" long including the handle and it was described as a jewler's screwplate. I threaded a 4d nail with the smallest hole. The biggest hole is about a 8-32. This one has the taps with it!

The next bigger screw plate has a nice range useful for period gun work, from maybe a #4 to a #12 screw, but no taps.

The big screw plate has about 8 holes but limited range and would be best for cock screws I think, and no taps.

I am exploring making lock bolts/screws from nails but don't know if it's practical to forge a head on them. I have about 8 sets of lock castings needing assembly and 3 or 4 original locks needing restoration. So I need to purchase or make a lot of screws and I have no lathe. Plus I like learning old ways.

If I use common nails as the basis for lock bolts, side nails, tang bolts, etc I need to forge heads on them. I was thinking of using a split block drilled to clamp the nail, with a countersink on top to form the head. One hole on top would be a narrow countersink to get the upsetting started. Another header plate could be used to square up the head a little. Obviously they were not made this way originally (from perfect round stock like 16d nails) but were made by drawing out rod then sizing the bodies and forming the heads in a die (one man shop) or lathe (gun manufactory) methinks.

Acer Saccharum · « **Reply #5 on:** October 29, 2012, 08:46:57 PM »

A friend of mine had a foot-treadle metal lathe..... I wonder whatever happened to that?

Jim Kibler · « **Reply #6 on:** October 30, 2012, 01:43:33 AM »

Rich,

You might want to check out the JHAT book on lock making. Shows cutters for sizing screw shanks and cutting the heads. I made some of these a long time ago and they worked okay. Think this would work better than trying to forge heads on round stock.

Jim

flintriflesmith · « **Reply #7 on:** October 30, 2012, 02:02:39 AM »

Jim beat me to that response. Look at Volume I of JHAT.

Also --- my understanding of the period process of forging screw blanks (and even larger nails) was to start with stock nearer to the head size and forge the shaft down. That is much easier than starting with even diameter small stock and forming enough metal by upsetting to make a thick screw/bolt head.

(regular square hand forged nails were forged with the long taper then dropped into a header but their heads a very thin)

Gary

rich pierce · « **Reply #8 on:** October 30, 2012, 04:42:35 AM »

Good advice Jim and Gary; I was just tempted by cheap and accurate round stock in ordinary nails.

Here are some pix of the screw plates
All 3

Closeups of small one

medium and favorite a Stubs,:

Big one

Eric Smith · « **Reply #9 on:** October 30, 2012, 07:55:00 AM »

Quote from: flintriflesmith on October 30, 2012, 02:02:39 AM

Jim beat me to that response. Look at Volume I of JHAT.

What is JHAT?

Michael · « **Reply #10 on:** October 30, 2012, 12:08:48 PM »

JHAT
Journal of Historical Armsmaking Technology. 5 book set. I got my set from the Colonial Williamsburg book store.

rich pierce · « **Reply #11 on:** October 30, 2012, 01:53:49 PM »

Did not know these are still available. I only have 1 volume.

James Wilson Everett · « **Reply #12 on:** October 30, 2012, 02:59:54 PM »

Rich,

It is really wonderful to see your work on screwmaking. I hope that your efforts are successful and rewarding. Probably the best screwplate to use is the Stubbs. Here is what I have done with mine.

1. Clean the screw holes using modern bore cleaning brushes - .22, .30 cal, etc.

2. Get a good set of number drills (I assume you already have a set). Use the drill bits as a set of go-no go gauges to find the minimum diameters of all the holes. For instance, for a certain hole you can find that a #22 drill bit will pass, but the #21 drill bit will not, so you know the minimum diameter to +/- a few thousanths of an inch.

3. You will find that one side of the paired holes is very slightly larger, this hole is for making the tap, the slightly smaller hole is for making the screw.

4. File or turn a rod a bit larger than the minimum hole diameter for a first trial. Say if the hole minimum diameter is 0.120, try a rod at 0.140 to see if the threads form OK. Unfortunately this is a try - correct - try again process. Use plenty of oil.

5. Once you get the diameter sized for a well made screw, go to the tap hole in a similar way, but there is no need to use good steel yet fot the try - correct - try again.

6. Lastly use good steel to form the tap. I use W1 steel rod from Mcmaster Carr and fully harden them, no temper.

7. Of all the holes I have in several screwplates, I only use 4.

8. As to the material, I use either wrought iron, which is the best and original, or I use leaded steel, 12L14 (Ithink that is the proper designation) again from Mcmaster Carr. The long iron/leaded steel rod gives you something to hold in a vise as you make the threads.

9. I have made the screw blanks by forging, for a crowd show-n-tell, but I find it easier and quicker to just file down a rod to the proper diameter and finish with a screw grinder.

I hope this helps. Again, I wish you the best.

Jim

rich pierce · « **Reply #13 on:** October 30, 2012, 04:42:40 PM »

Thanks, Jim, just the information I need. Next step will be making a screw grinder. I think I have a lead on JHAT volume 1. So far I only have volume 4. But if you've shown a screw grinder or could show one here, that would be great. Thanks again.

brobb · « **Reply #14 on:** October 30, 2012, 04:56:06 PM »

The book "The Gunsmith's Manual" by Stelle & Harrison has a chapter on making screws. It covers the making and use of screw grinders, taps and other tools.

Bruce Robb

brobb · « **Reply #15 on:** October 30, 2012, 05:59:50 PM »

Screw grinders are hollow milling cutters. The ones in the photo are for size six screws. They are made from drill rod and the cutting teeth were filed in by hand. To make a screw blank you select stock that is slightly larger than the screw head diameter. Leave your stock long and file the shank portion of your blank so that it is slightly oversize. Hold your grinder stationary and use a brace to turn your stock into the shank grinder. This will make the shank the correct diameter and make a square shoulder under the screw head. Use the brace to turn your stock into the grinder that has a counterbore which forms the screw's head. Use a thread plate or die to make the threads, cut the stock at the top of the head and saw the screw slot.

Bruce Robb

Acer Saccharum · « **Reply #16 on:** October 30, 2012, 06:01:18 PM »

Use a high pressure oil, with molybdenumdisuphide in it (black and messy) or lithium (whitish color) or a sulphur based thread cutting oil. Motor oil is not going to help much.

flintriflesmith · « **Reply #17 on:** October 30, 2012, 06:46:50 PM »

Quote from: Acer Saccharum on October 30, 2012, 06:01:18 PM

Use a high pressure oil, with molybdenumdisuphide in it (black and messy) or lithium (whitish color) or a sulphur based thread cutting oil. Motor oil is not going to help much.

And which of those is the most period correct?

I used those tools with only inseed oil as a lube for years at the CW Gunshop.
Gary

Acer Saccharum · « **Reply #18 on:** October 30, 2012, 10:42:19 PM »

Ok, ok, how about lard and some powdered graphite, or lead oxide?

PPatch · « **Reply #19 on:** October 30, 2012, 11:54:01 PM »

Oh yeah, how about lead oxide... Be sure it is fritted - I used to work with it when I made pottery, both white and red lead. Serves as a sort of flux to make low fire glazes melt more readily.

dp

James Wilson Everett · « **Reply #20 on:** October 31, 2012, 06:24:16 AM »

Guys,

Here are some photos of one of my screw grinders. This makes about a #9-30 machine screw from my screwplate. Make the grinder diameter big enough in diameter to cut the bottom face of the screw heads for the cock/tumbler screw and for the lock nails (the long ones that hold the lock through the sideplate). They can also be used to make the much smaller lock interior screws. I made flats on the sides of the grinder to help hold it in a vise or to give wrench flats if I chose to use it that way. File the screw shank very close to the final dimension and just use the grinder to finish. My screw shanks look sort of octagon-ish before using the screw grinder.

Jim

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Author Topic: making screws with a screw plate (Read 10482 times)

Michael

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brobb