Roller Coaster Gantries
At the CBA, we make a lot of our own tools. These are shared design elements and ideas that we use when we're spinning up custom machines: they're parametric, aim to be reconfigurable, and we can make them in the lab with a minimum set of stock hardware.
The goal is to provide a set of components from which most other automation equipment can be composed.
Machines Using RCT Gantries
Mother Mother, a generalist
Claystack, a ceramics 3d printer
the Madison Park Vocational Machine, for high schools
Usage
This repository should help you figure out how to build your own axis: it contains some explanatory drawings, videos, as well as CAD files and Bills of Materials for various design elements.
A typical machine-level workflow is described for machineweek, at this link.
Gantry for NEMA23 Motor, 0.375" HDPE
| Type | Size | QTY | Where Used | McMaster PN |
|---|---|---|---|---|
| Button Head Thread-Forming | No. 6, 3/4" | 10 + (4 * rail tab) (lots) | Connecting Lap and Tab HDPE, Belt Blocks, Chassis | 99512A265 |
| Button Head Thread-Forming | No. 6, 1/2" | 2 | Belt Blocks | 99512A259 |
| Flat Head Thread-Forming | No. 6, 3/4" | 8 | Flush Mounting HDPE | 95893A258 |
| SHCS | M3x40 | 2 | Used only when pre-loading bearing rollers | 91292A024 |
| SHCS | M3x30 | 2 | Used only when pre-loading bearing rollers | 91292A022 |
| Belleville Washer | 3.1mm ID | 24 | Used only when pre-loading bearing rollers | 96445K157 |
| Locknut | M3, Nylon | 6 | Used only when pre-loading bearing rollers | 90576A102 |
| SHCS | M5x10 | 1 | Connecting Nema 23 Motor | 91292A124 |
| SHCS | M5x16 | 3 | Nema 23 Motor through tensioning arcs | 91292A126 |
| Shoulder Screw | 8mm Shoulder x 8mm x M6 | 10 | Guide Roller Shaft | 92981A198 |
| Shoulder Screw | 8mm Shoulder x 16mm x M6 | 2 | Belt Guide Roller Shaft | 92981A202 |
| Bearing Shim | 8mm ID x 10mm OD x 1mm Thick | 38 | Roller Separation | 98089A381 |
Gantry for NEMA23 Motor, 0.25" Aluminum
In Fusion[^2], you can open this file up and use (from the top menu)
Modify >> Change Paremeters
Each of these models should have some parameters starred, these are what you'll want to configure. Go ahead and set axis lengths, material thicknesses according to what you're doing. When you're satisfied, you can export the model as a .step file, using the file menu, to prep it for fabrication.
File >> Export
Make sure to change 'type' to .step, and check the 'save to my computer' box.
N23 / 0.25" ALU Hardware
| Type | Size | QTY | Where Used | McMaster PN |
|---|---|---|---|---|
| SHCS | M3x12 | 8 | Connecting Lap and Tab Aluminum, and Belt Blocks | |
| FHCS | M3x12 | 8 | Nice option for flush-mounting things | |
| SHCS | M3x35 | 2 | Used only when pre-loading bearing rollers | 91292A033 |
| SHCS | M3x45 | 2 | Used only when pre-loading bearing rollers | 91292A025 |
| Belleville Washer | 3.1mm ID | 12 | Used only when pre-loading bearing rollers | 96445K157 |
| Locknut | M3, Nylon | 2 | Used only when pre-loading bearing rollers | 90576A102 |
| SHCS | M5x10 | 1 | Connecting Nema 23 Motor | |
| SHCS | M5x16 | 3 | Nema 23 Motor through arcs | |
| Shoulder Screw | 8mm Shoulder x 8mm x M6 | 10 | Guide Roller Shaft | 92981A198 |
| Shoulder Screw | 8mm Shoulder x 16mm x M6 | 2 | Belt Guide Roller Shaft | 92981A202 |
N23 / 0.25" ALU Parts
| What | Spec | QTY | Where Used | Link |
|---|---|---|---|---|
| 608ZZ Bearings | 8x22x7 | 14 | Rollers | VXB 10, VXB 1000 |
| GT2 Belt | 10mm Wide, Length Dependent | 2 | Belt! | Amazon |
| GT2 Pulley | 10mm Wide, Motor Bore Diameter | 1 | Transmission! | Above, Combo |
Of course, you'll also need material. In this case, just 0.25" aluminum. I use 6061.
N23 / 0.25" ALU Tools
A list of the (perhaps) specialty tools you'll want to have to make this gantry:
| Tool | Where Used | McMaster PN or Link |
|---|---|---|
| M3 Tap | Extensively | |
| M5 Tap | Extensively | |
| M6 Tap | Shoulder Bolts | |
| Countersink Bit | Flush Mounting |
90 Degree Block for 1/4" Aluminum
RCTBLK-90-025ALU Fusion CAD File
Shared Purchase Parts
| What | Spec | QTY | Where Used | Link |
|---|---|---|---|---|
| 608ZZ Bearings | 8x22x7 | 14 | Rollers | VXB 10, VXB 1000 |
| GT2 Belt | 10mm Wide, Length Dependent | 2 | Belt! | Amazon |
| GT2 Pulley | 10mm Wide, Motor Bore Diameter | 1 | Transmission! | Above, Combo |
| Stepper Motor | NEMA23 x52mm | 1 | Torque ! | StepperOnline |
| Stepper Motor | NEMA23 x76mm | -or | Torque ! | StepperOnline |
REF
Find Open Assemblies Hardware Reference for shorthands etc.
Jake's Notes
- gantries still want fully described end conditions / mounts
- belt tensioning / assembly video
- working examples on video