By the time the sun rose on Monday morning, the itch to restart the Munich Helles brew just needed to be scratched.

But first, we needed to do some repairs to our trusty rig.

It was fascinating to look more closely into the failure. The wort had obviously gotten very hot as there was a lovely caramelised wort plug in both the nylon hose that had failed, and just after it in the copper pipe where the temperature probe was housed.

The nylon hose had failed immediately on the chamber side of the plug. This makes sense, as the super-heated wort would have been under pressure, partly from the pump trying to push it through the obstruction, but mostly from the heating in the chamber.

The hose failed because the nylon was forced outwards away from the reinforcing twine with a combination of temperature and pressure. The main failure point shows a 5mm hole.

We decided to remove the plugged inline temperature probe for now and use the probe where the wort enters the mash tun as the probe used in our PID control. This simply meant installing a slightly longer nylon hose to connect the heat chamber to the rest of the system.

We also removed the heat chamber to clean it thoroughly and to test and clean the element. The result here was surprising.

The element was in very good condition considering what had happened, with only the smallest amount of carmelised wort present. I suspect that the machine had tripped off on an earth leakage well before the element had a chance to burn itself up. This could have been for any number of reasons, but hot sticky wort found itself into several 240VAC plugs, any of which could have tripped the breaker.

We replaced the faulty connecting cable between our control picaxes, coded in a failsafe condition in the control picaxe, and then completed our quickest brew day ever, taking 3 hours 40 minutes to have everything fully cleaned and packed away.

The next step will be to upgrade our control buttons.

cheers, Arnie.

This article from Dal Wheeler gives ideas about aligning double-sided boards, and also about using a laminator rather than an iron to get the transfer onto the board.

Thanks Dal.

Decent PCB's on the cheap

A year or two ago we experimented making PCBs using glossy photo paper but found it incredibly frustrating with results that were not anything like many in the US who used the method.

It seems that the paper available locally is likely the problem - more specifically it is likely the papers we were using were too high a quality.

Alberto Ricci Bitti suggests that early glossy inkjet paper had a gloss that was water soluble. These papers worked because the gloss would dissolve in contact with water, leaving the ironed-on artwork on the copper board.

These papers are now waterproof - good news for photos, but not for PCBs.

In the following link he explains how cheap glossy advertising magazines are ideal for using. As they come free, they are also a lot cheaper than the blue Press n Peel sheets that we normally use.

PCB making tutorial

Last night we had a catastrophic failure on HERMAN 

In the space of a few minutes being distracted when a friend arrived, HERMAN went from a normal HERMS mash to spilling all the mash liquor and scorching the heat chamber element.

The first sign that something was wrong was a burnt element smell. The second obvious sign that things were not well was that the machine had tripped off on an overload. The third obvious sign that things were really bad was the absence of liquor in the mash tun.

From there, a bit of CSI-type sleuthing was needed.

The leak was easy to find. On the outlet side of the heat chamber we have a very short length of reinforced nylon hose that joins the chamber to the rest of the plumbing. This is in effect a safety valve - and it had done its job and ruptured.

The pattern of wort spray suggested there had been some pressure behind the rupture, although at this stage we did not know why. The other important bit of information was that the driver circuit to the heat chamber was showing itself to be 100% powered on - where it should have been a relatively low duty cycle like 20%. (The control gear has a battery backup, so was still running).

The penny was beginning to drop. We knew there was an occasional faulty connection in the cable that connects our main picaxe chip to our control output chip. The problem with the picaxe we are using for outputs is that if a serial command is not received properly (as can happen because of the faulty cable), then it will wait and wait and wait until things are received properly.

At best this means that controls are not updated. At worst, controls will freeze in their current state, whatever that happens to be. It just so happens that the coding has not added a failsafe to ensure outputs stay OFF once serial communication has been initiated. Some simple coding could have prevented this disaster ...

At least I can be a little philosophical about it. If I had fixed the connecting cable earlier, I would not have considered coding in the failsafe. The problem could have lurked around for a lot longer because one masked the other.

Anyway, the graph below captured the story of what happened while we were distracted. The purple line shows the liquor temperature just before it is returned to the mash tun. The red line shows the mash tun temperature. You can just see it beginning to rise on the right (it actually rose quite rapidly after this point). The purple line rises dramatically and then almost flatlines as the temperature back into the mash can barely get any hotter. It peaks at 91 degrees C. The green line is the heat chamber temperature. It is easy to tell when the control system failed and turned on the chamber to 100% power. At the 24.5 minute mark (probably the time the doorbell rang) things went terribly wrong. The green line keeps rising until the chamber is boiling. At 29 minutes the purple line drops dramatically. This is the point where the hose has ruptured and the liquor is no long recirculating.

 OK, so we lost all our wort, and we may have lost the heat chamber element (yet to be tested). But we have also gained insight into how important failsafes are when you are trying to automate things like pumps and 3600W heating elements. It highlights how important it is to finish jobs as well. We even have a liquor sensor plumbed into the outlet of the heat chamber, but it is not yet connected to anything.

Having said all that, it will only take a few smallish tweaks, and HERMAN will live again.

Many years ago I went searching on the net for paddle designs for mixing grains and water during dough-in. I have built a wooden mash paddle, and it still comes in handy on occasions, but having mechanical assistance at this point makes things so much easier on brew day.

The original paddle design for HERMAN came from a long lost source on the net. Thanks to Jye who recently alerted me to the original article here at Brewing Techniques. The beauty about this design is that it creates mixing "currents" which seems to help the process along quite nicely.

I made my paddle from copper because it was easy to manufacture with the skills I had and equipment at home. It has done very good service over the years, and I'm sure will continue to work very well.

Having an affinity for things shiny (especially stainless steel), we began to think about how we might make a mash paddle for the new HERMLET project. The old spire from a 50 litre keg seemed the ideal starting place for a shaft. For the drive, we have a 12V automotive worm-drive window-winder motor that looks like it has enough torque to cope with dough-in.

It was Leah who came up with an ingenious blade idea. She suggested we use stainless steel serving spoons. So for a few dollars we bought 4 spoons and cut half the handles off, cut matching slots in the shaft - and presto, an all stainless mixing paddle for HERMLET.

The final feature in this paddle is that the spoons have been mounted on a slight angle to the shaft. This means that on one side the paddles will push the grains down, while on the other side they will be lifting the grains up. This mimics the idea from the original paddle to create a mixing current.

 To fix the blades in place and to couple the shaft to the drive motor, we figured the simples thing was to pour epoxy down the tube and embed some stainless bolts on the top to mate with the motor. The longer piece of wood in the photo below has a 25mm hole bored into it. This acts as a plug for the bottom of the drive shaft to prevent epoxy from leaking out. The smaller square of wood is the fitting for the top of the shaft. Using a template we drilled holes to match the spacing required for the bolts to mate with the motor. What you see is about 2mm of the bolts extending above the timber plug. The underside of this piece has a 25mm hole as well, with the rest of the bolts for embedding into the epoxy at the top of the drive shaft.

 The photo below shows the timber square in position on top of the shaft. The motor above gives an indication of how the two will mate to drive the paddle.

Once all seemed ready, we eagerly poured epoxy down the spire.

But we had forgotten to plug the small openings where the blades fit ...

So after a quick patch up job with blu-tack, we tried again ...

Once things had cured, we drilled a hole in the bottom of the shaft to locate the paddle in the centre of the false-bottom. A timber platform on top of the tun holds the motor in place over the shaft.

You Tube video of paddle

Another happy day inventing ... now it must be time for some product research.

In a recent blog I mentioned my excitement at discovering Dan Ward's book called The Simplicity Cycle. Having devoured the concepts and been inspired, I've been doing some work to apply good design to the HERMLET project.

I spent some time this morning working on a menuing system for the machine, and this continues to be a work in progress. There are several ways where simplicity has already made for a better product.

While musing over lunch, another piece of the simplicity jigsaw fell into place. The original HERMLET idea called for the mash tun to be inserted in the boiler and operate in a manner similar to a double-boiler. After mashing, this meant the mash tun needed to be lifted above the kettle and the liquor given time to drain from the grains.

To automate this process is more complex than I had wanted. The use of an electric hoist, and a way to simply disconnect plumbing during the raising process had bothered me since the original idea was conceived.

While thinking about the various capacities of the tun and kettle and fermentable wort, I considered that if the mash tun was raised a little out of the kettle, the system would be capable of holding more liquor during mashing, particularly because the pump would keep topping up the mash tun before all the liquor could be drained out of it.

BINGO! Why not put the mash tun above the kettle - not partly inserted, but fully above?

The grains in the mash tun ought to slow down any liquor that might want to overfill the kettle. The pump can be throttled back so that the mash tun does not overfill (although an overfill would simply have liquor returning to the kettle anyway - it just would not be very elegant!).

A sensor or two in the mash tun could show when the pump ought to be turned on or off, and for this extra complexity, there is the bonus simplicity where the mash tun will not need to be raised or lowered.

... it might make it a bit hard to claim this as a one vessel brewing machine now though. ;-)

In the Make: tools n' tips email that I just received they mention a book by Dan Ward called 'The Simplicity Cycle'. It's thesis is that design ought to be simple and elegant, not too clever or complicated.

As a maker who struggles to keep things simple I was immediately drawn to look further. I was pleasantly surprised to find that it is available for a free download.

The HERMLET brewing machine project was conceived from a simple idea, and I think I'm probably in danger of over-complicating it again. Thanks Dan for making this text available.

"What are we going to do today, Brain?"

"Same thing we do every day, Pinky...
try to take over the world."

The 'Pinky and the Brain' cartoon kind of captures the vision of Google, as their search engine, mapping, picture sorting and 3D software seems to be more pervasive than even Microsoft.

I'm not much of a conspiracy theorist, just observing the ever far reaching and clever marketing of Google. In fact I'm quite impressed by how clever it is.

I downloaded their 3D drawing program, SketchUp, the other day thanks to an article in Make: magazine about it. It is the kind of 3D program I've been looking for for ages. Not only is it a free download (the best price, you could argue), but it is so easy to use. The integration of wonderful tools like online catalogs of structural components, and the ability to draw a building and then place it directly in Google Earth for everyone to see is quite impressive.

I guess they are very clever at understanding human nature and pitching it to their advantage. I am not concerned enough about Google filtering my web searching with their own specific algorithms that might miss some things to do anything about changing my search engine. I like what Google gives me and especially how easy it is to use. And then they make it even easier, and now I have a little toolbar on my web browser so that I can find google anytime.

And their photo program, Picasa, is easy to use, and the kind of photo sorting program I've wanted for ages. I can now very simply catalog the many digital pictures I have and never lose them again through poor sorting. I haven't even begun to look at putting photos online to share with friends.

And then back to SketchUp. How clever to allow a worldwide web of individuals who love to play with their computers and have lots of disposable time to create cities in 3D and add them to Google's own tool to take over the world, Google Earth! I'm not one with enough time or the desire to do it, but what a great marketing angle that has a flow-on benefit to me. A free 3D program that I can use to design anything I like.

So I can admire Google's efforts to take over the world, and in particular their clever understanding of human nature. Now ... it's time to make something ...