Auf Wiedersehen PET


This week marked the end of 8 years of roasting on our Petroncini machine. A coffee roaster is just a tool but like any other tool the more you use it the more it seems to fit your hand and the connection with user and instrument becomes more than just a physical one. A roasting business relies heavily on this single piece of equipment and our 'PET' has been foundational in its growth.

Those of you that have been along for the entire journey so far would know that Dave bought the machine unseen and untested from someone in the Czech Republic through a UK broker. There were a couple of fuzzy pictures, promise of a manual and absolutely no guarantee of operational condition. ie. it was a big £15k risk. On arrival its general appearance, functional readiness and lack of TLC from the previous owner were obvious and very disappointing. A one page manual in Czech, some components that had seen much better days, and no clue as to how run a 3-phase powered machine off a domestic electricity supply did not inspire an auspicious beginning.

Looks like a coffee roaster.. but does it work ?

No 100 off the production line of this T7.5E model built in 1995.

It took time, money and a significant amount of help from friends (Richard in particular needs a mention) to get the machine working in Dave's garage, and then it was all systems go.. or so he thought. Learning how to roast felt a little like learning how to drive. It seems impossible to think about using one foot to operate two different pedals and at the same time steering the vehicle, changing gear with one hand and using the other foot to disengage and re-engage this clutch thing whilst navigating the roads, being aware all the time that you could crash and cause the vehicle, yourself and/or someone else serious damage.

With a coffee roaster, harm to someone else isn't such an immediate concern, but you are working with fire and some very hot moving parts, with a goal of turning green coffee a nice even shade of brown and allowing the potential of the coffee to come through to result in something delicious when brewed. One (of the many) mistakes Dave made in those early days was to buy cheap green coffee to use to 'learn' how to roast. There's absolutely nothing to be gained from cheap low-quality coffee. It's never going to taste good regardless of how it's cooked (after all that's what coffee roasting is in its essence), so a minute here or there, 5C degrees here or there means nothing. The coffee would taste 'bad' (underwhelming, flat, uninteresting) regardless. Obviously very badly roasted and it'll taste grassy or burnt but beyond that it's of little value. 

Where it all started

In 1995 unlike today, a coffee roaster was 'designed' with some very basic controls for gas and air. ie. ON or OFF for gas, and a baffle for rudimentary air-flow adjustment. Clearly the Petroncini had been used simply to turn cheap coffee from green to very very dark brown with a hint of oily black. Learning how to 'control' the machine with these basic controls was a challenge but it wasn't long before Dave started acheiving some decent roasts with some consistency by adding some better temperature probes and connecting them to some recording software. A few sales, a little money coming back in to spend on better quality green coffee (the essential component), a web site and Crankhouse was a GO.

The roasting process enables a myriad of complex chemical reactions to take place inside the seed, which done well results in beans when brewed give some characteristics of the nature of the coffee (origin, processing etc). Of the many reactions, some that happen towards the end of the roast generate smoke as the cellular structure breaks down. Unless blasted with another heat process (aka afterburner), this goes up and out of the flue into the surrounding environment (that's why medium to large roasting businesses are in remote locations on industrial sites away from residential areas). Even though the PET had an afterburner it didn't work very well and one of Dave's neighbours took offence to the smell eminating from his garage and made numerous calls to the councils environmental health department. One day whilst Dave was roasting there was a knock on the garage door by a nice man from the council.

Oh - hello.. yes, please come in Mr EHO man

After the EHO visit and a warning to move the 'business' to a commercial site the Petroncini was relocated to a converted barn at Longdown on the edge of Dartmoor. Remote, idyliic and very very quiet. With the help of Richard (again) and a very generous neighbour (thanks Paul), Dave took the opportunity of the move to strip the machine down and get it tidied up. Powder coating, new bearings, new thermocouples AND a new fully modulating burner (thanks to David T). Better than a new one. Full control of gas and more accurate and responsive temperature readings meant the PET was more like an instrument than the blunt tool it had previously been. A great place to focus on growth and quality.

View from the roastery window at Longdown

Longdown was nice but the vision was always to have a retail roastery space that people could come and see the operation first hand and experience the sights, smells and noises. To get immersed into the process whilst drinking something delicious roasted only a few steps away. In 2019 an opportunity came up for a perfect site just off Fore Street in Exeter, with a dedicated production space, room for a cafe and a separate training and education space. So the PET made one more move and had a few more modifications and improvements (David T again). Even better than before. It needed to be since business grew and Dave began buying some extraordinary coffees with special processes and remarkable flavour profiles that required very precise and consistent roasting.

2019 next step, big step, step up. Keys to a retail-roastery space in Exeter

Now the PET is turned on 5 days a week and roasts approximately 250-300Kg of coffee per week. Still a small roasting business, but it does mean that someone has to stand in front of a hot noisy rotating oven for many hours and be attentive to the way the coffee is responding, making small adjustments to gas and air to achieve the desired profile. It's physically and mentally tiring work. It's time for a bigger machine.

Yesterday Dave roasted his last batch EVER on the Petroncini. Thousands of batches, tonnes of coffee, some incredible award winning micro-lots exclusive to Crankhouse and a growing reputation for quality and consistency amongst peers and customers. It's being dismantled over this jubilee weekend and will go to its new home in Brighton. The new owners have promised to look after it and once they learn how to depress the clutch, engage 1st, release the clutch, move the other foot off the brake onto the accelerator, whilst steering to avoid obstacles and obeying the road rules to get to their destination they'll be producing some amazing coffee!

Next step, big step, step up.

1 Comment

  • Roberto on

    What a nice read! All the best with the new beast!!

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