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filing a hand forged flintcock

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Clint:
This post is the follow up to my previous post about forging a flint cock but I don't know how to add a link to it. CW


Filing the flint cock

The first area to file on a new forging is the top surface of the lower jaw. This gives a base line for the rest of the piece. upload image
The jaw is filed flat and the comb is filed at ninety degrees to the jaw.
By holding the oversize comb in the vise, the face and the back of the body can be filed close to the proper thickness. The body, on both front and back rise in thickness to meet the width of the lower jaw. A ten inch half round file should get you there. At this point it is almost mandatory that you have a model to refer to. If you have a flint lock of any kind, take the flint cock off and remove the top jaw  and screw. After filing a bunch of these pieces you will probably dispense with the model and go simply by drawings or measurements.
The locks we are building here are for rifles and are 4 7/8” to 5 1/4” long. The flint cock throw will be 1 1/2” or a tiny bit more. We are going to measure from the face of the comb and cut the length of the jaw to 7/8 “ this length will reduce to 3/4 “ or so by the time we are done fiddling, but we will start here. The cock throw for this lock should be 1 - 1/2 “ so we will measure, with dividers from the lip of the jaw, and swing an arc across the front of the body. On small pieces like this I use permanent ink markers to color the piece, then scribe the layouts. Using a common washer, I find the center middle of the body and mark the mounting hole.
Assuming that the washer is close to the right size, it can be traced for a filing guide and we can begin to approach the shape of the finished flint cock.  Study your drawings and photos of the style you are aiming for and adjust the outline shape to fit We now have a “four sided” iron flint cock and the final contours can be approached. A lot of filing can be accomplished by holding the piece in the vise, but an angle jig gives easier access to many parts and makes for more consistent bevels.

This is the filing jig, in it’s crudest form. It is made from an old door hinge with”jaws” welded to it. I have several sizes and use them extensively in filing 18th century house hardware.
Now that we have the basic geometry blocked out , we are going to drill a 1/8 “ hole where the two scribed lines intersect. Using the drill as a mandrel we will fit the flint cock to the lock plate we made yesterday and mark a line on the back side of the cock where it will rest on the lock plate. The edge should rest just above the fence, aft of the pan. stupid people movie
Cut the shoulder with a hack saw just out side of the line and file up snug to the line.



We need to look at the thickness of the body and make sure that the front and back faces are parallel , good idea to keep track of this in all stages that involve reducing thick ness. It is hard to illustrate, but it is also important to keep track of how close to center the comb is. You can easily see this from the front and back view of the piece.

The face of the comb usually has a ‘step’ about 1/4” up from the jaw surface. This step can be started with a hack saw and filed back to a depth of 1/16 “. The step gives a stopping point for the top jaw and provides clearance for the top jaw screw. The back of the comb is filed and contoured according to the style that you are emulating.
On many locks, the top jaw fits into a narrow slot, cut into the face of the comb. This slot is easily cut with a blacksmith size ‘engraving ‘ chisel, followed by a narrow (1/16 “) cape chisel. I use small hook scrapers to finish and straighten the slot.
To drill the top jaw screw hole, I use a drill press vise and pay close attention  to get the comb face parallel to the axis of the drill. The hole is center marked 1/8 “ in front of the step on the comb then it is drilled and tapped for 1/4 X 20.

Top jaws are difficult to hold , while filing and simple to forge. A roughly hammered and filed jaw is filed up on the end of a piece of steel which is used as a master to make a top jaw swage.
The master is hammered into a piece of hot steel, 1/2 “ thick and all of our jaws are forged in this die. The top jaw is left on the bar for the initial filing and the screw hole is drilled to accept a 1/4 “ screw.
Using a 1/4 “ bolt, measure the gap between the comb face and the bolt body.

Add 1/16 “ to this measurement to account for the guide key and transfer the measurement to the top jaw and separate it from the bar.

By sighting the slot in the comb, we can zero in on the location of the top jaw boss and file away the metal out board of it.
The jaw is fitted to the comb, using Prussian Blue or inletting black . After the jaw fits, it can be traced with a scribe to match the shape of the lower jaw.

I usually make the top jaw screw on a lathe, but I know that not everyone has a lathe so I made a forging die for this group of locks.
A 1/2 “ round bar is used for the screw and it is heated and stuffed between the die faces. Hammering is done carefully but heavily. Keep the screw blank rotating to avoid flat spots and take a number of heats to fill the die.
The screw portion is filed to 1/4 “ diameter, using a hole as a no go gage. The end is tapered to match the entrance of the thread cutting die and the lower half of the screw is threaded to match the flint cock. A couple of 1/4 “ nuts will act as thread protectors and gripping surfaces in finishing up.
After the screw is separated from the bar , the head is filed very closely to finish. The nuts are removed, and the screw can be spun in a drill press. Amazingly enough, the piece is pretty concentric and completely presentable. Slot the screw with a hack saw and file the slot with a thin tapered file.
The three flint cocks on the right were forged identically and were filed to appear different from each other.  All  three are cut to 1 - 1/2” throw. The forging on the left had two fatal flaws, so I soaked it in weak battery acid for a couple of days to reveal the grain flow.
I should comment about metal cutting files, here, because I have been so casual about filing this and that. The sad truth is that good files are hard to find, especially in “hardware “ stores. The best place for me to get files is at a flea market about 20 miles north of here. Learn to feel for sharp files and get them by the box full. There are not very many people buying old files, so they tend to be very inexpensive. More expensive files are made in Europe, but I can’t afford them. I keep my files in racks and regard them as highly as sharp carving chiselsWe still need a couple of frizzens and I will write about them soon, work gets in the way…

So that was pretty easy, everyone should be getting used to filing iron by now, No wonder they didn't make anything out of steel unless they had to.

Curtis:
Here is the link to the forging post, Clint: https://americanlongrifles.org/forum/index.php?topic=58494.msg585199#msg585199

Excellent work, my kinda job!  Looking forward to seeing the rest of the project.  Thanks for posting.

Curtis

KC:
This is a really interesting series you're doing, thanks for posting. I don't imagine I'll ever do this but it sure is neat to see.
K.C.

WadePatton:
Good work. 

as to buying old files--I just look for the best ones--that aren't chipped out.  Dullness is no problem since I learned the vinegar "trick".  They perk right up.

D. Taylor Sapergia:
Wade:  vinegar trick?

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