Notes from the field:
I have just recently been working on a frame for an addition to my house.
I have been intrigued by this topic and having posted opinions previously I thought perhaps I could test my theories and observations and/or learn something. (It could happen!)
Report as follows
Project: Thru motises-7 ½” & 9 ½” deep, cross sec-1 ½”x3 ½”
Material: #1 Doug Fir
Tools:
· 1 ¼” drill bit
· 3/8” drill bit,
· 1-1/2HP Router w/½” shank 2 flute bit 2 ½” cut length
· Reciprocating saw w/12” blade (don’t be frightened)
· Chisels and slick
Procedure:
· Layout mortises and score across grain
· Build jigs for router (dimensioned to index router base) and 1 ¼” drill bit
· Drill two holes 1/8”from both sides using site built jig
· Remove waste between holes w/saw (carefully) Starting at top and slowly moving saw to vertical
· Attach jig using screws where it won’t show, clamps where it will
· Set router to 1 ¾” –2” (depth not critical), remove material by “circling” around hole removing approx 1/16” per pass
· Set router to greatest cutting depth (3 ¼”) and repeat previous
· Repeat routing on other side of beam
· Drill 3/8” hole at corners of mortise thru material left at center.
· Remove remaining material and true mortise with chisels and slick
Thoughts and suggestions:
· I would suggest a larger router (in my case this was disallowed by a bout of budgetus interuptus),
· Keeping more than one bit on hand if doing production work.
· My plywood jigs seemed to be showing signs of wear, if long use is expected and the joint is standardized enough, perhaps metal jigs?
· A fence on the jig indexing the reference face (if doing square rule) might aid both speed and precision
· I a top bearing bit or a base mounted guide might allow for aligning the jig on a parallel plane with the reference face if it is on the opposite side of the member. This would keep the tool in alignment with the reference face. (Not incidentally this technique would work well for housings)
· Hearing protection for everyone within half a block. This is the loudest possible bit in a loud tool.
Overall I think the router could be a great tool for quickly cutting precise, standardized mortises after most stock has been removed by other tools. Used in conjunction with a chain mortiser I think that this could be a technique that could be very fast and quite precise.
