• This guy made his entire lens with housing from scratch
• This guy makes lenses from sand and rocks
• Making telescope lenses at home by hand
• Optical lens making in 1600s for microscope lenses by Corning Museum of Glass
• Making lenses on the CNC router
• Camera lens making in Japan, beautiful overview documentary over the entire process
• Doing it from acrylic
• Zeiss grinding machine
• Interesting monolithic mini telescope lens, just to show a more advanced version of what you can make out of glass
• Making eye glasses in rural India - yes, simple physics allows for the making of extremely high-precision optics. Similar to Dobson
• Classic John Dobson video on telescope making

Prior Art

I am building this project on the basis of a few fully-integrated systems that come pre-built to allow for easier modification of the system and a way to test different valves and sensors. The control firmware will be based on CTRL+P by Clark Teeple.

The CTRL+P pressure manifold developed by Clark Teeple that allows for up to 8 channels, using some continuous-modulation valves for low-pressure pneumatic applications

The FlowIO platform by Ali Shtarbanov, Hyejun Youn, Ozgun Afsar, Joseph Paradiso of Media Lab. Again, a great general purpose, fully-integrated system. However, I want to open this system up for more modular expansion and modification

Hacky Prototype

In order to figure out what functionality I need to make my shield both as flexible as possible and still provide common functionality for pneumatic control, I just took a box full of old weird undocumented pressure-application equipment from our lab (pumps, valves, tanks, pressure sensors, flow rate sensors, and anything in between and beyond) and tried to interface it with an Arduino Uno.

Granted, a lot of the components' documentation is hard for me to understand and the existing platforms might not be ideal for interfacing them - but this is exactly the challenge I am trying to solve. So I went ahead and just built the pressure and electronics circuit around it. While the result looks absolutely hacky, it helped me isolate what elements I need to integrate on my board to provide the basic framework for building something like this in an integrated way.

Once I got everything to work, I used PlatformIO in Visual Studio to run some basic operation of actuating a single valve and plotting the measured pressure in the pressure chamber attached to the valve. In the following pictures, I am sending different input values over PWM to the valves.

WTF is going on?

As I tried modulating the valve along a linear pressure trajecory using PWM, you know, easy peasy stuff, I noticed that I couldn't get it to follow the trajecory consistently. The valve seemed to either stick open or closed, and if I sent a voltage in between, it erratically opened and closed. Notice the comforting sound in the video that definitely does not sound like a happy valve.

Now this is how I found out how these valves actually work. If you know anything about pressure applications and specifically how valves work, you probably already know this, but for a simple valve, there is usually a simple solenoid inside that either lets pressurized air pass in or out of the system.

So did I just try actuating a solenoid using PWM, hoping that it would be able to maintain an intermediary stage? But wait! The specific valve I was playing with was actually rated for continuous modulation! Which means that they are built with two solenoids! So why am I not able to continously modulate the pressure?

At this point, I have a few theories. Theory 1 is that I actually may need a real analog-to-digital converter, because the PWM signal might not work with these valves opposed to a true analog signal. Theory 2 is that maybe my pressure chamber is so small (just a hose) that it can't work. I'm still working on finding out

Modular Pneumatic Manifold

This week, I workers on the electronics for the pneumatic manifold. As the goal of the project is to have a modular and versatile controller that works with a variety of valves, pumps, and sensors, I wanted to build it on top of a widely available board. Luckily, I came across an open-source firmware for a multi-channel pressure controller in C that someone had built in the past. Going from the specifications, the firmware is optimized for the Teensy 3.5 and the Arduino Mega 2560 R3. As I happened to have a Mega lying around, and as it’s pretty widely spread amongst beginners, I am assuming this as the basis for my build. I started by importing the part into my design and then drew out the schematics of all the components. Basically, my shield will have space to mount one valve with up to two channels (enabling continuous-control valves with a pressure and a vent channel) and one sensor, enabling full continuous pressure control in one output. The valve can be modulated over PWM, the sensor value can be read as an analog signal. After finishing the design of my PCB, I started milling the board on the Roland SRM-20, traces on the 1/64 mill and outlines on the 1/32 carbide mill. Unfortunately, our lab lost the sacrificial plate somehow and I had trouble machining the traces accurately. I will stuff the board by next week and run it with the firmware I found online.

NC Shop Vac

This is part of the coolant and abrasive slurry system. The idea here is to use a shop vac, which may just be the most widely accessible „compressor“ / „air pump“ to deliver coolant to the optics CNC I am building. My plan right now is to use the underpressure the stream of air exiting the shop vac generates to pull in a bit of coolant and cool the cutting process, without needing a separate water pump (in essence, the shop vac would act as the pump). Think of something similar to how a carburetor injects fuel into the fuel air mixture.

I started by pulling apart one of our shop vacs at night to see if I can find a way to manipulate the motor speed. A variable resistor might be the best way to control the motor speed. I have only rudimentarily tested its effectiveness in pulling distilled water from a channel in the side, but it seems like it could work. The only bigger challenge I came across is the fact that the water pulled in gets rather mistigfied into small droplets instead of forming a spreads stream. Next, I will make a board that can easily be interfaced via I2C to interact with the shop vac and change the coolant flow and extraction

Kofferdamm Coolant Bell

This is again part of the coolant flooding and extraction system for the optics mill. I thought through different options of managing coolant, but ultimately, most options seem like they would be spraying coolant all over the machine, which is exactly the problem I want to avoid for a small machine like this. The current solution I am thinking about is a somewhat dentist-inspired approach. I am assuming it is not possible for me to locally extract all the coolant that will spray all over the part. Under that assumption, I want to contain the coolant as much as possible to one local area, have it spray all over the place in there but not leave that area in an uncontrolled manner. The best I could think of so far is a combination of a bell-housing that retains any spray water and contains it to a local area as best as possible. In addition, the top inside of the housing is designed to minimize water contact to the spindle. For the inside of the collet holder (?) and the spindle itself, I designed a sacrificial filter inspired by the ones serological pipettes use, that may have to be changed from time to time if it gets wet. I started making a mold for a silicone cast of this bell, in a screw-on fashion.

System: Optics CNC Mill

Most things happened here this week. I got components and parts from Jake and designed the mill as a 3 axis mill system, mostly going off of the design of the Open Builds Mini Mill and the Milo 1.5, but only using components CBA has readily stocked. Work in progress

TODO: Insert Fusion screenshots here...