Roller Coaster Gantries

These are machine design elements that we use at the CBA 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.

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.

First, find the model you'd like to start with on this page and download it, or clone the whole repo. The .f3d files are parametric Fusion 360 files. Files here are tuned for material thickness choices - but the exact thickness of your material can be tuned in the model: i.e. the 0.375" HDPE model will also work for ~ 8 - 11mm HDPE if you're working with sensible units in another country.

In Fusion, 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 and material thicknesses according to what you're doing.

There are also two sets of hole patterns in the last two 'groups' of features on the feature history bar. One puts a 20mm square grid on top of the axis, the other on the bottom. You can leave these in, or customize them, or add whatever mounting-to-the-next-bit design you'd like.

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. Now you're ready to import it into another assembly.

Alternately, you can save the changes to a new file and import that model into another Fusion 360 Assembly.

Gantry for NEMA17 Motor, 0.25" ALU

-42.3 mm - ( 6.5 * 2 ) * 1 mm

https://www.vxb.com/20-625ZZ-5x16x5-Metal-5mm-Bore-Miniature-p/kit250.htm

Flat Heads

• 20mm for reach-thru on motor runner

• ? there are more ?

• holes in plate

• wj plate

• wire organizer test, plate feet

• 3dpnext

• wj

• do we have belts, do we have pulleys, order bearings, last mcmaster, admirals, etc, close it out and next up we do software problems

Notes from the First Build

Increased preload from 0.2 to 0.4mm A few fitting things ... motor mounts get lots more clearance Increased sizes for heat-set inserts to make overflow smaller.

Gantry for NEMA23 Motor, 0.375" HDPE

RCTN23-0375HDPE Fusion CAD File

pulleys-that-are-the-wrong-size-hotfix

BOM N23 0375HDPE

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
Locknut	M5, Nylon	4	Connecting Nema 23 Motor	93625A200
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
Less Expensive Bearing Shim	5/16" Screw Oversize Washer	38	Roller Separation	91090A110

Gantry for NEMA23 Motor, 0.25" Aluminum

RCTN23-025ALU Fusion CAD File

BOM N23 025ALU

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
Locknut	M5, Nylon	4	Connecting Nema 23 Motor	93625A200
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