CNC Tesla - First Prototype

    The first attempt to build an CNC machine from ground up.





    Note: Page Under Re-Construction


    Development
    Build and Assembly
    Further Research
    Creations




    Intro:

    This page displays the CNC Tesla design and its evolution. Scroll through to see the changes made during development of the design and also see the assembly of the design.






    The Next CNC Machine:


    Having MakeBot's CupCake around is nice, but it can do only so much. New bigger and better CNC machine would add to the manufacturing abilities. The Tesla CNC will be controlled by more common software for CNC machines that allows for milling, drilling etching and other abilities that are common in these machines. Unlike CupCake which has its own software of control that has limited gcode command acceptance.
    The name Tesla CNC come from the hope that the experimental EDM (electrical discharge machine) tool head will be completed and would be able to process harder metals.





    Beta Video

    A bit longer movie promoting the design of the CNC Tesla Mark 3

    Part 1.


    Part 2.




    Evolution of the Design

    Design of Mark I.

    The first design (mark I) is somewhat based on original RepRap Darwin whose frame was cube with reinforcing cross braces for frame stiffens. First Tesla CNC designs was very similar, but further modifications heavily changed the appearance and functionality. The main difference is that all xyz axises are joined together unlike Darwin's design where z axis is separated form XY axis. Another main difference between Tesla and Darwin design is that the moving parts are quite massive unlike Darwin parts, that are made of plastic and thin rods.

    Further modifications of mark 1 were made for ease of manufacturing. These included simple wooden blocks as the connecting corners. This was to emulate purpose of aluminum plates in mark 1 design into the same shape. However this was proven to be difficult to manufacture with home tools.


    Upgrade to Mark II.

    The Mark II was thought to be manufactured with minimum numbers of tools and to have the simplest structure possible. The frame was to be made of wooden cubes that should be easier to manufacture then metal. In additions, the more complex parts would be printed by CupCake. However this was proven to be too difficult as the dimension of the machine are larger than what CupCake can produce. Even if the parts would be made of segments, they would still need to have 4 hours print time and CupCake can not handle such long print times without modifications.
    There are no renders of Mrk II as the only thing that had been done was the prototype assembly that showed the behavior of the machine. This experience helped produce newer design, Mrk III, that has better and more stiffer frame.

     


    CNC Tesla Mrk I was fully designed in CAD program. However the material used and methods to manufacture the CNC changed the functionality and appearance of next designs.
     The linear motion rods were sold in standardized lengths, therefore the Mkr II design was forced to have tetragonal or square cuboid shape.



     Bill of materials for the Mrk II assembly

     

    Prototype assembly of Mrk II.

    Major Components and Hardware





    The New Design: CNC Tesla Mrk III

    After prototype assembly has shown the the structural behavior, there was a need for further modifications of the previous design. The Mrk III design includes more structural support and better xyz axis.

     
     CNC Tesla Mrk II (under development). The new design introduces higher stability
     and lower working height that can be adjusted according to the work conditions.





    Assembly Instructions

    There is a PDF version of the CNC Tesla Mrk III Complete Description (v0.75) available here.



    Acme Upgrade (3/8" - 12)

    An ACME upgrade had been added to the design. As the M10 and 3/8" have similar diameters (3/8" is 0.475mm thinner), it is possible to simply upgrade the existing design. The original M10 threaded rods were chosen due to cost efficiency, but for increased cost the mark III can be outfitted with the more reliable and durable motion system. 

     

     

     

     


    Water Jet Parts

    The below picture show all the water jetted parts for mark III design as well as the aluminum corners that have yet to be machined. Picture also include updated linear motion brackets which replaced the extruded ABS plastic brackets from version 0.75. 

     
     Water Jetted Parts were order from Big Blue Saw


    Mark III Pre - Assembly


     


     

    Detail view of the Main Axis (X axis) motor and coupling joint
    Partial Axis Assembly





     



    Main Axis

     
     

     


    Sub Axis


       



     Z Axis

     
       


    Plan B

    As the machining of the aluminum crones for the Tesla CNC is proving to be challenging, a backup plan is been exploited. So called "Plan B" is a emulation of the aluminum corners with 0.25inch plates with interlocking assembly. It simplifies the manufacturing process by substituting aluminum plates that can be made by water-jet or cnc machine. This allows the Tesla CNC to achieve self-replication where only few easily accessed components are needed such are threaded rods, nuts, bolts, and raw aluminum plates.


     

     



    Making Some Progress

    Finally, all the parts are complied at one place for complete assembly. Some minor adjusting and fitting of the parts was required, which included sanding and light girding. The water jet parts had satisfactory precision and fitting. Note that in the CAD drawing compensated for tight fit by 0.2mm space between all pats that had to fit together.


     Detailing view of the Plan B corners

    Notice that all parts have no sharp inner corners

     
     

    Bracket for the drill DC motor
     

    X Axis two square brass nuts for motion transfer
       
     

    Full view of the Work Table

    Detail view of the Printed Timing Wheel
       
     
    Drill motor lowered to the Work Table

    Overall View
       


    First Tests



     

     
     Simple Plotter Tool-Head
    Finished Plotting



     
     
    New Fixture made of 2012 rods from 80/20 Inc.
    60 Degree Drill Bit Etching

     
     
     The First Test of the Etching on PCBs
    Note:the misshaped circle was due to vector conversion error, not the cnc machine
    Wood Test Engraving
    (4mm deep)


    New Drill Bits


    Need had arose for more aggressive drill bits than hose that come with the Proxxon Drill. After careful searching I found store [CARBIDE-PLUS] that sells PCB hole drilling bits, but also have miniature end mills bits.

     

    New Bits

    Sample of Different Types of Bits
     

    Initial Test
    Note that the drill was spinning at ~16,000rpm

    Result
     with 1mm resolution and 4mm depth in MDF


    3D Milling Sample

     This test consisted of a semi-sphere with cutout of a smaller sphere at the top. Simple test for the contour and depth control.


     


     

     

     


    PCB Etching Test

     Simple sample for manufacturing PCB's from EAGLE board layouts. The final results were unsatisfactory, however this was due to software not been calibrated for CNC tool size. New tests are under way with smaller tool bits.

     

    Schema of Predator Segment

    Board Layout
     

    POV Render

    Finished Etching
     

    Note: the etching was done with 30degree bit

    Test fit assembly of holes for all components


    New Gantry



    Some of the sample test have shown that the Z-Axis has a minor glitch that can reduce the accuracy. The tool bit does not move in a perfect line up and down. This is due to the design flaw where the smooth rods are placed too far way from the centroid and motion transfer point. The flaw only shows up when the tool moves up and down freely or with little resistance, such as etching or vector drawing. It does not show up when drilling or milling a material that exert larger forces.
    This issue has been addressed in new gantry system that replace the previous design. The new gantry was designed to be made on current version of CNC Tesla.
     

    New Gantry Mark 4

    More detail view of the new mechanism

    Aluminum Etching and Milling

     To make the Mark 4 gantry, sample milling tests into aluminum are required. First test the gcode in MDF and then repeat the code in the 6061 aluminum sheet. Unfortunately the gode was not well calibrated in terms of speed and the type of tool. This resulted in broken drill bit.
     

     
     

     

     

     

    Successful Aluminum Milling


    This aluminum part was made at 250mm/min at depth of 0.2mm into 1/4 inch 6010 stock.
     



     
     



     
     

     


    Second Part


    Made with 1/8" helix endmill, at 400mm/min with depth cut of 0.1 to 0.124 mm.

     



     
     



     


    Getting The Job Done


     

     

     
     
     

     

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