Occasionally I need to draw arcs to lay out some project part. My previous jig was simple - long thin stick of wood with a little slot for a pencil point at one end and holes along the length for a screw wherever I need a radius.
|Old arc-drawing jig|
In his excellent blog, Dennis Laney posted in late 2014 about drawing ellipses. In discussing this, he said "everyone needs a set of trammel points", and well, who am I to disagree with him.
So I looked on the internet and sketched a few things.
|A few notes|
|Tight fit on this side|
|Not so good on this side|
|The completed prototype|
|Mortising by eye|
|Verifying that the mortise wall had no hump ...|
|... looking at both sides|
One of the trammels will be fitted with a 2" length of pencil. I found the center at the end of one trammel and drilled a hole for a tight fit. I also shaved off the arises of the hexagonal shaped pencil to make it more round and to fit better in the hole.
|Hole drilled for first trammel|
|Before and after shaping|
|Mo, Larry and Curly (or is that Shemp?)|
|Wedge shape laid out and relief cut made|
|Sneaking up to the line|
|Shooting for a perfect fit|
|Tight this side ...|
|... and tight this side|
|Too much wedge on the right side|
|Much better balance|
|"P" for pencil trammel, "1" and "2" for the two nail trammels|
|Stick a fork in it - it's done|
|Hanging out on the side of my tool cabinet|
Now I gotta get out of this funk and get on to some decent projects.