Shake Table Design
Mission Statement (Design Brief)
Design and built a shake table for ME 491 design competition that can provide a
platform that is shaking at 2 cycles per second with a ½ inch peak-to-peak motion.
The prototype is to be finished by Oct 24, 2011 and cost less than $50.
Make a Plan : A simple chart showing timelines and resources
Developing product design specifications (PDS)
Criteria
Performance
Environment
Life in service
Quantity
Shelf life
Cost of production per part (material and labor)
Size and Shape
Weight
Maintenance
Installation
Ergonomics
Safety
Materials
Manufacturing facilities
Shipping
Packaging
Aesthetics
Requirements
2 cycles per second +/- 5%
½ inch peak to peak +/- 5%
Uses wall transformer (<10 watts)
Motion profile: sinusoidal (desired)
Indoors
100 hours
1
N/A
$50
Clear moving platform 6 by 6 with
pattern of ¼ inch holes.
< 1x1x1 feet envelope
Desired: more compact
< 10 lbs - desired < 5lb
None
N/A
N/A
No pinching points, No sharp
corners, stable with a 1 lb weight on
top, input power < 10 W,
Enclosed moving parts desired.
None (no constraints)
None (subject to $50)
N/A
N/A
N/A
Quality and Reliability
Must withstand
 overloading (not dropping)
 side loading
 running at higher speeds
Applicable codes and standards
Testing
N/A
Life testing at nominal load
withstand overload test w/o damage
withstand side load test w/o damage
withstand higher speeds
N/A
None needed
N/A
Finished by Oct 24
N/A
No loud or high frequency noise
Company constraints and procedures
Documentation (processes)
Legal (Related patents)
Timelines
Disposal
Other (Noise)
External Search
Existing products and technologies
 Hydraulic actuators
 Pneumatic actuators
 Solenoids
 Linear motors
 Geneva mechanism
 Four-bar linkages
 Cams
Internal Search
Several vastly different designs were suggested. The following design was
selected as the most workable concept.
Further simplification of the concept lead to the final selected concept below
Detail Design
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Motor selection : based on power and frequency of motion
Voltage selection: Based on frequency of motion
Materials: based on weight, ability to machine easily, and cost
Overall dimensions: bases on space allowance, weight
Cam design: Based on motion amplitude, motion characteristics, life of
device
 Bearing selection: Noise level, maintenance, life, cost
Prototyping
Mass Production Scheme: Build all parts, assemble later (interchangeability)
 Requires an assembly plan first
 Requires precision machines and workmanship
 Requires adherence to all tolerances
 May not work at the end …. Requiring reworks
Prototype Fabrication Scheme: Fit-and-Build as you go
 Requires a more elaborate fit-and-build plan
 Requires less precision machines
 Requires less precision tolerances
 Usually works at the end
Fit-and Build Plan
There are 3 sub-assemblies - these can be built separately:
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Frame assembly
o Base plate (1)
o Side plates (2)
o Top plate (1)
o Bearing (1)
o Screws (8)
Motor assembly
o Motor
o Motor bracket
o Cam
o Screws
Slider bar assembly
o Slider bar
o Follower plate
o Platform plate
o Screws
o Spring
Procedure to build and assemble the frame sub-assembly
1. Make the two side plates from a single plate.
a. Make a cleaning cut on top using a mill
b. Without changing the set up make the cut in the bottom.
c. Make a cut in the middle to divide into two plates.
d. Make fastener holes where the plate screws to the base plate. They do not need to
be precisely located.
e. Place one side plate against the base plate and transfer the hole pattern by marking
with a marker.
f. Drill and tap for the screws being used. Be careful not to break the taps in the
hole. Ask someone with experience to show you.
g. Screw the side plate
h. Do the same procedure with the side plate. They do not need to align precisely
but the two should have the same level height above the base plate.
i. Make 4 holes in the top plate and 4 tapped holes on top of the side plates.
j. Assemble with screws.
k. Disassemble the top plate and make drill and ream a hole in the center of the top
plate for a slight pressfit to the brass bearing.
l. To pressfit the bearing we can cool down the bearing if it is too tight. However,
do not pressfit the bearing yet. We need it to check the fit with the slider bar.
Base Plate – no machining required (except for fasteners)
Cut both plates at the same time. Cut a 110 by 100 piece, machine and cut into two.
Top Plate – use ¾ inch drill for the bearing fit
2. Motor Assembly
a. Attach the bracket to the motor. Make sure the bracket is square enough so the
spindle of the motor comes out parallel to the base plate.
b. Machine the cam. The cam profile needs to be programmed on CNC. The cam
should have a hub long enough for two set screws. The hole that fits the motor
shaft should be a sliding fit. Make radial cross holes in the hub and tap for set
screws.
c. Attach the motor shaft to cam and tighten set screws.
3. Slider bar Assembly
a. Cut the slider bar to the designed length (no precision necessary)
b. Reduce the two ends of the bar slightly (about 1 mm) and leave 1 inch of length
unreduced where the sliding action happens with the bearing.
c. Clean the 1-inch sliding length (very tiny cut)
d. Check the fit against the bearing bore for a sliding fit. use some oil.
e. If the fit is too tight use some sand paper to reduce it slightly until the fit is good.
f. Make the top and bottom plates and attach to the end of slider bar using screws
through radial holes in the slider bar and hubs of top and bottom plates.