Alternative method to hand cutting a big mortise?

Re: Alternative method to hand cutting a big morti

Wiley Horne

>Wilbur,

I would use a double M&T approach. Use, say, two 1/2-inch mortises, or two 3/8-inch.

Wiley

Re: Alternative method to hand cutting a big morti *LINK*

Manny

>How about a bit brace?

http://www.daikudojo.org/Classes/20061202/pics/2006_1202_143207.JPG


Making a wide mortise

Re: Alternative method to hand cutting a big morti *LINK*

VLParisian

>check out the rest of his pictures...Very impressive (and large) stuff.

Victor - killing a few minutes at work


other pictures on the site

Re: Alternative method to hand cutting a big morti

ThomD

>I do that all the time with a morising machine... It's often faster to not set up a new chisel for a one off. So I put the most useful chisel in there like a 5/16", and use it for everthing.

I think it depends on what your objectives are, are you just trying to slide by with fewer chisels, or are you trying to go faster or stronger. IN some cases you could make a case for double smaller tenons. So if you have a timber and a 1" chisel you could fire in two smaller wider spaced tenons.

Just to get it done, the normal way would be to use an auger to remove the majority of the waste, and then use a full width mortice chisel which looks more like a large bevel chisel, and one can usually find one for around 10 bucks if not in a rush. Lacking that, on could use a smaller chisel to pare the sides and endgrain. Keep in mind that a lot of chisels aren't long enough to get very far in there if they aren't actual timber mortice chisels.

Re: Alternative method to hand cutting a big morti

Pam Niedermayer - Austin, TX

>If you're building something large enough to require a 1-1/4" mortise/tenon, it's certainly in the budget to buy a big atsu nomi or chutaki or whatever is needed.

Pam

Re: Alternative method to hand cutting a big morti

Warren in Lancaster, Pa

>In hand work, most people use a mortise chisel for small mortises and an auger and chisels for large mortises. If the mortise is a half inch or under we ususally use a morise chisel. If the mortise is over an inch we generally bore a hole first. For mortises in the 1/2 to 1" range we use either method depending on type of wood and availability of tools.

For timber frame mortises it is nice to have a large auger near to the size of the mortise. I have used a hand-crank boring machine, a T handle and a very heavy electric drill. If your auger has a square shank, you can make a T handle from a piece of hard wood say 18 to 24 inches long with a tapered square mortise in the middle. I was using an old chairleg 35 years ago. Even a large brace is awfully tough going if the auger is large (over 1") and the timber hard. For cleaning the sides of the mortise most people use a corner chisel and a large firmer chisel. I don't like the corner chisel so I just use the firmer.

The method you suggest is one that I have also used and I think is more precise than what we do in timber framing.

I have also used the double tenon (side by side) method suggested by Wiley, which also is more precise than the boring method and is perhaps the classic solution for furniture. I generally excavate the portion between the two motises to a depth of 1/8 or 1/4 inch so I don't have to clean the matching area between the tenons so carefully.

Re: Alternative method to hand cutting a big morti *LINK*

Manny

>Was busy so I didn't get to elaborate on my method.

This was a through-mortise for a spline that would join two members, from opposite sides, to one of the main posts.

I did one joint using a large atsu-nomi and attacked it from both sides of the beam. That was too time consuming since I was mortising through about 8 - 9" and had a lot more joinery to get done that day. I needed more speed so I used a brace with a bit that was smaller than the mortise width. The final mortise size wasn't quite as large as what you want 1 1/4". If I remember correctly it about 11 - 12 bu (The Japanese Shaku measuring system), which I think is right around an inch. Since it was a through mortise, I layed out the joint on both sides of the post (we lay out our joints using the centerline of the lumber) and bored halfway from both sides to meet in the middle somewhere. I get more accuracy that way because if I bore only from one side I could be off a bit in my technique and won't know where I will end up until the bit comes through the other side. Some people are good a boring straight..I'm not. After I bored through the post I cleaned up the mortise to size using a large slick.

Here's a better link, Victor. You won't have to open up each individual picture. It shows project from start to almost-finished. We have put up and installed the gate but haven't posted the pictures yet. I'll look for a link to where one of our members stored the pictures from the install and post it later.


Gate Project

Re: Alternative method to hand cutting a big morti

wilbur

>This was actually more of a thought experiment, but thanks for the responses!

Wiley, I considered the double mortise route. The problem with double mortises was that I was also intending to drawbore this joint, and I'm not sure how well that would work with a double M/T joint. Besides, it gives me two chances to screw up the tenons, and the less chance I have to screw something up, the better.

Manny, your mention of laying out the mortise from the center is great -- I never considered laying out mortises that way before. I've been referencing mortises from the edge, but this would be good for future projects.

Thom, with your method of removing the majority of the waste, does your auger bit go all the way to the sides of the mortise, or do you leave a little bit so that the chisel has something to bite into? I have made large mortises before by drilling out the waste and then cleaning up the sides, but I seemed to spend a lot more time with the clean up than I thought I needed to. In my case, the bit I used went all the way out to the sides of the mortise, and the side walls of the mortise were much rougher than I thought they should be.

Re: Alternative method to hand cutting a big morti

ThomD

>-Thom, with your method of removing the majority of the waste, does your auger bit go all the way to the sides of the mortise, or do you leave a little bit so that the chisel has something to bite into?-

I have done it both ways. When I started out and was trying to do those rounded end mortises a la Krenov, I drilled tight to the mortise sides, and I almost always had one of say four mortises over the line, even using machines. I assume that is why Krenov didn't drill but used an end mill.

It works better for square holes to leave the hole a lot undersized, and keep it back from the ends far enough that you are able to hold the chisel in the end grain, which is just something you have to develop a feel for. There are two ways to go about the whole thing. One is to auger the holes then use a mortising chisel in exactly the same way as you would without the holes. That is the say the edge perpendicular to the long side and full width in the mortise. For the bigger stuff, normally they are laid out either to 1.5 inches or 2.0 inches in accordance with the size of your framing square, you underdrill the mortise, about on sixteenth or one eight on the sides and maybe a quarter or less on the ends, depends how tough the material is. After drilling you go around all the sides and pare them off. The framing square is excellent for ensuring you are parallel sided, square to the beam, and at correct depth, just don't use it with force or it won't be square for long.

There are a lot of ways of laying out depending on your situation. You can lay out from the sides of the piece, but this only works if your pieces are perfectly dimensioned, or at least perfectly enough. Keep in mind there may be a later stage of planing up, after assembly, take for instance joists that get planed up in place and the extra meat can be left in place for a better structure; There is laying out on a center line. This is a good method and allows the joints to be on plane, first thing, its fast since you can just snap a line, or on shorter pieces use a ruler. It's not great for dealing with wacky dimensions, the material needs to be straight, but it does get the joinery on plane; Another good method is laying out in reference to a surface. This gets done on stuff like using floors as a reference in constructio. But it's also possible to lay out from true surfaces, and this is done a lot for metalworking, where one can lay out from a granite block. It works for woodwork too an example being jigging up a chair on a flat surface and then scribing in the leg length from the surface up; or can also lay out timbers from your framing square by using a pair as winding sticks and then laying out the mortise seats from those readings. This allows one to lay out timbers than don't really sit straight, but are going to be used anyway.

- have made large mortises before by drilling out the waste and then cleaning up the sides, but I seemed to spend a lot more time with the clean up than I thought I needed to. In my case, the bit I used went all the way out to the sides of the mortise, and the side walls of the mortise were much rougher than I thought they should be.-

I think it is mostly a time saver with small projects where you can use the chisel conventionally also. You don't save much time, but you get a conventional result, so what time and effort you save is gravy. The prossess is a lot like hollow chisel mortising, with the drilling and chiseling done in sequence. In HCM the drill is quite undersized.

On the timber sized object, and the large mortisers, it's just the best method, it takes a fair amount of time to pare five sides, but unless you have a beam mortiser you don't really have a practical option.