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How They Work: Media rotators continuously and slowly spin a disk that holds sealed vials. The electric motor that drives the rotation has been slowed down to a lower rotation speed by either geared connections or a potentiometer.

Advantages: Media rotators provide long-term rotation in a very maintenance-free setup. They have minimal parts and they can be built with a variety of flexible parts.

This Rotator can rotate a total of eight centrifuge tubes at constant speed (our design is for four 50 mL and four 15 mL tubes). Various speeds can be set. Power supply is a wall outlet. The motor rests on a platform that can be angled to rotate the centrifuge tubes while they are horizontal, vertical, or at approximately 20 degrees from vertical.

  1. Figure 1: Build overview
    • Figure 1: Build overview

    • Figure 2: Finished rotator, without any samples loaded.

  2. Using the drawings provided, trace out the design on your piece of sheet metal. The holes marked by arrows indicate the holes used to adjust the rotator angle between horizontal, vertical, or at approximately 20 degrees from vertical.
    • Using the drawings provided, trace out the design on your piece of sheet metal. The holes marked by arrows indicate the holes used to adjust the rotator angle between horizontal, vertical, or at approximately 20 degrees from vertical.

    • Units in the drawing are in inches.

    • For the prototypes built for Tekla Labs, both steel and 5052 Aluminum were used, the latter being much easier to with.

    • Using either a band saw or metal shears, cut material along the cutting lines.

    • If desired, use a belt sander or metal files to round off any sharp edges or corners.

    • Using a 0.5” drill bit, drill out the holes that were marked for the switch and potentiometer. Depending on the specific parts you have, the drill size might vary.

    • Using a 10-32 clearance drill bit, drill out the mounting holes marked towards the edge of the sheet.

    • It’s not necessary to stick to the exact dimensions specified (it’s probably the case that what you have access to will be sufficient).

    • Using the bending feature on the metal shears, or a vice, bend the aluminum sheet along the fold lines to the specifications in the drawing

    • Once again, exact dimensions are not necessary, and “eye-balling” where things need to be should be fine.

    • With the left over sheet metal, sketch, cut, and bend the bridge for the media rotator and drill out the respective holes.

    • Make the disc: Using the remaining sheet metal, sketch out a circle according to the specifications listed in the drawing and with a band saw and belt sander cut out and smooth out the disk (exact precision is not necessary).

    • Drilling the holes for the vial holders: Clamping the disk down, you can use a drill and eye ball locations to place mounting holes for the vial holders

    • It’s important that the holes are equally spaced just so that everything is balanced when spinning.

    • Attach the vial holders with tapping screws.

    • Epoxy the motor mount to the back of the disk. The connection of the circular plate to the motor was connected with “JB Weld” to a connector. Epoxy would also work. (Image 3)

    • Insert the potentiometer and toggle switch into the holes of the frame.

    • With the potentiometer and switch secured into the frame, you’re ready to begin the wiring process; throughout the wiring process, the diagram will act as a good reference and can help clarify any questions you might have.

    • Solder the positive (+) wire of the AC-DC converter to one of the points on the switch and another separate wire to the negative terminal of the potentiometer.

    • Solder another new wire to the (+) output of the potentiometer.

    • Connect the open terminal from the switch to the positive (+) terminal of the potentiometer.

    • Attach the bridge to the frame of the media rotator with screws and washer

    • Zip-tie the motor to the top of the bridge.

    • Depending on the type of motor that you have sourced, the method you use to connect the terminals will vary, for this particular setup the motor we found required slip on connectors. Connect the positive output (+) from the potentiometer to the positive terminal of the motor and attach a new wire to the ground (-) of the motor.

    • Image 1: Close up photo of negative terminal of the motor.

    • The last step is to connect the negative terminal from the motor, potentiometer and AC-DC converter together.

    • After connecting all the grounds, you’ll have your finished media rotator. Add the disk to the motor.

    • Validations 1. The rotator should spin smoothly and at a continuous speed without wobbling. 2. Adjusting the resistance in the potentiometer should change the speed of rotation.

    • Testing 1. Fill two 50 mL tubes with about 25 mL of water. Both vials should contain an equal amount of water. Insert the tubes into opposite vial clips on the rotator. 2. Plug in media rotator and flip on/off switch to on. Gradually turn knob to higher setting. Rotator disc should spin faster as potentiometer resistance is lowered and motor is operated at a higher speed. 3. The water in the in tubes should become thoroughly mixed throughout the tubes as the rotator spins. The rotator should not wobble as it spins.

    • Safety and Maintenance

    • Operator safety 1. When working with hazardous chemicals, rotator should be kept in secondary container to catch any spills

    • Operator Safety 2. Always ensure samples are sealed completely in their vials.

    • Maintenance 1. Always balance the rotator disc when using it. This means that the vials should be placed on the rotator disc with radial symmetry, so that it is evenly balanced. Each vial should contain the same weight of sample (same volume if identical samples)

    • Maintenance 2. Keep electrical components dry.

    • Maintenance 3. Unplug when not in use.


List of specifications

1. Vial holder rotates at an adjustable speed. Maximum rotation rate depends on the motor, power supply, and potentiometer. An acceptable range is 0-80 RPM.

2. Vial holder can be adjusted to remain horizontal, vertical, or at approximately 20 degrees from vertical.

3. Rotator operates on plug-in wall power. Wall power allows the media rotator to operate for long periods of time.

2 other people completed this guide.

Tekla Labs2

Member since: 04/05/2012

15 Reputation

1 Guide authored

One Comment

Very Nice,

Thank you for this project buddy,

I will make this and will e-mail you my result

Albano - Reply

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