I’m trying to understand the mortise and tenon “Rule of Thumb,” specifically when using machinery (not chisels). Everyone quotes the Rule of Thumb differently, and I’m left . Below are various “rules” I’ve come across, with [brackets] indicating variations in the “rule”. Please tell me which “rule” you follow and, if possible, the source of your rule.
Thickness
Should be [1/2] [1/3] the [tenon] [mortise] stock
Height/Length
Should be [4x] [5x] tenon thickness
Should be [1/2] [2/3] [3/4] the width of the mortise stock
Width
Should be 5x tenon thickness, not to exceed 4” or the tenon is divided
Should be full width of tenon stock, less Ľ”
Now, tell me your M&T sizes for these 2 scenarios, each having the M&T in the center of the stock, assuming no haunched tenons, etc.
Scenario 1
Rail stock: ľ” thick by 3” wide
Stile stock: ľ” thick by 3” wide
Scenario 2
Rail stock: same as Scenario 1
Stile Stock: 3” thick by 3” wide