Grin and Replace the Bearing: DIY Coffee Roaster Repair
This week I thought we would take a look at coffee roasters (the machines, not the people). How a roasting machine works, what can go wrong and how you can fix it. Be warned – the following content is only suitable for hard core coffee geeks. Still reading? Then let's dive in. In this installment, we'll discuss how to replace roasting drum bearings.
Coffee roasters are amazing machines. Pound after pound of coffee beans cycle through day after day, year after year, with nary a hiccup. Many of them are elegant, even beautiful, in a certain shiny, industrial-design kind of way. They're fairly simple mechanisms with variations on just a few basic parts: a heat source, a rotating drum, and an exhaust system. Like any machines, coffee roasters require regular maintenance to keep operating properly. Still, sometimes things break down and require repair or replacement.
Our trusted Diedrich IR-3 had been merrily roasting coffee for years with just basic cleaning and lubrication. Most conventional drum roasters rotate on a shaft held in place by two bearings, in front and in back of the drum. The front bearing on our roaster started to make occasional popping noises. It also became harder to lubricate the bearing through the Zerk fitting. After research and much pondering, I concluded the bearing's lube passages were blocked and it was starving for grease. It still turned fine, but was only going to get more noisy as time went on. It was time to replace the bearing. New bearings can be obtained directly through Diedrich Manufacturing in Sandpoint, ID. They are also available from Grainger Industrial Supply.
It seemed like it would be a huge ordeal, but turned out to be a pretty simple job. I placed a block of wood underneath the drum to prevent it from falling once the bearing was removed. The two sides of the bearing were marked with a pencil to help position the new bearing once it was in place. Two set screws are used to hold the bearing to the drum shaft. I loosened these with a hex head wrench. The two bolts that hold the bearing to the faceplate were then removed. I was concerned the bearing would be stuck to the shaft because it had been on it so long. The moment of truth had arrived. I carefully put two flat head screwdrivers underneath each side of the bearing and pried outward. It came off with no problem.
After cleaning up the shaft I installed the new Timken bearing. The bearing bolts went back in and after aligning the new bearing with the pencil marks I tightened them up. Done!
I heated the roaster up and checked the gap between the drum and faceplate. Everything looked and sounded good. Ready to roast.
A lot of maintenance and repair can be done yourself. You'll save money and learn something new about your machine for the next time something goes wrong. Plus, it's pretty satisfying to fix something on your own. Of course, every situation is different; what worked so easily for me might not for you. Disassemble at your own risk. Take photos of each part in place if you think you might have trouble getting all the right bits back together. And remember that there are definitely situations where calling in the experts is the way to go. Learning to recognize when you're in over your head is a big part of do-it-yourself repair work.
Good luck, and good roasting!