Yesterday was a long, noisy, busy day. I had expected that the machining for the top would take 3 days. I started at 10 am, took a brief dinner break, and finished at about 10:30 pm. The time projections were based on 2D work, the 3D times turned out to be a bit less.
There were several areas that had not filled with the epoxy pours. I used epoxy putty to fill the worst ones, but some remained below cut level. I’ve ordered more from Lee Valley, and will manually fill and blend in the missing areas. Once the entire piece is painted in epoxy with selective colouring I doubt any of these areas will be obvious.
A person who liked some of my other work commissioned me to make two commemorative boxes. The are the same general pattern as some others I have made. Each is slightly different, not only in size. These two us the same approach of having two Walnut strips, whereas previous ones only had one. I also made the feet simpler by just using the half inch magnets without the wood dowel to hold them. It looks cleaner and avoids the potential problem of the release magnets being in the wrong direction. I also added two locator marks on the top and corresponding end, since the lids are sized to fit exactly, which makes them non-symmetrical.
I recently had a request form someone who had seen my work at the Valley Artisans Co-op. She wanted a book stand. By co-incidence, Jayne had expressed interest in one as well. The one on the right is Jayne’s, the other for the inquirer, if she likes it. This project took far longer than it should have, partly because I used wood from the leftovers bin. The verticals are inset in the cross-shelf by about 2 mm. I used epoxy because of the small bearing area. In the left one I also added reinforcement corners underneath. Both stands are more robust than they appear.
Whenever I’ve done a flattening run on anything, whether a spoilboard or work piece, there have been low ridges. I finally made a CBE tramming device out of dowel and length of stiff wire. It bounces, but is good enough for my purposes. I got the Y axis set very close, but the X axis isn’t really adjustable. Even so, today’s flattening passes on the fountain base have ridges that are barely noticeable to the finger. They show up visually, but that’s due to the wood fibres. Given that this is end grain, I’m satisfied. The base is now 105 mm thick with a ± variance of about ±0.05 mm in the Y axis and about ±0.2 mm in the X axis. That’s with the spoilboard as reference, which isn’t necessarily flat either.
That was certainly messy! I started with the Shop Vac attached to the dust boot. However, since I was using my longest straight bit, the boot was all but useless. Then I attached the dust system hose and used the Shop Vac to keep the work area from getting too filled with chips. The total cut time was over 3 hours. I had to stop the machine path for the copper pipes. For some reason I had specified them as 12.5 mm. After updating the tool path for 16.5 mm I re-ran it as the last tool path on the bottom.
The piece is now mounted top side up, aligned on 4 dowels. I’ll have to run a flattening tool path on the top. I thought that flattening the bottom would make the top parallel, but there is about a 5 mm difference from one side to the other. The top is also quite uneven, not that that would matter. All the irregularities will be cut in the various toolpaths anyway.
Mitch and Liana dropped off the potted base this morning. Now the long, detailed CNC work can begin. But first I sanded the perimeter clean and glued on sacrificial hold-down blocks. Once the glue is fully set I’ll drill hold-down holes. The bottom is fairly level but I will still run a flattening pass. The top is less flat, so I shimmed the gaps all around. The order of operations will be flatten and machine the bottom cavities first. This shouldn’t take more than a few hours of machine time and is not dimension sensitive for the most part.
Well that had its’ frustrating moments. Some of the wire contact pads tore out, so I had to solder in bypass wires. Then half way through I realized that I didn’t need a return line for power and ground from the tops, I could just home run all the power connections. So the wiring is a combination of daisy chain and home run. Only the data line is consistently daisy chained, as it must be to work, and to produce a fully sequential pattern.
Next I have to epoxy everything together and ensure that the top transition from copper to wood cap is watertight. Then these get put aside until the base is machined.
Soldering the wires onto the tiny contact patches on the ribbons turned out to be far less frustrating than other times I’ve done it. The key is to scrape all the silicone off the contact area with a machinist’s file until the copper is glossy, tin the pad, then apply the pre-tinned wire. It was trickier getting the shortest ribbon wrapped evenly around the shortest tube section. I also managed to reverse the ribbon sequence, from end to beginning, but as long as I’m consistent it’ll work.
There’s a blank area at the top of this one because of the pre-attached termination. Before I glue this piece together I’ll see about pushing the ribbon up a bit. I have a couple of days to think it through, since I’m otherwise busy Saturday.
I’ll also have to be very careful about colour coding of the wires. I used interconnect wires colours similar to the coding on the ribbon, which is White = Ground, Red/Yellow = Data, Black = VCC. That’s of course reverse of North American convention. The latter is used on the power supply. I just have to be careful and consistent.
I think I have the sequence of operations figured out. Today I epoxied the top caps in place and coated them with epoxy. For this I used System 5 epoxy, since a 5 minute setting time was fine. It just meant wasting quite a bit, with a separate batch for each cap. I didn’t have disposable brushes so I used the folded corner of a bit of paper towel. Half way though I though to heat the part after spreading the epoxy, thus lowering the viscosity and making for a smoother surface. You can see the epoxy coating on the caps by the gloss.
I also cut interconnect wires and removed the silicone coating from the ribbon section ends. Soldering wires onto the contact points is a finicky, frustrating operation which I will tackle tomorrow. If that goes well I will wrap the ribbons around the copper pipes. Then I’ll assemble the pipes into the tubes and epoxy the tops to make the copper/wood transition waterproof. I’ll tack the spiders in place but not glue them, so as to allow for thermal movement.
Using a crappy old pipe cutter is a good way of wasting expensive copper pipe. I found one in a box of plumbing supplies from my father. As long as I maintained significant sideways pressure during the first couple of rotations, it tracks true. Otherwise it travels a spiral. With only about 20cm of waste, I got the pipes I need. I’m guessing a bit on the exposed extension that will work, based on space available but with no idea about how I’ll run the pipes back to the manifold.
In any case, the pipes within pipes are ready for the LED ribbons, which I also cut to length. I purchased the waterproof ribbons this time, but they are stiffer due to the silicone coating and won’t conform to the copper pipes as well as the uncoated ones I’ve used in the past. I’ll think about it and have a go tomorrow.