My office is a little small and barely able to contain all the machines I’ve accumulated. The 3D printer I turned into an etcher for specular holograms was obnoxiously tall, and really doesn’t need much vertical range. I chopped the aluminum extrusions so it would fit in an unused corner of the room. I’ve been doing occasional tests here and there, nothing worth showing yet. Results are very hit and miss, and finding good subjects is hard too.
I started going through the massive amount of oak that was dropped in my driveway last Winter. It’s fun and fast.
Everything is massive with this oak. I excised some of the cool knots, not sure if I’ll ever do something with them but I figure they might be cool in some project. They need to dry a few years first so now’s not the time to think of what that could be.
Beyond the knots, we thought it’d be kind of a shame not to get a few boards out of such a special tree. It’s oak, it really stood out as a tree, it’s close to 200 years old, and we walked past it for 10 of them. So after researching possibilities, I bought a chainsaw mill with a 24″ bar and a ripping chain. The saw is a monster when fully equipped.
I haven’t taken it on its maiden ripping yet, all in due time. And now I’m dreaming of going deeper in the woods and building a cabin with lumber milled on the spot.
7 days, 47438 pen strokes :\. Lara’s work and a recurring dragon on this blog :). I sped up the machine to make it 7 days instead of 10, so it’s slightly more inaccurate, but more importantly I failed to anticipate that ink would run out faster. I used to have about 1.5 days between pen swaps, here it’s barely above 1 day. No harm done I got there in time, but I should have thought about it when I adjusted speed.
I lined it up with a big public event and tons of people got to see it.
No sure if there’s anything more to say about lasers & post-it portraits, it was the now usual formula. I’ve enhanced the pipeline some to do auto-face-cropping as it is a step we usually waste lots of time on. Esther & I rehearsed over the week end. She runs the operation during the event.
Some recurring questions I get asked at these events:
“What are the machines for normally?” Nothing, their sole purpose is to drag pens and shine cat lasers.
“Is this your job?” Nope, just a side quest.
“So how does this work?” I try to see what part they’re interested in before I launch into a 3 hour tirade :).
“Did you build this?” yes.
It’s very gratifying to see people stare at your work for a while. You can see the gears turning in their heads. I’ll sit by the big machine sometimes to watch people’s reaction to it. When I swap its pen people will come up and tell me how much they like it. I’m just glad for having the opportunity to do something cool in the world.
I spent the whole week end in the sugar house, maple trees have been relentless this past week. We have ~5 gallons of syrup canned so far with at least 3 more coming. The smells are incredible in the Spring, Winter makes you forget that the world has any smell at all. Wet soil hits the hardest after a long Winter, and it’s quickly followed by pine smoke and sweet sap.
I was invited back to the science museum to do something cool with my machines. Any time I do a public event it’s an opportunity to figure out what’s engaging and do better the next time around.
I was maybe a little too motivated and brought several machines, almost my whole apparatus, and deployed them in various modes. 1 PewtyBot, 1 Mirror PewtyBot, 1 PlottyBot & 1 SkecthyBot doing portraits, and 1 PewtyBot people could control with their phones. The laser portraits worked wonders again, but the original PlottyBot drawing post-it portraits worked even better.
People were clearly keen on getting a tangible souvenir from the evening. Having a robot draw their portraits on a Post-it note struck a chord hard. I think what I’ve learned from this event is that while the lasers throw a lot of pazzazz at you, they are more complex machines that most people don’t try to engage with beyond taking in the light show. While a pen based machine is doing the same thing you’d do with your hand so it’s more approachable to be curious about. As usual a small fraction of them were fixated beyond reason on watching the machine at work. There has to be a “drawing automaton obsession” gene present in ~10% of the population.
Unfortunately, I only had one PlottyBot doing the Post-it portraits, and they take much longer than the lasers so I spent much of the evening trying to keep track of a queue of people who wanted one.
I built 2 4’x4′ photoluminescent paper holders so I could deploy this easier. In the past, finding a decent spot on a wall for the rolls and unrolling them was difficult and time consuming. I also have plans for doing random outside events at dusk in random places this Summer, which is why having something deployable was worth the construction effort. I tried it some already at home last Summer and it’s kind of cool to have the lasers go on a warm Summer night.
I had several people ask me if this was AI :), this seems to have become the go-to explanation for anything tech based that can’t be explained easily. Much like Clarke’s law that “Any sufficiently advanced technology is indistinguishable from magic”, only now it’s AI instead of magic. I’d respond that it was just good old organic grain-raised free-range “I”.
As usual, it was very hard to capture the coolness while manning it so I don’t have much visuals to represent what went on. Ultimately it’s just me running 5 machines, a software stack and talking a lot. Suffice it to say people were into it and I’m emboldened to keep trying public events. Fun times!
Pretty simple yet cool stuff, I’ve tried both transparent & white filament. And a very well done website helps make the STLs.
The mirror based PewtyBot proved conclusive enough but since the laser is reflected twice, a degradation is clear on the medium if the mirrors aren’t high quality. Clearly the cheap plastic ones I got to test with aren’t, but they served their purpose. With much research on mirror specs & bounding agents, I went ahead and spent $70 on two tiny “surface first enhanced aluminum” mirrors. Once again, I forgot everything about my high school physics lessons, but some vague notions are left to help me navigate through specs. And this being 2026, of course there’s a website dedicated to optics of all sorts I can buy any sort of mirror from. The modern world has its flaws, but access to information and stuff is definitely covered.
These new fancy mirrors are extremely crisp. Unfortunately, one of them slid on the epoxy as it cured, this won’t impact use but I’m bummed for I really did all I could to get everything perfect.
I tested the upgraded machine and it performed just as well as before, but the laser pointer was pristine as it hit the medium. This might not be a $70 improvement, but if I’m going to build a machine it’s hard to leave it lacking. The kids have been curious about this new development, it’s always fun to see the gears turn when they engage.
He watched the Olympics and created all sorts of jumps and grinds.
The wood piles are reaching their ends so it’s time to supplement them with dead (dry) stuff from the forest. We’ve gone through a lot of wood this Winter.
We don’t need another stove but we also couldn’t let this one pass. It’s our same Heartland SweetHeart we know really well from a decade of intense use, with a water tank, extra bells and whistles, a few decades newer, and for a good price. Since this is very much a key piece of our household, an upgrade even small goes a long way.
These things are heavy.
The design of PewtyBot 1.0 left something to be desired: the whole top section (stepper motor, assembly & laser) is moving, and that is a decent amount of mass that needs to be accelerated rapidly many times over.
As I was tuning parameters, it became obvious that I needed to slow things down to avoid inaccuracies from the vibrations of a fast accelerating mass. I found happy parameters which led to several public deployments, but deep inside I knew I wanted to try the mirror approach. Instead of moving the laser, it remains static and only a couple of light mirrors are doing all the moving.
Introducing PewtyBot 1.1!
There’s a funny story in there about losing code, reimplementing, and a core issue I was struggling with being solved without knowing why. As always, a few unforeseen challenges got in the way, but ultimately the math is exactly the same as PewtyBot 1.0 so that was a relief. It’s just the motion code that needs to be adjusted some to deal with mirrors.
And well the results are cool, but somewhat mitigated. Definitely not “rocks your socks off” levels of cool. I can definitely move the laser a lot faster. Although through the exercise, I’ve realized that the “slow” speed of PewtyBot 1.0 may have been in the perfect sweet spot for laser light retention on a photoluminescent medium. And so maybe I got lucky there. Of course I could get a beefier laser that emits more light to compensate for the reduced time it spends on any particular area. I’m pretty convinced though that I want to remain in the “cat laser” realm for risk & safety. And so the other variable I get to play with is mirror quality, and I shouldn’t be surprised that there exist a whole world of mirrors of various specs. I got some very cheap craft type acrylic mirrors at first to test concepts. But you can tell the pointer hits the medium diffused and discolored. And so ultimately I’ll want to spend the money on a few square centimeters of first surface mirrors rated for blue light wavelengths. But first I’d like to convince myself that the mirror approach actually brings something extra to the table.
lots of trials, lots of refinements, 4 days on the etcher bed. The load cell addition makes for the most precise etching.
Without light
with light
It feels different in person. What’s funny with this specular stuff, is how enthralled I was with it when I didn’t understand how it works. But now I kind of don’t see what the big deal is. I have to remind myself it’s really cool to keep forging ahead.
Since I can control pressure, I’m trying all sort of materials and pressures. I’m literally throwing under the tip any garbage that looks like it could yield a glint, and getting good surprises. I’m of course trying the classics like acrylic and aluminum with various pressures, again to find the best parameters.
I’ve had mitigated results with my specular holographs, I ran several trials, and only one was really worthy so far. I’ve learned a few lessons, but I’ve had enough success that I want to spend time and resources refining. The way the tip action worked so far was very blunt, I rigged a servo on a 3D printer which could instead have 2 steppers driving the pen up & down action. But that was an easier first step for my plotter stack. So the obvious thing to refine first is to replace the servo with the existing steppers, which is more of a programming challenge. And that part wasn’t too bad. What was much harder though, is how to move the tip so that it presses against the medium with defined and reproducible pressure. With the variations I can’t just “count steps”, and some media (acrylic) require very little pressure, unlike aluminum which was more forgiving. So I know I want to experiment with tip pressure, which means getting a load cell. And that on the other hand was a whole can of coding worms. I won’t go into the boring details, what matters is that it’s etching!
I have the tip go very carefully down until it reaches a pressure of 20g, and then it tries to maintain it while moving. Between the incessant taring, and the slow motions, it’s made everything a thousand times slower. I don’t care though, I can do other things while it works.
The machine makes really cool noises with all the extra stuff to find the right pressure. Simply keeping an ear out while doing other things has been a great tool to debug and improve algorithms.
The town’s been wanting to remove an oak that is rotting and is just enough on the road that they hit it with the plow sometimes. It’s a family favorite as it’s on a dirt road we often walk on, and it’s absolutely massive. It has 3 enormous trunks, and each trunk has several branches the size of the trees I usually take. It’s next to a power line, rotted and far bigger than anything I can reasonably tackle. Let’s just say I’ve been excited when I heard about their plan to drop it. In Vermont when a town or utility needs to clear trees, the landowners get to call dibs. That was a year ago and I thought maybe they had forgotten about it. And so one day, I hear some chainsawing in the distance, and when this happens, I usually follow the noise to make sure no one is poaching my trees, and because I like to chat with neighbors. To my surprise a whole crew is there, 7 guys with heavy equipment going at the big oak. In a very typical Vermont interaction I get to meet the road foreman, and I tell him I’m definitely keeping the tree. He was aware, the information wasn’t lost in the year it took for the gears to get in motion.
I tell him he’s welcome to leave it over the bank for me to come grab, to which he responds he’ll drop it in my driveway if I prefer… Yes sir, I very much prefer not moving several tons of tree by myself :). And that’s how 31 nice big chunks of oak showed up in my driveway. I didn’t have to lift a finger, and I got to enjoy a good show (watching pros and heavy machinery at work). It’s Christmas all over again.
Some chunks are massive, and there is still a very full day’s worth of work left behind in the woods. All in all there’s probably 2 years worth of firewood. But maybe some of it is worth milling, we’ll see.
