Introduction: Off the Grid Pour Over Coffee Maker
There are endless ways to make your perfect coffee without electricity. Brew over, French press, cold brew, whatever. You can spend days or months trying to figure out how to make your perfect coffee.
For an off the grid coffee maker, simply taking a gas stove and a pot for your brew over coffee is too easy. The real craftsman designs and builds his own stylisch version of a coffee maker. Of course :-)
The project lasted for 8 months. This is due to the fact that I changed the design a lot with Fusion 360, I used cheap silicone for the moulds which cracked afterwards or I just had a lot of setbacks with the heat exchanger.
Usually you see such projects in a youtube video within 20 minutes in fast motion. Which sometimes frustrates me a bit, because I definitely take longer and longer and I seem to make more mistakes than the typical DIY YouTuber. See this as an encouragement not to give up and maybe lose the fun if it looks too easy in some DIY videos :-)
Step 1: The Prototype
This is by far the most important step. Here I have tried out several designs of the heat exchanger. This is the part that is directly above the burner. Small changes have had a significant impact on the flow and temperature of the water.
You must find a good balance between the amount of copper of the heat exchange, diameter of the silicone tube and the strength of the gas burner.
As a rule of thumb, I found that you should have as little material as possible on the heat exchanger.The diameter of the internal coil (a copper pipe is wound inside the cap like a snail) is 8mm and made of a very thin-walled copper (0.8mm).
For the prototype I put a copper disc on top of the heat exchanger so that the heat accumulates underneath it and does not simply escape upwards.
In the final version I took a copper cap from a fence pole. This closes also very nice on the outside. (see attached image)
Unfortunately all the changes were not enough to bring enough heat into the copper spiral without using a very large burner. One goal of the project was to use fuel paste. This is safer than gas and cheap to get.
The solution was to paint the heat exchanger black with exhaust paint. This boost the complete process of water heating and reduce the time by 1/3.
Step 2: The Fusion 360 Design
After the technology was validated in a prototype, I set about drawing the design in Fusion 360. I have to say that I started without a concrete idea of what the final coffee machine would look like. I simply drew the tank, check valve and heat exchanger with the dimensions I had determined for my prototype. Then I modeled the rest around these components. I am pretty sure that this is not the fastest way. But Fusion supports you here very well with versioning, timeline, components, variables...and I didn't really feel like I had to make a first draft on paper.
Now it is time to think about dimensions of the required components and where to get them.
Comes from a candle wind light. You get this already very cheap for under 10 Euro in any dimension.
Replacement part of a normal brew over coffee machine.
Brew Over Coffee pot:
You get them in glass of like the used version "Theo" in ceramic from any internet store.
Brass connection piece
Boat water tank connection nozzle or water valve connection part.
During the design phase of the coffee maker I respect the dimension "a little bit" and used for all dimension variables. Every dimension in the design is calculated by this variables. If something changes or the part is not available in the required dimension - no problem. Just change the variable in fusion and the job is mostly done.
This happens several times and I'm happy that I made the decision to use variables.
The Design is available at: https://a360.co/2FlZTNH
Step 3: CNC Milling
The project is a mix of many manufacturing processes. 3D printing, CNC milling, CNC turning, making moulds for epoxy resin.
If only one parameter changes, e.g. the diameter of the check valve, then all CNC jobs are recalculated without exporting, importing or manually reworking the project. I know this sounds like a promotion for Fusion 360...which it indirectly is. But I assure you that I am not paid or favored in any way. I'm just thrilled and grateful that I can use the software. Quite simply.
All the brass parts milled with my DIY CNC Router from a 2mm brass sheet. brass is a little beast for me for milling. get hot and needs a lot of drilling oil.
The Oak is carved in two steps from top and bottom. Setting up the milling jobs for the pockets and handle are dead simple.
Step 4: Mold Making
The water Tank is the most complicated part. First of a I split them in two parts. The top with the brass water outlet and the base. All of the them are 3D printed, painted with car underbody protection to get a nice surface (like leather). After the sanding and painting I create a silicone mold of the parts (the green silicon in the images). At this point here a good advice: Never use cheap silicone (the gray one in my images) for moulds which cannot be easily unmolded. Cheap silicone will crack very quickly and the mould will be lost.
for the base I split the mold into three parts and add 3D Printed support them keep them together. The reason for this is to avoid that my mold breaks during the unmolding process.
Please forgive me for not showing how I made the forms. There are really very good tutorials on this portal how to make shapes. I have also looked at these and simply followed the advice in them. I can highly recommend it. These are well done and can not be surpassed by me at this point.
Step 5: Making Coffee
Finally I'm able to make coffee :-)
Participated in the
CNC Contest 2020