Sunday, October 28, 2012

Colas de milano en sierra sin fín

Dovetail joints on the bandsaw
When you read a lot of "fine woodworking" style magazines, sometimes it seems woodworking is all about the hand cut dovetails. Personally, I'm not that infatuated with this type of joint, but I thought I'd play around with them a bit. Now, I don't have the kind of patience required to cut them out by hand, so I sped up the process with my bandsaw. Dovetail joints require angle cuts. Some bandsaws can tilt the table right and left, although that does require removing the 90 degree stop. My homemade bandsaw table doesn't tilt left. So I made a jig to hold the stock at an angle. But as you'll see later, this jig also comes in handy later on for cleaning up the joints.
The jig is clamped onto my table using two of these funny "fence clamps" shown at right. They are good for holding sacrificial fences and such. I originally bought them to use on my table saw, only to discover that they don't open up far enough to reach over the saw's fence.
My jig also conveniently serves as a fence. I set it up once for each cut, and then make the same cut on each of my joints without having to mark them.
     
After having cut both sides of the joint, I make some more cuts to start hogging out the material between the pins.
I make a turn as tight as the blade allows to start cutting out the material between the fingers. I do this with my work piece my jig, sliding the jig around as I make the cut. That way, when I end the cut at nearly a right angle, my piece is still slanted so the cut is flat on the bottom.
I have to work from both sides. The pieces for my bandsaw stand are a bit longer than my bandsaw is wide, although it was still workable. The blade guard on the left side is only a little bit forward of the blade on my bandsaw, so I can swivel the piece to nearly a right angle. Note how my workpiece is on the jig. For the clean up cuts, I always slide the jig with the work piece.
Here's my pins cut. I cleaned up the bottom of the space between by just grazing it with the front edge of the sawblade.
Now to transfer my marks onto the mating pieces. I tried doing this with a marking knife, but my joints always ended up tight. Worse yet, after I cut them, there was no trace of my marks, so I wouldn't know where to trim them. With a pencil line, if I cut away half the line, it fits. And if the joint is too tight, I can see the rest of the pencil line, so I know where to cut away more.
Cutting the tails is easy compared to the pins. No jig required.
     
Checking the fit
I used lots of glue when I put the joints together. I figure that way, the glue can fill any gaps that I might have in the joint.
And here's one of the finished joints, which is part of my mobile bandsaw stand. The glue and sawdust nicely filled any remaining gaps that I had in my joints. <      

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