Mortice vise and method

[Corneel]

For me too, much easier to chop vertical then to drill vertical. Chopping a nice mortise is still not quit intuitive for me, I take quite a bit of time, but they always end up vertical easilly enough. But when I drill a hole it almost always wanders one way or another.

 

[Andy Kev.]

Two questions though: if, say, you are doing a 3/8" mortice would you use a 3/8" bit fully confident that you will be absolutely bang on or would you go for, say, 5/16" or even 1/4" so as to stay within the marked sides? The second question question would apply in any case: having drilled there are bound to be lots of scoop shapes running vertically down the sides. Do you then use a wide chisel (ideally as wide as the mortice is long) to clean up the side walls? I ask this because going along a largely chopped out mortice with the relevant width mortice chisel would surely be a mare of a Job.

Hi Andy

First of all - for perspective here, folks - there are many ways to skin a cat. Drilling out is a legitimate alternate method for mortices. And even if you were not making a mortice, this is another way to remove waste by hand (no electricity). Some need to be able to do so, and quietly.

Both questions are answered together: If I were using this method for a mortice, I would aim to leave 1/32" each side of the drilled hole. If using a drill press, one could overlap the holes and remove all the waste. However, with a brace, there is some overlap, but not all. Some waste remains. One needs to pare this away from the inside of the mortice towards the gauge line. Then one final clean up along the gauge line with a wide paring chisel.

Regards from Perth

Derek

Hi Derek,

that is as I thought.

Your point about leaving around 1/32" either side led me to a new (to me) idea: it's conventional to set the mortice gauge to the width of the chisel but if one were to use a forstner bit as per the clip, one could set it to the diameter of the bit plus 1/16" or indeed plus whatever margin one felt comfortable with. That could be useful to somebody who had a few forstner bits but relatively few morticing chisels or for that matter, to anybody who needed to cut himself a bit of extra slack for fear of wandering from the vertical.

All the best,

Andy.

 

[Andy Kev.]

I've just tried the Forstner bit method (as per Derek's link). For the pilot hole I used the smallest bit I had which looked to be around 1 mm. I then took my smallest Forstner bit at 12mm and set the gauge a bit wider (subsequent measuring showed it to be 15 mm). The key thing seems to be marking the dead centre between the two gauge lines. Drilling out the hole worked like a dream. This is definitely a weapon to have available in the armoury.