Instructables

Pocket size Espresso Machine with integrated alcohol stove.

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Introduction

I’ve always been fascinated by small things. I remember going to the mall as a kid and seeing all the Hello Kitty mini stuff at Spencers, and being really disappointed that they only made girl stuff (it was years later before they came out with boy stuff)
So, when the Pocket Size contest was announced, it really inspired me to design and build something new.

“Mmmmm Ok, now what?” I said to myself.

So I started browsing Instructables, trying to find some inspiration when I remembered that the year before, my Espresso machine had died, and I had played around with the idea of building one.

I looked at all the Instructables relating to coffee at the time, but no one had built a machine. The quest ended that Christmas with the gift from my wife – a new espresso machine (I know, she’s really great :D ).

This year, a quick search showed that there were still no Instructables on how to build an Espresso machine….and inspiration came: I would build a pocket sized Espresso Machine.

Now, I’m going to stray a bit from the normal Instructable format and include two sections: Design and Build.

One reason to do this is because I’ve noticed a number of kids on the site, and maybe, just maybe, reading about the design process might inspire them to build great stuff.

Another is that, because it had to be pocket size, I took some decisions that may seem odd, and telling you how I got there will help you modify this project more easily to better meet your coffee needs (like making it bigger).

Also, as it turned out, the alcohol stove that came out of this is a rather novel design, easily modified, that might breed a whole new class of alcohol stoves. :D
Three cheers to giving back to the community!!
 
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Step 1: Step 1: Design Constraints.

Design constraints are some of the most important points of any product design; they tell us what the limits are. The tighter the constraints, the more limited the design, and we have to be more creative to be able to meet them.

On this project, I set the following ones.
1- The product had to fit in the pocket of my jeans.
2- The product had to be made out with common, cheap and easily obtainable materials from any home improvement store or corner hardware store.
3- The product had to be made using simple tools that most makers would probably already have, or could easily borrow or buy cheaply.
4- The product had to be self-contained.
5- The budget was maximum 30 dollars.

These five simple constraints really guided the design and build of the espresso maker, sometimes in unexpected ways.

Step 2: Step 2: Research or “Don’t reinvent the wheel”.

First of, what is Espresso?
Wikipedia defines it as:
Espresso is a concentrated beverage brewed by forcing a small amount of nearly boiling water under pressure through finely ground coffee.

So, lets start writing some more constraints: 

How much water and coffee?
Again, Wikipedia tells us that:
The size can be a single, double, or triple, which corresponds roughly to a 1, 2, and 3 US fluid ounce (approximately 30, 60 or 90ml) standard (normale) shot, and use a proportional amount of ground coffee, roughly 7–8, 14–16, and 21–24 grams; correspondingly sized filter baskets are used.

How much pressure?
Wikipedia says,
There is no universal standard defining the process of extracting espresso, but there are several published definitions which attempt to place constraints on the amount and type of ground coffee used, the temperature and pressure of the water, and the rate of extraction

A quick web search tells us that the maximum pressure is nine bars, but if we have less, we could still call our coffee “an espresso”.

I took a measuring cup and a scale and measured out water and coffee for 1, 2 and 3 shots, and due to design constraint number 1, this will have to be a single shot machine, since there was no way I could fit a larger machine in my pocket.

Now that I knew the dimensions that my machine was going to have, I went looking for “the competition”.

I googled “pocket sized espresso maker”, and found only two: The Handpresso and the Mypressi Twist.
The Handpresso uses a nicer relative of a bike pump to achieve the required pressure, while the Twist uses a gas cartridge to deliver the 9 bars of pressure. But both have one thing in common: they both require you to “add hot water”. This meant that there was an external heat source that got the water up to the “near boil”, as Wikipedia told us.
But, constraint number 4 tells us that it had to be self contained, so this puts my little machine in a different category.

This led to a problem…how to get the water to the correct temperature in a self-contained machine?

The only viable option was some kind of stove. A lot of online research further narrowed it down to an alcohol stove.

Now, a little bit about myself: I’m more than a bit clumsy, so the thought of alcohol burning close to me kind of freaked me out.

So I came out with design constraint number 6: It must be safe.
This constraint turned out to be the toughest one of them all.

The Espresso Machine is divided into 3 parts: The brew head, the boiler and the stove.

So, on to the build and more design choices!

Step 3: The Boiler.

Design:
Since constraint number 2 said that the parts had to come from a local home improvement store or hardware store, off I went to Home Depot.

I knew that what I needed was copper plumbing parts, because they’re cheap and copper is soft and easy to solder.

Once I got there, I just stared at what was in front of me and figured out how to make those pieces fit into what I needed, which was a kind of tiny Kelly Kettle.
I only bought the parts I needed for the boiler, because it would define the size and general shape of the machine, and to make sure that once built, it would still fit in my pocket.

I chose the 1in sized parts as the maximum sized ones, simply because they where the largest diameter tubes that fit comfortably in my pocket.

Step 4: Considerations on the materials used for the build.

Some makers have commented on two possible problems they see with the build:
1) Lead in the solder
2) The use of copper and food.

The first is very easy to address: just use lead-free solder.

The second one, no so easy….the main concern is that the acidity in food will rust the copper, and the resulting salts are bad for your health.
This worried me enough to call a doctor (a family friend) and asked her to look at the Instructable and to give me her medical point of view.

She said that, in general, no to worry because:
a) Copper is not toxic and we need trace amounts in our diet. As a mater of fact, there is such a thing as copper deficiency.
b) Some copper alloys are in fact antimicrobial, which is why some hospitals have copper doorknobs.
c) As in all things, an excess of copper in your body is very bad for you
d) The brewing process is short, so the possibility of corrosion will be very small.
e) If corrosion does occur, the coffee grounds will probably trap it.
f) Tinning the brew head will eliminate any possible copper corrosion.

Step 5: Parts and tools

Part list:

Pluming parts:

2    1" cap
4    1/2" cap
1    1/2" tube (3in long)
3    1/2"  coupler (two will be flattened as a source of copper)
1    1" coupler
1    1 to 1/2" reducer (the type that fits into a 1" tube) for the brew head
1    1 to 1/2" reducer (the type that fits over the 1" tube) for the boiler
1    1/4" copper tubing (some 4")

Screws and nuts:

For the brew head:
1    6-32 3" screw
1    6-32 wing-nut

For the water intake hole:
1    Small nut and screw
  The screw no more than 1/2" long and the nut some 3/8" wide

For the stove:
1     Small nut and screw
The screw must be thinner than the 1/4" diameter of the copper tubing and about 1/2" long.

Plastic parts:

2   1" rubber gaskets
2   Small rubber gasket used in some faucets. (for the water intake hole and the brew head wing- nut)
1   Syringe (number 10)
1   Small scrap piece of wood (to make a jig)


Tool list:

1 drill
1 hacksaw
1 soldering iron
1 150 grit  sandpaper
1 wire cutting pliers
1 pliers
1 hammer

Drill bits:

1/4in
1/8in
1/16in

some small nails

Step 6: Build part 1

Since the pictures I took sometimes don’t show very clearly what’s going on and also because a blueprint is worth 6 pages of directions, I drew one with the espresso machine cut in halve, and all the part measurements and hole sizes.

1. Drill the 4 holes into the 1 to ½in reducer
2. Ugly solder the ½ in pipe into the 1 to ½in reducer

Ugly solder?

Design constraint 3 says that only simple, cheap tools could be used. I considered that a blowtorch would not fit the bill because not everyone has one, and I would probably burn myself using one. Also, if one of the younger members wanted to make one of these as a Christmas present, I would have to find another way to solder everything together in a safer way. The only other tool that came to mind that fit the bill was a soldering iron. But nothing is free in life. It’s slow and the end product is really ugly.
I had to file the solder to make them look a bit nicer, but it was the only way to stay on the good side of the constraints.
So, I decided to call this “technique” ugly solder.

Note: Use only lead-free solder.

Step 9: The Alcohol Stove

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Stove.jpeg
Design:

With the boiler now finished, I had the dimensions of the stove. This was where the project would succeed or fail.

I found out that of the two kinds of small alcohol stove designs out there, the sealed ones where a bit safer. But still, if you tipped one over, you could still get alcohol lit all over the place.

And there was also the problem of the amount of fuel need. In all the designs I found you filled up the stove with fuel and used it until it ran out.

I build prototype #1 based on this concept. It was small, it ran for 20 seconds before using up its fuel and almost got me burned.

Now I knew that I needed to get more fuel into the stove, but that meant a bigger stove and that would break constraint 1. This told me that my stove had to be externally fed.
Online research only gave up 1 type of stove that fit the bill (www.minibulldesign.com/) but looking at those beautiful stoves, it was clear that they broke design constraints 2,3 and 6.

I had no option but to design a new kind of tiny, externally fed, intrinsically safe, alcohol stove.

It took me over a month of work, lots and lots of research and tinkering and refining ideas, but finally, lucky prototype number 13…..Waass aaliiiveee !!!

It ran 18 min, 36 seconds on a full charge of alcohol.
I actually had the intention of staging an “accident” where I would tip over the stove full of fuel in a controlled environment.
Luck would have it, that my clumsiness got there first: during a second run of the stove, after about a minute lit, I accidently hit it with my hand and tipped it over.  Since I was still using a piece of tape as the security cap and air flow control, all the alcohol got out and spilled over the table and on me. The stove turned off immediately after it tipped so the spilled fuel never got lit.
The design was a success!

The end design is really simple and obvious in the way good designs tend to be. The hard part was getting there.
The stove has three main parts:
1. Fuel tank with flow control
2. Vaporizer
3. Diffuser and heat exchanger.

The stove works on the principle of vaporizing only the amount of fuel to be immediately burned. This gives us two good things: it allows an external fuel source and since only a small amount of vapor is available to the flames, any interruption in fuel supply would automatically turn off the stove (constraint 6).

I made a lot of different types of flow controls (one using the valve out of a lighter) but in the end, a simple unplugged syringe with a bit of tape over the top with 1 pin sized hole in it gave me the one-drop per second that a stove this size needed. It was simple and cheap (even though they don’t sell any at Home Depot, you can get them at any pharmacy). The flow rate is so small, that the fuel tank tap only needs a tiny hole at the top to balance the pressure and keep the flow going. This also is a big win in the safety department, because the hole is in fact so small, that if you tip the fuel tank on its side, no fuel comes out.

If you want (and I can bet someone will) you can very easily scale the stove to a size big enough to use as a camp stove (there’s an idea for a future Instructable).

Step 10: The Alcohol Stove, build part 1

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1. Cut and drill all the parts following the blueprint.
2. In a scrap piece of wood, drill a ¼ in hole , ½ in deep (sawing jig).
3. Place the ¼ in tube into the sawing jig and cut the 4 groves (2 at the same side, the front and back)
4. Assemble and ugly solder the fuel tube and the syringe holder
5. Place fuel tube into boiler, and ugly solder stove bottom.
6. Ugly solder the stove top
7. Once the vapor tube is in place, put the diffusion tube on top and screw in place
8. Only if needed, file the screw and nut at the bottom of the stove.

Step 12: The Brew Head.

Design.

I ground 7 grams of coffee to see how much volume it took up. Then I looked over the parts that I had that could be made into the brew head. Since the boiler is really small, I decided to use another 1 to ½ in reducer as the main body of the brew head, so that I could get an espresso cup under and between it and the boiler. The reason I needed to do this was because of the small size of the machine. If I couldn’t fit the cup in there, I would have to place the espresso maker on a higher level than the cup, and that would have to be an add-on, braking constraint 4 and possibly 1.
Fortunately, everything fit great.
The last problem to overcome came from finding a way to make the metal filters that espresso makers use.
Since drilling very small holes in metal with a hand drill is rather hard, and very likely to snap the drill (and a small drill press would brake constraint 3), I had to come up with a simpler method.
A few experiments later I had the technique nailed down.


Note: Some people have expressed a bit of concern about the use of copper and food. Since the brew head is the only part of the machine that touches food (essential, life giving food :D ) you may consider:
A) Tinning the interior of the brew head and filters
B) Using a different type of metal for the brew head and filters

Step 13: The Brew Head, build part 1

Picture of The Brew Head, build part 1
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1. Cut and drill all the parts following the blueprint.
2. Cut open a coupler using a hacksaw and flatten the copper.
3. Hammer down the copper until it’s roughly the thickness of a needle.
4. Cut it to the size of the interior of the 1 in cap.
5. Cut another circle to the exterior size of a ½ in cap

Step 14: The Brew Head, build part 2

1. Using a hammer and a nail over a scrap piece of wood make a “dimple” in the copper disk
2. Continue until you have a bunch of dimples.
3. Using sandpaper, ground out all the dimples.
4. On the dimples that left no holes behind, repeat.

Step 15: The Brew Head, build part 3

Picture of The Brew Head, build part 3
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1. Ugly solder the small copper filter to the 1 to ½ in reducer.
2. Ugly solder the ½ in cap to the 1 to ½ in reducer
3. Cut the water tube coming out of the boiler so that it’s flush with the 1in cap.
4. Ugly solder in place
5. Cut a ¼ in piece out of a 1 in hose gasket
6. Place in brew head top
7. Place 1 in copper filter
8. Place 1 in hose gasket to hold the filter in place.

Step 16: The Brew Head, build part 4

1. Drill a 1/8 in hole through both copper filters once in place (just to make sure they’re aligned.)
2. Assemble the brew head together with the 6-32 3in screw and wingnut.

Design:
The problem came up of how to hold the brew head to the boiler body without the later popping out due to water pressure.
One thing I tried was to make the brew head out of a pair of copper hose connectors. The problem was that they were too big, it made the brew head as long as the boiler and screwing them together really tight was no easy because of the restricted grip on the piece. I then came up with the idea of using a simple screw and wingnut to hold everything together. Easy to build, easy to use and cheaper than the first alternative .

Step 17: Use and calibration.

Once you’re done, wash everything and fill the espresso maker with water using the hole with the soldered nut. Place a screw in the nut with a small gasket (I used one that’s used inside some hot water faucets.)

Fill the fuel tank with alcohol and pressure place the ½ in cap.
Wait some 15 seconds for some alcohol to fill the stove.
Hold the espresso maker by the brew head and lift it. Use a lighter to heat the stove from the bottom until it ignites (takes some 10 sec.)

Place it on a flat surface and wait for the water to fill half a cup (1 oz) – takes about 3 minutes.

Wait until it cools down and repeat the process, but this time with coffee in the brew head.

Enjoy!!
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I agree wholly with kaeldra, a video of this device in action would be fantastic, I'm considering using this to make an art piece that will in theory make you a cup of coffee as well, and as this is diy and leaves room for spatial modification, it's perfect. Keep up the great work and please please please try to post a video

kaeldra6 months ago
I'd love it if you uploaded a video showing this in use! From the start of fueling and filling to the finished cup of espresso if possible. This is really neat! Beyond my current abilities I fear (never have soldered anything as of yet) but maybe something I could attempt in the future! Plus you are right it did give me ideas for more projects! (which are also out of my league but maybe someday!) :-)
InTheory11 months ago
That is insane I need to make something half this cool.
urant (author)  InTheory11 months ago
Yes, my wife also thinks i'm a bit insane :P
InTheory urant11 months ago
Sir, you are a genuis.
Geli121 year ago
I LOVE your introduction!
I adore miniaturized things, too :D
urant (author)  Geli121 year ago
Thank you very much!
OliverBoy1 year ago
Hey

This is a fantastic instructable and I am looking forward to making it.

I live in the UK and we use the Metric system for measurements. It seems that we don't have matching plumbing fittings, our fittings are a little bit smaller.

Given how concise this project is in the original design I was wondering if you think I will come across problems making the more intricate parts (stove).

Thanks

PS are there any videos out there showing the construction of this, that would be more than useful! haha
urant (author)  OliverBoy1 year ago
Hi Oliverboy!

No, I don't think you will have any trouble "translating" to metric. Just get the nearest sized fitting that you can.

Sorry, I didn't film the making process.

Tell me if you need any help on the way, and may be you can make a metric version of this instructable :D

good luck!
Man.. no problem about being copper made.. if there is no scratch the copper, it would not harm anyone. BUUUT... a friend of mine that is a chemical engeenier alerted that the solder can and will release toxins on heating.. on high levels. Theres no solder that is not toxic. So, that is the only flaw on your project. Anyway its a cool design, ill be looking foward to a non-toxic design.
-sighs and shakes head sadly- it makes me wonder how many MORE people will spout this ignorant crap. -clears throat- ELECTRICAL SOLDER IS TOXIC! PLUMBING SOLDER IS NOT TOXIC! USE PLUMBING SOLDER!

if it was so "toxic" do you think the building codes would allow it to be used in your home? that would be a resounding HE** NO!

(from step 4)
Some makers have commented on two possible problems they see with the build:
1) Lead in the solder
2) The use of copper and food.

The first is very easy to address: JUST USE LEAD FREE SOLDER*.

*caps done by me

btw copper is ALSO not toxic. i have no idea where people come up with these crackpot ideas. even if it WAS toxic, the absence of scratches wouldnt matter since the properties of the metal would leach into the hot liquid an'way through the rest of the surface.

besides, if it was so "toxic"...do you honestly think they'd allow it to be used as residential water lines? THINK ABOUT IT! you my friend need to do more research.

if you're looking for a "non toxic" design, according to your thoughts, you'd have to make it from food grade stainless and fusion weld the damn thing together with TIG. to make one with his design constraints? you might as well forget it existed.
acoleman is not exactly right about most of this post.

He's right enough that his info is not likely to get anyone killed but wrong enough to warrant a gentle correction. I'm not trying to be a tool, but there is some important corrections here.

"Just use lead free solder" ... Like plumbing solder? Except most plumbing solder contains antimony, or copper, or cadmium, which are are all toxic when in contact with food. When a soft solder says 'silver' it actually means 'silver-bearing' which means that most of it is tin and antimony, and copper.

"if it was so "toxic"...do you honestly think they'd allow it to be used as residential water lines?" ... This can get a little technical, bear with me. What is the ph of drinking water? It's near 7, neutral. So materials like lead, copper, cadmium, antimony, etc. which produce toxins as a reaction to acidity (or lack of) do not pose any real threat when used in residential water supply lines.

The issue of copper in particular is covered in Chapter 4 of the 2005 FDA Food Code with further explanation found in Chapter 3 of the 2005 FDA Food Code Annex.

Coffee, if you are doing it right, is acidic. Everything from where the water touches the grounds onward should be some other material. Many old houses have lead water pipes. Many water mains are cast lead pipe. Lead poisoning from these sources is practically unheard of. Really they didn't need to ban lead  plumbing solder but... meh. Nevertheless, I wouldn't serve lemonade out of a lead pitcher.

Solutions:
I hate to point out a flaw without offering a solution.

Get a stainless filter from an old portafilter or mokka pot or whatever. Or make it per instructions but use stainless steal from the bottom of a sapporo can.

Then tin the inside of the brewing chamber. Get 100% tin from a HVAC shop and a suitable acid flux heat the thing up and lay it in. Nice, neat, food safe.

Solder with a nice food-safe soft solder. I like SoldaMoll 220 by brazetek. It flows great and if you got bucks to spare you can tin you brew pot with it so it will look prettier. Also it will wet and flow much nicer than plumber's solder.
Dec 28, 2011. 3:00 PM
acoleman3 says:
It's near 7, neutral. So materials like lead, copper, cadmium, antimony, etc. which produce toxins as a reaction to acidity (or lack of) do not pose any real threat when used in residential water supply lines.

get a grip....the coffee is in one small portion. the rest of it is dedicated to fuel and guess what....care to guess? thats right....WA-TER! which as you say, is only ph 7. that blows your comment about how dangerous it is. the brew chamber is small as well as the exposure time for the acidity of the coffee that the amount of copper you would be ingesting is minuscule.

not only that....but you need to do more research on copper itself. what is dangerous is cupric sulfate (copper II)....not the element copper. copper is used as a health supplement, don't you know that? besides, according to the fda, you can ingest 1.3 mg/L a day and be safe. im pretty sure what you get from this coffee maker is far below that.

plumbing solder does not contain lead and the amount of antimony is small. so much so that it does not pose a health hazard. you can, according to the fda, ingest .006 mg/L a day and be ok. im pretty sure what solder the coffee encounters leaches amounts way below that.

if you look at his constraints....you will see on item 2:

The product had to be made out with common, cheap and easily obtainable materials from any home improvement store or corner hardware store. (sure as hell not from an hvac shop or your soldamoll 220 since it's not sold at your local diy....such as lowes and home depot)

not to mention in the front page he specifically says a maximum budget of $30. im sure your ideas blow way past that figure since you said "if" when talking about tinning the coffee chamber. im also sure since your solder isn't sold in your local diy, its gonna be more of an expense in itself then general plumbing solder.

"if you got the bucks to spare"
that blows you tinning idea right there since its out of the financial ability of most people, especially teenagers who have to live on a budget and who's parents im pretty sure are NOT going to fork out the money to have such a small item treated in this way.

you have an idea for a better way? great...make your own instructable for those who can afford to get such things as you've mentioned.

think in a practical manner, according to his instructable, and wake up to reality.
Kage-- Relax. I'm sorry, but on so many parts of this you're just wrong.

I said at the beginning this espresso machine is a great build, but some of the concerns about the use of copper and plumbing solder are warranted. Specifically, from the point where the water meets the coffee grounds. You seem to be taking it personally. Instead of asking informed questions and offering constructive criticism, you are lashing out at one who is doing just that.

I need to do more research on copper? I'm supposing that you think that elemental copper is not dangerous because some wikipedia article tells you that it is copper (cupric) sulfate that is the toxin. Follow me on this. Copper reacts with acids to form copper sulfate. Acids in coffee, acids in your stomach. That is why it is safe to use copper for drinking water and unsafe for many food applications ... like coffee.

Your argument that copper is safe is ridiculous. I say this with love but I'm sorry, it is. Copper is so safe that the FDA (an authority you cite) BANS its use where it may come into contact with acidic foods ... like coffee. There are safe doses of lots of toxic things. But if someone published a cookie recipe that included a milliliter of gasoline I would be inclined to offer a few alternative ingredients. No one ever got sick from ingesting 1/12th a  milliliter of gasoline (recipe yields a dozen) so there should be no problem. Common sense revolts at such an idea.

"Copper is so safe because you can buy a copper supplement...(para.)". You can buy a lot of unsafe things; guns, cigarettes, marriage licenses. Try and buy copper supplements. What follows is the warning that comes up when I tried (emphasis added):

"WARNING: WARNING! This nutritional supplement,contains COPPER, a potentially TOXIC mineral. Do not take more than 4 mg of elemental copper per day. Accurate measurement requires the use of an analytical milligram scale! If you do not have the analytical skills necessary DO NOT USE THIS PRODUCT! Improper use may require emergency medical treatment! Seek medical care for accidental use. The only safe way to measure this product for individual use is by using a milligram weight scale that is accurate and precise to 1/1000th of a gram, or 0.001 grams. PureBulk offers many scales of various accuracy and precision."

If you want to play Russian roulette with heavy metal and copper poisoning then great. But people should know that there's a risk involved that really doesn't need to be there. There is certainly no functional benefit that comes from building this project in ways that expose its user to these toxins.

You seem concerned on the grounds that a teenager might not have the kind of cash (or sympathetic parents) to build this project the way I suggest. This is a dangerous mindset. It leads to cutting corners. The easiest, cheapest, and fastest way to do something is always: right the first time.

You know what would put you way over the $30 budget? A trip to the ER because after a long camping trip you wake up one morning with blurry vision and the runs.

There's easy ways to play the game safe that don't violate the maker's self-imposed constrictions. I gave a few suggestions and when I say "If you got the bucks to spare" I'm talking about 2 or 3 of them. Using stainless steel for the filter mesh will save the cost of a copper slip coupling (about $2). So there ya go.

Tin the brewing head with tin ingot.
Tin ingot is cheap, but can be a little tricky to find. It can be ordered online or from an HVAC shop.

Tin the brewing head with silver solder.
I like SoldaMoll 220 but Harris' Stay-Brite is easier to get. Home-Depot carries it. It's more expensive than Plumber's solder but for the quantity used it doesn't represent a significan increase in the budget. And, using it to join the rest of the project will have an aesthetic advantage.

Use a stainless steal pipe for the brewing head.
a short bit of stainless is easy to find for a resourcefull maker. It will need to be hard soldered (brazed) to the copper but the same propane torch will do the job and a small job pack of safety-45 silver solder is not cost prohibitive either.

Here's another:
Electroplate the inside of the brew head with nickel or chrome or gold.
The kind of fun stuff a maker would enjoy doing. A primative plating set-up is not expensive.
What kind of acids are we talking about here? Unless it is sulfuric acid, you need a source of sulfur to make a sulfate. Copper, while commonly used in sauce pans is recommended to be coated in a less reactive metal (as you say). Tinning is a good idea. I think at also goes without saying to not skimp on the right solder since that sounds like it will be the major source of troubles.
http://www.clemson.edu/extension/hgic/food/food_safety/handling/hgic3864.html

As to other leeching, is the heat plus acidity where any of the issues come from because there are many substances where they are inert at room temp but react when heated sufficiently. ("proper" solder assumed)

To any other readers who took the care to browse the comments. Regardless of what you take from this discussion of toxic metals, I would not advise using this for a daily espresso maker unless you have the ability to have testing done on the amount of metal leaching to know if it is safe, "safe enough" or down right dangerous.
Fair enough, I was speaking rather basically about the nature of copper and other reactive metals. And also, for the life of me, I was sure sulfuric acid was one of the acids present in coffee and gastric acid. Its not.

The point is academic. Coffee contains Citric Acid which combines with elemental copper to form the poisonous salt copper citrate (a pesticide). It contains malic acid which reacts with copper to form copper malate.

The point being, that even if elemental copper itself is not toxic (a point I would not make) it will react with many of the 30+ acids found in coffee to create salts which are toxic.

The point being, that copper poisoning is not a joke. Heavy metal poisoning (lead, cadmium, antimony(?)) is not a joke. And just because drinking water might be able to flow safely through these materials does not mean they are safe for preparing food.

I'm a little shocked at the backlash at my suggestion of some ways to mitigate a great deal of this risk. Looking through the list of symptoms for copper toxicity, I'm sure there must be something in there that would make a little extra effort worthwhile. For me it is either the possibility of blindness or 'tarry black feces'.

my comments not showing up all the time is beginning to piss me of.....but an'way. i love how you've thrown common sense right out the window here. the surface aria of the brew chamber is about 5 sq inches with an exposure time of about 40 seconds. do you honestly think you are going to get your 4mg of copper out of that? besides.....the figure *i* gave you was *way* smaller then that. does 1.3 mg/l remind you of an'thing? so you just proved that the body can take in even *more* then the fda limits.

according to http://www.drlera.com/minerals/copper.htm they say it's 1.5 mg and point out how rare copper toxicity really is. you have to have an intake of 10mg a day for over a few weeks before you start getting into the horror you're trying to push on us. i also said the antimony limit is .006. now considering there is less then .75 sq inches of solder exposure in the brew chamber.....well....again youve thrown common sense out the window.

where's your chemical analysis on this, you tell me....how many mg/l of copper is really in this coffee and how much are you gonna get poisoned by drinking even 2 shots a day. according to your proof, since you can ingest 4mg a day, your argument is irrelevant since an acid as weak as coffee is not going to strip away that much copper and im pretty damn sure i'ts *not* going to contain 10mg/oz..

yeah....way to go on equating health.....yes HEALTH supplements with tobacco and guns. that was a rather idiot statement and an irrelevant comparison. especially since pretty much all multivitamins contain high concentrates of copper. what....shall we ban those because they're so "toxic"? OH GOD THEY CONTAIN HIGH AMOUNTS OF COPPER! THROW THEM AWAY QUICK!. give me a break. if you have proper zinc intake, at a 1:8 in favor of zinc, the copper in the body *will* be kept in check. not just zinc but manganese, caffeine, selenium, iron, b-6, folaic acid, vitamin c and sulfur as well.

what causes copper toxicity in the first place is the lack of binding to ceruloplasmin and metallothioneine. two proteins that transport it to the mitochondria where it can be broken down for cellular fuel. after all, copper toxicity is coupled directly with copper deficiency.

sorry, try again
Just use sliver solder, it is used on many sufaces in drinking flasks and tankards that solder is the best due to its resitance. Just a thought!
You ask how much copper will leach into the espresso that comes in contact with 5 sq in for 40 seconds. I don't know. Do you? What method do you use to determine this?

You point out that drinking water can contain up to 1.3 mg of copper per liter. How much do you drink per day? Water, soft drinks, etc? About 2 liters per day is average so for all you know you are getting two and a half mg of copper a day just from what you drink.

And as your Russian herbal medicine website explains, copper is present in many foods. It's highly concentrated in some foods.

How confidently can you claim to know what your average daily intake of copper is before you add something like a bare copper coffee pot?

Will you remember to warn every guest you serve a shot of espresso to that the coffee was prepared in a bare copper pot? Some people have severe reactions to even small levels of copper.

This is what common sense is. It is making a rational decision. Risks must be balanced by reward. Big risks require a big reward to make them worthwhile. Little risks, likewise, may be justified by little rewards.

You have acknowledged that the risk of using this item as described is greater than zero. You and I may disagree over how much more than zero it is but that's not the point.

So what is the reward of building it this way? I've shown that a few changes in materials and you can build the same thing, using the same tools, for the same money. Well within the constrictions listed.

So what is the benefit that you get out of raising your exposure to copper toxicity (even by just a tiny amount)?
I'm hoping I did not sound like backlash with how I presented my response.

Food-safe or not can be a big deal for homemade projects.

I was bothered by the seeming: "you're wrong," "no, you're wrong" argument I saw unfolding.

I had some additional questions I though could fill some gaps. It's great if we do some research and decide for ourselves, but this is a big issue the community needs to know about too.

Everything else aside, it seems this can still be a wonderful portable boiler, short some of the modifications you mentioned.
After some further research (including talking with a materials science engineering professor at my University, it sounds like there may be some value in determining the corrosion rates for copper exposed to an espresso mixture (the details of running such tests were left out of the recent discussion pending further research pertaining to EPA standards for copper contamination).

Speculative assessment (given this is NOT his specific field of study, but his background knowledge of material chemistry) puts expected leaching quantities for the physical scale of this project in the nanogram order.

Additionally, one of the hard facts he did provide was that unless we are getting different reactions from the acids, (which are themselves edible) that are creating compounds that are not salts (since a salt is ironically bonded, learn some chem. for implications) the anion does not matter. The salt is a copper delivery system, not a unique toxin.

Furthermore, being a metal used in bodily function, you do have means of clearing Cu out of your system when levels are in the manageable range.

Water leaching standards are based on the assumption that you are already consuming average amounts of copper containing foods and drinking average quantities of water. So rather than copper being toxic if you ingest >1.3mg Cu diluted into 1 L of water, the maximum contaminant level also assumes that is your average liter of water, not a single given liter of water.

My opinion as an informed researcher, not an expert, is that this should not be an item for daily use, but given proper cleaning/maintenance is safe for making espresso.

@cobright, thank you for your concern. I hope this helps.
"it sounds like there may be some value in determining the corrosion rates for copper exposed to an espresso mixture"...

I've been stuck at this point myself. Here's what I did:

I built a porta-filter out of copper that would mate with my espresso machine.

With the stainless steel filter I ran 40 shots of distilled and tap water through using a plug to slow the water down through the filter-head (it's used for cleaning the unit). I drew off one liter from each and called them samples A and B. I tested both samples with a test strip that reads positive at >=0, .3, .7, 1.0, and 1.6 mcg/liter. Neither sample tested positive at any level.

Then I did the same with the copper filter head. Samples 1 and 2. Neither sample tested positive at any level.

Then I tested both systems using tap water from my brother's place (a different water system): Samples C and 3. C tested positive at > 0 and 3 tested positive at >.3.

Conclusion so far... I have great tap water, distilled water has no copper in it, My brother's tap water not only contains copper but is acidic enough to absorb some copper out of a copper espresso brew head. I suspect his water was just under the threshold for the higher result and actually absorbed a very tiny amt. but enough to change the result in a sample size that large is significant.

Then I brewed 20 shots of a three different types of coffee using distilled water. Samples I, II, and III in the stainess and Ic, IIc, and IIIc in the copper filterhead. I passed the results through a ceramic filter to remove particulates that tinted the test strip. Samples from the stainless system did not test positive at any level. Samples from the copper system tested >0, >.3 and >.3 respectively.

Any sample brewed through coffee in the copper head, when dried on filter paper and burnt produced a green flame.

That is the end of my diagnostic capacity. I don't have access to atomic machines anymore and it is little more than a corollary interest to begin with.

As I said at the very beginning, I'm not terribly worried about this build making anyone sick. But the distribution of bad information by ill-informed and self-proclaimed authorities could do much worse.

When someone tells you that copper is not toxic, they are wrong. Like most toxins there is a level of intake below which you will not suffer from copper toxicity.  An WHO report on the subject found a significant portion of the population will experience harmful effects at levels as low as 3mg in a day. Considering that you might already be taking in this amount from your normal diet and drinking water, I would say that steps to avoid additional exposure are reasonable.

If you know with a certainty how much copper you are taking in presently and exactly  how much copper using this device will add to that and exactly how much copper you excrete a day ate every level of intake, then you could reasonably calculate your risk of copper poisoning. All of these are dependent on a multitude of  variables, none being easy for the average person to measure.

Further, there is the concept of 'best practices'. When you settle for second best once, it becomes easy to do it as a matter of practice. I do it all the time when best practice adds no value to my build. A high-gloss finish on metal adds no value to me so I rarely expend the resources to do it.

But putting that finish on a project takes a lot of extra time, effort, even money, and I get nothing I value out of that investment.

Building this espresso maker in a way that mitigates all or most of the exposure to copper poisoning and heavy metal contamination does not add to the time, effort, or cost of this build. If you can reduce a risk under these conditions you probably should. Unless you just like risk. In which case I recommend taking up skiing. If skeeing goes badly people will love to hear your story about a broken leg. If you get too much copper, no one will let you tell them about your sticky black BMs and accompanying stomach cramps.
apperenty my reply didn't post so i had to do it this way.
As far as i know the solder plumbers use is silver solder,and needs oxy acetaline,ie very high heat.
Some old houses still run lead pipes ,and copper ,with lead tin solder.
I get that heat will release toxins from the solder. I just doubt that this gets that hot. When I make one I will know for sure. However, I do know that there are copper pipes that have been soldered coming out of my hot water heater and I seen to still be alive even though I have ingested a decent amount of it.
vreme2 years ago
I have used an electric stove for soldering copper parts (cpu water block) with good results. The only drawback is that it heats all the copper parts at the same time, so you have to secure them in place somehow.
After some further research (including talking with a materials science engineering professor at my University, it sounds like there may be some value in determining the corrosion rates for copper exposed to an espresso mixture (the details of running such tests were left out of the recent discussion pending further research pertaining to EPA standards for copper contamination).

Speculative assessment (given this is NOT his specific field of study, but his background knowledge of material chemistry) puts expected leaching quantities for the physical scale of this project in the nanogram order.

Additionally, one of the hard facts he did provide was that unless we are getting different reactions from the acids, (which are themselves edible) that are creating compounds that are not salts (since a salt is ironically bonded, learn some chem. for implications) the anion does not matter. The salt is a copper delivery system, not a unique toxin.

Furthermore, being a metal used in bodily function, you do have means of clearing Cu out of your system when levels are in the manageable range.

Water leaching standards are based on the assumption that you are already consuming average amounts of copper containing foods and drinking average quantities of water. So rather than copper being toxic if you ingest >1.3mg Cu diluted into 1 L of water, the maximum contaminant level also assumes that is your average liter of water, not a single given liter of water.

My opinion as an informed researcher, not an expert, is that this should not be an item for daily use, but given proper cleaning/maintenance is safe for making espresso.

@cobright, thank you for your concern. I hope this helps.
TwistedJack2 years ago
This is fantasic, cant wait to make it. only thing i wish i couyld take it to school and show it off, but no lighters or fire preducing things.
You sir are a genius. I can't wait to make this but mine will probably end up making an alcohol fuelled pipe bomb! thank you for making this instructable!
I'm sorry that I upset you. I'm not saying that to be flip or imply that you are emotional; it truly was not my intention to be offensive. I try to say only things I am certain to be true and which can be supported by credible sources if challenged. When I am shown to have said something in error, I correct it and thank the person who does so. It is my nature to speak boldly as Keynes said, "Words ought to be a little wild for they are the assaults of thought on the unthinking."

Please remember that I entered this conversation after you (or acoleman3 if he is not you) made factual statements about the safety of a material used in this instructable. Namely, that the materials used in plumber's solder is not toxic and that copper is not toxic. I think everyone would agree that these types of remarks are exactly the kind of statements that should be scrutinized.

Statements which, rather aggressively, berated the concerns over the safety of these materials raised by fellow members. " ...how many MORE people will spout this ignorant crap..."

Several of these factual assertions and resulting conclusions were, in fact, unequivocally wrong. It is not my fault that they are wrong. If the error was about a matter of low consequence instead of about the safety of mixing copper and food I would have ignored them out of politeness.

My post was polite and every statement of fact in it is verifiable. Copper and other metals used in many plumber's solders (even those labeled 'silver solder') are in fact toxic and unsafe for use in food preparation. This is not my opinion, it is the judgement of the FDA. If someone chooses to be less cautious than the FDA then that is fine too, but facts are facts.

Quick question: do you tamp the coffee down at all? if so, how do you do it with the screw in the middle?
urant (author)  bobiffer01232 years ago
No tamp is needed
kfifield2 years ago
I am having a lot of trouble getting the stove to light. any tips? I feel like the alcohol isn't vaporizing and is just coming out the bottom where the screw goes through.
urant (author)  kfifield2 years ago
When that happened to me, it was because to much fuel was getting into the stove. If you are using the syringe, paste a piece of tape to the open end of the syringe and poke a single hole into it with a needle. This will slow the flow rate of the fuel getting into you stove and should have the small volume necessary to evaporate the fuel.
Tell me how it goes
spdrcr10102 years ago
I saw your instructions and couldn't resist! It took me about 3 days to source parts and build. I did something a little different in the brew head by soldering a ring below the water inlet to sandwich an o-ring between the cap and reducer. Also instead of a syringe I just used some very small copper tube to meter the fuel. I might need to change that tho because the tank can get warm and start vaporizing the fuel in the tank making a larger than desired open fire.
Made some tasty black beverage tho. Cheers!
IMAG0527.jpgIMAG0529.jpgIMAG0526.jpg
I'm having a hard time finding these:
1 1 to 1/2" reducer (the type that fits into a 1" tube) for the brew head
1 1 to 1/2" reducer (the type that fits over the 1" tube) for the boiler

I found one type, but not sure which one because I don't actually have any 1" copper pipe to test :-/
when you go to the hardware store just dry fit it into a piece of 1" copper pipe on the rack.
acoleman32 years ago
would it help to angle the preheat tube up like...3/16 in to help the fuel flow into the combustion chamber better?
urant (author)  acoleman32 years ago
Not really, since the fuel never flows in the stove. The moment it leaves the syringe and hits the tube, it vaporizes. As a mater of fact, the stove "ticks"; you can here the fuel hit the inner tube and vaporize.
tdshelton2 years ago
I'm really enjoying building this coffee maker, and was hoping you could clarify one point -- the syringe.

What exactly is a #10 syringe? Is that a regional description, or the way a particular manufacturer labels their syringes? Searches both in local pharmacies and online for a "#10 syringe" yield nothing.

If anyone has a link to a syringe that's appropriate for this 'ible, I would really appreciate it. Otherwise, advice on brand, syringe capacity (ccs? ml?), and needle gauge would be helpful, too.

Thanks!
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