End tendon on plywood

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Forum topic by George656 posted 10-06-2016 02:33 PM 240 views 0 times favorited 6 replies Add to Favorites Watch
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2 posts in 22 days

10-06-2016 02:33 PM

I am building a 6’ long dresser. The sides and dividers are 3/4 cherry plywood. The joinery is to
have a 1/4” long by 3/8” thick tendon on each divider.
I did some testing on scrap plywood and found that the router cut was sloppy.
The plywood divider is 20” wide and 72” long. So, using my table saw I don’t think
is the right tool.
I would like to ask others what tool they use and the setup?
Thank you in advance for your help.

6 replies so far

View ShaneA's profile


6429 posts in 2022 days

#1 posted 10-06-2016 02:58 PM

Is the question how to produce a tenon on a 3/4” pc of cherry ply that is 72” long? A dado stack and feather boards is one way. Do you have a router table? Or even a rabbiting bit that is 1/4”? If I understand, those methods…with proper set up should deliver workable results.

View Mosquito's profile


7928 posts in 1716 days

#2 posted 10-06-2016 03:03 PM

What was wrong with the router? I’ve used a knife to mark the shoulder line before I used a router with a rabbeting bit, or a straight bit with a guide fence on the piece to make tenons before. Worked great for me… Make the first pass shallow (like 1/32”-1/16”), and then go from there… I’ve generally gotten favorable results with that.

-- Mos - Twin Cities, MN - -

View George656's profile


2 posts in 22 days

#3 posted 10-06-2016 03:32 PM

Hello and thank you for your feedback/suggestions.
The dividers are 20” wide by 72” long 3/4” cherry plywood.

The tablesaw with dado blade is difficult to hold flat against a fence. And I have limited space
inside my garage workshop.
I used a 1/4” straight bit to cut the tendon. I did not think about a
rabbit bit. I have a clamping straight edge for the router.
Sometimes I need assistance from hobbyists like you. I very
much appreciate your help.

View TheFridge's profile


5682 posts in 910 days

#4 posted 10-06-2016 03:46 PM

Ditto what mos said. Rabbeting bit in the router for the tenon.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View JBrow's profile


754 posts in 344 days

#5 posted 10-06-2016 04:05 PM


I am not clear on what you mean by sloppy; a loose fitting tongue and groove, a ragged cut, or a crooked cut.

To get good fitting tongue and groove joints, my first cuts are the grooves. I prefer cutting grooves with the stacked dado set, but with large unwieldy work pieces, I use the router, a spiral down-cut bit, and a straight cutting jig. Cutting a tongue that fits into the groove with a good friction fit requires several test cuts to get the thickness of the tongue just right using the straight cutting jig and down-cut spiral bit. Once the router depth is set, the tongues are cut and test fitted. Even after all the fusing to get the correct router depth, the tongues can sometimes be a little too thick and hence will not fit into the groove. A pass or two with a shoulder plane corrects the problem. I work real hard to avoid cutting tongues too thin to make a good connection. When this happens the options are cut a new work piece, reinforce the joint with screws, or glue a thin shim to the length of the tongue and re-cut the tongue.

If the cuts are ragged, scoring along the cut line(s) with a razor knife can help. A zero clearance jig for routing grooves with a straight router bit of some design can work well since it provides support of the veneer fibers. A down-cut spiral or compression router bit would probably offer the cleanest cut.

If the straight cuts are crooked, then a straight cutting router jig could keep the router running true. The jig can consist of the ½” plywood base. The border of the base is from 1” x 2” hardwood strips milled with straight edges. The hardwood strips are position so that the router can run smoothly from one end of the jig’s base to the other between the strips without any slop. Once the jig is built, a zero clearance slot is routed in the base.

View pintodeluxe's profile


4827 posts in 2237 days

#6 posted 10-06-2016 04:41 PM

A tablesaw and dado set will almost always be easier and cleaner cutting than a router. Especially raising a tenon on plywood, I am much more comfortable at the TS. Even an average dado set will give you a clean, straight cut.
Set the blade height by making test cuts on a scrap of the same plywood. That way you don’t have to make multiple passes with the long pieces.

Use a roller support on the infeed side, and an outfeed support on the TS.
I agree with Shane, a featherboard is really helpful. I use a magnetic one that is really convenient.

If you don’t have a TS setup to handle sheetgoods, I’m afraid building dressers or cabinetry will be a tough row to hoe. Luckily there are things you can add to your setup to make it work.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

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