I have been playing with different joinery techniques since I built my CNC machine. I was intrigued by Gerry's thread but unfortunately my machine does not allow for vertical clamping and the use of fixed size dovetail bits limits the use somewhat. Louie's older thread of flat machined dovetails with a v-bit was more feasible for me but the use of 2 different bits and flipping the boards precisely is an issue. Drawing the geometry in VCarvepro isn't that trivial, as well.
So I dug out some 30-year old geometry skills (or what was left of it) and wrote a Basic program to machine tapered dovetails with only a 30-degree engraving bit from one side. Works pretty good and I did some preliminary practical tests.
- con(s): The board to be machined must be clamped at a 15-degree angle to the CNC table (assuming a 30-degreee engraving bit). However, such a wedge jig is easy enough to make and I believe most CNC machines that are not set up for vertical clamping get close enough to the table edge for that (mine does easily).
- pro(s):
> Only one machining process needed per board end
> Only one bit needed (a 30-degree engraving bit, e.g. $10 for a 1/4" carbide bit from Drillman at eBay)
> any desirable board thickness is possible (I guess 1/8" is a practical lower limit due to setup accuracy)
> tail and pin side may have different thickness
> the generated g-code will cut the dovetails and pins and square the board end as well
> variable pin/tail distance as well as dovetail-free joint ends
> no CAD or CAM software needed, g-code is generated directly from the machine and material parameters
> selectable overcut (to make sure to cut through), roughing/finishing skin and glue gap thickness.
So far so good, first results see below in the pictures. Now my question is what to do with that. In the first place I developed this for my own purpose but I am wondering if there may be a market for such software. I never developed software for sale but maybe you guys have an idea what to do with it. Any suggestions are welcome.
V-Bit in start position:
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Joint in 3/4" plywood:
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G-code visualization:
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more pics in the next post.
So I dug out some 30-year old geometry skills (or what was left of it) and wrote a Basic program to machine tapered dovetails with only a 30-degree engraving bit from one side. Works pretty good and I did some preliminary practical tests.
- con(s): The board to be machined must be clamped at a 15-degree angle to the CNC table (assuming a 30-degreee engraving bit). However, such a wedge jig is easy enough to make and I believe most CNC machines that are not set up for vertical clamping get close enough to the table edge for that (mine does easily).
- pro(s):
> Only one machining process needed per board end
> Only one bit needed (a 30-degree engraving bit, e.g. $10 for a 1/4" carbide bit from Drillman at eBay)
> any desirable board thickness is possible (I guess 1/8" is a practical lower limit due to setup accuracy)
> tail and pin side may have different thickness
> the generated g-code will cut the dovetails and pins and square the board end as well
> variable pin/tail distance as well as dovetail-free joint ends
> no CAD or CAM software needed, g-code is generated directly from the machine and material parameters
> selectable overcut (to make sure to cut through), roughing/finishing skin and glue gap thickness.
So far so good, first results see below in the pictures. Now my question is what to do with that. In the first place I developed this for my own purpose but I am wondering if there may be a market for such software. I never developed software for sale but maybe you guys have an idea what to do with it. Any suggestions are welcome.
V-Bit in start position:
Joint in 3/4" plywood:
G-code visualization:
more pics in the next post.