Deep(?) mortise

[lgb]

I want to cut a 1.5" deep 1/4" mortise using a router. I didn't have a bit long enough so I rooted through my catalog collection and ordered a Freud bit that was 2.875" long with 1" of carbide.

It arrived yesterday and although it has a 1/4" shank, there appears to be a section just above the carbide that is thicker than 1/4". Even if that's an optical illusion, the package says I should only cut 1" deep (the length of the carbide) with it.

I didn't see any other bits that were even that long.

How do you cut 1.5" mortises with a router? Or should I just give up and use some other method?

Up to now I have cut mortises on the drill press or by hand. But this project (an entertainment center) is going to require about 100 so I thought I'd try the router with a jig.

And no, I can't afford a dedicated mortising machine :-).

[DJ Delorie]

Use the router to do the first inch. Use a mortising chisel for the remainder (and to square off the round corners); the router slot will (1) look pretty, and (2) guide the chisel.

1.5" on a 1/4" bit seems too flimsy to me. I've done 2" deep mortises with a 1/2" bit and even that's scary.

[brianlanning]

I'd worry about lateral forces on a router bit with a 1/4" shank extended that far from the collet. If you do get it to work, make sure you do 1/4" passes or something. I've seen really long half inch shank router bits that would probably handle this better. But they're half inch.

If you have to use the router, you could rip the workpiece in half, route both pieces, then glue them back up. That's annoying though. A dedicated mortiser would have no problem with this depth, same for the drill press.

brian

[gandalf]

--------------- If it looks like one of these:

then you should be OK. According to Trend it is for doing just what you want, deep mortises. They do however say to take extra care with small passes, for that cutter that would 1/8" at a time.

[Wilson Lamb]

[pat]

Through mortices on the back of the fence (bottom of

page) were cut with a 1/4" cutter to 1-1/16". Have gone deeper but indeed this is on the fringes of what a router can & should be doing. Must you? Use a a good plunger, DW 621 for example, plunge ~ or <

1/16"/pass and get long cutters (air trimmer solid carbide) from Southeasttools.com .

[dadiOH]

Cut in multiple (shallow) passes. As long as you have enough shank in the collet and what's left will allow you to cut deep enough you are fine. Do take shallow cuts though.

BTW, this would have been a good spot for a single cutter bit. IMO, YMMV.

Also, a long bit with shorter cutting edges would have allowed you to make a hardboard or plywood template and guide on that template with the shank of the bit. To do that now, you would have to cut deeper than 1" which is way to much.

You can still use router templates with it to guide on a bigger template. If the thickness of your made up template makes the bit too short, remove the template toward the end and use the router shank to guide on the mortise edges.

-- dadiOH ____________________________

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