When I started along the dovetail journey, I used a sliding bevel gauge to mark my angles. It quickly became tiresome and error prone when working with narrow pieces of wood as my gauge needs a gargantuan effort when tightening to stop it moving, and being poorly balanced it has a tendency to tip. I had seen some commercial dovetail guides, and thought they couldn’t be that hard to make.
Using some aluminium angle I had left over from a project long forgotten, I decided to make three guides with ratios of 1:5, 1:6 and 1:7. Rather than trying to explain how I calculated the angles, I’ll let Paul Sellers share his method, which is what I used.
Once I’d calculated the pitches, and using a protractor converted them to angles, I set the angle on my sliding compound mitre saw, and cut the aluminium stock as required. Once cut, the edges were smoothed over with a file and they are ready to go.
I have now used them on several projects, and oh, what a pleasure they have been. They may not be the most beautiful but they are certainly functional. Used in the below orientation they mark the tails, or flip them over to drop the vertical pin lines.
From memory they took less than an hour to make the whole set. If I loose them I wouldn’t hesitate to delay what I was working on to whip one up again. They are just so useful. Interestingly enough, I can’t recall using anything other than the 1:7 guide. So perhaps I’d just make the one next time.