final presentation - shapeoko

To Mechanically Analyse the Design of the ShapeOko

CNC Mill Eoin Robinson

Supervisor :Gerard Ryder

4th Year Mechanical EngineeringStudent no: X00066779

Designed by Edward L. Ford (not an engineer), designed several iterations of the Shapeoko Lathe .

Open source: Design, Materials , tips all available on Inventables.com .

Background

What is the Shapeoko CNC Lathe?

Image courtesy of www.inventables.com

X – Axis Gantry

Y – Axis Gantry

Z – Axis Gantry

Edward L. Ford (not an engineer), designed several iterations of the ShapeOko Lathe .

“For a guy who isn’t an engineer and had never really “designed” anything mechanical before, this was both challenging and rewarding, as the cliché goes.”

No evidence to suggest any Static , Dynamic or Numerical analysis was conducted ; Ford treated the project simply as a design and build .

The Shapeoko CNC lathe presents an interesting exercise for Mechanical Design analysis

Why do we need to analyse it ?

The objective of this project is to mechanically analyse the Structure of the ShapeOko CNC machine.

Objective

Design • Stage1.

Manufacture • Stage 2.

Assembly+ Redesign • Stage 3

Project stages

Numerical +Physical Tests (2x)

• Stage 4

Analysis • Stage 5

Design Optimizatio

n • Stage 6

Project stages

The project will be conducted in 5 stages which are listed below:

1. Design the structure on Creo Parametric 2.02. Manufacture the components based on the

CAD Drawings rendered.3. Assemble and commission the machine 4. *Conduct Numerical and Physical tests

on the structure.5. Where necessary suggest design

optimisation(s).

Stages

Project stages

Design • Stage1.

Manufacture • Stage 2.

Assembly+ Redesign • Stage 3

X-axis Gantry Y-axis Gantry Motor train with V- Wheels and Idler drums Completed Structure Assembly

Stage 1. Design

X-axis Gantry

Y-axis Gantry

Motor train with V- Wheels and Idler drums

Completed Design

14 weeks of manufacture Utilized a variety of equipment, bandsaw,

CNC mill ,CNC lathe , Lathe , Fixed Drill, etc..

Differences from Original :Used less bearings washers, spacers .Different extrusion bars , built guiderails .

Stage 2.+3. Manufacture + Assembly + Redesign

Numerical +Physical Tests (2x)

• Stage 4

Stage 4. Testing – Stress Deformation

What are the effects on the Z Axis Mounting plates when

statically loaded?

Physical deflection Testing

Measure deflection using a dial gauge

Apply masses to the XZ Plates to simulate

the effects of a Dremmel

Numerical Testing

FEA simulations

Used FEA in CREO to simulate stress – deformation test.

Conducted FEA and Physical stress deformation test on the XZ plates only, not the entire system – More efficient !

Broke the system into sections did FEA on each

A. Combined assemblyB. Y Axis GantryC. XZ plate + Mounting plate

Stage 4. Numerical Testing


• Combined

• Y Axis Gantry

• XZ Plate

Max deflection 0.00025 m Highest stress concentration 1.00 E+00 MPa


Objective (1) :To show the effects of static loading .

Experiment: A series of weights will be applied at different points on the X and Y gantries. Their respective deflections (△L) will then be measured using a dial gauge.

Mass : 500g – 8000g Deflection : mm

Stage 4 : Test 1- Stress- Deformation Test

Stage 4. Physical Test – Stress Deformation test

The apparatus utilised in this experiment consists of :1. Spanner for 5mm Bolts2. Dial Gauge 3. Z-Axis Gantry mounting plate 4. Masses (500g– 8kg)5. Stand/Support system for holding the plates6. Hook


Mass


0 1 2 3 4 5 6 7 8 90

0.00005

0.0001

0.00015

0.0002

0.00025

0.0003

0.00035

f(x) = 4.05882352941177E-05 x − 0.0000300000000000001R² = 0.979911908780307

Deflection Test

Mass(kg) vs Deflection (m)Linear (Mass(kg) vs Deflection (m))

Mass (kg)

Defl

ectio

n (m

)

Deflection Test Mass (kg) Load (N) Deflection (mm) Deflection (m)

0.5 4.905 0.01 0.000011 9.81 0.03 0.00003

1.5 14.715 0.04 0.000042 19.62 0.05 0.00005

2.5 24.525 0.06 0.000063 29.43 0.08 0.00008

3.5 34.335 0.1 0.00014 39.24 0.11 0.00011

4.5 44.145 0.13 0.000135 49.05 0.17 0.00017

5.5 53.955 0.2 0.00026 58.86 0.21 0.00021

6.5 63.765 0.23 0.000237 68.67 0.26 0.00026

7.5 73.575 0.29 0.000298 78.48 0.31 0.00031


Objective: To determine the natural frequencies of the structure

Semi Dynamic test. This will help in the design optimisation.

Accelerometer measures acceleration against time. An Accelerometer will be attached at several

locations on the X axis beam and Y axis beam. Labview = Measure Vibration data Fourier transform utilised to find our natural

frequencies (.

=

Stage 4 – Test 2 – Tap Test

Accelerometer put in 14 positions on different Axes around the drill + motor.

Case study : Accelerometers

Courtesy of : ‘Modal Analysis of the Milling Machine Structure through FEM and Experimental Test’ S. Pedrammehr1, a, H. Farrokhi2, A. Khani Sheykh Rajab

FRF= Trying to isolate the frequencies for which vibration is occurring for that system.

Objective : Get an overall series of frequencies that describes the vibration of the machine structure, then matching each natural frequency for each component of the system.

Why? To know what natural frequencies occur so that during operation they are avoided. This will stop resonance occurring.

Stage 4 - Mathematical modelling :Fourier transform

Stage 4 - Labview

Accelerometer 1 XZ Plate

Accelerometer 2 Z axis Gantry Mounting plate

Accelerometer 3 Y axis gantry mounting plate

Stage 4 – Accelerometer locations

Stage 4 – Strike locations

#1 - #4 Z Axis

#5 Y axis

#6 X axis

Answer Planes /axes of vibration

Stage 4 – Strike locations why different axes ?

Dremmel - Planes of vibration The 3 axes of vibration are shown below 1.X – axis 2.Y- axis 3.Z – axis

Forces acting on Drill Piece

We are concerned with the AXIAL + LATERAL movement

X Plane Y Plane

Z Plane

Axes of Vibration

Axial Accelerationazc

Axial Accelerationayc

Axial Accelerationaxc

X

Y

Z

Axes of Vibration

Lateral Accelerationaxc

Lateral Acceleration ayc

Planes of Vibration – Plan View

XZ Plate

Z Axis Mounting Plate

Y- Axis Gantry Bar

Stage 4 – Questions to ask?

Find common ωn for the entire system

1.Find common ωn for each individual

accelerometers

2.Find Common ωn for each strike location

3.Find common ωn for each surface

Does the wn change with surface ?

0 217.02170200.0000020.0000040.0000060.0000080.00001

0.0000120.0000140.0000160.0000180.00002

Floor

Accel 1 50g (Power Spectrum)Accel 2 50g (Power Spectrum)Accel 3 10g (Power Spectrum)

Ampl

itude

276.03552.060.00E+00

1.00E-04

2.00E-04

3.00E-04

4.00E-04

5.00E-04

MatAccel 1 50g (Power Spectrum)Accel 2 50g (Power Spectrum)Accel 3 10g (Power Spectrum)

Ampl

itude

0 136.513651273.027303409.5409540.00E+00

1.00E-03

2.00E-03

3.00E-03

4.00E-03

5.00E-03

6.00E-03


Ampl

itude

Operating Range

Dremmel Operating RangeRpm 35000 30000 25000 20000 15000 10000 5000Hz 583.3333 500 416.6667 333.3333 250 166.6667 83.33333

Air is the best surface to obtain clear readings

What are the system natural frequencies ?

0.00 73.01 146.01219.02292.03365.040

0.0001

0.0002

0.0003

0.0004

0.0005

0.0006

Air - Loc #5

Accel 1 50g (Power Spec-trum)Accel 2 50g (Power Spec-trum)Accel 3 10g (Power Spec-trum)

Ampl

itude

(m

m)

0 136.513651273.027303409.5409540.00E+00

1.00E-03

2.00E-03

3.00E-03

4.00E-03

5.00E-03

6.00E-03


Ampl

itude

Operating Range

Dremmel Operating RangeRpm 35000 30000 25000 20000 15000 10000 5000Hz 583.3333 500 416.6667 333.3333 250 166.6667 83.33333

Dremmel safe Operating range

The maximum deflection is 0.00035m . Thicken the bolts. Redesign the XZ plate. Another Guiderail on Y axis gantry Increase the mass and thickness of the

mounting plates from 1mm – 3mm, this will reduce the natural frequency, and move the resonant frequencies away from the Dremmel Operating Range

Stage 5 – Analysis + Conclusions

Same conclusions found in ShapeOko 2

Stage 5 – Analysis + Conclusions

Thank you any questions?

final presentation - shapeoko

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