Build a 3D Printed Rotational Platform

I have recently undertaken to design a complete set of 3D printed tools for high precision positioning. You can find my printed micromanipulator here, my set of linear translation stages here, and this instructable will show in details the building process of my rotation stage (called it RZ stage for Rotation around the Z axis).

For all these tools, my design objectives where to achieve high precision (positioning accuracy below 10 micron) while keeping the build very economical (under 5 USD) and using only easy to procure standard mechanical elements.

To build this stage you will need the following tools:

• A 3D printer
• A pair of pliers
• Screwdrivers
• Hot melt insert tool (soldering iron or lighter if you don't have better available)

You will also need:

• A 6200 ball bearing amazon, taobao
• A MR95-ZZ ball bearing amazon, taobao
• 2x 6mm, 1x 16mm, 7x 18mm M3 screws (7x nuts) amazon, taobao
• 1x "large" spring 5.5 to 8mm inner diameter 16 to 25mm long amazon, taobao
• 1x "small" spring 3 to 8mm inner diameter 8 to 15mm long amazon, taobao
• 16x (or optionally 4x) hot melt inserts amazon, taobao
• 1x M5 90mm bolt amazon, taobao

This rotation stage is built around a 65mm diameter circular platform and has a thickness of 24mm. It can rotate freely over 360°. The rotation can be precisely controlled by turning a knob, or you can disengage the driving screw and freely rotate the stage by hand. The stage can also be locked in place using the brake.

The rotation mechanism relies on an M5 bolt connected to a printed worm gear to ensure a precise control. Each complete rotation of the bolt (connected to the control knob), cause the platform to turn by 1,6°. The bolt is kept in contact with the worn gear by a spring connected to the "engagement handle". By drawing and locking this handle you can disengage the bolt and leave the platform free to rotate.

The stage top surface includes 16 M3 mounting holes arranged in a 20mm array. An array of holes with the same spacing is also pierced on the stage base to fix the stage to a substrate with M3 screws. A magnetic version of the base is also available. Feel free to contact me if you need specific hole positionings.

To build this stage you will need to print one of each of the following files: "RZ stage table", "RZ stage base", "M5 spacer", "M5 nut", "M5 knob", "Engagement insert", "Engagement handle", "Break handle", "Brake", "Bearing holder out" and "Bearing holder in". All files can be found here: makerworld, printable, thingiverse

Among those parts only the "RZ stage base" and "M5 knob" require supports. The "RZ stage table" also comports some fine geometries used to connect to the driving bolt. You may want to use a specially detailed printing profile with this part. In case those details are not correctly printed it may cause and increased wear on the part and a diminution of the force applied by the driving bolt on the stage (the stage will not rotate well when the knob is turned).

Start to build your rotational stage by fixing the main bearing in place. Place 4 nuts in the hexagonal holes of the "bearing holder out" part, and use it to hold the 6200 bearing against the "RZ stage base". Turn the base around and use 18mm M3 screws to fix it in position.

The engagement system apply a constant force on the driving screw to ensure it engages with the worn gear and governs the rotation. Il is also used to disengage the mechanism and allow the stage to rotate freely. To build it start by assembling the "engagement insert" and "engagement handle" together with a 16 to 20mm M3 screw. Do not screw the bolt too much so that the handle can freely rotate around its axis.

Use a 6mm screw to fix the small spring at the extremity of the assembly and insert it all into the "RZ stage base". Use the second 6mm screw to fix the other extremity of the spring into one of the 3 possible holes. Choose the hole depending on the length of your spring. It should remain slightly under tension when the engagement assembly is fully inserted into its grove, but should allow you to bring it back and lock it in position by rotating the handle without permanent deformation.

To assemble the driving screw, first insert the MR95-ZZ ball bearing in the "RZ stage base". It should be a tight fit, if not you will need to glue it in position. The add the "M5 spacer" and the 90mm M5 bolt. From inside the base, add the large spring and screw the "M5 nut" until the spring is compressed. At that point the tip of the bolt should be lodged in the hole of the engagement assembly from the previous step.

You can now add the "knob". It includes a hexagonal extrusion to insert inside the bolt head. You may also glue that part if the fit is not tight enough.

To assemble the brake first insert an M3 nut in the hexagonal hole of the base and place a 16mm screw in the "brake handle". Then position the "brake" on the hook shape printed on the side of the base and fix it in position with the handle. Do not screw the break all the way in before assembling the table.

To finish your build you only need to add the "RZ stage table". First add two M3 nuts to the "bearing holder in" and place it under the assembly. Draw on the engagement holder and turn it to lock it in the "open" position. Place the "RZ stage table" on top and fix it in position with two 18mm screws.

At that point your rotating stage is complete. Check that the table can rotate freely, then close the engagement (rotate it until it goes in) and turn the knob. The platform should slowly rotate accordingly.

You can add the hot melt inserts on the stage's table depending on your need (only 4 inserts are really useful if you know which mounting holes you will use).