The C-Turtle makes progress, then snags

Now that my first CNC machine is completed and working, over the holiday weekend I continued to try and refine the design of my other experimental machine, the "CNC Lathe Attachment" based on John Klienbauer’s Wood Turtle design.  That machine is now also complete, as John designed it, and it works successfully as a CNC-lathe duplicating machine, but that was not my purpose in building it.  I wanted to make a machine that could be used to cut creative spiral patterns in wood spindles…that was the original goal of my whole Rube Goldberg venture into CNC!

In the meantime, I’ve learned a lot about CNC, and I really expect that my "7th Sojourn" milling machine is the one that I will use the most.  That’s good, because I’ve hit a snag on the "Wood Turtle" spiraling machine design (I’m calling this modification of John K’s design the C-Turtle).

Over the weekend, I completed a more solid mount for the C-Turtle to the lathe.  It is now rock-solid and has no wiggle at all in its mounting to my Nova lathe.  This will allow it to work better even in its original duplicating-machine functions…but I’m shooting for spirals.

Next, I designed and built a mount for a stepper-motor which attaches to the "outrigger" on my Nova lathe.  This outrigger in its folded position allows me to line-up the stepper-motor with the outboard hand-wheel on the lathe headstock.   I then mounted essentially a jamb-chuck into the cup of the hand-wheel.  I installed an 1/4" axis on the jamb chuck and linked it to the stepper-motor with a 1/4" coupler.  Now I had a stepper-motor that could turn the lathe’s main axis under control of the computer.  So, basically, I could carefully coordinate motion of the C-Turtle’s cutter head with the very slow rotation of the lathe’s axis (much slower than the lathe’s motor could turn).

Everything works great.  The problem is that my 60-oz stepper-motor can just barely turn the lathe’s axis and if any pressure at all is applied to the wood, the motion stops…the stepper-motor is just not strong enough to work like this.

So, I’ve proved two things:

1.  My design for the C-Turtle works in concept, but
2.  I will need a strong stepper-motor to make it work.   The stepper-motor on this axis does not have the mechanical advantage that the 1/4" threaded rod drive screw provides on the other axis.

Since my FET-3 board will require a bigger power-supply and a resistor to drive a bigger-stepper, a cascade of upgrades occurs in order to take this experiment to the next level. 

I may put this experiment aside for a while before I invest more money and time into it.  I am happy to  have completed one of the CNC machines and may move to another project for a while before returning to CNC design school.   I am now confident that this contraption would work if I spend some money on parts…but that may wait for a while.

About mattsanf

Matt Sanfilippo is the Chief Partnership Officer (CPO) for the College of Engineering at Carnegie Mellon University (CMU) and Co-Director of its Engineering Research Accelerator. In this role, Matt coordinates and enables strategic and sponsored research opportunities across the college, and stewards the development of proposals for major research opportunities along strategic themes. Additionally, he enables collaboration among the college's research institute/center executive directors, and industrial and government relations personnel in the pursuit of opportunities with industry, federal and state governments. Before becoming CPO for the College, Matt was the Senior Executive Director for Research Initiatives, the Executive Director of CMU's SII (Smart Infrastructure Institute) and ICES (Institute for Complex Engineered Systems), and Associate Director of PITA (Pennsylvania Infrastructure Technology Alliance) and RAMP (Research for Advanced Manufacturing in Pennsylvania). Before CMU, Matt was Managing Director of Applied Technology for Michael Baker Corporation, an engineering and energy services firm. Matt managed Baker's technology division including Geographic Information System (GIS), software and web development, multimedia, virtual reality, visualization, Global Positioning System (GPS), mapping and surveying services. Before joining Baker, Matt was an Innovation Director for Redleaf Group, a Venture Capital/Operating Company focused on information security, supply chain and mobility solutions. While at Redleaf, Matt managed technical due diligence for seed-stage investments and coordinated relationships between Redleaf and their partner companies. Prior to Redleaf, Matt was CIO of GZA GeoEnvironmental Technologies, an infrastructure engineering firm, and operations manager for their Internet start-up that focused on web-technologies for health and safety and manufacturing metrics. Matt is on the board of Larson Design Group (LDG), past Chairman of the Board for the Pittsburgh Botanic Garden, current board member of the Pittsburgh History and Landmarks Foundation (PHLF), current Vice President of the Sewickley Heights Gun Club (SHGC) and former member of the Information Sciences and Technology Advisory Board for the Pennsylvania State University Beaver. Matt is also former Vice President of the Pittsburgh Chapter of the Association of Internet Professionals and former Vice President of the Board of Trustees for Baker Combined Charity of Pennsylvania.

Posted on November 28, 2005, in CNC. Bookmark the permalink. Comments Off on The C-Turtle makes progress, then snags.

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