Instructables

Coffee Burr Grinder Attachment for KitchenAid Mixer

FeaturedContest Winner
Picture of Coffee Burr Grinder Attachment for KitchenAid Mixer

I just recently started to enjoy a cup of coffee in the morning.  I had a "helicopter blade" coffee grinder for years and decided to upgrade to a cheap hand-crank burr grinder (Kyocera CM50 - $39 on Amazon).  This grinder has conical ceramic burrs that produce a MUCH more consistent grind for drip coffee than my previous grinder.  I was astounded that I could actually taste the difference - much smoother once I found the right grind setting!

I then started looking into motorized burr grinders.  Most high quality grinders were $500+.  The cheapest conical burr grinder I could find was the Bodum which was $80.  Not bad, but I thought, why don't I make a burr grinder attachment for the KitchenAid mixer that's taking up a ton of my counterspace?

When coming up with the design, I held myself to these rules:
 1. Priced below the $80 Bodum
 2. Meet or exceed the grind quality of the Kyocera CM-50
 3. Able to be made with tools a "tinkerer" might have - no fancy CNC milling machine parts
 4. Easy setup/removal (less than 15 seconds each)

NOTE: I designed this for my Kitchen Aid 600 mixer I have a design in mind that would work for all other square-drive Kitchen Aid mixers and will post shortly.
 
 
Remove these adsRemove these ads by Signing Up

Step 1: Parts and Tools

Picture of Parts and Tools
Screen Shot 2012-02-13 at 8.32.54 PM.png
Screen Shot 2012-02-13 at 8.31.06 PM.png
Essential Parts:
 1. Kyocera CM-50 ceramic burr coffee grinder ($39)
 2. Milescraft 90 degree drill adapter ($15)
 3. 3/8" x 1.25" long coupling nut ($0.99)

Parts/Materials that Can be Substituted:
 4. 3/4" x 1/8" thick aluminum bar
 5. 3/4" pine board
 6. #12 x 3" long wood screw
 7. #10 x 1" long wood screws
 8. 1/2" x 1/4" long copper tube

Tools:
 - Hand drill
 - Jig saw
 - 3/8-16 die (cutting screw threads)
 - Bench grinder 

Step 2: Couple Mixer Output to 90deg drill input

Picture of Couple Mixer Output to 90deg drill input
Screen Shot 2012-02-13 at 9.31.22 PM.png
Screen Shot 2012-02-13 at 9.21.51 PM.png
This step converts the square drive output of the mixer to the 3/8" input shaft of the 90deg drill:

1. File/grind generous taper onto the 90deg drill input shaft.  A big taper will make it easier to cut threads in the steel

2. Use a 3/8-16 die to cut threads in the 90deg drill input shaft.  I used a wrench/vise to lock the input shaft while cutting threads.  Threading tips:
 - keep cutting die perpendicular to input shaft
 - use cutting fluid on input shaft: 3-in-1 household oil/WD-40 are OK

3. Use a bench grinder to turn one end of the 3/8-16 coupling nut into a 0.45" square.  I bought two coupling nuts: ground one into a square using digital calipers and a second using a gradual grind method (no measurements).  Calipers were much quicker, but the trial/error method worked just as well (just took 3x as long as I ground very little between trials)  Should grind at least 1/2" of the coupling nut into the 0.45 square profile.

4.  Screw the ground coupling nut to the threaded 90deg drill input shaft.  Test fit drill assembly with mixer!


Step 3: Attach 90deg Drill Output to Kyocera Grinder

Picture of Attach 90deg Drill Output to Kyocera Grinder
1. Remove the Kyocera grinder from the shipping box.  DO NOT attach the hand-crank handle that comes with the Kyocera grinder!

2. Use drlll key to tighten drill chuck around Kyocera grinder shaft.  Make sure Kyocera grinder shaft is CENTERED in the drill chuck!  It is very easy to tighten the drill chuck uncentered.  An uncentered drill/grinder assembly will result in a wobbly/unreliable/loud grinder (but will likely work for a short time!)

Step 4: Attach Grinder to KitchenAid Mixer

Next, I had to keep the grinder assembly from falling out of the mixer. 
The mixer comes with a 5/16" screw and the drill/grinder comes with a 3/8" bolt.

I looked around my basement for anything that could connect these two.  Luckily I found some 3/4" aluminum bar that would work perfectly.  But aluminum is not necessary.  A few wraps of string, a bunch of rubber bands, etc would accomplish the same thing: Keep the grinder shaft from falling out of the mixer.

If you do want to duplicate my design, 3/4" x 1/8" aluminum bar can be found at Lowes, HD, ACE for less than $5.  i would honestly recommend looking around for an alternate before buying the aluminum as this is a low-stress part.

If you like the design/look, here's the process I used
1. Look at drill/mixer top/down
2. Sketch curve on MIN 3/4" plywood (NOTE: Gentle curves/transitions are best! Sharp bends are weak/hard-to-form)
3. Cut plywood in half with jigsaw - following sketched line
4. Place aluminum bar between plywood halves - in vise
5. Crank vise until aluminum bar is bent
6. Drill 5/16" hole in mixer end of bent bar
7. Attach bent bar to mixer
8. Mark spot where 90deg drill intersects with aluminum bar
9. Drill 3/8" hole at intersect spot
10. Connect mixer to grinder assembly

Step 5: Lockdown Grinder Rotation

The grinder attachment must be locked down in 2 rotational axis (see first pic).
The 3/4" bar can prevent rotation around the first axis, but over time could bend/break the aluminum.

1. To prevent the drill/grinder assembly from flipping around the entire mixer, I created a "boomerang" that locked into the mixer's bowl pins. See pic for boomerang dimensions.  I used 3/4" pine wood that I had laying around as this is not a high stress part.

2. To prevent the grinder from spinning around the 2nd axis it needed to be clamped down.  Here, I created a "handcuff" clamp.  See attached for clamp dimensions.

3. Drill thru hole in "handcuff" (I used 3/16" bit 2.5" deep)

4. Cut slot in "handcuff"

5. Attach "boomerang" to "handcuff"  (I used #10 x 1" long wood screws)

6. Insert #12 x 3" wood screw into "handcuff" to clamp around grinder

7. (Optioal) Sand boomerang-handcuff assembly.  Round corners with router

8. Drill 3/8" holes in "boomerang" to match Kitchen Aid mixer pins (TIP: Use Forstner drill bits in wood for crisp holes).

9. (Optional) Paint to match Kitchen Aid mixer color

Step 6: Final Assembly

Picture of Final Assembly
Final Assembly:
 1. Tighten #12 handcuff screw to clamp Kyocera grinder.  Do not crank on screw.  Lightly tighten at first -> If grinder slips, tighten gradually until it no longer slips.  It is easy to apply enough force to the #12 screw that will crack the "handcuff" clamp.
 1. Tighten 3/8-16 "crown nut"
 2. Raise Kitchen Aid bowl holder so than pins align/insert into "boomerang"

Step 7: Using Grinder

 - For drip coffee, I tightened the adjustment nut as much as possible, then backed it off 3 notches.  BUT I highly recommend experimenting with your own settings based on your beans/brewing method.  
 - I did trial the finest grind settings in an espresso machine . . . it was too fine and only sludge came thru.  I eventually found an espresso "setting" but it took a lot of trial/error
 - Even on the Kitchen Aid #10 speed setting, there is no risk of heating/burning the beans.  IMHO, #8 was the best compromise of grind speed and loudness of machine.  Please let me know if you have any suggestions for reducing noise at top speed!

El__Quijote made it!1 month ago

I absolutely love this project!!! So much that I had to do it... My first Instructable project and now I'm hooked. It took me a while to find a machine shop that could do the threading for me (since I don't have the tools for the metal-work). However, I'm happy to say that the project is 90% complete. The only part missing is the metal latch, but that will be complete soon enough. Thanks for sharing such a useful Instructable.

PS. I do use my KitchenAid Mixer constantly. This is just one more use for it.

20140614_142610.jpgIMG-20140614-WA0022.jpg
EB Keller2 months ago

This is a very ingenious idea, I often think of what else my Kitchenaid Mixer can do the other 350 days of the year I don't use it..... I do have to brag that I did find the Kitchenaid Burr Grinder Home/Professional Model at a garage sale for $5 after I talked them down from $7.50, I do know that this will be used 365 days in a year..... now what to do with my Vintage Hobart/Kitchenaid Burr Grinder that I have used for the past 20 years and it still keeps on ticking.....lol

$_57.JPGmClfDpGE9zPVPGgXpdO17Kg.jpg
riverpro1 year ago
Please keep me posted when you do shaved ice attachment! Thank you.
This is a great idea. My parents had a kitchen-aid from the 1950s. The attachments were much stouter back then, cast aluminum instead of plastic. Re. the other commenter about food processor: Kitchen-aid does sell a set that has graters and slicers, the modern plastic housing tends to flex and allow stuff to get between the rotor and housing though.

Be careful with using the K-A for a power source. My dad had the great idea to use it to run an ice-cream freezer. About the 3rd batch of ice-cream the kitchen aid's armature burned up. So after dad rewound the armature, the adapter got pitched in the trash to make sure it didn't get used again. Running at high torque for over a half hour at a stretch is just too much work for too long for a motor that has no cooling air going through it (so it doesn't suck in flour!)
jtmcdole2 years ago
Black & Decker CBM220, $35 electric burr grinder. It uses metal disks, with one fixed and the other one spinning.
jeffkobi (author)  jtmcdole2 years ago
I did see the CBM220 but decided not to use it as a competitive benchmark because it only had 15 reviews on Amazon - and of those reviews was rated 2.5 stars. The Bodum had 350+ reviews and was rated an average of 4.5 stars - by far the highest rated, most reviewed burr grinder under $100. Again, I'll say that I'm relatively new to the world of coffee and really don't understand the nuances of flavor . . . because of this I just had to trust reviews and ratings online. I do personally have the Bodum grinder and have zero complaints!
Great project!

I have been into coffee for years, upgraded my equipment part-by-part over decades and have a good Rancilio grinder and espresso machine at home (Silvia and Rocky). However, Its frustrated me for years that my KitchenAid mixer has been sitting idol while I use a grinder to do something for which KitchenAid surprisingly does not have a solution. Years ago I purchased KitchenAid's Grain Mill attachment expressly for the purpose of grinding coffee. Its a burr grinder with a hopper and its worked well once it was calibrated. This led to lots of wasted coffee since each time you took the attachment on and off, you had to repeat the calibration.

I like where you're going with this project. Please update soon.

sarah051482 years ago
I think a series of instructable/ mods for the Kitchen Aid motor shaft would be really a great service to the community. I just bought a food processor for my daughter and it puzzled me why there was no attachment for that ( besides the obvious one that they make a stand alone processor). any takers? the coffee grinder is a great inspiration, thanks.
jeffkobi (author)  sarah051482 years ago
Great suggestion! I definitely think the KitchenAid attachment is an untapped DIY opportunity! Sadly, I'm short on new attachment ideas, BUT extremely eager to develop any new/popular attachment suggestions.

Anyone who's reading this - please let me know if you have a KitchenAid attachment idea you'd like me to work on. Please keep in mind that the KitchenAid output drive is relatively low-speed(RPM), but high-torque

Thus:
- Attachments like a high-speed blender would require an expensive gear box to multiply the RPM's to an acceptable level. At that point, it may be more cost effective to just buy a quality blender for ~$100
- An example of an ideal attachment would be an ice-shaver/shave-ice/italian ice attachment . . . which spins a large block of ice at low speed. Hmm, now that I think about it, that's actually a great idea (I grew up in Hawaii and love shave-ice). Stay tuned for a shave-ice attachment!
This is a great instructable! I'm interested in Open Kitchenaid attachments. The only other example besides your project I've found so far is this rotisserie.

As you've identified, the KitchenAid is best suited for low-speed high torque output. But I think it could be useful to extend applications beyond the kitchen; there's no reason you couldn't use this powerful, expensive motor in other applications.

I'm also interested in trying to make this simpler for people without a lot of tools at home. I wonder if there's a custom CNC or even 3D printing resource that would make coupling the drill attachment to the KitchenAid simpler.
I created a Google Group to share notes on DIY Kitchenaid attachments: https://groups.google.com/forum/?fromgroups#!forum/kitchenaid-diy
spike35792 years ago
I liked your idea so much I made a version of your coffee grinder. There's an instructable here and a blog post here.

coffee grinder- blog21.jpg
helen412 years ago
Congratulations on the win! This is an excellent instructable
I think you are on to something! KitchenAid really seems to like having all kinds of attachments that don't always do just what they are supposed to do, but this actually works! Great Job!
Over my wishes my wife bough a cuisinart for 20 bucks (sale item plus coupon), errr I had to appologise best coffee ever it is a burr machine DBM8. Perfect coffee always for 20 bucks, no muss no fuss. fill ,set, turn on, done! For perfect beans I suggest BJ Wholesale's brand 100% Columbian whole beans .

MMMMMMMmmmm
gunna have a cup in a few minutes

Nice instructable though,

ciao
Oh man, this is great! I've always wondered why KitchenAid doesn't make a decent coffee grinder attachment for my mixer. AND I have the same burr grinder! I'm definitely going to have to give this a try. Thanks!
Definitely cool, but we bought a KitchenAid Coffee grinder (Stand Alone, not an attachment) some time back, and grind all our beans in it.

Thats why they don't make an attachment too probably, they have a Coffee Grinder on the market already.

Kudos for the ingenuity though.
jeffkobi (author)  wgwalkerii2 years ago
Yep, did a lot of research before starting this project and came to the same conclusion you did: KitchenAid already has a ~$200 standalone burr grinder, so why sell the same or better quality grinder attachment as a competitor (most attachments are ~$100 or less)?

That being said, I do think there is a huge cross-section of people out there that have an under-utilized mixer, love coffee, and value their counterspace (who doesn't?).

That being said, my next KitchenAid Burr project will use "professional" ø68mm Mazzer conical burrs. Will definitely be an "open source" design where the CAD is freely distributed. Send me a private message if you're interested in helping - be sure to include which CAD systems you prefer!
cmjake0072 years ago
no doubt to your ingenuity, kudos. I love good coffee, so quality grinder is a must. I just think there are better alternatives to tying up an amazing mixer. The effort to break it all down and set it up when you want to mix something, maybe a great bread dough. I kinda like the hand crank mill as it was, but to each his own, few turns, back it goes in the cupboard, but very nice job building what you wanted !! What I need is how to build a kitchenaid out of my coffee mill !!
jeffkobi (author)  cmjake0072 years ago
I couldn't agree with you more about not wanting to tie up an amazing mixer! Just updated the my design rules to explicitly state this goal: less than 15 sec for setup/breakdown.

After re-reading the instructable, it's definitely not clear just how quick this action is. There are only three points of contact with the mixer, one thumbscrew and two 3/8" pins. Once you remove the thumbscrew (came with mixer), you just have to pull on the drillhead and lift the entire assembly up to remove it. Attaching a photo . . . will hopefully upload a video shortly. Thanks for your comment!

burr grinder.jpg
mdeblasi12 years ago
As I watched I could smell coffee grinding. : )
sgt_rock2 years ago
Yes, I have a Cuisinart Burr Grinder. But if I didn't I'd make this one! Very cool!
I can't imagine any cooler accessory for your Kitchen Aid mixer then installing a drill attachment. That is too cool.
I have the same Grinder and have been trying out attaching it to my hand drill, but this is a much more elegant solution. Now I just need a Kitchen Aid :)