by Randy Mosher (Brewing Techniques)
You too can piece together your own automated 15-gallon brewery from junkyard parts and scrap metal.
For more than five years now, I’ve been working toward my goal of constructing a fully robotic brewery capable of operating in outer space, controlled through telemetry from my personal ground station. At this point, I am one two-thousandths of the way to completion. But let me assure you, the brewery, Earth-bound, is fully functional and capable of providing a lifetime of brewing if I choose to stop right now. The important thing is that the lessons I have learned on the first 0.05% of this fantasy project have been by far the most important ones. I thought I’d share some of them with you.
I use a three-vessel configuration comprising a dedicated mash kettle, a lauter tun, and a boiling kettle. The mash and wort boiling kettles are of conventional junkyard design, albeit copper-bottomed and fitted out in a fairly complex way. The lauter tun is one of my more recent projects and is made of rolled sheet metal. I also have a hop percolator (my term of choice for a hop-back), a grant to collect the runoff, several pumps, and a modicum of electronic measurement and control devices. I usually ferment in glass carboys, but recently I built a 12-gallon unitank from an old milk can.
I built all this equipment myself, with a little help here and there from my local stainless steel surgeon. A “buck a pound” is literally what I paid for it, having rescued the parts from meltdown at scrapyards and surplus shops wherever I could find them. Here’s some of what I learned in the process of souping up my home brewery.
“You’re not going to pay a lot for this brewery”: You have to be willing to take an opportunistic (read: flexible) attitude about how your system develops over the span of a few years, but if you don’t have to have any specific part tomorrow, you really can buy most of your brewery for cents on the dollar.
The industrial world spews mountains of choice goodies that end up in auctions, surplus outlets, junk shops, and scrapyards. Even if you are perfectly happy with your picnic cooler mash tun, it’s worth it to learn where good second-hand parts sources are in your region and to become familiar with them. I even search them out on vacation; but then, I’m kind of a sicko when it comes to this topic.
Start haunting bargain equipment environments and buying anything that might be useful: pipes, tubing and fittings, pumps, valves, screen and perforated metals, instrumentation, and nuts and bolts. Buy every kind of stainless steel fitting you find. Keep collecting stuff until it becomes obvious that you have enough to use for your brewery. Whatever’s leftover can probably be traded for something useful.
Anything made from nonmagnetic stainless steel that doesn’t look like it fell off a satellite is probably 300 series stainless, also referred to as 18-8 in reference to its nickel and chromium content — just what you need to build brewing equipment. You are likely to encounter two flavors of 300 series stainless steel: 304 and 316. The 316 metal has added molybdenum for extra resistance to acids and other corrosives. Both work equally well for brewery applications. Which brings us to the next point:
Stainless steel is the devil’s own metal to work with: It is a beautiful, enduring, versatile, but obnoxious material. It is difficult to cut, weld, drill, tap, polish and bend. (See the box on page 40, “Working with Stainless Steel,” for some tips.) Once you get it together, though, it will last for centuries, resist all common cleaning and sanitizing chemicals, and impart nothing to the finished beer. Its only drawback is that it is a poor conductor of heat. As a direct-fired vessel — and most people use it this way — you could hardly engineer a worse material. Scorching and sticking are the main problems (which is why I went through the trouble to attach a copper bottom to mine).
Buy a serious die grinder: This Dremel tool on steroids (at right) can handle a wide variety of tasks. You can move a lot of metal in a short time with a ¼-in. chuck spinning at 25,000 rpm, and if you want to grind down your welds and make them look nice you absolutely have to have one. The cost is about $ 100, which is well worth it for its versatility.
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Working with Stainless Steel |
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Stainless steel is hard to work with, but its rewards make it worthwhile if you’re willing to use some elbow grease. You have to attack each fabrication step with the correct tools and techniques or you’ll make a mess of things. Drilling: Very sharp cobalt drill bits will do the trick if applied to the metal. Do this slowly and firmly and with a lubricant. Start with a small (⅛–¼ in.) hole, then step up the diameter with larger and larger bits until you reach your finished size. Stainless steel gets harder as it heats up, so curb your natural inclination to speed up the drilling. I have transformed cobalt bits into red-hot nuggets of useless spaceage metal by misapplying my frustration this way. Threading holes: Tapping (threading holes) is exceedingly difficult and may not even seem worth it if you inadvertently break off a hardened steel tap in the hole; some steps can be taken, however, to improve your odds. Spiral taps, if you can find them, work much better than straight ones because they clear the chips out of the hole and prevent them from gunking up the tap. Spiral taps are strictly an industrial item, but they do occasionally show up at the junk shops. You absolutely must use a lubricant and very gentle pressure, backing the tap out of the hole frequently to clear the chips. Whatever the recommended drill hole size is for a given finished threaded hole (check your hardware store for this), you can make it a little oversized, relying on stainless steel’s superior strength to keep the threads from failing. Some taps are also available in sets of three; each tap is designed to take a slightly larger cut than the preceding one until you reach the desired thread size. Cutting: Stainless steel may be cut in a number of ways. For sheet metal, the slickest device is a plasma cutter, an electrical unit that sends a needle of 12,000 °F (6,650 °C) ionized gas shooting through the metal. At $ 1,000, plasma cutters are obviously too pricey for a buck-a-pound homebrew lark, but they often may be rented from welding supply houses. With a plasma cutter, slicing through metal is literally like cutting butter; the metal simply falls apart as you move your hand. It cuts so effortlessly that it’s easy to forget that the just-cut metal is hot enough to seriously burn you if you drop your guard. For us normal folks, simpler tools will suffice. A saber saw fitted with a bimetal blade and run at its lowest speed will do the job. (If it’s not making a hell of a racket, you’re doing something wrong.) Carbide grit blades are a little slower, but are more forgiving in terms of speed and technique. My low-rent tool of choice is a ¼-in. die grinder with a 3-in. cut-off wheel. The wheel will give you a very precise cut once you get the hang of controlling it. The die grinder itself (essentially a 25,000 rpm motor with a chuck on the end) is also good for many other fabrication tasks (more on this in the main text). An abrasive cut-off saw is the first choice for cutting rods, tubes, and other stock shapes. This tool is just a scaled up version of a die grinder, with a clamp to hold the item to be cut and a far larger motor and disk. An old circular saw can be fitted with an abrasive cut-off saw, but be sure to set up the project safely in an area that can endure a serious shower of sparks. Rolling: Rolling and bending parts requires specialized tools and is not a realistic possibility because of their size and expense. Keep in mind that stainless steel is quite tough, and a tool designed to contort a certain thickness of mild steel will be able to handle stainless that is only two-thirds as thick. If you want your sheet metal rolled, bent, or sheared, a sheet metal shop may be willing to handle the job for a small charge. |
You’ll also need a bunch of cutoff wheels, grinding wheels, flap sanders, carbide burrs, and polishing buffs. All of these are industrial items, though your local home improvement store will have a smattering. Any large flea market will have a guy who sells drill bits, and usually he will have an assortment of carbide burrs and other useful tools at a fraction of their usual retail price.
Learn to weld: Learning on your own is commendable, but welding classes help immensely. A welding class will generally teach you basic techniques and may offer access to a large, well-equipped metalworking facility. Bring your project along; on an hourly basis, taking lessons is cheaper and far more sensible than renting or buying the equipment. Shop departments are disappearing from schools all over the country as we increasingly become a nation of people loath to get our hands dirty, but some do still exist in high schools and technical colleges; make a few calls and explore the offerings. Gas tungsten arc welding (GTAW or TIG) is considered an advanced technique; you will likely have to put in some time with an oxyacetylene torch to get a feel for joining metal (and to satisfy your welding instructors). For tips on welding stainless steel and other metals, see the box, “Welding Tips."
Think modularity: This may seem like a no-brainer, but it helps to standardize all the connections in your brewery with the same type of fitting. I use ⅜-in. industrial compression fittings for all my vessels, pumps, hoses, and so forth. I also use Tri-Clover sanitary fittings (at right) to attach most of the auxiliary bits to my vessels. They are quick, easy to clean, strong, and yes, modular. They make it simple to just pop everything off and haul the kettle over to the sink for cleaning.
Automate everything you can: It’s not simply how many hours it takes to brew but also how much attention you have to pay to each step that counts. If you can step up your mash or lauter without having to oversee each moment, then you’ve freed yourself up to sanitize carboys or weigh hops, which cuts down on the length of your total brew day.
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Welding Tips |
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Once you learn the fine art of melting metal together, you will have to confront a few more of stainless steel’s bad personality traits. Because stainless steel conducts heat poorly and expands at a high rate when heated, it tends to warp badly when welded. Unfortunately for brewers, this effect is most noticeable on thin sheet metal. A number of things can be done to improve the situation.
Even a plain copper bar 1 in. or so wide and ⅛ in. or more thick will provide physical support and draw heat from the weld zone. The stainless will not stick to the copper. Another aid is a material called Solar Flux B, a gray powder that can be mixed with alcohol and brushed onto the back of the weld. With or without backing bars, the flux keeps the back of the weld cleaner and less prone to blow through. Silver brazing can also be used to join stainless. This technique requires a good propane or MAPP (methylacetylene–propadiene) gas torch, some cadmium-free silver braze (not solder), and the appropriate flux. The joints must be absolutely clean and fit very closely so the gap between the parts is small. Silver braze is very thin and liquid when molten and will not fill gaps. Smear the parts with flux, clamp or wire the parts in place, and heat. Add the brazing rod when the flux turns watery and the joint is just turning red-hot; the procedure is similar to sweating a pipe fitting. Brazed joints will suffice admirably for most brewhouse tasks, but the process doesn’t work well for joining overlapping sections of sheet, which is why I’d stay away from this technique when it comes to constructing fermentors. |
What can you automate? Theoretically everything, but some pieces are easier than others. I have a motorized mash mixer that, combined with my copper-bottomed kettle, allows me to step up a mash by simply glancing at the thermometer every couple of minutes or so.
I am also fond of float switches and have three of them in the brewery. They run about $ 200 at surplus electronic stores. One sits atop my liquor tank and shuts off a solenoid valve on the filtered cold water supply. This feature has saved me countless times from having to mop spills from the floor. I run my brewing liquor through a charcoal filter rather slowly; it takes an hour or so for it to fill completely. The float switch is situated so that it closes when the water level is about two inches shy of full (the extra space allows for expansion when the water is heated). Another float switch resides in the grant and kicks on a pump that transfers wort to the boiling kettle when the grant starts to get full. The third is strapped to the wall of the new lauter tun; it turns on lauter liquor when the level starts to fall. It simply pops off for cleaning, transportation, or storage — like all of my equipment. I am in the process of insulating the lauter tun with semi-rigid fiber glass insulation board of the sort used in HVAC applications. The finishing touch will be to clad the whole thing with teak or some other durable hardwood.
Another key item in the liquor tank setup is a solenoid valve connected to the water supply with a relay box in between. The float switch sensor plugs into the relay box and uses a low voltage to trip a relay attached to a pair of outlets. When the sensor is closed, one outlet opens and the other closes. This way, the relay box can be used to oversee a variety of instruments: the filling valve, heaters, fans, and more. Two of my pumps are hooked up with similar relays built into the bases, so the same float switches or thermostats can be used to turn them on or off.
Use the resources that are out there: Welding supply shop clerks are very helpful and will usually offer you some advice. I also highly recommend the rec.crafts.metalworking newsgroup on the internet. These guys are building everything from steamboats to working model jet engines, and few metallurgical challenges exist that they can’t handle. Check them out.
Once you have the skeleton of your brewery assembled you can begin thinking of ways to make it easier to operate and to enhance its appearance and utility. My brewery may not yet be anywhere near operating by telemetry, but it does have some neat features to keep me happy in the meantime.
Copper-bottomed kettles: As already mentioned, stainless steel makes terrible cooking pots. Kitchen cookware often incorporates aluminum or copper layers sandwiched together, so why not apply this material to brew kettles? I managed to latch onto some 9/100-in. copper sheeting I thought would be perfect. My plan was to saw out all but a couple inches around the rim of the keg bottom, overlap the copper about a half an inch, then weld the two together somehow.
The problem is that few methods exist for joining copper to stainless. Silver brazing is one choice (be sure to use a food-safe alloy), but requires a very tight fit, which is hard to achieve on the bottom of a curved vessel. I did one of my kettles this way, riveting the copper to the stainless every inch, but it was extremely difficult and I ended up patching the pinholes later with another method. Still, it can work. The method requires an oxyacetylene torch — not for blazing heat, but for the massive BTUs that must be pumped into such a large hunk of copper to get it hot enough for the braze to melt.
An employee at a welding supply shop suggested I use an aluminum bronze TIG welding rod (at right) to join copper to stainless as an alternative to silver brazing. Welding aluminum requires AC current rather than DC, which results in a slightly wilder and woollier welding experience, but it gets the job done. The aluminum bronze is very thick when molten and fills gaps beautifully. The trick is to get the heat applied in such a way that it more or less welds (melts) the copper while brazing the aluminum bronze to the stainless. A fellow keg-welder reported great results using a silicon bronze TIG rod. This material can be welded with straight polarity DC current, making it more controllable.
The glorping valve: I first saw this trick on Darryl Richman’s brew rig. It is a large pipe fitting at the bottom of the mash kettle through which the mash can be discharged without scooping it out by hand. I have fitted my mash kettle with a 1½-in. Tri-Clover fitting, which can be attached to a large ball valve and a foot-long elbow of the same size pipe. This elbow leads into my lauter tun. At the end of mash-out, I simply turn on the stirring motor to fluidize the mash, open the valve, and let it glorp. It takes about 30 seconds to do the transfer. The glorping valve doesn’t represent a huge benefit; it’s just another thing that makes brewing easier and faster. And that giant valve looks really cool!
Lauter tun tricks: My lauter tun is of fairly conventional design; it’s just a big tub with a perforated screen close to the bottom. In addition to the float switch mentioned earlier, I have installed a couple of features that improve its performance.
Vacuum gauge. This gauge measures the pressure on the bottom of the lauter screen to help me prevent mash bed compaction. The gauge is connected to a tube running below the screen through the side of the vessel. It allows me to determine the rate at which the grain bed is being sucked down so I can prevent it from draining with so much force that it solidifies the mash into vegetable concrete. I open the tap carefully when starting the runoff, and if the needle starts to swing too far I close it off a bit. After doing a few brews with this you get the hang of it and don’t really need the gauge any more, though the weird oat or rye beers I like to brew can sometimes throw me a curve. It may seem like a foolish luxury (if anything that costs a dollar a pound could ever be called a luxury), but saving half an hour to an hour every time I brew makes the gauge worth its weight in, as it happens, really nice zinc.
My gauge is nothing more than a pressure gauge dismantled from a CPR dummy. I took the gauge apart and bent a part inside so it reads vacuum instead of pressure. Commercial breweries use manometers — liquids in tubes — to do this. If you are searching for a dial gauge for this purpose, you want one that deflects with the gentlest of breaths.
Sparge loop. My lauter tun also sports an external copper coil manifold that loops around the lower third of the tun before it is allowed to spray onto the goods. It works like this: The sparge liquid is delivered to the lauter tun through a ⅜-in. copper tube that splits into a manifold made up of four separate 5/16-in. tubes. The manifold tubes reconverge into another ⅜-in. tube and from there the whole sparge is directed up to the sparge arm. This sparge loop helps to maintain the temperature of the mash — critical to a swift runoff. It goes without saying that this entire heating loop can be bypassed, if desired.
Hop percolator: You can assemble one of these in a variety of ways, but I opted to start with a 2-gallon Cornelius affair from a soda carbonator (see figure at right). I adapted it by adding a finely perforated stainless “bucket” from a scrap yard that fit inside with ½-in. space all around. I cut the lid off the Cornelius keg, sawed out the keg hatch with ½ in. of flange, and threw the rest of the original lid away. The hatch is a standard Cornelius hatch — it’s how I get hops in and out and clean the inside. Then I cut a circle from a fresh scrap of steel to serve as the new top, welded in the Cornelius hatch, and added a CO2 fitting (for venting) and a 1½-in. Tri-Clover elbow to connect the keg-cum-percolator to the brew kettle. Once all that was welded and cleaned up, I welded the perforated basket to a narrow solid rim and then to the lid assembly. When I was finished attaching those parts I polished the welds thoroughly. Then, I welded a 1-in. Tri-Clover fitting very low on the side. The final task was to weld the whole lid assembly to the rest of the can, align it in such a way that the large elbow pointed away from the outflow fitting on the bottom. For obvious reasons, it was impossible to polish the lid weld like the others, so I always use great care in cleaning and sanitizing around it.
I use the hop percolator to add hop aroma by charging it with hops, or simply use it empty as a coarse filter to remove hops from the wort. I usually sanitize it by boiling a little water inside it, and then I load it with a pound of hops and attach it to the matching 1½-in. valve at the bottom of the brew kettle. I fit an open-ended gas hose to the gas fitting and clip it so the open end is above the liquid level in the kettle. This vent tube allows air to escape from the percolator as it is filled by wort, and making its opening higher than wort liquid level ensures that none will spill out.
At the end of the boil I allow the wort to settle for a few minutes, then crack open the big valve until the percolator fills with wort. After letting the wort do a little more settling, I open the valve attached from the bottom fitting to the pump (and thence, to the wort chiller) and pump wort through the chiller to the waiting carboys.
In-line aerator: This little gizmo (below) guarantees that my aquarium pump does an adequate job of getting oxygen into the wort. It consists of a tee fitting into which the unaerated wort enters and from which aerated wort exits. Air is pumped in through a ⅛-in. compression fitting. The compression fitting holds a few inches of ⅛-in. stainless tubing that protudes into the fitting. A pump with a sterile filter in the line attaches to the other end of the ⅛-in. tube. Before attaching the hoses I slip a disposable plastic aquarium “stone” snugly over the tube. I turn on the pump as the cooled wort is transferring into the carboys so that the foamed wort has to go through a few feet of tubing before hitting the carboy. With this device I’m noticing quicker starts compared to those aerated using the same stones simply immersed in the cooled wort.
12-gaIIon unitank: This was a project to see how far I could press my fabrication skills. Fermentation vessels require an interior finish of such quality that it represents a quantum leap over that of other brewhouse vessels. Any pit, crack, or scratch can harbor bacteria. Building a reasonably sanitary fermentor entails spending 20% of the time cutting and fitting, 10% welding, and 70% grinding, sanding, and polishing.
I constructed my fermentor from an 8-gallon milk can, a Cornelius-type hatch, various Tri-Clover fittings, and two rolled-up bits of stainless sheet. I welded and finished it in two halves; I did all the polishing work on the halves while I could still access the areas that needed work so that the only seam I had to grind out after the vessel was assembled was the one around the middle.
So far, I have made one batch of very nice beer in my handmade fermentor; however, my verdict on it is still up in the air. A couple of seams still contain a few pinholes that warrant hauling the fermentor back to the high school and having another go at it. I’m fairly sure I’ll eventually end up with a serviceable vessel, but as an investment of time versus utility, this project turned out to be no bargain. Still, I learned a lot and am a better welder now than when I started, so the next one probably wouldn’t be as difficult. The grinding and polishing it takes to finish the welds is a tedious, demanding, filthy job. I have acquired a profound respect for those who build this kind of equipment for a living.
My real goal, aside from the remote-operation satellite brewery mentioned at the start of the article, is to have a brewing system that functions effortlessly, can perform any brewing operation, and has the look and feel of a fine craft object. I ultimately envision an arts and crafts hammered copper kettle with decorative hop and barley flourishes, loads of mahogany and teak, and perhaps a touch of decorative tile. But for now, at least, I am happy to have my brewing jalopy fully functional while I make my junkyard rounds in search of parts to supplement the Buckapound Brewery.
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