60$ Electric Coffee Espresso Grinder - Conversion From Hand Crank Timemore C2 C3

Inspired by the design of the Weber Workshops Key grinder and using a cheap AliExpress Timemore C2 38mm burr grinder replica I made a pretty decent electric espresso grinder design that has been making me and my dad coffee for about 6 months now without any problems!

Timemore C2 or C3 or AliExpress replica (body 52mm) - https://www.aliexpress.com/item/1005005221124778.html

• DC Motor JGB37-550 175rpm with bracket - https://www.aliexpress.com/item/4000722028029.html
• 16 tooth bevel gear 1.5M, one with 6mm and the other with 12mm hole - https://www.aliexpress.com/item/1005004909671199.htm
• M10 12mm diameter 70mm long shoulder bolt - https://www.aliexpress.com/item/4000523679119.html
• 2x Needle bearing HK121718 (12x17x18mm) - https://www.aliexpress.com/item/1005002674922707.html
• Axial thrust bearing 12x21x5mm - https://www.aliexpress.com/item/1005004267376382.html
• IEC 320 C14 electrical socket with fuse and power switch - https://www.aliexpress.com/item/1005004246846738.html
• KJD17 YH02A Electromagnetic Push Button - https://www.aliexpress.com/item/1005001792535480.html
• 12V 3A LED Power Supply - https://www.aliexpress.com/item/1005005553964246.html
• 19x Round head M3x8mm Allen head bolts - https://www.aliexpress.com/item/4000896301219.html
• 19x M3 Threaded inserts for 3D print
• 2x Countersunk M3x8mm bolts for power socket, you can also use the round heads, you can't see them from the front
• 4x M8x20 or M8x25 Socket head cap screws for the front mounting clamps
• 4x M8 hex nuts
• 1/4" Hex driver extension
• 51mm Dosing cup for espresso - https://www.aliexpress.com/item/1005005342872172.html
• 1 Meter of wire 0.75mm2 or 1.5mm2 and 6.3mm spade connectors
• About 750 grams of 3D printing filament (PLA, PETG)

• For the electronics of the soft starter (not necessary), you will need a small prototype solder board,
• IRFZ44N N-channel mosfet or similar
• 2x 10kOhm resistor
• 10kOhm or more trim potentiometer
• 220uF Electrolytic capacitor
• 1N4007 or similar diode
• Terminal block for 3 or 4 wires

All parts minus the grinder are around 60$ ordered from AliExpress plus 30$ for the replica grinder if you don't already own one to do the conversion.

3D Print the components and press in the threaded inserts using a soldering iron.

I also included the Fusion360 design file if you require any modifications

Using the provided schematic you can solder the components on a protoboard and achieve a nice soft starting feature when powering up the device. Also, this part is needed to compensate for the overcurrent protection of some Switching-Mode power supplies because the DC motor can draw huge currents on startup and then settle around 0.9 to 1.1 Amp while grinding. In case you have a smaller capacitor you could run a larger resistor or use the trim pot like I did for some fine-tuning. The circuit relies on the RC time constant to trigger the MOSFET so you can do a little math here to figure it out but a 10kOhm resistor and a 220uF cap will get you in the ballpark.

• Small Protoboard
• IRFZ44N N-channel MOSFET or similar
• 2x 10kOhm resistor
• 10kOhm or more trim potentiometer
• 220uF Electrolytic capacitor
• 1N4007 or similar diode
• Terminal block for 3 or 4 wires

Mechanical assembly:

After the prints are done you will have a boatload of support material to remove (be careful not to break the main bits), then comes the time to press in the bearings, use general-purpose grease on the inside and outside of all three bearings, it is a very light press fit so your fingers will be enough. Insert the 4 M8 nuts into the 3D printed holes on the front grinder clamps.

You will have to shorten the magnetic driver bit holder using an angle grinder or a handsaw and a file. File the hex bit until it fits in the shoulder bolts hex socket.

Electrical Wiring:

DISCLAIMER! Here you are working with live AC voltage and if you are not experienced please get some help from a professional! The circuit is very simple, AC power that comes from the socket first goes to the little red switch and then to the terminal 1 and 3 of the electromagnetic starter switch which is a kind of self-latching relay. From the starter switch terminals 2 and 4 live AC wires go to the LED power supply. +12V and GND wires from the LED power supply first go to the motor soft starter if you are using one, or directly to the DC motor. Don't forget to connect the earth wire directly to the power supply! Insulate everything using electrical tape or heat shrink tubing to prevent shorts.

You just made yourself a new coffee tool! And saved a ton of money by not buying the real Weber Workshops grinder :). Make sure to put it to good use and enjoy every new cup of coffee knowing that you built the machine that made it! Cheers!