Author Topic: Fitting a new cock (Read 6506 times)

sydney · « **on:** October 23, 2009, 06:57:50 PM »

I have a lock plate that needs a new cock fitted to it
Not having the old one to measure how does one
measure exact to order a new one??
Thanks Sydney

Dave B · « **Reply #1 on:** October 23, 2009, 07:21:25 PM »

Sidney,
You must measure the distance from the center of the tumbler shaft to the center of the flash pan. If you have a set of dividers you can use the screw hole in the tumbler shaft as the pivot point and rest the other end on the pan at its center. Obviously you may not get a cock that matches this exactly but should be able to get it close enough. Cocks will normally be listed by stroke length which is determined by the distance from the center of the square hole for the tumbler to the face of the bottom jaw that grips the flint. Goose necked cocks are easier to adjust than the double throated style. What Lock are you trying to get a replacement cock for? I ask because I have had the fortune to find a replica of my original lock that was missing a main spring and cock and the replica parts fit perfecly with out any adjustment other than the shaft hole being recut to match the old tumbler.

sydney · « **Reply #2 on:** October 23, 2009, 08:09:23 PM »

Hi Dave-I am in the process of fitting the pans in the front plates of
of a swivel breech so i want to locate the pans to suit
The cock i have is appox 1.4" center of sq hole to
bottom jaw
The measurement i need is from the center of the sq hole
to the center of the pan
Hope i explained the problem
Thanks Sydney

Acer Saccharum · « **Reply #3 on:** October 23, 2009, 09:49:50 PM »

If you can, get the cocks without the square hole cast in. It is maddening to fill the hole and re-cut it 27 degrees.

Randall Steffy · « **Reply #4 on:** October 24, 2009, 08:26:38 PM »

Sydney,
I have been there, done that, as the saying goes. I believe you will find that your 1.4" throw of cock dimension will be matched by the distance from tumbler hole/shaft center to the lowest, closest to the tumbler, edge of the frizzen, when pan is closed. In other words those are the same dimension. From that location you will find your pan center and touch hole location. I hope this helps.

sydney · « **Reply #5 on:** October 24, 2009, 10:05:59 PM »

Thanks for the information
That s my next job on this project
Always get good info on this site
Thanks again Sydney

Bill Brockway · « **Reply #6 on:** October 24, 2009, 10:27:22 PM »

Sidney -

The information you listed (throw dimension) is what you need to order the cock. Fitting the cock to the pan involves a bit more work.

First, you start with a cock with a small round hole (or a square hole) drilled through it. The first step is to file the underside of the cock (the side next to the lockplate) smooth and shiny and spread a fairly thick layer of soft solder (ordinary lead and tin solder will do) on the shiny area. Next, screw the cock to the squared end of the tumbler axle, and rotate the cock until the edge of the flint at the bottom of the forward stroke is positioned in line with the center of the pan (front to back) and level with the top of the pan. When the cock is positioned right, tighten the screw and give the cock a good whack with a brass or lead hammer.

This will leave a square imprint of the tumbler axle in the solder film, just exactly at the right angle to fit the cock and flint being used. Using the imprint as a guide, file the square hole with a little draft until the cock will just slip over the end of the axle. Then squeeze the hammer over the squared axle in a vise, which will give you a tight swaged fit, with no rattle. You may have to repeat the filing and swaging a couple of times to get the cock fully seated.

If you have done this properly, you may have to re-tap the screwhole in the axle due to shrinkage caused by the swaging operation. It's easier to do than to describe.

Bill Brockway

Bill Brockway · « **Reply #7 on:** October 24, 2009, 10:32:11 PM »

Sidney -

I just noticed I misspelled your name, for which I apologize. Hate it when that happens.

Bill

BJH · « **Reply #8 on:** October 25, 2009, 09:58:06 PM »

Thanks for the tip Bill! I would have never thought of using solder as a lay out aid. Not in a million years. Thats a real keeper. BJH

Acer Saccharum · « **Reply #9 on:** October 25, 2009, 11:13:33 PM »

Great tip on the solder! Never would have thought of it.

Another tip for making the square hole: Make a hardened tapered square punch. Drive it into the hole to form the square. (I seem to remember Stophel came up with this tip)

John Archer · « **Reply #10 on:** October 26, 2009, 12:43:57 AM »

Jerry Huddleston wrote about using a square broach a few months ago. If you use the search function for "broach" he has lots of good information....as usual!

John.

Randy Hedden · « **Reply #11 on:** October 26, 2009, 12:57:09 AM »

Quote from: Acer Saccharum on October 25, 2009, 11:13:33 PM

Great tip on the solder! Never would have thought of it.

Another tip for making the square hole: Make a hardened tapered square punch. Drive it into the hole to form the square. (I seem to remember Stophel came up with this tip)

Tom,

I think that if you drive a square tapered punch into the hole you would have a good chance of breaking the cock. Probably like a 90% to 100% chance of breakage. Just my opinion, but I sure wouldn't do it.

Randy Hedden

Acer Saccharum · « **Reply #12 on:** October 26, 2009, 03:21:19 AM »

I would rough file the square, then form it with the punch. I think you'd be asking too much to drive a round hole into a square one. I doubt a soft casting would break, but I have not tried it yet. Certainly on nothing that's been casehardened already.

Dave B · « **Reply #13 on:** October 26, 2009, 06:33:45 AM »

I would be inclined to heat the hole area with the torch then square punch it hot. Cliff Noal talked about making a swedging set for doing cocks and tumbler shafts, one being a female puch made from the square puch when your done its a perfect fit every time. I believe he discussed this durring a class he did on lock building and you make the shank taper before drilling the screw hole in the tumbler. I have yet to bulid my self one but I love to have the swedged fit rock solid for better sparking.

Acer Saccharum · « **Reply #14 on:** October 26, 2009, 04:41:26 PM »

Nothing worse than the cock rattling around on the tumbler square.

BJH · « **Reply #15 on:** October 27, 2009, 11:59:09 PM »

Just remember if you try to hot punch anything. You really have to be fast driving the punch back out. Or the part being punched WILL lock down on the punch. Think about shrink fitted wear rings etc. BJH

frogwalking · « **Reply #16 on:** October 28, 2009, 07:55:47 PM »

C'mon. Where's Leatherbelly's comment?

T*O*F · « **Reply #17 on:** October 28, 2009, 09:35:37 PM »

I think this topic is being overthunk. I have a pair of tapered, 4-square, doublecut files. One has a single safe side. I mike the square flats of the tumbler axle and drill a round hole to the smallest dimension. Then I spray the back of the hammer/cock with Dykem, orient the hammer/cock and imprint the corners on to the backside. The lead method would work as well, but the Dykem works fine. Using the 4 sided file as a broach, start working it in and out until it just starts on the axle flats. Then switch to the safe sided file and clean the corners up until a tight, tapered fit is achieved. Takes about 1/2 an hour.

Acer Saccharum · « **Reply #18 on:** October 28, 2009, 09:46:10 PM »

Quote

I think this topic is being overthunk.

Overthunk? For who? I like to do the simplest job in the most complicated way.

My thoughts on this: if you are doing a lot of fitting, the punch is a good idea. It also compresses the metal, making it denser around the square hole, which is a good thing. You also get a straight thru hole by punching, whereas you some bell mouth by filing.

T*O*F · « **Reply #19 on:** October 28, 2009, 09:52:15 PM »

Quote

You also get a straight thru hole by punching, whereas you some bell mouth by filing.

Maybe on modern locks, but you will find that the axle square on many original locks is tapered giving a tight interference fit. The ones that aren't are usually the ones which are oblong and need a new one fitted...............you know, the ones with all the punch marks on the backside to attempt to tighten them up.

rich pierce · « **Reply #20 on:** October 28, 2009, 10:10:03 PM »

That's for sure, that originals had tapered axles and holes. I handled an original early Dutch musket lock where this was so exaggerated, I could not believe my eyes. Must have been at least a 12 degree taper.

Acer Saccharum · « **Reply #21 on:** October 29, 2009, 12:46:00 AM »

Taper....

Too much taper on the shank, and the cock is held on entirely by screw pressure. Never seen that, Rich, but I am a believer. Straight sided shank, and there is no option for fitting. It's gotta be exactly right.

A little taper, 2 to 5 degrees, this allows for fitting, this is a beautiful thing. With a light press fit, there is no wiggle. Should things ever loosen up, if you have enough gap, the cock can be moved a tad closer to the plate to improve the fit.

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Author Topic: Fitting a new cock (Read 6506 times)

Bill Brockway

Bill Brockway