Jess Ong
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desktop lathe

A miniature lathe for aluminum and steel

This page is under construction.
2.72/2.720: elements of mechanical design
This class, taught by Proressor Marty Culpepper,  covered "advanced modeling, design, integration, and best practices for use of machine elements, such as bearings, bolts, belts, flexures, and gears....based upon rigorous application of physics, mathematics, and core mechanical engineering principles." The goal of the semester-long team project was to "synthesize, model and fabricate a design subject to engineering constraints (e.g., cost, time, schedule)."
The main project for this class was to design and build a desktop lathe that is accurate to within 50 microns and capable of cutting a range of materials, from delrin to steel. We were given a specific set of requirements and constraints around which to design the lathe. At the end of the semester, our team of five won a class competition to turn a part that was graded based on time, dimensional accuracy, taper, and runout. Our lathe also had to pass a series of tests in which Prof. Culpepper dropped it from a distance, hit it with a sledgehammer, and rammed the tool into a par as the motor was running. The final test was to have a team member (me!) stand on the lathe and "ride" it while a teammate drove the x- and z-axes. 
Picture
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​As the finite element analysis "guru," I was responsible for using FEA to iteratively converge on final values for the critical dimensions of the each of the flexure "beams." I also performed FEA analysis to verify that the flexures would not buckle under expected loads, would not fatigue under displacement over a predicted number of cycles, and that cross-slide vibration mode frequencies were safely away from the spindle speed. Finally, I was responsible for waterjetting and machining each of the flexures. 
(Hover over images to see captions, click to enlarge.)
Waterjetting the cross-slide
Finished cross-slide flexure. This flexure is compliant in the x-direction and stiff in the y- and z-directions, which provides precise tool control without the backlash that a typical leadscrew would have
Assembled cross-slide. Lock nuts keep the leadscrew coupled to the base while still free to rotate. Back-to-back blocks on the other end of the leadscrew engage opposite sides of the thread to create a novel anti-backlash mechanism
Using a dial gauge to measure backlash, which turned out to be zero
Front face of the dancing man flexure
Tapping the middle component of the dancing man flexure. This component was cut out of 1-in. aluminum using a waterjet
Assembled dancing man. This flexure couples the z-axis leadscrew to the rest of the machine. It is designed to be slightly compliant in x and y to avoid over-constraint in the machine, while being stiff in all other DOF
Preparing to assemble to z-axis
Assembling the z-axis and putting the dancing man into his new home
Completed spindle shaft with a press-fit tapered roller bearing. The spindle was precisely turned from a single rod of steel
Assembled spindle with a seal to keep grease inside and protect from outside debris
CAD cross-section of the chuck and inside of the spindle tube with two opposite-facing tapered roller bearings
Thermal image of the lathe with motor running to verify that the spindle is thermally stable over a period of time
Electronics for feedback control of motor speed. A knob connected to a potentiometer sets the desired speed. The arduino measures spindle speed using a linear magnetic encoder over I2C. It controls the motor speed via a digital motor controller using PWM
Final assembled lathe, including electronics and protective cases over the leadscrews and drive belt
© COPYRIGHT 2018. ALL RIGHTS RESERVED.
  • HOME
  • PERSONAL PROJECTS
    • MACHINIST'S CUBE
    • MACHINED RESIN CANDLEHOLDER
    • LASER CUT PROJECTS
  • RESEARCH
    • MOBILE-ENABLED DIABETIC FOOT ANALYZER
    • BLOOD PRESSURE IMAGER
    • ROBOT FLOWER GARDEN
    • HYPOSURFACE
  • PROJECTS
    • DESKTOP LATHE
    • ANIMATION WHEEL PUZZLE
    • SOCCER JUGGLING ANALYSIS
    • DELTA LINEAR 3D PRINTER
    • GALAXY YOYO
    • "OPERATION" ROBOT
    • FIREFLY FOOTBALL
  • SPORTS
    • SOCCER FREESTYLE JUGGLING
    • ULTIMATE FRISBEE
  • CONTACT