Finding correct line for tang bolt

[Jerry V Lape]

Not being a machinist, I needed a way to locate the entry and exit points for the tang hole with the entry on the tang perpendicular to the surface of the tang so the bolt head would look right.  So here is my home made solution.  Small round magnets about the same diameter of the tang bolt head, found on the refrigerator photos (I used two stacked), were positioned on the tang and a long screw with the head trued up on top of the magnets.  The magnets naturally find the perpendicular, the screw giving me a long guide. 






I then eyeballed with a ruler the center line of the screw and drew a line on both sides of the stock.  Carried the line across the bottom which gave me a check on the accuracy of my eyeballed  lines.  Intersection of the lines with the centerline of the stock marks the two locations for the entry and exit of the drill. 



Hope this helps someone else

[Jim Kibler]

I usually just eyeball things, but that's a pretty clever idea.  Looks like it will work well.

[B.Habermehl]

I like the idea. Being a ex machinist I would use one of the flat head lock bolts instead of the deck screw. The lock bolts head is machined and should be more perpendicular to the shaft. I can only guess the manufacturing process for deck screws, but I doubt the squareness of the face to shaft is much of a priority. Great idea just my two cents. BJH

[Jerry V Lape]

BJH, I didn't have a flathead lockbolt and I wanted a long object to help with the eyeball alignment.  I did use diamond plate to flatten the deck screw head which is the same diameter as the tang bolt's head. 

[J Henry]

"The Gunsmith of Grenville County" Building the American Longrifle ,  by Peter A Alexander, ISBN 1-880655-13-6, pg 47-48 (drilling) has a Jig that fool proof for aligning drill holes.  

[P.W.Berkuta]

Interesting concept --  ??

[Jerry V Lape]

J Henry, the jig in Gunsmiths of Grenville County is quite useful but you have to know where to put the two ends of the jig into the stock.  My little magnet setup helps with that.  I use a portable form of the same jig for most of my drilling with a portable drill.  Short bolt on the right side is hollow and accept either a 1/16" drill bit and I have another bolt for a 1/8" bit.  Clampl the jib in a vise and hold the wood on the spike end.  Works slick and I avoid having to arrange clamping for the drill press. 

[FDR]

Clever idea Jerry!  I would also find the jig useful especially with the hollow bolt.

Fred

[Joe S.]

Our own Dave Rase sells a similar jig if your interested,shoot him a PM

[Mark Elliott]

I have a number of problems with this method,  the first is that your screw isn't straight.  The second problem is that you are assuming a number of surfaces are either perpendicular or parallel that really are not.  Essentially,  you are just eyeballing things and fooling yourself into thinking that you are doing something more precise.

Now,  these days,  I pretty much eyeball things, but I don't think that I am doing anything else.   I realize the probable error and generally use the second of the methods given below to allow for the error.

The pretty standard way to drill the tang screw hole is to screw a pointed bolt into the center hole of your drill press table and then align the point of the bolt with the point of the drill bit.   Then you put the point of the bolt where you want the drill to come out on the bottom of the stock and the drill bit where you want the hole to start of the top.   You then drill almost all the way through; flip the stock over with the pointy bolt in the hole at the top of the stock; and the drill bit in the divit at the bottom of the stock.  Drill the rest of the way through and your are done.

The other way to do this is to eyeball it; and drill from both ends toward the middle with a smaller diameter drill bit than you want the finish hole to be.   Once you have connected up the two holes, you drill through with the final diameter drill bit.   This method usually also works pretty well with lock bolts.  

[Boompa]

  Get one of Dave Rase's drill jigs.  I bought one a year or so ago and will never be without one of these. Takes the guess work out of the process.

[Long Ears]

Jerry, great idea, I think some of the guys are missing what you are trying to show. The jigs mentioned do nothing to align the head of the tang bolt to the angle of the tang so when you counter sink it one edge of the bolt head doesn't stick up. I own a couple of the drill gigs and they are great for drilling straight AFTER you get the start point. Good job. Bob

[Boompa]

  With the jig you replace the top bolt with a common flat end bolt and a nut on it. Open the jig and place the nut flat down on the tang. Mark on the trigger plate the location of the point on the lower bolt.  Measure the outside of the nut and divide 1/2 to locate the entry of the tang bolt. You now have the angle of the tang bolt. Return to the bolt that came with the jig and drill away.

[davec2]

Jerry,

Great idea for getting really close to a perpendicular to the surface of the tang quickly.  I use magnets for a lot of things, including fixturing, etc.  I use these "Ultra-High-Pull Neodymium Magnets" from Mcmaster Carr.  They are incredibly strong and come in a wide variety of sizes.

Funny story about these very strong magnets.....well not so funny for the nimble nut who did it......At any rate, I had two magnets, each 5/8 inch in diameter.  These particular magnets had a pull strength of 27 pounds....each....and I was using them to keep some sliding doors closed.  I had them in my pocket when I went to the hardware store and I showed them to the guy behind the counter.  I had one in my upturned palm and was moving the other one around under my hand.  The one on top moved to where ever the one underneath moved.  He said, "Hey let me try that", so I handed him the magnets.  I turned away for a second and I heard the guy yell.  When I looked back, he had one magnet on either side of his ear lobe.  Now I don't know if any of you have squeezed an ear lobe with 54 pounds of force, but this guy was dancing around on one foot trying to get the darn magnets off without pulling off the whole ear.  I couldn't really help him and it was fairly humorous to watch.  When we finally got the magnets off his ear, it looked like his ear lobe had been hit with a hammer.

The moral of the story is, if you use these magnets, don't try to wear them as earrings.

[Jerry V Lape]

Mark, maybe I am deceiving myself but the last two tang bolts I drilled, halfway from each side, hit head on the first pass.  And the countersink came out square as well.  So I think I will keep the system and upgrade the blue screw to a machine bolt next trip to the hardware store.  The drilling jig was not my invention as it has been discussed on here for years.  I just had one made to my specs by a friend with a machine shop.  

[eddillon]

David Rase makes a fixture that I have used for tang bolts, lock bolts, pins and wedges.  Suggest that you get one of these time saving fixtures.

[BOB HILL]

jerry









Jerry,this is a great idea. I've always eyeballed mine with a square off the tang. I think many are missing the point that you are finding the two points to drill from, not using this to drill the hole.
Clever idea, thanks.       
Bob

 

[J Henry]

 Bob Hill,, That is what the jig in Alexanders book does,lines  the entry and exit hole,mounting in a drill press takes out all the "eyeball" guess work.Read the description in Alexanders book,the jig is also shown on page 175,,slick as Frog Fur.

[Boompa]

  You can find the correct angle using the drilling jig but I think I like Jerry's idea of determining the angle better, it looks to be quick and easy. 

[Joe S.]

I think the moral of the story is to have your bolt,screw sit flat to the surface.When this is accomplished  and you countersink the hole your screw should sit down flat and after filing should be pleasing to the eye.Folks here tell you how they got there,how you get there is up to you.I like his idea.There are Sometimes more than one way to build a mouse trap

[elkhorne]

Hey guys, I was just thinking about Jerry's new technique and read the comments about the vertical screw held with a magnet and a line drawn to represent the path of the tang bolt. Well, I got a package of 1/2" magnets from Hobby Lobby (watch the fingers and ears as these things literally jumped out of the package and it took a lot of effort to separate them!). I placed one under the short/heavy leg of a machinist square. Next, I placed it along the top of the tang of a rifle I am building and centered it on the spot that would line up with the frontal area of the trigger plate. The square provided a straight edge to draw an accurate line for the tang bolt path. I hope this variation of Jerry's technique will help all to be able to get their tang bolts drilled a little more precise. I also, like others, recommend either David Rase's or Tom Snyder's drill fixtures for the most precise holes possible. We are always looking for a new and better "Mouse Trap" and thanks to Jerry, his idea has opened a whole new technique(s) to get our lock bolts installed more accurately. Maybe someone else will be able to think of a better way to build on our ideas. I sure bet the "Ole Masters" would have used any new technique to make their gunmaking better and more accurate!

[Jerry V Lape]

Elk Horn, 

I like your idea too. 

Jerry Lape

[B.Habermehl]

Jerry, when you get a flat head screw to use with your magnet system, I would suggest that you get a machined one from one of our muzzloading suppliers. The hardware store variety screws and bolts are often cold headed using much the same process as nails are headed. Once again squareness of the face of the head to the shank is not a high priority. I never hurts to have a few spares any how. BJH