The main ones are: A hollow chisel mortiser, a chain mortiser, drill most of the waste and then pare the "Vs" and sides to size, and using chisels to waste the wood. Sometimes finding or having a chisel of the correct size can be a problem but if you have a chisel of the correct size and you are only doing a few mortises I think beavering away with a chisel is the fastest and best way to make a mortise.
The mortises of the last couple of days are an example. I needed a large mortise to hold the tusk tenon that makes the base of the Moravian workbench. I had a 32mm bench chisel that fit the bill for width so now it was just a matter of chopping half way down on one side, flipping the board over and chopping through on the other side. Once through the board all that remains is cleaning up the ends and fuzzies on the sides. Reasonably quick and easy.
Here is a photo of the mortise after one pass down the length with a return to the starting end to level the approximately 30mm it took to get to the 30mm depth of the first pass. Each following pass will be slightly less deep because of restricted lever room but with a total thickness of the stretcher of 130mm it doesn't take too long to get to the 60 or 70mm depth needed on each side.
I probably will not get "break through" on the next pass but I expect it will happen on the third. Then it will just be a matter of cleaning up and getting the correct angle on the ends. The floor and top of the mortise needs to be 15* to match the angle of the legs.
ken
- Sunday
ReplyDelete"While I use a lump hammer as a mortise mallet I do not go all Conan on the chisel. I find light taps gives better control and is faster than whacking it hard. "
I also try to "work with sensitivity" as Paul Sellers recommend. Listening to the sound: "tap, tap, ..., tap, thud". Stopping when the sound changes. After all, the goal is not to nail the chisel down in the wood.
- Wednesday:
"restricted lever room"
If one look attentively to this Paul Sellers video:
https://www.youtube.com/watch?v=q_NXq7_TILA
one will see that (with his technique) it is the drifting movement of the chisel induced by the bevel that shears the wood at the mortise sides. (drifting from the vertical).
There is practically no lever action needed (and no risk to snap the chisel).
Of course one need to evacuate the waste which P.S. does with a narrower chisel or a "paint can opener".
I looked at this video several times before doing my first mortises. It has worked perfectly with my no-name Chinese flea-market chisel when doing my workbench.
Sylvain
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ReplyDeleteSylvan,
ReplyDeleteSomeone said not too long ago to go slow to go fast. Mortising is the same, finesse is much faster. Use taps rather than whacks and when the chisel stops, stop and remove the waste. It is win win the work goes faster and you should have a cleaner mortise hole.
If there is a pigsticker of the correct size to do the mortise then that is my preference but a bench chisel works as well. The difference is a pig sticker is designed to make mortises.
ken
Ken what is the secret to the clean walls of the mortise?
ReplyDeleteRalph,
ReplyDeleteI'm not sure it is a secret but back to not hitting the chisel too hard and not letting it twist in the cut. As I've said, don't hit too hard, just hard enough to drive the chisel and I usually use either a Japanese chisel hammer or a lump hammer. I feel I have more control with a metal hammer because it takes less force to drive the chisel.
ken