How to drill a mortise

[Leo Graywacz]

You have two sides of the mortice. You have the side that will be covered by the tenon pc and the open visual side. What I might do is on the visual side use a router to make a nice neat clean sided hole, doesn't have to be all that deep, maybe 1/2". You can square up the corners with a chisel. On the other side youcan go the drill bit and chisel route. No need for it to be a clean looking cut as long as the mortise/tenon is pretty well fit it will work fine.

[Terry Beadle]

A brad point 3/4 bit would remove the waste a lot quicker than the forstner but would leave the sides a bit more ragged. Since you would be using a chisel to take the last little bit, squaring the cut, etc. It would be better to use the brad point IMO. Just buy a reasonably priced brad point 3/4" which a quick search shows it should cost less than $12.

I would definitely cut the mortise from both sides after careful knife layout. Take the time to make sure that nice DP is dead square in the cut.

[Brian Kent]

I just got the 3/4" Freud forstner. I have brad points up to 1/2". I'll try it on some scrap and see which I can personally do the cleanest job on for the exit side.

Thanks all.

[Alan Schwabacher]

The trickiest part is paring out the waste without making part of the mortise too wide, assuming you used a solid fence with nicely squared stock, and put the same face against the fence while drilling from both sides.

To keep the chisel square, use the bored holes as a guide. Check to see that the curved portion remaining after each cut does not change width from top to bottom. If it's even, you are paring parallel to the hole. If the hole was square, so is your mortise.

[Chris Parks]

To keep the chisel square get a nice piece of machined timber maybe three inches thick and clamp it to the marked line. Use the straight side of this to lay the back of the chisel against and the side of the mortise end up truly square.

Drilling, attach a fence to the DP so that the drill bit can't encroach beyond the layout lines and use anything you like to drill it with. Set the depth stop on the DP so you finish up at the same depth right across. I would drill the two ends first and the rest will take care of itself.

What you could do is take some scrap timber and practice chopping it by hand if time allows. I am no bleeding heart advocate for hand tools but the more you do it the better you get, DUH! With the amount of video techniques available nowadays you can largely self teach from the net and yes it is very satisfying to acquire skills.

[Jim Neeley]

I ran into a somewhat similar issue wanting to use my router to cut 3/4" dog holes through my 3" thick benchtop and found a solution.

In my case I made a template by drilling a 1-14" hole on a piece of 3/8" MDF and inserting a 1/2" bit in my router with a 1" guide. I started with a long freud bit (~1-1/2" long cutter) and took it as far as it would go.

Then I replaced it with a 1/2" bit with a 3" long cutter to complete the hole. The key with such a long bit us to use a large "tank" of a router and limit the depth of each pass to 1/4" or less to avoid too much side-stress on the cutter. Hey, I'm a chicken when it comes to a 3" long, double-bladed cutter spinning at about 12,000 rpms.

I found the bits for cheap for <$12 on ebay at a store called "super carbide tools". You can also find them by searching for "router bits" and looking for pictures similar to the ones I've attached. They have a distinctive placement of block-text on their pictures. Yes, they are cheap. Yes, they aren't domestically made (but I couldn't find any, let me know if you know of a domestic manufacturer). I did feel somewhat better since I could insert the bit about 1-1/2" into the benchtop before turning up the router. It also let me get around having less than a 3" plunge action.

Also FWIW, the shank of the ones I got were pretty long so I didn't have to really extend the bit but a small amount from bottomed in the collet to get the length. I don't have any connection with the store other than they get praise from a number of active members on another (router) forum.

YMMV.

Jim

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[Brian Kent]

The Freud 3/4" bit worked very well. The photos are on my thread on building an outdoor sunburst dining table:
http://www.sawmillcreek.org/showthre...ng-Table/page3

Only the corners are left to clean out.

[Jerry Lawrence]

My first mortises I made with a forstner bit, but instead of chiseslling out the corners, I rounded over the tenons with a wood rasp. Of course, these were not through mortises, so appearance wasn't an issue.