cutting a dove tail.

Hi Alan, Sounds like you need a piece of thin plywood sort of U shaped to hold up against the blank for a template. You might find it helpful to make one for every typical diameter you need. Regards, Richard

First, make a go/no go gage, allowing a bit of fudge factor on the high side. Holes in plywood for me, though you can do the pencil center mark and dividers. I always strive for a minimum size beginning, knowing I can expand, versus a large size.

I like to use my 1/4" pointy gouge to establish the depth, then undercut and clean up a mating surface with a skew used as a scraper. Remember, it's a wedge grip, not an outward circular grip.

I have a scraper chisel used to cut inside left corners and edges. This was one of an old set of heavy duty scraping Sorby chisels with HSS laminated on top. It's shaped (top-down view) like a skew modified to be a scraper, with a notch on the long side (for doing rim work). If I hold the edge flat against the bottom of the bowl, the long pointy end is the perfect angle for a dovetail. (or it is now if it wasn't).

It would be easy to grind your own... You don't need the notch.

Hmm. Wonder if you could glue a thingie on top to make it a one-piece go/no-go scraper. Like a wedge, with lines drawn for various jaw sets.

Here's what I do:

Put two adjacent the jaws on the chuck. Close the chuck. Set your calipers for the widest part of the jaw (else you won't get it to fit in). You can also use dividers or a compass; the compass is what I usually use. If your calipers are rounded over, note that you're setting the tips of the calipers, not the faces. I.e. the part that will touch the wood in the next step.

Anyway, set your whatever to the widest part of the jaws. This is the smallest recess you can create without it being too small. Position the toolrest across the base of the piece, just below center, about half an inch away. Rest the dividers/calipers/compass on the toolrest, approximately centered, and LIGHTLY touch the LEFT point to the wood. The mark will make a circle, and you can look at the right point and see if you got the calipers centered. If not, move them half of the difference and try again. When you have it centered, press a little harder with the LEFT point to leave a mark you can find later to cut to. If you use a compass, put the pencil on the left side (duh).

As for tools, I use two. First, a bowl gouge hollows out most of the recess, leaving a 1/2 wide flat spot next to where the dovetail goes (for larger jaws, I leave a bump in the middle so I can go deeper inside the bowl). Next, I use my 1/2 skew to cut the actual dovetail, cutting thin plunging cuts one at a time until I get to the mark I made. Note that the skew angle on my skews matches the dovetail angle on my jaws, so I can use it as its own angle gauge.

Since I usually have the bowls on a faceplate at this point, I can test fit the chuck (with all four jaws on now) and expand the recess until it goes in easily but not too loosely.

The other way I do it is measure the jaw diameter with a ruler, and set the compass to half that. The books that came with my jaws tell you what this number is also, or you can figure it out once and write it down. You put the point of the compass in the center of the bowl's bottom and mark the dovetail's circle with it.