Homemade Coffee Burr Grinder




About: I have a compulsion to make stuff, all kinds of stuff. I'm glad to be here...

This project was inspired by jeffkobi's Coffee Burr Grinder Attachment for KitchenAid Mixer.  I was perusing past contests and discovered his winning entry in the coffee contest.  I loved it.  

The power take off on the Kitchenaid mixer is definitely an underutilized resource and his use of it was inspired.  I decided to make my own version of the same concept...well...because I wanted to.

 Let's proceed shall we?

Step 1: Stuff to Get It Done

I used the head of an angle grinder to transfer power from the mixer to the coffee grinder.  My coffee grinder was hiding as a peppermill right under my nose!  Some copper sheet did the job of connecting the grinder head to the coffee mill.

Step 2: We Need Power

The grinder head is perfect for transferring power from the mixer but it needs some modification to adapt it.

Kitchenaid attachments all have a square drive shaft that rotates inside of a cylindrical sleeve. The drive shaft fits into a square socket in the mixer and a set screw holds everything together.  I didn't want to feel left out so I decided to emulate this arrangement.

I had a threaded drill attachment that I ground square on one end to fit into the mixer.  The other end had a male thread so I drilled and tapped a hole into the shaft of the grinder to accommodate it.  I don't have a metal lathe but my friend has a wood lathe that worked just fine for this. 

Step 3: More Adapting

Once I had a drive shaft it was time to work on the outer sleeve.  I did some testing and discovered that 1/2" black pipe made a decent substitute for the sleeve.  It fit into the mixer with only a little bit of play.  Nothing the set screw couldn't handle.  Not bad for an off the shelf solution.  

The next task was figuring out fow to attach the pipe to the grinder.  Lacking a real metal lathe I looked at plumbing parts for a solution.  I ended up going with a floor flange.  It was enormous compared to the face of the grinder but I figured that could be remedied.  

I started by cutting the flange down with a metal cutting chop saw until I had a square about the size I needed.  I mounted this in the lathe and took an angle grinder to it until I had an approximation of a circular flange that matched the grinder.  It still had that handmade look but that's OK.  

The last part of this was to mount the flange to the grinder.  I drilled and tapped some holes for some small socket head screws.  The tolerances were rather close so it was quite a bit of fiddly work but in the end it got worked out.  

The other end of the grinder head was a breeze.  The coffee mill also had a square shaft.  It was dimensioned perfectly for the square end of a 3/8" socket. The shaft coming out of the grinder head had a layer of fiberglass over it and fit very snugly into an 11mm socket so I just took the socket and hammered it onto the shaft.  It friction fit perfectly!

Step 4: Attach the Coffee Grinder

I took the pepper/coffee mill apart just to be sure it was indeed a burr grinder and would work.  It looked like it had the right stuff to me.  I ran a test batch of coffee through it and it worked well albeit slowly.  All the more reason to motorize it!
I didn't want to demolish the grinder in the process of doing this project so I thought a long time about how to bring the coffee mill and the angle grinder together.

I ended up prototyping in cardboard until I had a design that I was happy with.  It only required one set screw into the coffee mill and attached to existing holes in the grinder head.

Step 5: Make It Real

I transferred my cardboard patterns to copper sheet and cut it out with shears.  I decided to rivet it together because it just seemed like the right thing to do.  I punched holes in the copper sheet and used some copper roofing nails as rivets.  A piece of patio furniture leg made a good impromptu anvil.  

After the cylinder for the attachment was fabricated I cut out the spout for the top and attached it with rivets as well.

Step 6: Well?

Yeah it works.  The grinder is best suited for small batches- a cup of coffee or a double shot of espresso.  I like it and have been using it although I wouldn't say it has been a kitchen revelation.  This was more a fun project that I just wanted to make.  I don't usually do much in sheet metal so that was fun to play with.

If you like projects, you know who you are, you'll find plenty more at our site: Mike and Molly's House where we chronicle our Mighty Projects on our Mini Farm (aka our backyard).


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    15 Discussions


    Not very scientific but I would say it turns at a medium speed. Not super fast. The gear reduction in the head slows down the input from the mixer.

    jpalmer-rye iii

    4 years ago

    id have to say perfect for a kitchen with limited space power burr grinders are bulky and pricey namely the kitchen aid models this really could be an idea worth marketing all in all fantasic idea


    7 years ago on Introduction

    Hey, I started a Google Group to try to get people together to share some notes on DIY Kitchenaid attachments. Seems like there are a handful of people playing with this now (mostly thanks to jeffkobi's winning Instructable).


    1 reply

    Reply 7 years ago on Introduction

    I love your grater Osvaldo. Very ingenious.

    I bet we would come up with some interesting inventions if we lived closer together.

    I have to admit I'd been hanging onto that broken grinder for a few years because it seemed like it would be useful for something.

    Any ideas for broken paper shredders? I have three of them :)


    Reply 7 years ago on Introduction

    My grater has some shortcomings:
    1. I should have used the head in the opposite direction, because as it is I have to turn the handle very quickly.
    2. Many cheese flakes fall outside the container, it is easier to solve and I will finish as some other more pressing projects.

    Reply 7 years ago on Introduction

    I noticed how much the motor speed of the grinder is geared down compared to the output of the disk. Guess they need the extra torque. Since the disk max is 10,000 rpms I wonder how fast the motor is turning? (rhetorical, I'm sure I could look it up...)

    Sorry about your hand. Power tool accidents happen so fast they are usually over before you can react to them. I'm very paranoid about damaging my eyes and ears. I rarely keep the guards on grinders. I may have to reconsider that.

    We still get to see the chulengo on Sat right?
    Yum... Barbecue


    Reply 7 years ago on Introduction

    Yes, on Sat, but not next Sat ;)

    My hand is healing, but I can't do certain movements because it hurts.

    Thanks for your concern, and put the disc cover to your grinder, soon! "Don't be stupid as me"

    I like the design very much. The pepper mill burr grinder seems pretty apt for the job.

    I have one caveat: consider using a pipe section made out of something other than brass. Brass looks awesome, and is esthetically an important part of your project, but brass is frequently - almost always - made with a small percentage of lead as part of the mix. This allows the alloy to deal with harsh or corrosive environments, but the lead can and does leach out of the metal. Heat exacerbates this, which is why it is a bad idea to drink hot water out of the tap. Using brass in a hand turned peppermill is potentially okay, but when you add speed, you add heat, and your coffee may end up with significant amounts of lead.

    I apologize for being a buzzkill.  This really is a very cool and clever project.

    2 replies

    That's a good point. It seems like there are always unintended consequences to everything we do aren't there?

    The actual grinding mechanism is steel. The grounds are not warm to the touch as they emerge from the grinder. In addition, the grounds are sitting in the lower chamber for maybe a minute. Not much time for any lead leaching to occur I think.

    If lead leaching still seems like a concern the lower chamber could be removed and the grounds could fall right into a filter cone directly from the burr grinding mechanism.

    Also a good point!

    Mostly, I'm just bummed that brass so frequently incorporates toxic metals like lead and antimony in it. It's one of those things where I just go "huh?" We took it out of our gas because it was toxic, took it out of solder because it was toxic, but leave it in our plumbing, food processors, keys, espresso machines, jar lids and door knobs because it's pretty?

    Anyway, once again, this is a cool build!


    7 years ago on Introduction

    Nice! I have to try building one when I have time. I have a few electric grinders, but it's cool to do it the old fashioned way too. I usually check up on Coffee Grinder Reviews to see their grinders, but most of those are electric.

    1 reply

    Reply 7 years ago on Introduction

    I think you are just linking your niche site up here but if you do make a grinder post some photos.