Popular Woodworking 2007-10 № 164, страница 19

Tricks of the Trade

CONTINUED FROM PAGE 21

Routing Through-mortises in Thick Stock

I recently had to make some through-mortises in a couple large, 3"-thick wood slabs to accommodate the tenons on a connecting stretcher. The size ot the slabs precluded using a tabletop mortiser or drill press to cut the mortises, so I decided to rout them. Unfortunately, I didn't have a router bit with a 3"-long cutting flute, which might whip around at that length anyway. And I didn't think that routing in from opposing faces would be successful enough to yield straight mortise walls, even with careful layout.

I solved the problem perfectly using a combination ot template routing and flush-trim routing. Using ¹/4^ll-thick sheet stock, I made a template to the exact size ot the finished mortise. After securing the template to the slab, I installed a pattern-routing bit (with a top-mounted bearing) in my router. Then I routed out the waste within the template cutout, keeping reasonably close to the edge without hitting it. When I reached sufficient depth to allow the bearing to ride on the template, I routed the perimeter.

Next, I used a large spade bit to drill out most ot the remaining wood, making a series ot closely spaced holes while keeping away from the finished edges. I switched out my pattern-routing bit tor a flush-trim bit (with a bottom bearing) and, entering from the opposite side ot the slab, I trimmed away the remaining stock with the bearing riding against the previously routed perimeter surface. The result was a hole with straight sides cut completely through the workpiece. All that was left was to chisel the rounded corner square - a relatively easy chore.

— Stephen Gross, Hilo, Hawaii

Top-mounted bearing

at

Pattern-routing bit

- Template

M

Spade bit

L

Flush-trim bit

Bottom-mounted bearing

STEP1:

Remove waste, avoiding template.

STEP2:

Rout perimeter with bearing againsttemplate, when cut becomes deep enough.

STEP3:

Drill out most of

remaining waste.

STEP4:

Turn stock over and rout perimeter with flush-trim bit.

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