Swarm Design of 2” Universal Axis

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• Based on the Universal Axis
• Main features:
• 2” steel cold rolled rods - 40’ feet total
• Belt - scaled to 3x 15 mm belts (per each axis)
• Pulleys - 8mm x 15mm
• Carriage - houses bushings
• Motor Piece - 3x7x3
• Have nut catchers
• Internal nut catchers in Carriage and motor piece
• Idler bearing
• Idler shafts
• Stepper mounting bolts
• 15 mm Pulley x3
• 2” Rods
• Endstops - limit switches?
• Belt Pegs
• Standard ½” bolts - clamping
• Counter
• NEMA 23 Motor - actual purchase
• Motor shaft Couplers - 8-10 mm
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2 inches

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NEMA 23 Stepper motor

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15mm GT2 Belt

Carriage

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Belt pegs.

D3D CNC Torch Table

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Design Concept = Modularity

Applicable to Torch Table, Large Printer, CNC Router, CNC Mill

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Y2 axis

• Use the Universal Frame System
• Use the Universal Axis - with 2” shafts for Heavy Duty CNC Mill
• Use the Universal Controller

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Design Concept - Requirements

Requirements:

1. 2” rod holes
2. Rods are 40’/12 = 3’4
3. 2.25” bushing hole length for carriage piece
4. Carriage - Holes for transverse attachment of X axis to Y axis in the overall system
5. Accepts 3 15 mm GT2 belts
6. Nema 23 motor bolt pattern with 4 holes
7. Pulley shaft must be 8 mm
8. 2 minimum bolt holes for attaching motor piece and idler piece to frame
9. Use ½” bolts
10. Use 4 bolts to attach idler piece and motor piece to frame
11. Use 4 nut catchers per piece
12. Second bearing support for pulley shaft
1. Top side of motor clam shell must hold a bearing
13. 7.25” height max constrained by 3D printer bed
14. 3 pulleys are mounted on a pulley shaft direct coupled
15. Coupler between motor and pulley shaft is 10 mm to 8 mm
16. Manageable print time -
• Balance print time with infill

Stepper motor

10 mm shaft

8 mm shaft

10 to 8 mm shaft coupler

8 mm Second support bearing

Part Library

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Li

Tiffany

2” rod freecad file

Idler freecad file

Eammon

Devin

William

Michael

Marcin

Justin

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1. Add to a part library - Each person Google Folder: https://drive.google.com/drive/folders/1nLsoIly9ROUV909yEOKn2sUOtMEBq0Ak?usp=sharing
2. Upload parts to Wiki Part Library during the process.

FreeCAD file

STL FIle

FreeCAD file

STL FIle

2” axis motor piece

STL FIle

Requirements - continued

Requirements:

• Belt peg holds belts on carriage
• Use 1 belt peg per belt
• Carriage fits bushings
• Belt peg hole has ribs
• Second belt hole in carriage allows belt to come through
• Idler 3dp piece holds idler bearings for free motion belt
• Idler bearings have 8 mm shaft
• Idler bearing must have a lip or flange which prevents belt from slipping
• Lock collar to hold idler bearings
• Need nut catchers on ends of the idler piece and motor piece

8 mm shaft

10 to 8 mm shaft coupler

Print Time - 3x3x7.25” Motor Piece

Steps for the Design Process

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• Requirements doc
• Specification doc
1. Breakdown of parts (module based design)
• Role allocation - each person takes one part
• Add to a part library - Google Folder:

Task List

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• Motor Mount
• Bolt layout for NEMA 23
• Diameter of axis shaft
• Additional thickness (say 1.26 mm)
• Carriage
• Idler Bracket+mount for limit switch?
• Belt Clips
• Entire Assembly in FreeCAD
• Convert all Units to Imperial (Eammon)

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Concept

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• Based on the Universal Axis
• Main features:
• Belt - scaled to 3x 15 mm belts
• Carriage
• Motor Piece
• Double-sided drive - no Idler Piece
• Internal nut catchers in Carriage and motor piece
• Linear Bearings
• Idler bearing
• 15 mm Pulley x3
• 2” Rods
• Endstops
• Belt Pegs
• 4+1 bolt pattern

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2” Rods

Considerations

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1. Scaling to 3 belts - how to do pulley?
2. Calculations - how to size motor based on pulley size?
3. Sequencing-
4. Redundancy

Practicalities: Printing Time

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• 2” axis pieces can take one spool of filament each! Need to optimize design
• 7 hours - 12” bar that fits rods with 7” of space between them - 0.8 mm nozzle, 20% infill, 326 grams (double sandwich). $1/hr basic print cost.
1. Metal plate over this is desirable
• 13 hours - 12” bar, 50%, 631 grams.
• For 6 axis system - need 4x this per axis - 24x this
• 168 hours of printing
• Take overnight=12 hours for the printing requirement -> needs 14 printers!
• We will have 10 printers, with 7 at 0.8 mm
• Conclusions: 7 printers @0.8 mm are sufficient, but part would have to be more like 7”, not 12”
• With 5 days for the design part of the workshop - we give ourselves redundancy

3D Printed Pulleys

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• OpenSCAD Pulley Generator

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Critical Force Calculations

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• Use a stronger motor - Nema 34 or 23
• If We want 200 lb tool force:
• Use 2 axis drive
• Start with 100 lb axis for iterative design
• Use 2 motors. Belt pegs must be robust.
• Each motor needs 50 lb pull
1. considering the pulley diameter used.
2. Suitable candidates
1. 425 oz in 27 in lb Nema 23 is good at D=1” pulley = 54 lb
2. Geared Nema 23 -
• Belts need to hold 50 lb

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Belt Holding Calculations

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• Breaking - 62 lbf per 3 mm of belt
• (500 lbf per 25 mm of belt)
• Working - 25 lbf per 25 mm of belt
• Belt length - 2.5 meter per strand - 18 strands for 3 axes - or 9 rolls
• For 1” axis single belt drive - need 6 strands - or 3 more rolls.

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Question: does double sided drive make effectively for double the strength of a belt to take advantage of a double strand of looped belt?

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2” Universal Axis General Concept

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• Simple 3 Axis Gantry Mill for milling aluminum, making, hydraulic pumps, honing cylinders, and making small engine blocks such as for modern steam power, or making hydrogen compressors.
• Can add rotary heads as heavy duty components at a later time
• Rotary head probably doable with 3D printed planetary gears - especially with availability of metal 3D printer and CNC milling
• Basic implementation - measuring practical limits of belt-driven precision at $1/foot of 15mm GT2 belt
• This tests the limits of Nema 17 motors for a 2x2 foot machine.
• Clear application needs to be selected for machine, such as CNC drilling, etc.
• It will be a tradeoff between geardown ratio - speed - accuracy.
• We can achieve geardown with planetary gears to 5x4x3 = 60x or 240 lb force per Nema 17
• 500 RPM for good torque - to about 10 rpm at 60 geardown or 15 inches per minute
• Careful analysis of cutting and travel speeds is necessary
• GVCS Ecosystem Requirements
• Print large axis parts with 3D printer , 4” thick, 8x8
• Develop geardown, probably use Nema 23 motors
• Use $10 bearings, later to be 3D printed with metal filament, 1.5 mil tolerance
• CNC cut cover plates
• 3D Printed belt systems; use toothed ones for peg-based locking

Printing - 1.2 mm nozzle

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Motor 3D Printed Clamshells Justin and Eammon

Idler 3D Printed Clamshells - Tiffany

Carriage 3D Printed Clamshells - Li and Devin

Motor + Shaft Coupler - 10mm to 8mm + 3 GT2 Pulleys - 8mm radius; 15mm belt + 8mm bearing

Aiden

Motor

Cost

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• 2” rods are $20/foot - $640
• ½”x4” steel bar for frame, small 3’ cubic frames - $500 - 3
• Bushings - Double axis on each for 6 axes - 4 bushings each - $240 total
• Belt and Pulleys - 3D printed. This is where we test the limits of accuracy.
• Get this to a science.
• Gantry style system allows for larger workpieces by reducing work table space requirement (workpiece doesn’t move, the head does)
• GVCS Ecosystem Requirements
• Print large axis parts with 3D printer , 4” thick, 8x8
• Develop geardown, probably use Nema 23 motors
• Use $10 bearings, later to be 3D printed with metal filament, 1.5 mil tolerance
• CNC cut cover plates with CNC torch table
• Develop [[3D Printed Belt]] technology

Important Links

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• Test-Driven Development
• OpenSCAD Pulley Generator
• Didn’t have preset for proper pulley geometry

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