Hell's teeth, if I have to do any more of these, I may have to take up drink...
So, here we go. How to mark out dovetails, quick and easy without making any bloody mistakes...
They come later!
Firstly, sort out the wood (maple used here) so the end has been planed dead square and true, then mark off the shoulder line (12mm in this case) and knife it in all way round.
Secondly, measure in from each side along the shoulder line, half the thickness of the wood plus a gnats todger. The maple here is 10mm thick, so I've measured in 6mm, a gnat's todger being a mm.
Mark these two points arrowed as small dots with an awl...
...and then mark the first two slopes, here 1:8 as it's a hardwood. Black biro used so the lines can be seen.
This particular piece of maple measured...
...85mm, so if the general 'rule of thumb' is used, the tail ought to be around 25mm, so three required here. Place the wood in the vice and with a little experimentation, divide the distance between the lines exactly in three by just stepping out across the end from the line at one end until it finishes on the other line.
Then...and here's the cunning bit, make the distance between the divider points a fraction bigger...maybe half a gnats todger and step out from the right hand side to make...
...two dots, arrowed. Keeping the distance between the dividers the same, step out now from the
...left hand side to make another pair of dots, each dot being rigtht alongside the other and being separated by the proverbial gnats thingie!
Use a square (or dovetail gauge in this case) to turn the pair of dots into parallel lines...
...and then draw down to the shoulder line...
...to make three identical dovetails. The distance across the bottom of each narrow pin ought, if the marking out has been done correctly, to be equal to, or a fraction bigger than the width of the dovetail chisel used to remove the waste. If it's too narrow, simply set the dividers a little bigger.
A gnats todger should do it!
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