Single or double marking gauge for M+T joint?

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pe2dave

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Single from both sides, double from marked face? Does it make that much difference?
I'm ignoring the quality of the gauge, please do the same.
I'm unconvinced of the benefit of a double, are there any?
Discuss ;-)
 
Doesn't really matter all that much. People who build two projects a year will argue for the "efficiency" of a double-pin gauge - same crowd that speak of 'efficiency' when planing. They wouldn't know it if it bit them in the buttocks. Others that own every mortise gauge known to man are even worse. Simplify, simplify, simplify. If you have a two-pin gauge, fine. If you don't, fine. You don't need to go out and buy one to chop a mortise today. Nor do you need to own a mortise chisel with a reliable provenance to Thomas Chippendale himself. One can make a perfectly reliable hole in a piece of wood with remarkably pedestrian tools.

 
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You're making the assumption here that all tenons are central to the stock, and that all stock is exactly the same thickness throughout. It is safest to use face sides and face edges as reference points at all times. For this reason it is easiest to use a mortice gauge, though you could easily use a standard gauge, or even a pair of them set to different widths.
 
The tenon can be anywhere it needs to be, central or otherwise. It just needs to be marked from the same face. And if the workpiece has been processed with reasonably accurate machinery, or fastidiously by hand, and thus is a consistent thickness, this isn't an absolute requirement. That said, it's simply easier to mark from the same face . And in this case, easy is more accurate and let's any inconsistencies in thickness run off to the non-show face. When working up the face side of stiles and rails, they need to be the show side. This isn't always the case with every component of a piece of furniture, but it is with doors.
 
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Always mark from a face side and face edge. If you have one a mortice gauge is the right tool where you set the pins to the width of your mortice based on the width of your chisel and then set the stock/fence to position your mortice and tennon usually centrally in the workpiece but not always
 
Always mark from a face side and face edge. If you have one a mortice gauge is the right tool where you set the pins to the width of your mortice based on the width of your chisel and then set the stock/fence to position your mortice and tennon usually centrally in the workpiece but not always
There are some circumstances where this can't be done, but they're fairly rarely encountered, so yes, one should follow the general rule of running marking implements against proven faces and edges.
 
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Summary (ignoring off centre mortises):
Use the face side for reference... Implies two gauges unless unset (cost).
I have never done a single mortise so I'll take that as a preference for a double (pinned / wheeled) gauge.
Thank you.
 
I generally use a single wheel gauge, but make up a little block the thickness of the tenon I want to make with a hole in it. You could just do this for every mortice chisel you owned.
Allows you to mark from face side/edge every time. Just put it between the stock of the gauge and the reference face for the second line.
I would say it’s useful incase the stock isn’t all exactly the same thickness. If one workpiece is .5mm over, then unless you fit each tenon custom and reset whatever machinery you use and mark out each tenon custom I wouldn’t trust it.
It’s quicker to have the peace of mind that all the mortices are marked in the same place and the same width. Obviously if using a hollow chisel morticer (not chisels etc) and only one plunge for the width, then they will be a tight fit, but if for example one is marked out .5mm oversize, which line do you go to ? Does it then pull the rail into rack, therefore creating a gap in one of the shoulders ?
 
Single from both sides, double from marked face? Does it make that much difference?
I'm ignoring the quality of the gauge, please do the same.
I'm unconvinced of the benefit of a double, are there any?
Discuss ;-)
It was always a Mortise Gauge for marking mortises, and always marked from the Face Side. This was to guarantee flush joints due to the possibility of uneven thickness hand prepared stock.

Not so much of a problem with machined stock but still nice to keep up traditions.
 
The video I posted above shows marking using a single-line gauge. Everybody has at least a marking gauge. If you do, you have all you need. There's no need to spend weeks researching and evaluating alternatives. Mark and chop if it's about woodworking and not tool ownership. If you bought a double-pin gauge early on, you're good to go as well. If you own one or the other, or both, and your mortising isn't going well I can assure you it's not because of the gauge you are using.
 
The video I posted above shows marking using a single-line gauge. Everybody has at least a marking gauge. If you do, you have all you need. There's no need to spend weeks researching and evaluating alternatives. Mark and chop if it's about woodworking and not tool ownership. If you bought a double-pin gauge early on, you're good to go as well. If you own one or the other, or both, and your mortising isn't going well I can assure you it's not because of the gauge you are using.
Ignoring the bevel on the 'wheel'? Tks for the video link.
My double / single gauge is just under 50 yo.
took me all of a minute to ask the question. Hardly weeks?
 
Mortise gauges have been a round for a very long time and for good reasons,but if you don't own one it isn't the end of the world.You can take a step out of the process if you own a bench drill,as with a block of wood cramped to the table,you have the basis of a mortiser and just need to clean up the edges.Face side to block if you didn't know and just a pencil line for the ends will suffice.
 
Single from both sides, double from marked face? Does it make that much difference?
I'm ignoring the quality of the gauge, please do the same.
I'm unconvinced of the benefit of a double, are there any?
Discuss ;-)
Makes a huge difference and ensures that all the mortices and tenons will match.
You can do it with two singles but always from SAME SIDE. Takes twice as long and introduces a possibility of error.
Single from both sides doomed to fail; having to readjust causes errors, timber not always the exact correct thickness, most M&Ts are not central anyway.
 
....One can make a perfectly reliable hole in a piece of wood with remarkably pedestrian tools.
...
Yes but it's easier, faster, more accurate with the right kit. If you had a lot to do then 2 single pin gauges would be better than one, but one double pin even better.
They probably knocked up simple non adjustable gauges when repetitive mass produced hand work was the norm.
 
You dont technically need to mark each side of the mortice ? The mortice width is normally driven by the width of you chisel. So you just need to mark one side of the mortice.
Mortice gauge are useful if you cut a mortice bigger than your chisel and need multiple passes to have the correct width (but it's more relevant for carpentry than furniture making).

That being said, I use a mortice gauge as it is easier to mark the mortice and the associated tenon, and allows to clean the mortice wall more easily (thus make a cleaner work).
 
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Why do you need to mark each side of the mortice ? The mortice width is normally driven by the width of you chisel. So you just need to mark one side of the mortice.
Better to have two marks as a double check and anyway you use the same gauge to mark the tenon where you do need two marks.
 
You dont technically need to mark each side of the mortice ? The mortice width is normally driven by the width of you chisel. So you just need to mark one side of the mortice.
Mortice gauge are useful if you cut a mortice bigger than your chisel and need multiple passes to have the correct width (but it's more relevant for carpentry than furniture making).

That being said, I use a mortice gauge as it is easier to mark the mortice and the associated tenon, and allows to clean the mortice wall more easily (thus make a cleaner work).
I find it a lot easier to centralise a mortice chisel between two marked lines than to carry out this same operation off the side of a single line. It is also handy when you are using a morticing machine as it helps you to keep track of whether the chisel is cutting in the right place on all components especially with monotonously large batches.

You can also find yourself in a position where longer components have to be worked from both ends, so that they can fit on the machine. Again it is a lot easier to tweak the adjustment of the chisel if you have the two sides of the mortice marked
 
I made a mortice gauge with fixed pins. The pin spacing matches the width of the chisel I always seem to use to chop mortices. No adjustment and very little thinking required.
 
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