Mortise Marking Tool

No, but I have ideas

Bill Houghton, Sebastopol, CA

>Since hand-cut mortises are sized to the chisel used, I've thought for a while that the logical thing to do is make one marking gauge for each chisel, and make the scribing points from a piece of flat stock the width of the chisel, with the center filed out - kind of like a scratch stock set up to make a bead.

If making separate gauges for each mortise chisel is too much, then make a gauge that can take interchangeable "points" made of flat stock, on the same principle as in the first paragraph.

I thought this was an original idea, and then saw this very idea in an old FWW or some such mag.

Re: No, but I have ideas

joel

>THe problem is that sometimes you screw up and end up with either a mortise or a tenon (depending on which you do first) which is either slightly too fat or too narrow. In this case what you do is simpley rescribe the mating peice to the new width and don't tell anyone. So having an infinite setting mortise gauge is very important.

While we are on the subject - over time I have accumulated lots of mortise gauges - everything from a new $14 sliding gauge to some nice really valauble old ones. MY favorite gets used all the time - the other guages get used on large projects because it's really convinenent to be able to set a gauge and then leave it for the duration of the project - that way I don't have to dress and mark every piece at the same time - I can do it as I need to - which for a hand tool only shop is mightly convinent. Sometimes they get set for months. I put a peice of tape over the screw so I know it's set and label it which what it is.

Question

Adam Cherubini, NJ

>In the Seaton chest there is a mortising gauge with a square wooden arm. Each side of the arm has a different pair of pins sized to the most used chisels.

If the mortise width is actually determined by the chisel (as is suggested by this gauge), why wouldn't a single line from a normal marking gauge be sufficient to layout the mortise?

Could it be that the mortising gauge wasn't used to mark the mortise? Perhaps the mortise was cut first, then the mortise gauge was set to the mortise's actual location. The mortise gauge would then be responsible for transferring the marks to the tenon.

If that's true, why do we call it a mortise gauge? Shouldn't we call it a tenon gauge?

Adam

P.S. I always cut the mortise first. That way I can trim the ends of the tenon until it fits just right.

Re: Question

joel

>All very interesting questions.

THe first question I have is we know that special craftsman made purpose gauges abound for production work but that this gauge (and I will take a look at the book later this evening) having multiple setting wasn't specifcally for production.

The tools in the seaton chest weren't used much either - certainly not for an entire career.

So was the guage made one day because SEaton needed two guages? (I have no idea)

your point on the single line is true from a theoretical point of view but whether or not you just chop a mortise or pare - it seems to be that a double line is a little more reassuring.

But in production work I can't imagine with practice if one or two lines made much of a difference.

And certainly for tenons it's handy.

In general I was taught to make the harder part of the joint to correct first. So most of the time I chop mortises because sizing a tenon is easy. but if you are setup for cutting tenon by machine it's actually easier to do the tneons first all to the same setting and then scribe the mortise to the finished dimension of the tenon. I pare sides of mortises which makes it trivial to hit any exact size).

And if you are doing angle tenons like on a chair - a very common operation then doing tenons first can be a lot easier - especially if you are working in production with hand tool because you can easily mark out and cut a pile of angled tenons all at once and then mortise them in - checking the setting each time.

In any case maybe that fixed pin guage wasn't a Mortise Gauge but a tenon gauge. I don't know - which came first the chicken or the egg?

Re: Question

Pam Niedermayer - Austin, TX

>I think you can work faster and more accurately by using two lines; and since it doesn't take any more effort to make two lines with a set gauge than one line, where's the pain?

Secondly, taking the size of the mortise rather than the chisel is also less precise, given the point design. How deep do you place the pins/bladelets in the mortise to take a measure?

I also cut the mortise first. At one time I had a reason for this. :)

Pam

Re: Question

joel

>if you cut the mortises first, checking the finished mortise against the already chopped mortise guage before scribing the tenons is a great way to trivally fix minor changes if the final mortise is accidently a little bigger or smaller than it should be.

What I typically do is chop all my mortises, then check them all. Most of the time everything is on the money and I go ahead and scribe the tenons - if not I will use another gauge to remeasure the mortise and scribe the tenons or do the custom tenons last so I don't loose my mortise gauge setting until after I don't need it.

note: In the way I was taught, and as descibed in very early literature I always pare the sides of my mortise to the scribe line, not only does this mean I can really chop fast and hard and sloppy, it means I can hit any dimension, not just the ones the width of my chisel.

Re: Question

Pam Niedermayer - Austin, TX

>I found out the hard way that when I nibble away at adjustments, I muck up everything. Kind of like pruning a bush, all of a sudden there's nothing left.

Therefore, I chop the mortise to the mortise chisel width, no paring beyond the chisel's width, cut the tenon barely outside the line, and try to insert the tenon. Often the tenon will be very slightly too large, so at that point I'll trim lightly and refit until it works. I suppose that's why I chop the mortise first, it's easier to trim the tenon to fit.

Since taking this approach, which was derived with Kingshott's help, my woodworking life is more enjoyable and efficient.

Pam

Re: Question

joel

>I fully agree with you about nibble away at adjustments, That's why I pare with a nice wide chisel at the scribe lines. If I do it right typically I don't have to trim the tenon either for a perfect fit.

With tenons cut on a table saw you get just enough variation so doing the tenons first is a lot faster (I don't do it that way as I don't have a table saw but I used to)

Re: Question

Pam Niedermayer - Austin, TX

>The only tenons I ever cut with a table saw are in 2X4's for carpentry; and even that's so much hassle (don't have a tenoning jig or dado blade, so talk about nibbling) I usually do it by hand nowadays.

Pam

Re: Question

joel

>A good tenoning jig is worth its weight in gold - and you need a good blade. I''ve never used a dado blade for tenoning - finish is too rough.

Re: Question

joel

>I finally had a chance to look at the Seaton book. According to the description in the book fixed pin mortise gauges were still popular because sliding pin mortice gauge were not generally in use this early (1797) THe Sheffield Key (1816?) shows a screw mortise guage so I guess we are just a little early.

anyway.

there are 8 mortise chisels - a matched set in the chest 1/8" - 1/2" all little used excetpt for the 1/2" and the 11/32" which have broken cutten edges. THe mortise gauges (there are two with fixed pins) only cover 5 of the eight sizes and of the 8 sizes the 1/2", 11/32, 9/32 have no guage match. THe gauges seem manufactered (my conclusion) not craftsman made but there is no noted maker's mark on the tools.

my question is if you are stocking a toolbox as thouguly as the seaton chest was assembled why don't there be more matches in the chisels. Why are the matched sizes in mostly the very narrow widths (1/8 - 1/4). is a larger fixed pin mortise gauge covering the larger sizes missing?

If Seaton chopped his mortises narrower than the scribe lines as I do then it makes less sense. But as there is always variation in the actual width of chisels you would expect a person scriibing to the exact width of the chisel as many do now, you would expect some care in getting a matched set of chisels and gauges. This also makes little sense.

My conclusion - based purely on speculation is that the gauges were purchased because it seemed like a good idea at the time, but push comes to shove, when and if Seaton did serious work he would either use a single pin guage or for more repeditive make up a custom gauge for himself. There is also a good possiblity that a larger gauge was lost.

If drawing a single line was done - as opposed to a double line with either a mortise gauge or two passes of a marking gauge - then we should be able to see the evidence on the inside layouts of disssembled 18th century furniture. As that isn't my area of research - I don't know what the furniture evidence is but I am sure someone can find out.