Touch Hole Location & Size..??

[Brad Foust]

I am finishing up my first build in over 30+ years or so and have forgotten allot more things than I remember!!
I recall something about the location of the touch hole should be about even with the top of the pan??
I think??
But really cant umember anything about the size of the touch hole??
I will probably end up someday with some form of liner, but for now would like to just drill the touch hole.
Any help on location and size is appreciated.
Thanks

 

[gunmaker43]

You mite get a builders book just to refresh your memory. I use 1/16" .0625....Tom

 

[MSW]

just one guy's opinion: free and no doubt well worth the cost!

I would put the touch hole so that the bottom of the hole is just touching a line formed by the edges of the pan and, of course, centered on the pan itself. this so- call 'sunset position' seems to work well for me.

as regards the actual size of the hole, well, that's sort of like asking if one should wrap their flint with leather or lead ... you can stir up a lot of dust just asking the question. I use White Lightenin' touch hole liners, and I go with the hole that's formed when you take off the stud, so I don't know the exact diameter. Some folks say it's too small, and some folks open it up, but I've left mine as is and it works fine for me.

I wouldn't open up a hole just on the say- so of anyone (and I'm not saying this to try to denigrate or insult anybody - most of the folks on this forum are much more experienced than I). try the thing before you take out your drill bit! then you know, and if it ain't broke, don't fix it.... if, however, you don't get the performance you want, and you are going to increase the size of the touch hole, go up in as small an increment as you possibly can.

good luck with your project, and make good smoke!

 

[Col. Batguano]

You ought to do a search and see what Pletch has to say on the subject. He's done a lot of studies on ignition time and flash hole size and shapes including some fascinating high speed video on the subject.

 

[Billnpatti]

The "proper" location for a touch hole is with the center of the hole even with the top of the pan and centered on the pan. This is often referred to as a "sunset" position because it resembles a setting sun on the horizon. As for hole size, most people find that a hole that measures close to 1/16 inch to give the best ignition. The ignition can be further improved by coning the inside of the touch hole liner. Lacking a touch hole liner, you can carefully cone the outside of the hole. This coning allows the main powder charge to be a bit closer to the flame from the pan. Pletch has done rather extensive research on pan charge location and has found that it makes no perceptible difference where the pan charge is located so long as the touch hole is not blocked by it. You can find videos of his research on You Tube.

 

[Zonie]

The others have described the best location for the touch (or vent) hole but you mentioned just drilling the hole without using a vent liner.

In my opinion, the comments about using a 1/16" vent applies to the size that would be used in a vent liner.
Vent liners almost always have a larger 1/8"(.125)-5/32" (.156) counterbore drilled on the inside leaving about 1/16" wall for the vent hole.

This allows the powder charge to be very close to the pan's powder flash so a small vent works fine.

A simple hole thru the wall of the barrel doesn't have a larger counterbored area so the powder flash will have to travel thru the whole thickness of the barrel wall. This means a larger vent hole is in order.

I suggest using a number size drill bit like a #50 (.070" dia) or a #49 (.073" dia).
If these aren't available use a 5/64 (.078" dia) for your vent.

 

[nchawkeye]

The bottom of the hole should be just above the line drawn across the top of the pan...This way it is behind the heel of the frizzen when shut so you don't have the fuse effect from filling with powder...

You hear on here plenty of times about fellows having to fill their pan half full, bank away or bank toward this or that to get their gun to shoot...This is because their touch hole is too low and it fills with pan powder...

Keep it high, ignition will be faster and more reliable...

 

[Stophel]

Actually, I think the idea that the best touch hole location is ever so slightly above the top line of the pan is a modern myth. "Common knowledge" that just ain't so. Pletch was mentioned earlier, and in his tests, he showed that touch hole position made no appreciable difference in ignition speed. Many old guns have their touch holes sunk way down near the bottom of the pan! Maybe they knew something we don't. The ideal is to get the priming as CLOSE to the main powder charge as possible (which certainly seems intuitive to me) :wink:

The only good reason I can think of for putting the touch hole so high is that it makes it easier to use a pick if you need to (and I virtually never need to).

 

[Birddog6]

My first concern would be the distance In Front of the breechplug Face....... as if you end up On the breechplug threads,
you have a problem. :idunno:

This is something that is figured out initially when building the rifle & installing the Lock & Barrel.

The Vent Hole should be in front of the breechplug face.

A Vent Liner should be entirely in front of the breechplug face so the threads of each do not intersect.

Then the vent hole or liner should be Centered in the barrel flat, if at all possible. You raise/lower the barrel to achieve this.

Then you want the vent hole even or slightly above the imaginary line across the top of the pan. Here ya must be careful,
as you want to BE SURE the closed frizzen is going to cover the hole. Locks do have dif frizzens, so look at what you are
installing before ya drill a hole.

And from what I have seen tested, up or down a tad really has little to do with ignition speed.
Same as a lil forward or backward of pan center seems to have little to do with ignition speed either.


Keith Lisle

 

[b737tvc]

Hey Bigmon, A lot of ideas and thoughts....good luck many good reads i.e., gunsmith of Grenville county? He tells it like it is and shows how.

Good Luck? Now if I can only find a good finish for my stock I hate my last one so now Im re doing the gun...er

Beaver T.

 

[Stophel]

Mine tend to end up being at or just a hair below the pan top edge, and usually a bit forward of center (to keep from having to notch the breechplug so much!). Many locks, such as a Siler, would benefit greatly by enlarging the pan opening forward. Not only to give you more room for touch hole positioning, but a bigger pan means more primer, more flash, and a larger area to catch sparks.

 

[Brad Foust]

Thanks so much to all. Very informative.
Just a few things. When I laid out the lock I positioned the center of the pan so that it's center was just ahead of the breach plug face. And in height figuring the top of pan at center line of barrel. So I think I'll be ok according to what you all have said.
Concerning the finish. Just what I did on this one and I like it so far.
It is walnut but I stained it with Tigerhunts stain and then applied a Herters stain / sealer I had.
After lots of dry time I saturated the stock with Thompsons water seal, which I am told is thinned BLO.
Then four coate of Linspeed oil.
Once dry I am going to was the heck out of it after light steel wool.
Thanks and take care