How do you cut a deep mortise in a rail?

[Tom Jones III]

I would like to make a 3" deep mortise in a 26" long rail. Does anyone have a good idea for doing this easily? I've got a jig for the plunge router that makes it very convenient, but it won't cut deep mortises. I could use my drill press mounted mortising attachment, but the drill press table is not the most convenient for sliding a rail oriented vertically. I could always do it by hand with chisels but that is going to get a little tough when it gets deep. Does anyone have a good idea for this situation?

[Jamie Buxton]

You're cutting this 3"-deep mortise into the end of the rail? If so....

You can use the plunge router if you get a long end mill, or maybe two different lengths depending on the stroke of the plunge. Use a template guide and template to establish the size of the mortise. Make it larger than the diameter of the endmill(s). Cut as deep as you can with one bit, then switch to a longer bit. When you insert this longer one in the hole, the tip will already be sticking out of the router's base. Continue until done. You can get long end mills from machinist-supply places. Enco is one (www.use-enco.com).

Or you may be able to use your hollow-chisel drill press. Can the press' table be rotated 90 degrees so that it is up-down? If so, clamp the rail to the table with the 3" dimension flat to the table. Bore, then reclamp it a little closer to the press's column, and repeat.

[Bill Houghton]

as did generations of carpenters, by drilling out the bulk of the waste with appropriate bits (smaller than your mortise) then cleaning out the walls and ends with chisels.

You need good, long chisels, one a little narrower than your mortise (say, 3/8" for a 1/2" mortise) and one wide one (1" or up, depending on the length of your mortise). I've got a wide paring chisel picked up at some garage sale that's 1-3/4", which is dynamite for lockset mortises and other long ones like that.

[Ralph Barhorst]

Use end mills like Jamie recommended. I have done this many times. Make sure that your endmill has two flutes as it will cut better than one with four flutes. I always buy my endmills from ebay. Just make sure that the endmill will fit in your router's collet. If necessary your can use an adapter bushing from MLCS.
http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/bushing_ball_bearings.html

Check out this endmill on ebay. Item Number 220354286724