Roller Coaster Gantries
- kinematic mounts are three button head cap screws on 20mm grid w/ reciprocal / wherever-u-like mount ins
- all axis have scroll-along top plate w/ connection to motor plate, final scroll kinematic triangle
- all axis have scroll-along bottom beam plate w/ 20mm grid w/ last scroll kinematic triangles
BOM
Hardware
| Type | Size | QTY | Where Used | McMaster PN |
|---|---|---|---|---|
| SHCS | M3 | 2.5mm Hex | 91292A110 | |
| SHCS | M4 | 3mm Hex | 91292A116 | |
| SHCS | M5 | 4mm Hex | 91292A124 |
| Type | Meaning |
|---|---|
| SHCS | Socket Head Cap Screw: machine screws with hex heads in a 'socket' - i.e. the head is the socket, not the driver. |
| FHCS | Flat Head Cap Screw: similar to SHCS but have triangular heads, used when making fastener surfaces flush. |
| BHCS | Button Head Cap Screw: rounded head socket heads ! |
| PLSTCF | Plastic Thread-Forming Screws: have triangular lobed threads and torx drive caps, wonderful in plastics as the beefy threads mean no inserts required. |
OLD DOC: move this to /kunits/README.md and /kunits/images
Scratch / Landing page for the roller-bearings and 2d-sheet-stock axis system.
With RCT, we break axis into individual kinematic elements - and roll those elements into machine designs.
A reasonable system for beginners, and easy to manufacture (with another CNC mill). Particularely, this system begets the Madison Park Vocational Machine
Building Axis and Machines from 'Kinematic Elements'
Machines are made of degrees of freedom, and those degrees can be assembled from 'Kinematic Elements' i.e. here I have one Motor / Pulley Unit, as well as Lateral (into the gantry) and Cross (across the gantry) supports. I'm doing a mediocre job of explaining this, but here are some images:
To scratch a machine together, I pull elements into Rhino as .step files, and lay them out into axis - here's one linear degree of freedom:
Then I assemble those axis together, keeping track of where I'll be adding plates of material:
Then I go about filling in detail design, adding tabs etc to bring beams and chassis together.
Fabricating Axis
I then mill these axis on our shopbot, or any CNC mill you like - the N17 size elements can likely be laser-cut with acrylic or similar (delrin would be nice, but is expensive and a bit toxic to cut, so goes the lore).
I do CAM in Fusion with a .step I export (after flat-packing) from Rhino.
Assembling Axis
I typically assemble machines one axis at a time. That's not saying much, but here's an image to get a sense of how the hardware goes together: