Every pass gave additional feedback for further adjustments. First it was clearance, then positioning, then depth of cut. The -0.375 mm clearance works well. The tenons still protrude because the flattening cut is of course at half the included angle. I decided just to skip the flattening pass and trim the extra with the band saw or plane before sanding. The other consequence of the adjustments is that the usable section length is shorter than my original plan. That just means that the fountain diameter will be less than planned by about 100 mm.
4 test cuts later, and I have a joint that works. I started with a -0.125 mm clearance on the mortice, moved to -0.250, then tried -0.5 mm. The last works, but is now a bit loose. I’ll try again tomorrow with -0.375.
I also completely redesigned the joint. The other one was adapted from my Raven Desk joints, which were cut with a 1/4″ cutter. This time I have to use a half inch cutter because of the depth of cut. This latest joint is based on circles with a 15 mm diameter, assuring lots of clearance for the tool.
One of the cuts dislodged the work piece in the fixture and I hit the Stop button as fast as I could. After that I ran screws into the workpiece from both sides, in addition to the Bessey clamps. The screw hole areas will probably be cut out anyway, both top and bottom.
I just realised that if I cut from the outer side instead, I can do a half-blind mortice and not have that gap at the joint., OK, back to “the drawing board” ie. VCarve tomorrow to try that approach.
First test of the fixture is a partial success. Nothing broke. No-one was injured. The joints don’t mate. I left the -0.125 mm allowance that has worked well in the past. I’m thinking I didn’t rotate or reflect the joint design correctly. Since this is my first asymmetrical joint, that’s probably the reason. The other good news is that the angle is exactly correct, within measurement error.
Man, it sure was nerve-wracking though. I don’t like long bits or deep cuts. I reduced the feed rate to 40 IPM with a 6 mm pass depth, so it was fine. But still, had the heart rate elevated.
The machining fixture is ready and fits the side pieces perfectly. The pieces for the side are clean and cut to size, ready for machining.
After thinking about this for several days and partial nights, I realized that adding fancy joints to the perimeter wall would add a lot of interest. The problem is that the joints will have to be at an odd angle, that angle dependent on the number of sides. I decided not at all arbitrarily to make 11 sides. I’ll leave the reason “as an exercise for the student”. In any case, I laid out a design for a machining fixture in VCarve and made it out of 18mm Baltic Birch. Now I just need clamps to hold down the work piece. Oh, and to design the joint file. Unfortunately Tailmaker’s software will do 90 degree or flat joints, not odd angled ones. Hence the fixture and a custom design.
I started with a composite image courtesy of the NASA Lunar Reconnaissance Orbiter, used a Fusion 360 plug-in to turn it into an STL file, then imported the STL into Vectric VCarve Pro. From there I was able to generate the tool paths for the CNC. The test piece is made of MDF. The white cylinders are a place-holder for the 7 that will eventually form a fountain. With the recent confirmation of water on the Moon, I think this is a timely project. I’ve since found a better composite image from the NASA Deep Space Program Science Experiment (Clementine).
Recently I took delivery of $900 worth of Eastern White Cedar (stacked in the background) and 8/4 Hard Maple. The cedar will make 4 Kitchissippi chairs. I estimate I’ll need 3 of the Maple boards for the LSP. The remainder are on the floor in the left background. Some of them will make the base for the “Nahrung” sculpture. Now if I could figure out a way of incorporating any of Tailmaker’s software, the project would be complete. Maybe a jointed base?
This LSP Fountain is a project which I have been contemplating for a long time. It brings together my fascination with all things celestial, my interest in wood, life-long experimentation with lighting and electronics, and gradual improvements in my CNC skills.
2020-10-26: The “Nahrung” project is in the early design stage. In the interests of extending my custom woodworking skills, I’ve undertaken another project for now, a more complex one but where I have a clearer idea of the design. The working title is “LSP”.
This is my first fully 3D project. I started with a composite image courtesy of the NASA Lunar Reconnaissance Orbiter, used a Fusion 360 plug-in to turn it into an STL file, then imported the STL into Vectric VCarve Pro. From there I was able to generate the tool paths for the CNC. The images above are a composite of the machining process. The last image is after a bit of manual sanding. This test piece is made of MDF. The final piece will be end-grain Maple. The white cylinders are a place-holder for the 7 that will eventually form a fountain. With the recent confirmation of water on the Moon, I think this is a timely project. Update: I found a better composite image courtesy of the NASA Deep Space Program Science Experiment (Clementine).
2020-07-11: Getting away, to a different environment with no distractions, can lead to some new custom woodworking project ideas. This past week did that. Several days on what my friend Andris and I call “Leisure Island” on Lake Temagami always lets us relax and recharge. This time it gave me the time to come up with my next major workshop project. It will be my first sculpture. The provisional title is “Nahrung”. But first, I have a master bathroom to renovate.
What does one make with scraps left over from other projects? Serving trays, of course! The first set were made from thin strips and are standard-duty. These are made from pieces of the slabs left over from the two Raven desks. They are substantial!
The first one is a simple tray, massing only 2.4 kg. I accidentally made it in the style of Piet Mondrian, with black epoxy inlay separating the sections. The second one is a slab sitting on a carrier, and it masses 2.65 kg. The slab can be removed for cleaning or for use as a cutting board. Although, why would you want to damage this fine piece of wood with a sharp knife? Once it’s yours, use it any way you want.