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TrevorWalsh 07-07-2011 02:58 PM

Brass and Exotics Dovetail Markers
 
6 Attachment(s)
As backstory, I've wanted to make some brass DT markers for forever, I'd had some pieces of brass left over from my machining days. These were doing to become brass jaws for my small horizontal milling machine.

Anywho I filed, drilled and mounted them to cocobolo (for a dual slope 1:7 and 1:5) and ebony (for square and 1:7). I overshot the countersinks so the screw slots still show, but I'm confident I can hit it next time.

Here are the pictures, I think the ebony with square is a better design. you don't have to fuss with a square and marker; and you can't accidentally switch angles while working. The wooden one there is a prototype for the second run of these. I'm buying 12 feet of brass bar because it's cheaper there than buying small quantities online. I also have to stamp the slope into them yet.

MichaelKellough 07-07-2011 03:22 PM

Re: Brass and Exotics Dovetail Markers
 
Well done Trevor!

I've never been able to get countersink to follow drilled holes concentrically enough for the level of precision this (seems to) require. On second thought, maybe extreme precision isn't required? You just need to use the same marker for each pin/tail pair?

I saw St. Roy cut DTs at WWIA in Valley Forge. He roughly laid the tails then cut them by eye. Then he scribe transferred the tails shapes to the end of the pin board and cut them. As long as each pin conforms to the shape of the tail it has to fit into all is well. Even if the angle of each side of each tail is different from all of the others it'll work. It'll be a bit rustic looking though.

TrevorWalsh 07-07-2011 06:33 PM

Re: Brass and Exotics Dovetail Markers
 
Yes, I cut tails first and it's very forgiving of screwups. For layout the brass is center punched, drilled and countersunk. Then you superglue the block of wood to the brass to hold it in place while drilling the pilots. It's all cleanup from there.

Some manufacturer has piloted countersinks, or drill/countersinks which would be really handy for this. Also getting the optimum feed rate and speed is a huge help... They also make what is called a zero flute countersink which makes no chatter.

FlairWoodworks 07-07-2011 06:39 PM

Re: Brass and Exotics Dovetail Markers
 
Very nice, Trevor. At least the screw slots are aligned. Could you fill them with epoxy and brass or wood dust?

MichaelKellough 07-07-2011 10:33 PM

Re: Brass and Exotics Dovetail Markers
 
Quote:

Originally Posted by TrevorWalsh (Post 70045)
Yes, I cut tails first and it's very forgiving of screwups. For layout the brass is center punched, drilled and countersunk. Then you superglue the block of wood to the brass to hold it in place while drilling the pilots. It's all cleanup from there.

Some manufacturer has piloted countersinks, or drill/countersinks which would be really handy for this. Also getting the optimum feed rate and speed is a huge help... They also make what is called a zero flute countersink which makes no chatter.

Thanks for the tips!

hasslefactor 07-07-2011 10:55 PM

Re: Brass and Exotics Dovetail Markers
 
Nice work, Trevor! :thumbsup2:

TrevorWalsh 07-08-2011 03:33 AM

Re: Brass and Exotics Dovetail Markers
 
Flairwoodworking, I might be able to, I've never tried that. I think the best solution is so stay well away from the depth I was countersinking to before.

MichaelKellough 07-08-2011 02:03 PM

Re: Brass and Exotics Dovetail Markers
 
Quote:

Originally Posted by MichaelKellough (Post 70039)
Well done Trevor!

I've never been able to get countersink to follow drilled holes concentrically enough for the level of precision this (seems to) require. On second thought, maybe extreme precision isn't required? You just need to use the same marker for each pin/tail pair?

I saw St. Roy cut DTs at WWIA in Valley Forge. He roughly laid the tails then cut them by eye. Then he scribe transferred the tails shapes to the end of the pin board and cut them. As long as each pin conforms to the shape of the tail it has to fit into all is well. Even if the angle of each side of each tail is different from all of the others it'll work. It'll be a bit rustic looking though.

Actually I'm not sure if he did the tails first or the pins, it was nearly 2 years ago. Anyone know?

TrevorWalsh 07-08-2011 10:17 PM

Re: Brass and Exotics Dovetail Markers
 
If memory serves I think St. Roy is in the pins first camp?

MichaelKellough 07-09-2011 12:59 AM

Re: Brass and Exotics Dovetail Markers
 
Quote:

Originally Posted by TrevorWalsh (Post 70080)
If memory serves I think St. Roy is in the pins first camp?

Sorta..."Then he lays out the tails by first marking the half pins at the edges of the tail board." But, he "likes to cut the tails first when he can, and he strikes his baselines with a cutting gauge set to the thickness of the work plus 1/32nd."

Found a review of the very demonstration I saw, and a photo of it as well.

http://www.popularwoodworking.com/wp...t_IMG_0627.jpg

Here is the really interesting part I forgot, "To transfer the shape of the tails onto the pin board, Underhill uses his dovetail saw. He places his tail board on top of his pin board (which is clamped in a vise). And then places the dovetail saw in the kerf and scores the end grain of the pin board. It's a light mark. Too deep and your saw will jump into the kerf when you are sawing out the pins. You actually want to saw in the waste next to this line.

Then he draws the shape of his pins on the pin board and cuts them with a dovetail saw. To remove the waste between the pins, Underhill uses a coping saw, which he lubricates with mutton tallow."


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