Manual Coffee Grinder Conversion MKIII (J-Max)

This is the newest version of the j-max coffee grinder conversion build with many improvements:

• Reduced hardware and hardware type

• Use of off-the-shelf items for the motor to grinder axle conversion

• Cut main structure into two smaller parts for smaller printers to print- max part height is 175mm (need at least 200mmx175mm print area for back panel)

• New power supply with screw terminals- no soldering needed

• Simplified assembly steps

Hardware List

• ¼-20 Threaded Rod cut to 95mm long (QTY.2)

• ¼-20 Nuts (QTY.6)

• ¼" Washer (QTY.2)

• SHCS M6 x 20mm lg. (QTY.3)

• SHCS M3 x 16mm lg. (QTY.8)

• SHCS M3 x 10mm lg. (QTY.3)

• M3 Heat Set Insert (QTY.11)

Purchase List

• Coffee Grinder

• Motor

• Receptacle Module

• Power Supply 200W

• Shaft Adapter/Coupling 10mm to 10mm

• Grinder Drive Shaft

• M3 Heat Set Inserts (Printed Hole Dia. is 5.5mm)

Print Settings

I printed all the parts out of PETG at 0.3 layer heights with a 5 walls for extra strength.

None of the parts need supports!

Note when using this setup

Large adjustments to the grind setting should be made with the grinder unclamped and not installed in the stand. When installing the grinder push the grinder up into the motor while clamping, this ensure the grinding burr wont jump up during grinding since the design of the grinder uses a spring to keep the burr down, when motorized the burr tends to ride up without this preload.

Funnel Options

There are 3 funnel options:

• Funnel Standin - A cap for where the funnel would be secured to the top (If you dont want the beans to contact any 3d print part, choose this option)

• Funnel Design 1 and 2 - I designed these funnels but since I don't have a way to safely print these I don't use them. They should work okay, one design is a simple funnel and the other is the same funnel with some extra feature that should prevent beans from deflecting out of the grinder.

Pre-assembly

• Cut the two 95mm lg. ¼-20 threaded rods to length and file/sand ends smooth.

• Cut the 6" long Neiko Bit Extension to 79mm (cut off the hex side of the extension - the round part of this extension is 10mm in diameter which will fit in the shaft coupling with the motor shaft which is also 10mm in diameter) This can be cut with a hacksaw.

Assembling

1. Print all of the parts, you will need 1 of everything and 2 of the knob bases and knob caps.

2. Install the heat set inserts into the bottom, top, and back panel. The back panel will get 5 inserts, the top will get 3 inserts, and the bottom will get 3 inserts. I would recommend installing the middle top insert in the dovetail from the inside.

3. Place two 1/4-20 nuts into the knob bases and glue the knob caps into the knob bases.

4. Push the ¼-20 threaded rods through the two holes in the bottom. Thread the nuts on the inside of the bottom to the threaded rods. Place a washer and nut on the outside and tighten the nuts to secure the rods into place. The threaded rod should stick out around 45mm from the printed part.

5. Slide the top onto the bottom dovetail and secure it with one M3x10mm screw in the front middle of the assembly.

6. Secure the power supply into the main body print using two M3x10mm screws at the corners. Orient the supply so the input is at the bottom.

7. Secure the motor into place with the three M6 x 20mm screws.

8. Either add a fork terminal, ferrule, or solder the wires to allow proper mating to the screw terminal. Connect the motor to the power supply ensuring the motor rotates clockwise.

9. Install the power input module/receptacle by placing the fork terminals coming from the module to the correct screw terminals on the input of the power supply. (Be careful with mains electronics and ensure the correct wire is going to the correct position on the power supply)

10. Put the back panel into the back of the assembly and secure it using the six M3x16mm screws. The receptacle module should be hanging out of the bottom hole.

11. Secure the receptacle module using two M3x16mm screws.

12. Remove the key from the motor shaft and place the coupling adapter onto the motor, ensuring it is halfway into the coupling, also ensure one of the set screws is going into the key pocket.

13. Put the Neiko bit extension that was cut to length into the other side of the coupling and secure it using the set screws provided.

14. Set the grinder to the setting you want and place it into the assembly making sure the hex drive is fully seated in the socket. Secure the grinder in place with the front clamp and knobs while pushing the grinder up into the motor.

15. You're done!