This is my design for a Turntable Traction Drive. It's meant to turn a large theatrical turntable covered in sets and actors in a safe reliable way. It can be built for less than $3000 USD.
I was inspired to take on this project by Alan Hendrickson's chain-driven design featured in Technical Designs Solutions for Theatre Volume 2 (Sammler/Harvey 2002). His design shows how a chain drive can rotate a turntable. I was interested in designing an easier-to-integrate "bolt-on" solution.
Feel free to make your own or iterate on this in any way permitted by the license! If you do happen to build one, send me a picture, I'd love to share it!
This project has a website.
| Document Name | Description |
|---|---|
| Safety and Liability | Discussion of the drive and safety factors associated with its use. |
| Design Document | Discussion of design and considerations made. |
| Parts Sourcing Guide | Instructions on how to buy the right parts to build your own Turntable Traction Drive. |
| Assembly Guide | Instructions on how to build your own Turntable Traction Drive. |
| Integration Guide | Instructions for Technical Directors on how to integrate this machine into your set desgin. |
| Operation Guide | Instructions for Technical Directors on how to operate this machine. |
| Bill Of Materials | A list of the parts required to build this machine. |
| Wiring Guide | Instructions for wiring up the VFD, Control Pendant, and Emergency-Stop. |
| Custom Parts Overview | A one-page PDF helpful when ordering custom cut steel. |
| Creative Commons Attribution 4.0 International | The license under-which these plans are made available. |
| Document Name | Description |
|---|---|
| Integration Checklist | A list of integration requirements for safe scenic integration of the Turntable Traction Drive. |
| Operations Checklist | A "preshow" checklist to verify before each use of the Turntable Traction Drive. |
| Part | Description |
|---|---|
| Chassis Parts | 2D CAD drawings of chassis parts to be cut from 1/4" mild steel. |
| Safety Placard | A PDF to be made into a printable label and applied to the top of the chassis. |
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Assembled Chassis Before Welding (photo)
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Full Speed Run of 23' Turntable (video)
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Full Speed Run of 6' Turntable (video)
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Rehearsing on a 6' Turntable (video)
| Traction Drive Feature | Detail |
|---|---|
| Design Units | INCHES |
| Height | 9.875" |
| Width | 32.875" |
| Depth | 33" |
| Chassis Weight | ~112 Lbs |
| Total Weight | ~228 Lbs |
| Number of Parts | 63 |
| Minimum Turntable Size | 6' Diameter |
| Maximum Turntable Size | Proven on a 23' diameter Turntable with steel and wood scenery. |
My motor decision was based on what I had lying around. You may easily sub in your own motor, but for simplicity of integration try to pick a motor matching NEMA Frame 145TC. Otherwise you may have to drill new holes in the Base Plate and Motor Gusset.
| Powerplant Feature | Detail |
|---|---|
| Model | General Electric 2HP TEFC (5KE48WN8167) |
| Speed | 1725 RPM at 60Hz |
| Layout | NEMA Frame 145TC |
| Gearhead | Morse 175Q140LR5 |
| Gearhead Ratio | 5:1 |
In order to vary the speed of drive motor we must use a Variable Frequency Drive (VFD). The VFD will be responsible for managing the speed and acceleration of the traction drive.
In our environment we have easy and plentiful access to 3phase 208v. For this reason we have selected a 3phase input VFD. If you have access to 3 phase power you can benfit from our integration notes throughout this documentation.
| VFD Feature | Detail |
|---|---|
| Model | Automation Direct DURA Pulse (GS23-22P0) |
| Input Power | 230V 3-Phase (208 is fine) |
| Output Power | 1.5 KW (2 HP) |
| Output Range | 0 - 600Hz |
| Safe Torque Off (STO) | Yes |
Our initial testing was performed on a .75 KW 120V VFD. We were able to easily turn the 23' turntable using just a single wall outlet.
| VFD Feature | Detail |
|---|---|
| Model | Hitachi L-100 (L100-007NFU) |
| Input Power | 120VAC 15A |
| Output Power | 0.75 KW (1 HP) |
| Output Range | 0 - 360Hz |
| Safe Torque Off (STO) | No |
We decided to replace this VFD for two reasons:
- In our environment 3-phase 208 is easily availble, and since 1HP isn't really up to the demands of our motor, the testing VFD didn't make a lot of sense.
- The intial wiring design of our e-stop buttons was not up to industrial automation standards. Critically, the e-stop was unable to constrain a runaway VFD. As a hedge agasint this risk we have selected a VFD with a Safe Torque Off (STO) feature. This feature adds independant hardware designed to reliably disconnect the output transistors of the VFD from the motor.