Workshopping: Vintage wooden coffee grinder restoration

If you are a woodworking coffee geek or a coffee drinking wood nerd, you might be thinking about breathing new life into a decades old coffee mill. If so, here are some of the shop supplies you may need to complete the project.

Vintage wooden coffee grinders speak to me, especially European models manufactured in the 1930s through the 1950s. These are interesting objects from an industrial design perspective. The materials—mostly beech wood, but also cherry wood and walnut—also appeal to me. And, best of all, quality grinders built during this period have good manufacturing tolerances, and often have useful life left in them.

Over a period of years, I’ve restored a dozens of these hand grinders as gifts—weddings, birthdays, housewarmings, births and so forth—for friends and colleagues. In most cases the vintage mill, with its hardened steel conical burrs, is an upgrade from an electric whirly blade grinder. It not only produces better results in the cup, but is beautiful to behold and enhances the ritual of making coffee.

For a minor restoration projects, I clean the burrs, lube the burr axel and polish metal parts, which requires a fair amount of disassembly. For a frame up restoration, I completely explode the mill so that I can also strip and refinish wooden and painted parts. Here is a list of useful shop supplies for these types of projects with links to representative products:

Coffee cleaner: Regular detergents and dish soaps are no match for decades old rancid coffee oils. So get yourself some coffee cleaner. If you are just doing a one-off project, your local cafe might sell or give you some. You only need 1 or 2 teaspoons per grinder. Soak the burr set for up to 24 hours, starting with boiling hot water, in parallel with the woodworking projects. Some burr sets require two rounds of soaking.

Metal polish: While there are many products to choose from, I’ve had good results using Maas polish. Many mills require multiple applications. I often use metal polish in conjunction with very fine steel wool or sandpaper or even a Dremel tool with stainless steel brush attachments. Be especially careful when using any abrasive on a plated metal. The plating is often very thin; if you remove too much plating, you’ll reveal the material underneath.

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Food-safe lubricants: Many of the better European coffee mills are designed such that the burr axel rotates on top of a small ball bearing that is held captive in a tiny cup. As part of any restoration project, you will need to repack this bearing in a food-safe grease like PETROL-GEL, which I found locally at a restaurant supply shop. You can also apply a thin layer of this heavy grease on the inside of the upper burr axle bearing, as this is a potential source of wear and squeaks. Many old grinders also have squeaky handles, which you can address by applying mineral oil to the handle knob axle. (Note that drugstores, like CVS or Walgreens, generally sell food-safe mineral oil at better prices than home supply or woodworking stores.)

Stripper: Stripping old finishes off of wood is a nasty process, really. If you want to make quick work of it, you have to pick your poison: gel stripper, liquid stripper, spray-on stripper. It all works more or less the same way, bubbling up the old finish, which you can then scrape off. I have some heavy duty gloves that I use for this process only. If you prefer a less aggressive approach, consider Formby’s refinisher. (Note that you can remove paints from metal surfaces simply by soaking these in boiling hot water with some dish soap or coffee cleaner added to it.)

Finishes: The simplest way to re-finish (seal) the wood after you have stripped, sanded and prepped it is to use a clear spray-on lacquer. Since these products are fast-drying, you can apply multiple coats in a relatively short period of time. If you are using a brush-on finish, like a water-based polyurethane, it is difficult to get finish that is as smooth as a spray application. My favorite way to finish old mills is to mix dewaxed shellac from flakes with denatured alcohol to about a 2-pound cut. I apply this shellac using a cotton pad, building up the finish in multiple passes. Once I am satisfied with the shellac finish, I apply a spay-on lacquer clear coat over the shellac for additional protection.

Spray paints:  Some mills have painted hoppers, handles or drawer pulls. The best way to select a product for this application is to take a color sample or a sample part to the building supply store and look for a spray paint with the desired color and finish. The best product I have found for the hopper funnels is a white appliance epoxy. Make sure to verify that these products are compatible with the material you are painting. Also, be sure to read and follow the reapplication instructions.

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Abrasives: I use multiple types of abrasives, including sandpaper, steel wool and synthetic abrasive pads. I keep sandpaper in 60–320 grit for wood surfaces, as well as 400–1500 grit for metal surfaces. I keep a wide range of steel wool on hand with an emphasis on the fine end of the range (0–0000 grades). However, I rarely use steel wool on wood or finishes, as the so-called synthetic steel wool products serve the same basic function without leaving any metal materials behind on your work surface. I also keep polishing wheels, pads and buffing compound in inventory.

Hand tools: My most commonly used hand tools for coffee mill restorations include: tack hammer, hobby knife kitChapman screwdriver kit, miniature pry bar, vice grips, small pliers, metric wrenches and sockets, bench-mounted vices, clamps, scrapers, etc.

Power tools: My most commonly used power tools for these projects include: orbital sander, Dremel tool kit, and a cordless drill.

Misc: Wood glue, wooden chopsticks or skewers (whittle down and glue into old nail and screw holes prior to reassembly for a tight fit that will last decades), painter’s tape, sanding pads, disposable latex gloves, safety glasses, lint-free cotton cloth, etc.

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