Homemade Coffee Burr Grinder

I’m on a quest for better coffee in our lives.  One of the victims of our austerity measures has been premium coffee.  First we stopped buying from the local shop that roasts their own beans and switched to Trader Joe’s coffee.  It was a little cheaper and a step down in quality but tolerable.

After the next set of cutbacks we switched to bulk coffee from a NM roaster that was being sold at Sam’s Club.  The price was much better but you had to buy 3 lb bags of the stuff.  The lower quality of the beans was obvious so I mixed it with some of the Trader Joe’s to help the flavor.

The next go-round I figured “What the hell? We’ve come this far down the road…” I squeezed that last bit of room out of the coffee budget and bought Sam’s Club Brand Coffee.  It’s not very good….at all.

Molly:  OK mister, I may have Scottish genes but I’ve got to drink this stuff in the morning.  Can’t we do any better?

Mike: Hey! I’m doing my best with what I have to work with.

Molly: Really? No coffee improving robots or anything??

Mike: Well, now that you mention it…

I’ve been researching coffee and coffee making for a while now trying to see what I can do to improve our morning pot of joe without spending a fortune.  We want maximal awesomeness in a cup for minimal investment.

There are a bunch of factors that go into how good a cup of coffee tastes:

1.  The Beans-  Better beans, ones that have been grown and processed with care, taste better and cost more.  Bulk commodity buyers are buying by the shipping container not the sack and aren’t as concerned about quality as price.  Freshness is an issue too.  Once roasted coffee beans are very perishable.  Even week old beans have lost a lot of their quality.

2. The Roast-  Dark, light, full city  It’s a matter of personal preference.  We’re fans of the darker side of the continuum but sometimes you find french roast that is synonymous with burnt beyond recognition.  Lighter roasts can show off the varietal differences of different beans if you’re into that sort of thing.

3. The Water–  Duh! bad water makes bad coffee.  Use good tasting water.

4. Regular vs Decaf –   It takes a good deal of processing to decaffeinate coffee and that costs money.  As consumers we don’t want to pay extra for it.  The producers solve that problem by starting with cheaper beans so they can hit the price point the market demands.  That’s why decaf often tastes like something scraped up off the road.

5. The Brewing Method-  Making coffee is a balancing act of extracting the flavors you want and leaving the other less desirable flavors behind.  Again, everyone has an opinion.  Drip makers are convenient and do an OK job.  Some people live for espresso and wouldn’t settle for less.  Each preparation style produces a slightly different result.

6. The Grind- OK,  now we are getting picky but…the fineness of the ground coffee particles needs to be matched to the brewing method.  Coarse for a french press, finer for drip all the way up to superfine for espresso.  Particle uniformity matters too for optimum extraction.

After looking at the above factors for achieving a great cup of coffee It’s clear that I’ve got to take roasting coffee into my own hands.  Buying green beans and roasting them at home takes care of the lion’s share of the dilemma.  Green beans on average cost about half of roasted beans even with delivery added in.   That’s a lot of margin to buy fancy pants high quality beans and still save money.

Green beans last for years so you can buy a bunch and just roast what you need for a week at a time.  Sweet Maria’s is one of several green coffee purveyors that sell all sorts of varieties of beans.  They even travel to the growers and work with them directly to ensure they are getting the best coffee possible.  Cutting out the middlemen saves us money and returns more to the producer.  Everyone wins.

This, however,  is not a post about coffee roasting so you’ll have to wait till I build my roaster before we go any further into it.  Yes, it’s in the works along with the robot.

Today we’re talking coffee grinders.

The standard coffee grinder has a whirling blade that chops up the coffee indiscriminately producing a mix of fractured bits of coffee bean.  You end up with a little of everything and don’t have much control over a fine grind vs a coarse one.  Blade grinders also generate a fair amount of friction which generates heat and can alter the taste of the coffee.

Enter the burr grinder.  A burr grinder grinds coffee through a set of serrated teeth.  This produces a more consistent particle size which allows for a better extraction.   The distance between the teeth can be adjusted so you can get a finer or coarser grind depending on the application.  Burr grinders also turn more slowly than blade grinders so they don’t create heat issues.

I came across a coffee grinder design on Instructables that mounted a manual burr grinder onto the end of a Kitchenaid mixer to turn it into a powered grinder.  I loved the idea and immediately decided to make one.

Molly:  He’s just like that.  There’s no stopping him once he gets going on one of his projects.  We just let him do his thing.  As long as I still get dinner I’m OK with it.

Is getting slightly better ground coffee really going to make a difference in our daily routine?


Is building a mixer powered coffee grinder going to save any money?


Is the unholy marriage of a mixer and a coffee grinder too cool to pass up?


The build

I’m just going to hit the highlights here.  You can find all the step by step details on Instructables.

First, I set out to the shop to see what I had that might get the job done.  There was broken angle grinder that would be perfect to transfer the drive from the end of the mixer to the coffee mill.  I rummaged around and found a few brackets and whatnot that looked like they might be useful.

Angle grinder head

Believe it or not this is going to be very useful

I was also going to need a manual burr coffee grinder.  I looked online and saw that they weren’t cheap.  With a budget of as close to $0 as possible I was stumped.  Just as I was about to head out to do a round of searching at the local thrift stores I spied our peppermill.  It looked suspiciously like a turkish coffee grinder.

I did a quick test of running some coffee beans through it and I’ll be darned if it didn’t grind coffee just fine.  It was very slow and tedious though so motorizing it was definitely a necessity!

Turkish coffee mill

We see you Mr. fake pepper mill!

I needed to find a way to make a connection between the mixer and the head of the angle grinder.  I had a threaded extension from a drill accessory that would work with a little lot of modification.  I took the grinder head apart, drilled the end of the shaft out and tapped it for the extension.  I also ground the end of the extension into a square shape to mate with the square hole of the mixer.

I did a number of other adustments to the grinder head and ended up with a working device that would transmit the power from the mixer to the coffee mill.

I ground several batches of coffee over the next couple of weeks just holding the coffee grinder to my attachment.   It was working but I needed a way to attach the two together.  After mulling it over and talking out various ideas I decided to just start making paper and cardboard mock-ups and see where it led me.

I eventually settled on a design that looked like it would work and transferred my cardboard patterns to copper sheet.  I cut out the copper, bent it and riveted it into place.  It took some fiddling but eventually I had the coffee grinder mounted to the power drive from the mixer.  Lastly, I made a spout so that it would be easy to fill the grinder.

All in all it worked out pretty well.  It looks like some sort of future / traditional tech.  It’s still kind of slow but works well for a single cup of coffee or a double shot of espresso.  I think you can taste the difference.  Coffee ground with the burr grinder tastes richer to me.

Next up I’m hoping to combine a propane grill, an electric can opener and some stainless steel screen into the ultimate backyard coffee roaster!!!

Molly(rolling eyes):  No folks, he actually means it.


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