I'm slowly working on Pat Warner's Router Table Fence, aka "Precision Fence" (see Fine Woodworking #144 (Oct. 2000) - "Micro Adjustable Router Fence" and http://www.patwarner.com/routerfence.html [soon to be revised]) and have some questions about taps and tapping in wood. Pat specifies tapping for some of the assemblies and refers to his article in Fine Woodworking #126 (Oct. 1997) "Threading Wood for Machine Screws", p. 63, where he features four sizes for thread holes: 9/64", 13/64", 1/4", 5/16".
I recall from metal working days that taps come in sequence, e.g. "taper", "plug", and "bottom". For an informative and concise summary of tap and tapping, I found the following site helpful: http://www.jjjtrain.com/vms/cutting_tools_hand_tap.html .
My questions are, all in connection with tapping wood:
1) Do you use a sequence of taps, e.g. a taper and plug, of just use a plug? I was reading at the web site referenced above about the compression of the threads and wonder if using a sequence of taps produces a better thread because each tap helps compress the threads. (The tap photographed in Pat's article looks like a taper tap.)
2) Do you use the recommended drill size for the tap, or try something more or less since we're tapping into wood?
3) Should one strive for American National and Unified Screw Thread system's "Coarse UNC" or "Fine UNF"?
4) What about using linseed oil both as a lubricant and something to help harden the threads -- you'd let the holes dry for a day or two before inserting the screws?
Are entertaining these question making my progress slow?? Answer: yes.