I was thinking about dovetail ratios, mainly because we have been invited to import tools from Sterling Toolworks U.S.A. Tools we have long admired, but more on that later.
So, Sterling Toolworks has 5 different ratios available in their "Saddle Tail" range of markers. (Really nice tools capable of gang marking 3/4 stock, Steel and brass construct, to enable you to use knives for marking). But, why so many ratios? 1:4, 1:5, 1:6, 1:7, 1:8. The important question, given I might have to buy all of them. My thought of course, what do I need? Then, what does anyone need?
I am not aware that this question has been asked in any literature, (might want to check that with Christopher Schwarz), so I thought I would put my 2 cents in.
Well, of course, you don't need all of them, but I might. When we had professionals making cabinets by hand for income, it was likely they did not use markers for the task of making dovetails, it was done by an experienced eye and hand saws. The question is at what angles (ratios) would they have used? I think it would have depended on material, aesthetics, strength, and durability, but they would definitely vary the ratio. Here's why.
Rob Cosman uses thicker material in his drawer fronts with blind dovetails to extend the length of the dovetails from base to tip (see photo) and therefore the contrast of the pins looks better, I agree. The ratio I used here was 1:6 the base of the pin was narrowed, correspondingly narrowing the tip gives a good look, the angle of the tail was not too wide which meant the extreme tips of the dovetail were not exposed to breaking off when assembling, ( the sides are meranti and the face was air-dried jarrah). The other thing in using a 1:6 ratio was it increased the long grain to long grain surface for glue strength with good enough flare in the dovetail definition for mechanical strength. This drawer is not finished yet but needs to be well built as it will be a display and storage drawer for, you guessed it, "Saddle Tail" dovetail markers.
If the drawer sides were half as high (the pictured drawer is 80mm high), I would have used a 1:8 ratio, maybe only 2 dovetails, this would have reduced the dovetail definition and like a box joint, increased the long grain to long grain glue surface, the mechanical strength would not be as important in such a drawer which normally would not have very heavy items stored in it.
If the drawer side was wider, a 1:4 ratio might be considered, with very good mechanical strength, great dovetail definition, and fewer dovetails to cut.
This is the top of a carcass for a saw till I am making the light timber is butternut and the dark wood is jarrah, the ratio is 1:7 that meant I could fit more dovetails in the width of the frame but with good definition, however, the pins were not too narrow, I found the air-dried jarrah to be prone to splitting and chipping so when sawing the pins I wanted some material width. If I had used 1:6 or 1:5 ratios I would have to use narrower pins or have difficulty in spacing the dovetails.
I like using a guide to mark my dovetails when making a display of them, I still use that as a guide to cut straight lines, when I have to use a sliding bevel, for instance, with this saw till carcass I find it is inconvenient and prone to error.
Will I be buying all of the "Saddle Tail", guides.........Yep!
