Safe alternative to using plunge router horizontally

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Forum topic by Dondy posted 01-08-2018 01:47 PM 868 views 0 times favorited 3 replies Add to Favorites Watch
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1 post in 921 days

01-08-2018 01:47 PM

Topic tags/keywords: jig tenon router diy


I have a simple shelf which I designed for which I produce a few dozen units a year. The main supports are 4 units of 6’ long 4”x4” post.

Each shelf consists of:
2 units of of 1.5’ long 2”x4” boards.
2 units of 3’ long 2”x4” boards.
1 unit of 1.5’ x 3’ x 0.75” plywood sheet.

The 2”x4” boards connect to the 4”x4” posts via a simple rounded-edge mortise and tenon joint. I use a plunge router with a jig I built to create 3.25” long by 1.25” wide rounded-corner slots in the 4”x4” posts, and a separate jig for my plunge router to round the ends of a 2”x4” board. The tenons are almost as big as the rest of the 2×4, to make them as strong as possible.


I’ve been asked to make some more of these shelves, but a bit wider (i.e. the 3’ long boards need to be swapped out with 5’ long board). Rather than insert 2 additional 4×4 posts in the “middle” of the shelves (doubling the number of tenons I now have to cut), I’d rather just make the 3’ long 2×4’s longer. I can’t do this though, because the board is now too long to point upright and use my jig plus router to create the 3.25”x1.25” rounded tenons.


Is there a safe jig that could be used to allow me to use my plunge router horizontally? If that’s impractical, are there any jigs for creating rounded tenons on long boards? I’d really like to avoid having to use floating tenons.

I also use mortise and tenon because, in addition to the shelves being required to be very strong, some of these shelves come in “pretty” versions where we swap out the plywood for painted MDF and a separate company decorates them.

Also, the rounded mortises save a ton of time on chiseling.

Thank you.

3 replies so far

View bigblockyeti's profile


6586 posts in 2501 days

#1 posted 01-08-2018 02:32 PM

Porter Cable used to make a lock mortise jig that would clamp to the edge of a door to create a mortise ~1” x ~5” with a fixed base router as it advanced the bit a little with each turn of the crank as the router was also driven up and down. I have no idea as to the dimensional adjustably of the mortise but it stands to reason there would have been at least a little.

-- "Lack of effort will result in failure with amazing predictability" - Me

View jmos's profile


917 posts in 3150 days

#2 posted 01-08-2018 03:02 PM

I think I would just lay the 2×4’s flat and use the router to take off as much as needed to make the tenon (setting router to the depth of the shoulder, rather than to the length of the tenon as you usually do.) You could gang your parts and do them all at one time this way too. (clamp parts together, set a edge guide or fence to proper setting to get the shoulder where you want it, and route them all, then flip, clamp, and repeat three more times.)

The result would be a square tenon, not rounded, but you can either round over the edges with a chisel, rasp, block plane…, or just cut the tenon so it’s a little narrower than usual, so the square edges fit in the rounded mortise.

I would avoid trying to use my router horizontally, but maybe that’s just me.

-- John

View Loren's profile


10477 posts in 4428 days

#3 posted 01-08-2018 04:33 PM

You can build or buy a Pantorouter.

The Matchmaker and Multirouter are similar.

If it were just the one task I might put together
a “stage” I could climb up on to cut the tenons
in the longer boards.

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