Cutting through mortises w/o dedicated mortiser

[Chuck Ketcham]

Hello all,

I need to cut some through mortises in 3/4" red oak for a bookshelf I'm making. The mortises are inset at least 3 inches from the edge of the wood, so I don't believe a dedicated mortiser would work (don't have one yet to try anyway). I know that I can cut these with a router and template, but that would leave rounded corners. So, I would have to use a chisel to square up the rounded corners. I'm not real confident in using a chisel for this. Most of the time when I've tried squaring up router-cut rabbets with a chisel, I've always been a little disappointed. So, is there a better way to cut these without using a chisel, or should I spend more time on my chisel technique? Or perhaps my chisels should be sharpened?

Thanks.

Chuck

[Jesse Cloud]

Here's a few thoughts:

A dedicated mortiser should be able to handle three inches inset. A sharp chisel is an absolute necessity.

How about leaving the mortises rounded off and rounding your tenon? A few strategies for this: use a loose tenon and round off on the router table (a little tuning and patience should produce a very good fit) or use an integral tenon and start the roundoff with a router for a good fit where it will show, or make a scratch stick from an old bandsaw blade or the like by drilling a hole the same size as your mortise width (say 3/8 for example) on the edge of the band saw blade. Cut the blade off to a useable length and use this to round off the tenon. (If you do the third one, might as well make a few of them while you have the set up).

Hope this helps.

[George Bregar]

I assume you are asking is the a better way than chisels to square up a rounded mortise made with router?

You can buy a tool that squares these up...it won't cut deep enough depending on the mortise, but would certainly handle the visible portion of your through mortise and give you a guide.

http://www.woodcraft.com/family.aspx?FamilyID=4433

http://www.woodcraft.com/images/family/web4433.jpg

I don't see why a mortiser wouldn't work although if you don't own one it's moot. I also wouldn't fo a rounded tenon, unless you like that look. Not very traditional.

[glenn bradley]

You're probably getting the responses you expected and not that "hey, try this. Its a miracle" response that we all hope for now and then. As you don't have a mortise machine let's talk chisels. Sharp enough to shave hair off your arm is just about right. Any less of an edge and your results will decline proportionately.

On the upside, if you have sharpened your chisels and clamp some guide blocks to assist you in lining up for that initial cut that shows from the outside, you should be OK. A tool as George presents could be used to set the initial cut and thereby give you a guide to follow. The exposed end is the critical one. The other end should be hidden by the shoulder and the inside (although in a perfect world, would be perfect) doesn't show at all.

If your previous dissatisfaction with chiseling was effort and not appearance, we're right back to sharpening chisels. . . no escape.

[Gary Keedwell]

I like to use a good sharp marking knife when I lay my mortise out. After drilling and rough chiseling....your final finish chisel cut should fit nicely in the cut line from your marker. You will be surprised how it just drops right in.
Gary

[John-Paul Murphy]

I have one of those mortising tools that attaches to the drill press. It works well.

[Mike Heaney]

I think my new thread may be the kind of thing you are talking about

http://www.sawmillcreek.org/showthread.php?t=73175

I nearly bought a mortiser to help with this project, until I worked out that I wouldnt be able to reach the middle mortise with a machine. I went down the route of a shopmade jig and careful routing (not all the way through) then using chisels for final clean up and squaring up. Its doable, but a lot of work- I'm glad to be done with mine- until the next project of course!!!!

best of luck!

Mike

[Kevin Groenke]

Good advise as always.

My .02.

A dull chisel isn't really a chisel at all.
Accurately mark out the mortise with a knife, use the knife cuts to start your chisel cuts, chop a shallow "relief" shoulder before making deeper blows to remove the waste.
A dedicated mortise chisel is easier to do this with as the square shoulders tend to be somewhat "self guiding" as it's driven into the stock.
Chisel skills do take some practice to attain, but it is well worth the investment. Once you master the hand fitted mortise and tenon, you'll be well on the way to hand cutting dovetails;).

g'luck

-kg

[Paul Joynes]

You could cheat. If you made your through mortise with a router, you could make your tenon so that it did not go all of the way through the mortise. Next make a rectangular cap/plug sized for good aesthetics on the show side, and profiled on the non show side so that it fits into the remaining part of the rounded mortise. You could even use loose tenons if you chose.

Paul

[Grant Morris]

Check out this video Chuck. It may help.

http://www.woodworkingonline.com/2006/11/15/video-podcast-2-mortise-tenon/