Cutting Long Through Mortises
Advice on tools and techniques for mortise and tenon joinery for a historical shutter reproduction. June 22, 2010
Question
I was wondering if anybody knows if I can get longer hollow chisel bits than the normal 3"? I hopefully have a job coming up that will require longer bits to do a through tenon on approximately 3 1/2" stiles. So a 4" chisel would be fine. Any help would be appreciated.
Forum Responses
(Architectural Woodworking Forum)
From contributor R:
Forrest City Tool used to be a good source for these tools. I think Wood Tech Enterprises may be a dealer for them. Personally, for a number of reasons, I think you would be better off using the tools you have and punching the mortise from both sides.
From the original questioner:
Punching from both sides is an option, but I am thinking that will introduce alignment errors and slow down production a little, but it is still an option.
From contributor L:
To the original questioner: your stiles are 3 1/2" for the mortise depth. How thick/wide are they? (3 1/2" X ?")
From the original questioner:
I measured the shutter that I am talking about and the stiles are 3 3/8 by 1 1/4. The longest bit that I have seen is 3 1/4. I may be able to make that work by pressing harder in the groove, if that gets dented it doesn't matter since the rail will cover it.
From contributor L:
From your original question, I take it that you're talking about running a through mortise to connect the stiles and rails. I'm wondering why you want to run the tenon all the way through instead of running a blind M&T instead. In addition, have you considered using a floating tenon like you can easily make with a router set-up or a tool like the Festool Domino?
From the original questioner:
To contributor L: the reason that I have to do a through tenon is that this job would be for the historic society in an older town. They want historically accurate shutters.
From contributor L:
Now I get what you're doing. I've cut enough mortises with the hollow chisel to offer the following hint: let's say your mortise is 1/2" by 1 1/2". I use a 3/8" drill, drilling several holes in a line. Then I go to the hollow chisel mortiser (don't even think about the drill press attachment - I've tried all of this stuff) and finish the mortise having very little material to remove at that point. I would also second Rob's suggestion to punch in from both sides. It's easy enough to set this up with blocks and stops so the alignment is right on the button. More importantly, you don't have tear out on either edge. It might seem like an extra step to drill first, but it'll save you a lot of elbow grease (literally) in the long run. If you have a lot of these to do, rig up a foot pedal. You'll see why soon enough. If you're really going into production on these, consider cutting the mortise with a router or better yet a horizontal mortising machine. Then all you have to do with the hollow chisel is square the corners.
From the original questioner:
Thanks for the input contributor L. I have an older foot powered mortiser and I love it. I would like to put an air cylinder on it with a foot pedal. I figured that the machine is from the forties. I love the old cast iron.
From contributor L:
Sounds like a cool machine. I have a modern Powermatic. It’s a nice tool, but nothing like the old school stuff. Air power sounds like the way to go. If you go that route, make sure it's both push and pull (double-acting).
