Thread: Mortice and tenon marker

Cool Idea JMK. I'll give it a go some time.
Thanks for sharing.
Kevin

Damn, there goes another excuse for me not progressing from half lap joints to mortice and tenons....

Nice design, jmk89, and thanks for sharing. I'll be making one, but I think I'll do it in timber.

Originally Posted by jmk89

I am sure this is not original, but because I hadn't seen one anywhere, I thought I might share it and tell you how I went about making it.

The method of dividing a length into equal proportions isn't novel, but I don't think l have seen it used in this way for setting out mortises. With a few refinements, this could be a handy tool for quite a few jobs.

Originally Posted by jmk89

I have never had much luck using standard mortice gauges to lay out mortices and tenons. In the end, I decided it was not because of the instruments themselves, but rather because they approach the job differently from how I wanted to do it.

Well, I like mortise gauges (though of course you can do the same job with a single point gauge, but you have to handle each part twice - no big deal for a couple, but a pain on a job with a dozen or more M&Ts).

A mortise gauge gives you two advantages not provided by your system, JMK. One, you should always work off a (single) marked face - it's a habit drilled into me as a kid, & it does help maintain precise fits where it matters. With a mortise gauge you are automatically marking both lines off the one face.
Secondly, & equally importantly, one usually marks the mortise to a chisel size, not a size dictated by the width of the member. For example, how does your method handle the mark-out for a mortise in a member wider than the tenon stock - a not-uncommon necessity in cabinet work? The 1/3rd rule is just a rule of thumb, so you pick the chisel that is nearest to 1/3rd, & set the gauge to that (or router bit, if that's your bent). Otherwise you will have a bit of trouble keeping your mortises accurate. Not such a big deal with jigs & power tools, I guess, but if your slot is wider than the tool forming it, it means turning the work around and working off two faces, with the chance of making or multiplying errors.

In fact, I for one don't adhere rigidly to the 1/3rd rule, anyway, because I don't think it's right for M&Ts in 3/4" (19mm) material, which of course is the most common thickness of cupboard doors, etc. A 1/4" (6mm) tenon can be a flimsy thing, and I prefer a 5/16" tenon, at the cost of fractionally thinner mortise walls. Similarly, there is little to be gained by going too much over 3/4" for a tenon in heavy stock, so I often make tenons that are less than a 1/3rd of the width, too - saves digging out unnecessary wood.

Sorry - not meaning to rain on your parade. I can see a few good applications for the tool, or something like it, but I for one won't be chucking out my mortise gauge just yet.

Cheers,

Originally Posted by IanW

The method of dividing a length into equal proportions isn't novel, but I don't think l have seen it used in this way for setting out mortises. With a few refinements, this could be a handy tool for quite a few jobs.



Well, I like mortise gauges (though of course you can do the same job with a single point gauge, but you have to handle each part twice - no big deal for a couple, but a pain on a job with a dozen or more M&Ts).

A mortise gauge gives you two advantages not provided by your system, JMK. One, you should always work off a (single) marked face - it's a habit drilled into me as a kid, & it does help maintain precise fits where it matters. With a mortise gauge you are automatically marking both lines off the one face.
Secondly, & equally importantly, one usually marks the mortise to a chisel size, not a size dictated by the width of the member. For example, how does your method handle the mark-out for a mortise in a member wider than the tenon stock - a not-uncommon necessity in cabinet work? The 1/3rd rule is just a rule of thumb, so you pick the chisel that is nearest to 1/3rd, & set the gauge to that (or router bit, if that's your bent). Otherwise you will have a bit of trouble keeping your mortises accurate. Not such a big deal with jigs & power tools, I guess, but if your slot is wider than the tool forming it, it means turning the work around and working off two faces, with the chance of making or multiplying errors.

In fact, I for one don't adhere rigidly to the 1/3rd rule, anyway, because I don't think it's right for M&Ts in 3/4" (19mm) material, which of course is the most common thickness of cupboard doors, etc. A 1/4" (6mm) tenon can be a flimsy thing, and I prefer a 5/16" tenon, at the cost of fractionally thinner mortise walls. Similarly, there is little to be gained by going too much over 3/4" for a tenon in heavy stock, so I often make tenons that are less than a 1/3rd of the width, too - saves digging out unnecessary wood.

Sorry - not meaning to rain on your parade. I can see a few good applications for the tool, or something like it, but I for one won't be chucking out my mortise gauge just yet.

Cheers,

Ian

You are not raining on my parade at all. I am glad that you think it may be useful for any jobs. And thankyou for taking the time and effort to comment.

The device was made to deal with a particular situation of common sized stiles and rails for a set of doors and it worked really well for that. However, I was aware of the problem with uneven thicknesses (eg table legs and rails). I think that what I would do in that situation is to combine it with a two-pin mortice gauge - I would use my device to mark the tenon thickness and then set the thickness of the mortice by reference to those lines. Then I would decide how far back from the front of the leg I wanted the rail and adjust the main fence of the mortice gauge to be that amount plus the amount of the tenon shoulder.

To respond to some of your other points - perhaps it is my technique (which I am sure can be improved on and probably would not pass any trade school exam) but although I choose a chisel which is close to the width of the mortice, I have not found there to be any appreciable difference if it is up to 1/16" smaller. Since I have several chisels of differing widths in 1/16" steps, I don't find that a major issue.

As to working off the single marked face, I think we had the same woodwork teacher (or his brother)! I was told the same. But I think that lying behind that point is the nature of device that was being used to do the marking. If you are using a marking gauge or a mortice gauge you are measuring absolute distances from a fixed line - so you have to use the same line as the base. However, as you point out, my gauge uses proportions, not distances, so neither face is a base line as such - together they make a distance which is divided. I may not have put that very well, but I know that there is a difference.

In relation to the 6mm tenon being too skinny, you may be right, but to date I haven't had a failure with the tenons that I have made this way. In part that is probably because I tend to cut mortices first and then saw up the tenons a bit 'fat' and then trim them down to fit with block and shoulder planes - the only problem I have had with 'thin' tenons is that once I leant heavily (accidentally) on a tenon while it was unsupported. I suppose packing underneath would prevent that happening, but it hasn't so I don't do that. Once the tenon is in the mortice, its cheeks are supported and it carries the load from narrow side to narrow side, not from cheek to cheek.

So far I haven't done a job with stock over 36mm (happily mixing metric and imperial as usual), but I see the point. Probably I would use my device to establish the "base lines" on a piece of suitable scrap, and then set the thickness of the tenon and mark the point adjustments required for that on the "base lines". I would then set the mortice gauge pins and fence by reference to that mark-up and then use it in the traditional way.

Jeremy - no sweat - all give & take here!

The good thing about being an amateur is that we are free to develop ways of working that suit us. In most trades, you were taught the "right" way to do something, and that was that. There may have been better ways waiting to be discovered, or already in use somewhere, but not here, mate!

Sometimes, the 'best' techniques require too much practice to do well, so we amateurs find other ways to achieve the same ends, & that give good & reliable results in less-practised hands. I think chopping mortises falls into that category. IMO, making a really sound M&T is harder than making watertight dovetails, hence the plethora of ways to go about it.

So you should do your mortises in whatever way gets you the results you want, of course, but I can't help giving you this one bit of advice. I would venture that most people find it easier to match chisel size exactly to the mortise. With a good & sharp mortise chisel, it's much easier to keep the walls perpendicular and even. Cutting a mortise with a chisel 1/16th less than the mortise width would result in a very sloppy mortise, in my hands. In my earlier days, I used to drill out as much of the waste as possible & pare the sides with a wide chisel, but I never got consistently good results this way. After reading the advice of the gurus, I swithed to simply chopping them out, & it really does work better for me.

I just remembered another advantage of mortise gauges - having the sides of the mortise defined by the gauge points helps prevent chipping of the edges into the rest of the piece.

Anyway - just keep making chips & enjoying it, that's the main thing!
Cheers,