Tapping and threading different types of woods.

[TwoGuns]

I have a project that requires putting threads on several one inch Oak Dowels. They will then be threaded into either Oak, Maple , Walnut or Aspen in one inch deep bottom tapped holes. My tap & die kit is from HF and has seen a lot of use. Are there any special tricks to stop tearing etc and keeping a crisp thread?

TIA Dennis

[Phil Again]

I recall, or at least I have a memory of, something about you shouldn't use metal cutting Tap and Die for larger diameter wood. Wooden Threads should be something like 6 or 8 threads per inch at your diameter, the depth of the threads is deeper for wood, and the slope of the threads for wood is not the same as for metal like iron.

Oak, IMHO, would be an incorrect choice due to brittle grain structure when fully kiln dried. Hickory would be a wiser choice.

But like metal threading, I still think it is a 1/2 turn cut, then back off 1/4 turn to clear out waste. Both uses a lubrication, I think wood would use a paste wax.

I did a Google, and Amazon.com is selling a wooden tap and die set from a tool vendor. Garrett-Wade may carry a tap and die set for Wooden dowels.

Should be other vendors.

[dadiOH]

The problem with cutting threads into dowels is that the die is cutting cross grain and those little, fragile pieces of wood thread break off easily (no problem using a tap into a hole perpendicular to the grain). That is true even if you turn the die in very small increments before "back cutting".

Even with the broken, raqgged threads you'll probably find that they hold pretty well. If not - or if you just want pretty threads - here's what I do...

1. Coat the broken threads with a liberal amount of super glue
2. Coat the super glue with a fine powder. You are trying to get a glue/powder mixture that is the thickness of the threads to be cut. The last time I had occasion to do this I used tile dust from Saltillo tile ( I had a lot available) but you could use any thickener such as Cab-o-Sil, talc, etc. meant to thicken epoxy. Sanding dust - very *fine* sanding dust - works too but not as well.
3. When dry, cut the threads again. Repeat if necessary. Done properly, you'll wind up with perfect, wire edged threads.

[Pat Barber]

[Fred the Red Shirt]

ISTR a recommendation to oil the wood with linseed oil before cutting the threads.

[Larry Blanchard]

Correct. And reapply more oil every time you back out the tap to clear the chips. About every other full turn, IIRC.