I bought my first espresso machine in the 1990s. It was a La Pavoni Europiccola, a small, retro-looking chrome job with a big lever you yanked down to express the coffee. It looked great on the counter but made vile coffee, was a bugger to clean and constantly threatened to explode in a shower of steam and shrapnel. When, one glorious day, it blew a gasket, I seized the opportunity to upgrade, but I needed advice.

A reasonable person might assume that coffee obsessives would gather in coffee shops, but these days they lurk in the labyrinthine OCD souks of internet chatrooms. In pursuit of the perfect home espresso - what they call "the God shot" - I gleefully joined their ranks, kicking off the most expensive and pointless addiction of my life.

The ideal espresso (according to the Instituto Nazionale Espresso Italiano) is a 25ml beverage extracted from around 7g of finely ground coffee, using water at a temperature of 88C, passing through the grains at a pressure of 9 bar. See, dead easy. It should be thick-textured, having emulsified many of the oils, retain most of the volatile aromas and flavours of the bean and be capped with a thick colloidal foam layer - "crema" - reddish, creamy and flecked. Each one of those factors is minutely variable, potentially causing thinness, bitterness, under- or overextraction or - the ultimate humiliation - a thin or patchy crema.

My first mistake, according to my online coffee-nerd chums, had been to buy a manual machine - they are spectacularly inconsistent. So I invested in the legendary Rancilio Miss Silvia (£310), the cheapest acceptable electrical-pump machine and, for a few blissful weeks, I chucked in a couple of scoops of ground Illy every morning and got out a nice little espresso. Then, one day, the crema failed to appear.

I returned despairingly to the chatrooms, where it was suggested that my problem was with the grind of my beans. Who knew? After much debate and guidance, I purchased a Rancilio Rocky (£180), one of the cheapest grinders operating with "burrs" rather than blades, which give a consistent grind without compromising the volatile oils. It was still expensive and took up as much counter space as a small shed. The fresh-ground beans definitely improved the flavour, but now the texture of my "shot" was inconsistent.

Millions of people probably get great coffee every morning with a standard home machine and ground coffee from a supermarket. I was starting to worry that, with a process that has as many variables as pulling an espresso, once you're daft enough to go off piste, things get monumentally messy in a way only explicable with chaos theory. Emails flew, recommendations were exchanged and argued. I could, they suggested, work on my "tamp pressure" - that bit where the barista scrunches down the grounds into the "basket" on the machine is crucial to the brew. I was, they said, going to need a tamper, custom-made for my machine and tamping hand by Reg Barber in Vancouver. After shelling out £75, and hours of practice with my new tamper on the bathroom scales, I got the hang of applying consistent pressure when packing the grounds, but still the perfect crema eluded me. "Temperature,", suggested the Nerds. "The mechanical thermostats on the boiler of your machine can be inaccurate to at least 10 degrees either side - you need to "Pid" your machine," wrote one.

A Pid is a small computer used in labs and industrial-process control to manage temperature. To fit it, you need to find secret instructions written by obsessed academics, hidden deep in websites. You need to ignore all the disclaimers about blowing up yourself and your coffee machine, you need to persuade obscure component suppliers that you are not a bomb-maker, and then you have to take your machine apart and rewire it, thus invalidating any manufacturer's warranty. "It's like a Jedi building his own light sabre," the Nerds said. Which, in truth, is how it felt, until I switched the damn thing on and watched the entire PID unit quietly melt. Obviously Darth Vader never confused the blue and the brown wires.

Another hundred quid and a fortnight later, my machine was Pidded, accurate to within a hundredth of a degree and still turning out crap coffee, which was when they recommended I take an angle grinder to it. This is a fashionable new modification where you chop off the bottom of the portafilter (the bit you put the coffee in that attaches to the machine) so there is nothing between the bottom of the basket and the top of the cup. This allows you to examine obsessively the flow for the characteristic "tiger stripes" of the perfect shot, but shoots half the coffee up the front of your shirt when you hit the "brew" button. Things were getting out of hand. In the following months, though I tried 18 different types of coffee, rebuilt the brew head and fitted an electronic timer to allow the machine to get up to temperature before I woke up, the God shot eluded me.

Today, my kitchen bench looks like a Bond villain's lair. I have invested hundreds of pounds and countless hours only to produce average coffee inconsistently. And what do the Nerds have to say? Apparently, the real pros are drifting away from espressos to experiment with syphon pots, those things resembling two spherical glass vases stuck together that put so many 1950s hostesses into the burns unit.

I've learned a painful lesson. When Giovanni Gaggia filed a patent for an espresso machine in Milan in 1947, it was designed to make coffee in industrial quantities at serious speed. Professional baristas get results because they use huge machines that deliver a thousand shots a day. The hand processes like tamping become consistent after the first hundred. To become barely competent could take me years. The boys in the chatrooms will denounce me as a heretic, but I now know that, for me, the best espresso will always come from an Italian standing coolly behind a big machine, not an obsessive Englishman throwing money at a small one.