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In:In the Shop

Comments Off on A Modified Marking Gauge

I had this idea pop into my head the other week and decided it wasn’t going to stop nagging me until I tried it.  So here’s what went down and where it’s headed next.

When sawing to a line, there’s a few typical steps and hand tool individual would take.  First, use a marking gauge to scribe a line parallel to an edge.  This creates a crisp target to work to, but trying to drop a saw against that line is difficult to do without crossing the line.  If you’re sawing off a tenon cheek, for example, you want that shoulder cut cleanly and free from defects caused by the saw jumping the line when trying to get the cut started.  So, step two is to chisel a little V that butts up against the knifeline you created prior.  You obviously want to remove the material on the waste side of the line.  Now drop the saw in the V and go to town.

Using a typical marking gauge, scribe the line you want to cut to in your board.

Using a typical marking gauge, scribe the line you want to cut to in your board.

Angle a chisel into the knifeline (obviously on the waste side) to create a shoulder.

Angle a chisel into the knifeline (obviously on the waste side) to create a shoulder.

I got thinking about this two-step process, looked at my Veritas dual marking gauge, and went to work.  The two posts each have a dedicated cutter at one end and nothing at the back end of the post.  I added a 45 deg bevel to the back of one post, tapped a 4-40 hole (which matches the holes at the front of each post) and installed a prototype cutter.  When the post was re-worked, I installed it so the tips of each cutter lined up.

Dual marking gauge in its original state.

Dual marking gauge in its original state.

One post removed for modifying.

One post removed for modifying.

Back end of the post with its bevel ground in.

Back end of the post with its bevel ground in.

... and now the tapped hole for the cutter.

… and now the tapped hole for the cutter.

Modified angled cutter installed next to the standard vertical cutter.

Modified angled cutter installed next to the standard vertical cutter.

When viewed from the side, the blades just line up at the tips of the cutters.

When viewed from the side, the blades just line up at the tips of the cutters.

The idea at this point was to drag the gauge across the board in the usual fashion, but after the vertical cutter has scored its line, the angled cutter would follow along scoring the little V typically removed by a chisel.

Test cut: after a couple passes with the gauge the waste material lifted right out.

Test cut: after a couple passes with the gauge the waste material lifted right out.

So how did it work?  Not too shabby.

Gauge/chisel line in the back, dual gauge line in the front.

Gauge/chisel line in the back, dual marking gauge line in the front.  Virtually identical.

When viewed from the side, you can see each method gave a nice V with one side vertical, one side angled.

When viewed from the side, you can see each method gave a nice V with one side vertical, one side angled.

I had no trouble tracking the line with the saw.  No jumping or wandering.

I had no trouble tracking the line with the saw. No jumping or wandering.

To be really effective I’d like to have a pair of custom cutters made up, that’s where I’m headed next.  For now it worked well enough to prove the concept.  I like the fact that the modification is really just an addition to the existing gauge without taking anything away from tool as it was originally intended to function.  Just flip the post around and you’re back to two vertical cutters.  So until new cutters are made, that’s all folks.

-WMT

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