Mortise chopping technique

[brian_j_roth]

I've been learning to make mortises the 'old-fashioned' way, by chopping by hand.

The first few went pretty well, but the edge of my mortise chisel (Lie Nielsen) will need some work on the 220 stone to restore the edge. I'm certain that my beginner technique is much too hard on it.

The wood is Cherry, and the angle is 30 deg from the factory.

How many passes should I expect to make on a 1 inch deep mortise? I suspect I am driving the chisel too deep and damaging the edge during the chip levering step. Or perhaps I am making the chips too big.

Any advice out there from seasoned Neanders?

[HappyGilmore]

What about a hand drill (bit and brace) to drill out the bulk of material in the middle then use the chisel to square up and clean the edges?

[Vijay]

[alexy]

I in no way qualify as an "experienced neander", so take this FWIW. My technique is to start with a series of very small and shallow (not much deeper than the score lines that define the edge of the mortise) cuts to ease registration of the chisel in future passes. Then I take healthy chunks a little deeper than the amount taken along the length of the mortise--maybe a chip 3/8" deep but only 3/16" "long". But frankly I'm having a hard time visualizing it for description. It just "feels" right. Most of the levering I do is removing wood that has already been cut free or is just weakly attached along the long grain.

Final cuts are several cuts on the last 1/4" of length to define the length of the mortise. These are paring or "mallet assisted paring" cuts looking more for clean surface than lots of stock removal.

[brian_j_roth]

A 3/8 by 3/16 chip doesn't sound to much different than what I am doing. Perhaps adding a 35 degree secondary bevel will help.

[brian_j_roth]

I'm going to add a 5 deg secondary bevel today and see how that works.

[Leon]

Did you sharpen the chisel before you first used it?

[Lowell Holmes]

Just my thoughts below and no more than that. :-)

I was taught at Homestead Heritage you strike the chisels 3 times and then go to the next chip. If you take a chisel and present it to the wood, the chisel will go in as deep as it is going to with 3 strikes of the mallet. I don't really hammer it either, just good crisp blows.

I define the mouth of the mortise with a series of small light chips, starting 1/8" from the starting end and stopping 1/8" from the end of the mortise.

If you can get your hands on Frank Klausz's video "Mortise and Tenon Joinery", I think it will help.

I have mortise chisels, but if I need a size mortise that I have no mortise chisel for, a bevel edge bench chisel does just fine. They don't use mortise chisels in the rocking chair classes at Homestead Heritage. They use blue handled Marples beveled edge chisels. The chairs will 45 -50 hand chopped mortises each.

If your having a problem with the edges on your Lie Nielsen chisels, I suspect you are striking the chisels too hard. I have the beveled edge Lie Nielsen's, and they do just fine for mortises or dovetails.

[brian_j_roth]

I put the 'three strikes' rule in effect and the edge held up much better. I think I might have tried to pry up too big a chip yesterday and chipped an edge....

[Lowell Holmes]

When prying the chips out, push towards the bevel on the chisel end. It will pop the chips loose with minimal movement of the handle. I start with the back of the chisel towards me and push away from me to pop the chips loose. If at the end of the mortise, you present the chisel to the work with the beveled edge vertical, strike the chisel, and then push the handle away the end chip will pop loose with not much movement and no damage to the edge.

It sounds like you are on your way. :-)

[Lowell Holmes]

Don't let the previous post confuse you. My thinking shifted from the cutting edge of the chisel to the edge of the mortise.

The mortise cut shouldn't be hard work. Smaller and quicker blows will make smaller chips with less effort will probably save time. The Klausz video would help. He can chop a mortise in less time than it takes tell about it. Taunton (Fine Woodworking) has the video.

You might want to view his video on dovetails on a drawer. He can dovetail a complete drawer in just a few minutes.

[brian_j_roth]

Another clue! I probobly was prying the other way, and thats what damaged the edge.