Recently I have seen several projects around the interweb featuring LEDs shining through very thin timber.
I found this intriguing enough to invent a way to make my life difficult in a pointless and unprofitable manner.
I wanted to use my new Adafruit Neopixel Ring to build an ornamental clock, using this interesting woodworking technique. Plus I figured that my milling machine might make this a feasible prospect.
Milling, in my very limited self-taught experience, is best done using a material that is of a consistent density. Wood, (again in my very limited self-taught experience) isn't consistent in it's density. Softwood especially. So I turned to the densest wood I could get my hands on and assumed that it would simply behave like a very soft version of aluminium. Here's the aggravatingly cursory build log...
Take one lump of Brazilian Purpleheart, and attack it for several hours with a selection of saws. This stuff is seriously dense. Cutting it to approximate size was a major ordeal, I had to use a long standard wood saw with regular applications of machine oil (worked very well) on the blade to stop it jamming in the wood. Took ages to get a roughly cubic chunk 2" on a side out of the heavy disc of timber.
Then it was a matter of using the milling machine to square off the rough lump of wood to make all the sides parallel and square to each-other. This was surprisingly easy, as the wood does allow milling, and yields a shiny and smooth finish when facing off a large area. A roughing cut followed by a higher RPM run with a slower feed rate does give a great finish. It will still need hand-sanding and making good to achieve a final sheen though.
Now for the hard bit. The plan was to mill out a deep pocket in the rear face of the clock into which would be placed the LED ring so that it shines through the front of the clockface. A daunting prospect because the block of wood I was using was an inch thick and the pocket had to be roughly 15/16" deep.
Long story short, it worked...
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It took ages to mill out this pocket. Partly because I have no woodworking experience and partly because I haven't had my milling machine long. Actually it was a lot of fun to do and was great practice for using the X, Y and Z axis motions on the milling machine. The added danger that calamity would befall me at the first careless turn of a handle simply added to the fun.
The final depth finishing cut on the interior of the block took the front face thickness down to 2.2mm. I didn't dare cut any thinner than that lest the hardwood fractured and split. At this thickness, it is more like a veneer!
At time of writing, the front wall thickness is still way too thick to allow the LEDs to be seen clearly in anything above total darkness. If they are to be effective, I need to carefully sand down the exterior surface to reduce the thickness and allow more light from the LEDs to shine through.At the same time this will hopefully give a smooth and attractive surface finish to the exterior.
That is a task for another day, however. For now I'm happy that I didn't completely destroy this rather nice piece of one of the world's most super-dense hardwoods. The milling machine did me proud, a 10mm end mill did the entire job with ease and showed no signs of wear after what must have been several hundred metres of cutting.
PS. for those interested, this type of timber really does turn purple after it's cut (as promised in the wiki page). I assume it's an oxidation reaction with the freshly exposed surface. I reckon it takes about 4-5 days to go noticably purple, so don't expect results immediately. In all other respects it looks like a striated mahogany texture, but I'm certainly no expert.
Watch this space for further updates on this project. The next thing to do is the firmware for the ATTiny85 microcontroller I plan to use to drive the colour patterns on the LEDs.
I found this intriguing enough to invent a way to make my life difficult in a pointless and unprofitable manner.
I wanted to use my new Adafruit Neopixel Ring to build an ornamental clock, using this interesting woodworking technique. Plus I figured that my milling machine might make this a feasible prospect.
Milling, in my very limited self-taught experience, is best done using a material that is of a consistent density. Wood, (again in my very limited self-taught experience) isn't consistent in it's density. Softwood especially. So I turned to the densest wood I could get my hands on and assumed that it would simply behave like a very soft version of aluminium. Here's the aggravatingly cursory build log...
Take one lump of Brazilian Purpleheart, and attack it for several hours with a selection of saws. This stuff is seriously dense. Cutting it to approximate size was a major ordeal, I had to use a long standard wood saw with regular applications of machine oil (worked very well) on the blade to stop it jamming in the wood. Took ages to get a roughly cubic chunk 2" on a side out of the heavy disc of timber.
Then it was a matter of using the milling machine to square off the rough lump of wood to make all the sides parallel and square to each-other. This was surprisingly easy, as the wood does allow milling, and yields a shiny and smooth finish when facing off a large area. A roughing cut followed by a higher RPM run with a slower feed rate does give a great finish. It will still need hand-sanding and making good to achieve a final sheen though.
Now for the hard bit. The plan was to mill out a deep pocket in the rear face of the clock into which would be placed the LED ring so that it shines through the front of the clockface. A daunting prospect because the block of wood I was using was an inch thick and the pocket had to be roughly 15/16" deep.
Long story short, it worked...
Below: Preliminary test of the Neopixels shining through the dense wood grain! It works.
Below: Purpleheart block with milled-out pocket for electronics. Shown here with a dead Arduino (the best kind) for scale...
The final depth finishing cut on the interior of the block took the front face thickness down to 2.2mm. I didn't dare cut any thinner than that lest the hardwood fractured and split. At this thickness, it is more like a veneer!
At time of writing, the front wall thickness is still way too thick to allow the LEDs to be seen clearly in anything above total darkness. If they are to be effective, I need to carefully sand down the exterior surface to reduce the thickness and allow more light from the LEDs to shine through.At the same time this will hopefully give a smooth and attractive surface finish to the exterior.
That is a task for another day, however. For now I'm happy that I didn't completely destroy this rather nice piece of one of the world's most super-dense hardwoods. The milling machine did me proud, a 10mm end mill did the entire job with ease and showed no signs of wear after what must have been several hundred metres of cutting.
PS. for those interested, this type of timber really does turn purple after it's cut (as promised in the wiki page). I assume it's an oxidation reaction with the freshly exposed surface. I reckon it takes about 4-5 days to go noticably purple, so don't expect results immediately. In all other respects it looks like a striated mahogany texture, but I'm certainly no expert.
Watch this space for further updates on this project. The next thing to do is the firmware for the ATTiny85 microcontroller I plan to use to drive the colour patterns on the LEDs.