Installing a touch hole liner.

[Cory Joe Stewart]

On the instructions that came with my touch hole liner it says "Tap hole with 5/16-32 tap leaving the bottom 2 or 3 threats only partially cut."

Any hints on how to do this? I am only experienced in tapping all the way through.

Coryjoe

[Metalshaper]

CoryJoe,

 just measure and try to stop the tap when you have part of the starting taper..still in the hole!  that way those bottom 2-3 threads, are not fully cut (un-like when you are through tapping )  this will cause the liner to tighten up as it is threaded into these
partial formed threads.

Just go slow, back the tap out often and look into the hole!  you can see where the threads are and if they are full cut or not. IF you need to.. get a scrap piece of metal stock and thread a practice hole.

Others may be able to explain it better??

Respect Always
Metalshaper/Jonathan

[Dr. Tim-Boone]

Made sense to me Jonathon.  The tap is tapered for approx i/4 inch at the tip. Once you have 1/8-1/4 inch of the tap through the hole ..stop.. don't go any further... as Jonathon said try it on a scrop ..you can feel when the taper ends...but you don't want to go quite that far.

[Dennis Glazener]

Cory,
Jonathan gave you good advice but be careful not to stop too quick. You need to make sure you firmly seat the touch hole. Its best to drill and tap the hole while in a drill press vise without moving anything. I drill the tap hole then I put a center punch in the chuck of the drill press then hold the tap/tap handle in the starting position and lower the quill of the drill press until the center punch is in the hole in the back of the tap. I put a little pressure on the quill and start the tap. Releasing the pressure to break the chip (back the tap out a ways) Keep doing this until you are sure the tap is well started straight. Then you can forgo using the quill. Then turn the tap by hand removing it when you are getting close to going all the way through. Look at the bottom threads and when you can see threads all the way to the bottom of the hole BUT NOT full depth stop. Then take larger bit or counter sink and cut the slight bevel on the mouth. Then try the touch hole liner. If it won't fully seat without extreme pressure remove it and run the tap a little deeper then try again, keep going until the touchhole liner fits TIGHT in the bevel you cut at the top with the drill bit or counter sink (either one works).

Now if you don't have a drill press its going to be a problem getting the hole/tap/bevel/countersink aligned correctly and you may want to go find a friend that has a drill press, very quick and easy if you have access to a drill press.
Dennis
ps if you MUST do all this by hand I would cut the bevel at the top of the hole very shallow. If you go very deep it will be harder to keep the touch hole champher to fit right into the countersink (bevel) you cut for it to fit to.

[Acer Saccharum]

For a white lightnin liner:

The '32' part of the tap nomenclature means there are 32 threads per inch. For each turn of the tap, the tap will advance 1/32" more.

Once you get the hole partially tapped, remove the tap, clean the threads, and screw the liner in by hand. If it stops way out of the hole, then you know you need to tap more. With caution:

So if the liner stops 1/8" from where you want it, you know that is 4 turns away form home(1/8 divided by 4 = 1/32). But according to instructions, you want it to stop 2 to three turns out....so tap one more turn, remove tap, clean hole, then try the liner again.  It should be 1/16 to 3/32 away from home. Take the liner out, degrease everything, loctite the threads(my personal preference) and wrench the liner down until the countersink and liner are kissing. Do not crank it home, just until the flange and countersink touch, with a little more pressure. Let the loctite set, then hacksaw off the liner boss.

Too much tightening on such fine threads will cause them to weaken, or strip.

[smylee grouch]

I agree with every thing said so far, and also suggest using good tapping oil when cutting those threads.   Smylee

[Dphariss]

If loctite is used use the REMOVABLE loctite. Not the permanent/stud and bearing mount stuff.
Liner must be no longer than the side wall or it will not allow cleaning all the way to the breech.
I like to seat the liner against a shoulder, fewer fouling traps that way.
Don't tap so deep that the tap cuts threads into the if the bore is close to tap size.

Dan

[Rasch Chronicles]

Dan,

Don't tap so deep that the tap cuts threads into the if the bore is close to tap size

I think I know what you mean,  "into the bore," right?

Best regards,
Albert “The Afghan” Rasch
The Rasch Outdoor Chronicles
Big Cutters, Rank Hogs, and Coffee!
ΜOΛΩΝ ΛΑΒΕ!

[mbokie5]

If loctite is used use the REMOVABLE loctite. Not the permanent/stud and bearing mount stuff.
Liner must be no longer than the side wall or it will not allow cleaning all the way to the breech.
I like to seat the liner against a shoulder, fewer fouling traps that way.
Don't tap so deep that the tap cuts threads into the if the bore is close to tap size.

Dan

Dan, let me be certain I'm understanding you.

Liner must be no longer than the side wall

Are you saying that the liner can be no longer than the thickness of the side wall?

I like to seat the liner against a shoulder

Would a shoulder be where two barrel flats meet?

If so, what approximation do you use, to tap how close to the point where the barrel flats meet?

How far should the top of the tap, the part you see, which will seat the top of the liner, be from where the barrel flats meet?

I apologise for asking what are probably real newbie questions.