Marking & mortising gauges have conical-shaped points where the gauge marks the workpiece. The shape of these points produces some amount of tear out when marking across the grain.It also
creates a wide mark. This can be good if you have trouble seeing up close, but if you need dead-on accuracy and prefer clean marks, file a flat on the side of the point 
that faces the fence of the gauge. If you are using a mortising gauge, file the two inside faces of the points. The difference in track marks between conical points and knife-edge points is shown in the top photo.
If you have an antique marking gauge, you may need to flatten the fence on a sheet of sandpaper. The fence on my antique gauge has two strips of brass that, when I bought it, stood proud of the wood, each to a different degree. One strip was about 1/32" proud, a
nd the other, a bit more. I resurfaced it on a sheet of sandpaper that I fixed to my jointer bed until the brass strips were flush with the face of the wood fence. A dead-flat face (why does that sound scary?) will improve the performance of the gauge.It could be that the gauge was made this way intentionally, with the brass not flush with the wood fence. But by relying on two thin pieces of brass to maintain a consistent distance between the fence and the edge of your workpiece, you risk making a wobbly line when you reach the end of your workpiece and one strip of brass is no longer in contact with its edge.
In short: a knife-edge and a flat face will improve your marksmanship.
Note added 3/12: in case you don't read comments, some readers are referring to Tage Frid's book that recommends filing a slight angle on the point so it will pull the gauge against the edge of the board.
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8 comments:
Hmmm, VC:
Those pins are very small! And I do use very old marking gauges. I must look at my inventory of files, and select a good one. And THEN hope I don't overdo things ;-)
Good luck, Al. If you overdo it, you can always tap the pin through the arm of the gauge a bit, file the tip of the point off, and start over.
I heard somewhere to file the needle at an angle so it pulls the marking gauge into the wood.
Yup, that is a long standing trick. File the point so that the flat is very slightly angled in towards the face of the gauge. This pulls the fence against the board, hopefully preventing the pin from following recalcitrant grain. I think I first read this in a Tage Frid book?
David Finck (author of Making & Mastering Wood Planes) taught me this neat little trick. I've never read the Tage Frid book but have heard many people mention it as one of their favorites.
I too read about the angled filing in one of Tage Frid's three book set. He also mentioned to use a flat file that is used to sharpen Russel Jenning's style auger point bits. The file has a narrow side that does not have file teeth on it. This allows the file to ride against the face of your marking gauge without damaging the wood or brass surface. I purchased one of these I think from Lee Valley, Garrett Wade, or Highland Hardware. I tried it on my Stanley gauge and it worked well.
I file a point that look exactly like yours, except the bevel of the knife faces the gauge's fence, since I want the cleanest side of the cut on the side that's farther away from the board's edge. That's usually the "keeper" side. Maybe the difference is that I use it as a cutting gauge.
Both of those ideas, the angled point, and the bevel facing the fence, sound like good ones. : )
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