Reaming hole

[Brad]

I have a question regarding cross holes for things like lube dies.

I get the die close to final size then drill the cross holes. I then polish to final size which also clears the burrs left by the drill.

Would I be better to drill the cross holes a little undersized then ream them? Would the reamer clear up some of the burrs left in the die?

 

[AMTom]

It probably would, but not completely.
Enlarging the hole after drilling is the better method, and you're doing that anyway.
The minuscule burr that you are pushed back into the cross hole can then be broken off with a punch the size of the hole.

 

[Pistolero]

Reamer will leave a bit of a burr, too, likely. I think what you are doing is pretty good.

Bill

 

[Brad]

Interesting you mention a punch Tom, that is exactly what I do now. Polishing the bore after cross drilling often pushes part of the burr into the lube holes. A fine wire easily breaks them off.

 

[Ian]

Good to know. Thread burrs take a couple steps to knock down, raise, and knock down again so this should be no different.

Now, how do drill a gas port hole without raising a burr? In the woodworking industry a sacrificial support clamped tightly will take care of most kinds of "splintering out", be it drilled holes or the end of an edge shaped across the grain, seems like a similar principle might work for metal?

 

[Brad]

I can tell you that drilling a gas port without a burr was a common discussion amongst highpower shooters. Some drove a slug into the bore to drill into. Most just shot the burr out. I don't know that either method was ever proven to be better.
I would just shoot it out with a jacketed round or two.

 

[Intheshop]

Drill geometry.Kinda hard,and most folks don't bother reshaping or sharpening small diam drills but.....

It's amazing how efficient a twist drill can be once you learn to facilitate"sharpening".Play around with the geometry on your drill.Otherwise it sounds like you've got a working system.Best of luck,BW