final presentation - shapeoko
TRANSCRIPT
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
Stage 4. Numerical Testing
• Combined
• Y Axis Gantry
• XZ Plate
Max deflection 0.00025 m Highest stress concentration 1.00 E+00 MPa
Stage 4. Numerical Testing
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
Stage 4. Physical Test – Stress Deformation test
Mass
Stage 4. Physical Test – Stress Deformation test
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
Stage 4. Physical Test – Stress Deformation test
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
Accel 1 50g (Power Spectrum)Accel 2 50g (Power Spectrum)Accel 3 10g (Power Spectrum)
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
Accel 1 50g (Power Spectrum)Accel 2 50g (Power Spectrum)Accel 3 10g (Power Spectrum)
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?