Vent liner trouble

[Tom Currie]

Installing a White Lightening 5/16 30 TPI .310 OD with a recommended 9/32 .282 drill . Boy that isnt much extra steel for threads. Didnt go well. Even from my press the whole opened up a bit and my first 3 - 4 threads dont grab the liner well. Last 4 or so do. 54 cal C weight barrel.

I haven't installed a liner with fine 30 TPI before, so maybe it's my inexperience here.

Didn't want to but I guess I'm going to the big 3/8 WL liner. Don't really feel safe as it is now. Any thoughts here ? Maybe a smaller drill would have saved me here, maybe .270, tapping would have been more delicate. Just thinking out loud.

[P.W.Berkuta]

If you don't clamp your work down to the table you can get a larger hole than what you wanted. The best way is to clamp your work and drill with a smaller drill then step it up either to the recommended size or a few thousands smaller and then with out moving the work piece remove the drill bit and put your tap in the chuck, apply some tapping fluid (not oil - real tapping fluid) and using your hand rotate the chuck while appling downward pressure to the feed wheel until you just barely break through into the bore. This will give you a tight fit to you vent liner. Good luck  .

[David Veith]

All so remember drill don't drill round and have a habit of drilling over size. On some things it pay to ream the hole. I am not saying in this case. The other thing when you started to tap it did you use a center point agains the tapping wreach to keep it straight. Witch might account for the first couple threads being sloppey.
David

[Mike Gahagan]

Tom,
     You should have used a letter "I" bit which is a .270.If you go with a 3/8" liner you will need a "Q" drill bit.

[D. Taylor Sapergia]

Paul, you're approach is identical to mine.  The key is to make sure that once the barrel is held solidly to the drill press table, either in a vise, or clamped, and 90 deg. to the drill bit, it does not move.  This involves leaving enough clearance for the replacement of drill bits, and the tap.  Once the hole is drilled, I remove the belt from the drill press, and rotate the tap in the chuck by hand, with lots of Rapid Tap cutting fluid.  The taps Chamber's provides are excellent quality, and cut very very nice threads.
As to you're dilemma, Tom, you may have to go to the next larger liner - a 3/8" x 32, and use the recommended tap drill for the final cut before taping the hole.

[flehto]

After using the proper shim for the swamped bbl  to ensure that the liner is at a right angle to the bore and w/ the bbl on the long wooden 3/4" reinforced  plywood that's clamped to the DP table, I just hold the bbl and first drill w/  through w/ a 3/32"  bit which picks up the center punch nicely and then go in w/ the letter "I"  bit which follows the 3/32" pilot hole. W/ the tap chucked , lubed and aligned  w/ the hole, the drill press is turned on and then off and while the spindle is coasting, the tap is lowered into the hole. The resistance stops the spindle and the tap is unchucked and the remaining threads are tapped in the bench vise.  If the drill bit is improperly sharpened and if one cutting edge is longer than the other,  the drill doesn't cut on it's axis but rotates eccentrically resulting in an oversized hole.  The initial spindle speed has to be fast enough that when shut off, there's enough remaining speed to tap 4-5 threads. ....Fred

[PIKELAKE]

Tom, I feel your pain. Last year about this time I made a major blunder. In the process of installing a W. L. vent liner I buggered the hole up pretty good. Tried to go to the next size liner but the hole would have run into the next flat. Finally decided to just replace the barrel and fit the old plug to the new barrel per Cody. The rifle was for all practical purposes was done which added to my problem. I did install a new liner on the new barrel and had no problems. The original drill bit was tossed with great hostility and a new bit was used. You may be able to redrill the hole one size larger I don't know. I do know this, rock solid set up, cutting oil and a brand new drill bit. Production Tool, in Redford, a couple of bucks and save your self some grief. By the way, that was not my first attempt at installing a vent liner, it was no# 19. Anything can happen to anyone at anytime.   JZ

[Dphariss]

Installing a White Lightening 5/16 30 TPI .310 OD with a recommended 9/32 .282 drill . Boy that isnt much extra steel for threads. Didnt go well. Even from my press the whole opened up a bit and my first 3 - 4 threads dont grab the liner well. Last 4 or so do. 54 cal C weight barrel.

I haven't installed a liner with fine 30 TPI before, so maybe it's my inexperience here.

Didn't want to but I guess I'm going to the big 3/8 WL liner. Don't really feel safe as it is now. Any thoughts here ? Maybe a smaller drill would have saved me here, maybe .270, tapping would have been more delicate. Just thinking out loud.

Unless pilot drilled with a smaller hole many drill bits will cut oversize.
Also the 1/4 32 I got with the last WLs I bought is plenty large for the diameter of the liner. I wish I could get an H1 tap but can't.
I solved this by making liners with a 1/4x32 split die so I can make it tight in  the hole.
I start the tap in the chuck that held the drill. This also helps prevent the tap starting crooked. But I remove it from the chuck, still in the barrel, then finish tapping the hole with a normal tap handle.

Dan

[KLMoors]

There must be something in the air. I managed to break a 1/4 inch one off last night.  I spoke to Jim today and ordered a 5/16" kit to replace it.

I generally use a bit that is a size or two below the recommended size for holes I'm going to tap for a white lightnin. I've only done 5 or 6 of them but when I did my first, I practiced on a scrap piece of barrel and I thought that the bit in the kit seemed too big by a hair so I now use a slightly smaller one and that seems to work better in my set up. (as long as I don't break it off!)

I'd have to go out and check to be sure, but I think I use a #3 (.213) or  #4 (.209) drill for the 1/4 inch liner instead of the recommended 7/32" (.21875) bit.

I'm going to have to go to the pre-drilling with a smaller hole idea. That makes really good sense.

[northmn]

I messed up installing a 5/16 vent liner this year on a build.  I hit the face of the breech plug and it made an oval.  Got in a hurry and of course had to spend more time fixing it.  Instead of redrilling I used a chainsaw sharpening grinder in my dremmel and opened it up for a 3/8 X24. Used a #5 grade bolt to make the liner so it would brown and not look like h---.  It made for a tight enough fit for the 3/8 and has worked for several shots. 

DP

[greybeard]

It's always a learning curve so it seems. May moons ago I was building a muelear over under in .45 + 7/8ths.  come time to drill the barrels for 1/4 =28 I drilled with the proper drill bit and put the tap in the drill press and put too much pressure on the press and turned the chuck by hand but the too much force on the quill I cut the threads nearly right off. Good theng they made 5/16ths + 24 so saved the day for me. A good  lesson for me as I have never done it since.   Bob

[bgf]

This is not the thread I want to be reading, as I'm nearing the day I need to drill a touch hole .  I think I will start with a 1/4" drilled and tapped hole, for sure.  That gives me 5/16's and 3/8's as a backup plan.

[KLMoors]

That's exactly why I've been using the 1/4 inch! LOL

[billd]

It sounds like someone has the wrong size drill.   I use a #4 drill with a 1/4" liner. This is the drill Jim sold me.  A #4 drill is .209, a 1/4" liner is .250. That's .041" difference.

A 5/16 liner is .312" and you used a .282 drill.  That's only .030 difference.  Something is wrong!!  (I hope it's not my math)

Bill

[Birddog6]

I always use a pilot hole to guide my drill when doing vent liners. And I use a specific drill bit for the vent liner that Jim supplied with the tap, and that is ALL that bit is used for.  Also start the tap in the drill press so I know for sure it is started straight, then after it is started good, I take it out & finish it by hand.

One issue with going to 3/8" vent liner on the .54 cal bore.  The size of the opening on the inside of the vent liner my cause some issue with the jag & patch. When you hit that area with it, the jag is going to move towards the hole in the vent liner, because of the diameter of the hole for the coned vent liner & the dia of the hole in the cone in the vent liner.   Have not tried it on this size to be sure, but sounds like it could. I do know if you go to a 5/16 on a bore smaller than a .50 you can sure feel it when you hit that vent liner area.
In this instance it might be better to mill a hole proper size & mill to a certain depth, then use a bottom tap & thus leave a shoulder for the inside of the vent liner to butt up against.   My not having the equipment to do this I cannot say it is worth the effort, but seems like D.Pharris mentioned one time of doing some this way.

Keith Lisle

[Tom Currie]

Thanks everyone for the replies and suggestions. It's good  to know I'm not alone, and in good company.

One thing I've learned on this is that with more threads per inch the prescribed drill diameter gets larger which leaves less margin for error.

Example 5/16 18 TPI .257, 5/16 24TPI .272 and 5/16 32TPI .282 or 9/32. It all makes sense, just a more delicate operation.

Pikelake, The 5/16 32TPI was hard to find. I did get it at Production Tool in Redford. They recommended the drill size.

[Kelhammer]

I am wondering, could you have the hole micro-tig welded shut?  I would want a mill to do the repair work how ever.  Using an end mill to recut the hole, to avoid any lead off from an uneven surface.

[Dphariss]

I am wondering, could you have the hole micro-tig welded shut?  I would want a mill to do the repair work how ever.  Using an end mill to recut the hole, to avoid any lead off from an uneven surface.

Very bad idea, if 12l14 its a really bad idea. Free machine steels do not weld well at all.
Gun barrels are good prospects for welding.


Dan

[bob in the woods]

Well, this is just my opinion, but, I say again, going through RCA 1 and 2,I don't see liners as being common on original American longrifles, and I get along just fine without them. I consider them as being a repair. In your present situation I would make my own liner. Where I've replaced liners in other folk's guns due to thread wear ;usually those who insist on removing them for cleaning, I make mine as per Hershel House's video, and have always used 1/4-28 threads with no complaints.