Variables

[mikejohn]

OK, I Googled!
I now believe this is a tapered sliding dovetail.


11010.gif

11011.gif

The shoulder and tail face (or is it pin face?) remain parallel along its length, the tail is the same depth throughout.
The width of the taper narrows along its length, as shown in red.
My intended method will allow this taper to be made, but not a taper that makes the shoulder and tail face tapering.
Can I taper just one side?
It will be necessary to tell the program whether the board is facing up or down, left or right.

.........Mike

[ron brown]

Tapering one side was common in older furniture. It can also be a superior method of assuring a part stays true to a certain plane.

The "Can you taper just one side?" May need review by the language use police. (Or should that be buy?)

Ron

[mikejohn]

Behave yourself,Ron. I've just had one thread suspended

[mrdovey]

Mike...

Your jig looks like a winner to me.

I can't imagine any reason why a very slight end-to-end taper couldn't be cut by positioning the bit at the low side and cutting toward the high side.

Do try this on a piece of scrap first, since the center of the taper cut will exhibit a slight concavity dependent on the diameter of the bit and the angle of taper. If the resulting quality is satisfactory, this should be a lot easier than putting shims under either jig or workpiece.

...Morris (not affiliated with language police!)

[charles_o]

Mike
Your second example is what I was refering to, allthough lass exagerated of an angel than what the picture shows. Morris' point of shiming would work, just be sure to shim the same edge on both sides of the workpiece. I guess you could do this on one side, but I would keep things symetrical I was doing it. I did do a repair on a wardrobe once that had joints like this.

11017.jpg

[mikejohn]

Morris and Charles
Thanks for your input.
I will give full details when I have completed my experiments.
The mathematics are quite straight forward to create the angle in the file, with just variables of width and thickness input at the start of the file.
My ShopBot manual is at the workshop (4 freezing cold, ice covered miles away) where I am now off to. I will check what commands are available in shopbot files.
Then I will make the jig (which is not complicated). Then I will cut the files and report back.

Morris, I recognise the slight concavity, but it seems very small, even over 150mm (6"), and shouldn't be a problem.

Charles, I did consider a joint like above, but was thinking more of dovetailing both sides, but only tapering one side.

Need to get the dog sled out now, and be on my way.
In the words of Oats to Captain Scott "I'm going outside now, I may be some time!"

...............Mike