Turn an Old Mixer Into a Belt File

Give new life to an old, unused mixer by transforming it into a powerful belt sander! This project is perfect for upcycling and creating a custom tool tailored to your workshop needs. With a few materials and some basic tools, you can build a functional belt sander that’s both effective and unique.

Materials

1. Old mixer (with working motor)
2. 200 x 80 x 7 mm plywood
3. Wood glue
4. 120 mm-long Ω-shaped aluminum profile (P1)
5. 180 mm-long U-shaped aluminum profile that fits inside the Ω profile (P2, see picture)
6. Sanding belts (width of your choice)
7. U-shaped aluminum profile with a width and length matching your belts (P3)
8. Bearing (size to fit your setup)
9. 50 mm-long aluminum rod that fits inside the bearing
10. Two rubber washers (tap seals)
11. Two small bolts with self-locking nuts (hex heads)
12. 50 mm-long threaded rod and a nut (M5, or similar)
13. Four screws matching your mixer motor threaded holes
14. Two cable ties

Tools

1. Hammer
2. Steel saw
3. Wood saw
4. Sandpaper
5. Drill and drill bits
6. Steel files
7. 3D printer (can do without but tricky)
8. Screwdrivers and wrenches
9. Soldering iron

Disassemble the mixer to access the electric motor. Remove any pulley, gear, or connector attached to the motor shaft. Set the plastic enclosure aside—you’ll reuse it later.

Take the 200 x 80 x 7 mm plywood board. Mark the center of the motor and the positions of the screw holes on the board. The end of the board (which will serve as the handle) should match the width of profile P1.

Drill holes for the screws and motor shaft, then mount the motor. Countersink the screws to prevent them from rubbing against the pulley later.

Warning: Ensure your screws are short enough so they do not penetrate more than a few millimeters into the motor!

Select a piece of wood slightly thicker than the width of your sanding belt. For example, if your belts are 14 mm wide, use a 19 mm-thick wood piece.

Cut the wood to match the handle you created in Step 2, then secure it with wood glue. Allow the glue to dry completely.

Once the glue is dry, attach profile P1 to the wood step using four screws. Insert profile P2 into P1 to check the fit. It should slide smoothly with minimal clearance.

Tip:

If the assembly is too loose: Slightly bend P2 to create a wider U-shape.

If the assembly is too tight: Apply grease or sand P2 lightly.

In this step, prepare profile P3 to house the bearing. Drill two holes with a diameter slightly smaller than the aluminum rod (this will be the bearing axis). Ensure the holes are perfectly aligned so the axis is perpendicular to the profile. Create a notch in the profile to make room for the bearing.

The axis is press-fit—no glue or screws are needed.

Use a hammer to drive the axis through the profile and the bearing. If the bearing is narrower than the profile, the profile may bend during hammering. To avoid this, use a bearing that matches your profile length or add washers to fill the gap.

Once the axis is in place, cut it to size and clean the edges with a file. Round the corners of the profile to prevent contact with the belt.

Cut profiles P2 and P3 to the appropriate lengths, based on your belt size and setup.

Profile P3 (which carries the bearing) should be shorter than the belt and the pulley on the motor. As a rule of thumb, leave 30–40 mm of extra length.

Fully insert P2 into P1. Wrap the belt around P3 to estimate their positions in the final setup. Cut profile P2 so it overlaps P3 by 50 mm for a strong connection.

Drill two holes in P2 and P3 for the bolts. Glue two rubber washers (tap seals) onto one of the profiles.

Attach P2 and P3 using the bolts (hex heads with self-locking nuts). The rubber washers will allow you to adjust the angle between the profiles later if the belt slips during operation.

If profile P2 is too narrow, flatten one edge with a file to ensure a proper fit (see picture).

Insert the assembly into P1 to check for smooth operation.

The next two steps focus on creating a simple tensioning system using a threaded rod.

Use a file to prepare the nut for the threaded rod so it fits snugly into profile P1.

Create an insert (from wood, plastic, or aluminum) that fits into P1. This insert will allow the threaded rod to push against P2.

Glue a piece of plywood to the end of the handle to hold the nut in place. Drill a hole to allow the threaded rod to pass through.

Drill a hole in a piece of wood that is slightly smaller than the threaded rod. Screw the rod into the wood.

Tip: It’s much easier to insert the rod if you secure it in a drill and spin while driving the rod through the wood.

This step depends on your mixer’s design. If it has a switch that must be held down continuously for operation, getting rid of it will make your life easier.

For example, if your mixer has a power adjustment switch (0, 1, 2, 3) and a separate on/off switch, you can bypass the on/off switch by soldering the brown wire directly to the PCB (see picture).

It’s easier to reuse the original enclosure rather than make a new one. Cut the enclosure at the position where the motor normally sits, so you can place it back once the motor is screwed onto the plywood base.

The simplest way to secure the enclosure is with two cable ties. Drill four holes in the back of the case and thread the cable ties through and around the motor. In most cases, this will hold the enclosure securely. If needed, add epoxy glue for extra strength.

Finally, screw the other part of the case back on to close the electronics.

The last step is to create a pulley. If you have a 3D printer, you can adapt the OpenSCAD design available here.

Adjust the following parameters (in millimeters) to match your motor shaft:

If you don’t have a 3D printer

you can use a large wooden rod (30 mm diameter) as a pulley. Attach it to the shaft and shape it using a wood chisel while the motor is spinning.

The final step is to install the sanding belt:

1. Wrap the belt around the pulley.
2. Insert profile P2 into P1 and guide the belt onto the bearing.
3. Tension the belt using the threaded rod.
4. Turn on the machine. If the belt slips to one side, use the two bolts between P2 and P3 to fine-tune the angle of the bearing. Adjust the tension to prevent the belt from slipping on the pulley. If the belt is too tight, you may notice overheating in the bearing or motor.

Congratulations! You’ve successfully transformed an old mixer into a functional belt sander. This project not only saves money but also gives you a custom tool tailored to your needs. Experiment with different belt grits and tensions to achieve the best results for your projects. Happy sanding!