LM Home Mini Temperature Gauge
This little project involved trying to read the temperature of the La Marzocco Home (Linea Mini). This machine actually has an accurate sensor installed, just no temperature display. LM have used a thermistor so it’s not too hard to jack in an read the temperature directly off the sensor.
If you’d like to have a go at this modification yourself, check out all the code on our github.
To read out the temperature I uploaded the code to Arduino Nano. Then it was a simple matter to send the reading to a 4 digit display.
The top left corner is where the board’s thermistor plugs in (I think).
It’s a really clever design that seems to be most accurate when the brew boiler is between 90°C and 100°C.
Simply reading this voltage and converting the number using steinhart equations should give an accurate temperature reading of the brew boiler.
There’s not much to see here. The roaster panel is how the factory made it on the surface. But you might notice the missile switch up the top. I was at Jaycar and I thought it looked pretty neat. It allows switching between automatic and manual modes. I didn’t want to have a situation where I was roasting, and the computer locked up and I would lose a batch. So, for redundancy, I put a switch here in case I need to revert back to the default mode
This is the front panel of the roaster. I placed three K type thermocouples on the front. One in the bean mass (you can see it through the glass on the front), one in the middle of the roaster (for environmental readings) and one next to the old analogue gauge. The roaster is very noisy electrically. I had these thermocouples made to specification by an engineering supplier and they work fantastically.
This is the newest control board that I've made. It uses an Arduino Nano to send information over Bluetooth to the computer. It uses some MAX31855 thermocouple amplifiers to read the temperature. It also allows electrical control of the heating element and fan speed. This allows me to turn the whole roaster over to computer control wirelessly.
I also changed out the insulation. I found I was wasting too much energy by not properly insulating the drum, I used a special grade of industrial insulation, which greatly increased the performance and energy savings of the little unit. The more head I can hold in, means the more heat that goes into the beans and the less I waste heating metal. Once this roaster gets hot, it stays that way until the days roasting is done.
I develop for Excel professionally and I wanted it use it as the basis for the computer program because I could get something together that worked relatively quickly. The program logs data, plans roasts and controls the roaster automatically. I use an algorithm I wrote to draw an ideal curve (red). The roaster uses the control software I wrote to change the element heat and fan speed to best approximate the curve. This means I can get near perfect RoRs, and really good coffee. When the batch is done, the computer saves the curve to PDF and I can start again. The spreadsheet also allows me to plan the batches ahead of time, and estimate how long it should take to complete the roasting program.
Custom Steam Tips
This is a project I've been working on recently. A customer came to me and was having trouble with their espresso machine. It was putting out a lot of steam, which is great if you want to froth up a few liters at a time but not so great if the cafe is doing a small run. Steam tips are something that can overlooked as cafe's transition their equipment from the mass produced lattes of the 90's, to the modern specialty coffee drinks popular now. Properly texturing milk requires a lot of control and skill from the barista and the existing technology was not suited to this. After searching for a good solution I ended up just spending and afternoon building some tips and I thought I'd share the results here. Hope you enjoy!
So this is the tool that's used to make the steam tips. For those who are unfamiliar the brass is mounted in the chuck on the left. It's then spun at high speeds and metal tools are used to cut it.
A steam tip is a small socket with a hole in the end. The size of the hole dictates how much steam will come out. A big hole means a lot of steam can come out, but this can be bad. If you're planning to steam a small amount of a milk a large hole will heat the milk up too fast. This hole is for a small amount of milk and is 2.5mm in diameter
First the part is faced and cut down to a 12mm diameter
A 45 degree cut is made in the tip to add a chamfer to the part.
A small hole is made so the tip can be hollowed out.
An 8.5mm Dia hole is drilled into the part at slowish speed
The depth of cut needs to be right up until the point where there's a chamfer.
The steam hole is slowly drilled through the part
The tip is then tapped in the lathe. I use a hand tap and just rotate the lathe by hand. Different machines will need different threads. The Wega commerical machine I did needed a M10x1.25 thread, whereas the Rancilio Silvia needs a M10x1.0 thread
I added a knurl so the part can be taken off easily. Brass will change size as it heats and cools. This can make it tricky to unscrew if it's hot, so a knurl helps here.
The part is then parted off from the tail stock
The surface is very rough at first so the part is turn around and finished with a facing cut
The original steam tip was flat on the end but I added a counter sink so the steam has some space to expand when hitting the milk. I find this allows for finer control for the barista.
So there's a slight difference between these two tips in the length of the chamfer, all things considered though it came out okay.
This tip is installed on the machine and the Royal Yacht Club of Victoria. It allows a barista much finer control over steaming milk. A set can be made so different sizes can be trialed at will.
Course this is the one installed at home.
The Rancilio Silvia is an excellent domestic coffee machine and is highly recommended for the home user. Several small modifications have been made to the machine to increase its functionality.
James' personally designed bench-top roaster is a heavily modified convection oven. The roaster is designed to roast to a curve paying special attention the rate of roast using process control software. Data is fed back to a laptop for analysis of the roast.
Slayer Solenoid Lock Washer
A friend of mine was chasing this spare part. It's a lock washer that is used on a Slayer Espresso Machines. Unfortunately this small piece of ABS broke off his machine and he was unable to order a replacement without purchasing the whole assembly. So I drew up a quick file ready to be 3D printed. Feel free to download and print one yourself! If you don't have a printer they are available at some officeworks stores, some local libraries and available for purchase at stores like Jaycar.
This is a small stand I made up after trying to balance my portafilter for too long and getting inconsistent results. This stand allows the portafilter to balance on the scale more easily so weight readings are easier to obtain. I find this useful, particularly for smaller scales. Please see the link below to the thingiverse file where you can print one off for yourself.