"Drill and tap?"

[ed dixon]

I've heard the phrase forever, but have never actually watched it done. What exactly is the tap part of d&r? What is entailed when a smith does this procedure? Also, what should work like this cost?

 

[Badger Arms]

Drilling and tapping a hole is one of the basics of gunsmithing. You drill a hole to a specific diameter based on what thread you want. This is done with a standard twist drill. You then use a tap to cut the threads. A tap resembles a screw with slots cut in it like flutes. This creates sharp edges where the threads are 'cut' in the undersized hole. The flutes create the sharp edges and allow chips somewhere to go. Taps are generally tapered so that they gradually cut deeper as the tap goes in farther. There is also a bottoming tap which cuts threads the correct diameter all the way down to the bottom of a hole that doesn't go through.

Smiths charge around $10 a hole in my experience. This depends alot also on where the hole is to be drilled. On a heat-treated receiver, you might have to anneal the area to be drilled. The cost is well worth it as doing this yourself can often ruin the part. Experience counts.

 

[jrhines]

For examples of the trials and tribulations of drilling & tapping see the post in this forum "Broke the tap off in the hole - ARGGGG!" from parumphcaveman. A good demonstration of what can result besides a threaded hole!

J.Rhines
Seneca, MD

 

[Traveler]

And for even more info just look a couple days prior to that.

http://www.thehighroad.org/showthread.php?s=&threadid=723