Ramblin' Dan's Workshop

4th Axis Project

I have a (bad?) habit of wandering many paths in my creative craft efforts. The reason there are so many posts on different subjects in my many blogs. 

Most recently, the last two years have been spent exploring the possibilities presented with the 3D printing craze that figuratively exploded into the hobbyist realm of possibility. I presently have 3 FDM and on DLP 3D printers.

A common need is present with all forms of CNC (computer) controlled activities. The object to be produced must be drawn is some form of CAD (Computer Assisted Design) or drawing software.

So, 3D printing has extended my use and skill using CAD. My current software tools are Vectric Aspire, RhinoCAD (Rhinoceros) and FUSION 360. I have used or explored many other CAD and CAD/CAM but cannot become proficient in ALL of them. My preference may and does not need to be yours.

My interest is fading in plastic parts 3D printing. Not going away, but only so many things NEED to be made with plastic. Most of the BEST things I make are NOT plastic. I will continue with 3D printing where it works for what I need.

I am returning to CNC subtractive machining using CAD/CAM and the making of things of much better quality and value than I have been producing in plastic. I really love wax carving master models and lost wax casting of metal objects. I tried 3D printing for making casting models and it works, but wax masters remain superior.

Wax is not the only material I plan on machining. I have no rules that limit my use of subtractive manufacturing. Wax just happens to be one of the best materials for intricate 3D carving with CNC machines. There are many alternate materials ranging from metals, wood and composites. 

At this moment I am venturing back into 4-Axis type CNC machining. This is not my first effort. I have used 4-axis CNC in several other projects.

Ring Mandrel

My newest project is the development of a CNC wax carving system for making finger rings or any rings of similar size. 

I will take advantage of the 4^thaxis now installed on my newer Taig Micro-mill. I previously used the 4^thaxis on my original (#1) Taig micro-mill. I have IT set-up for metal machining and is fully operational using MACH3 control. I moved the rotary table and stepper to the (#2) Taig micro-mill I use for wax carving. Its control program is LinuxCNC.

I have been using Vectric Aspire for my CAD/CAM creative design and g-code generation. The 4^thaxis operation is built into the software and is called “wrapping” which lay’s out the 4^thaxis (labeled as “A”) by “unwrapping” the rotary A axis as a surface plain in the Y direction. The result is that CNC moves in the Y direction are wrapped around the circumference of the A axis. X axis moves remain left and right on the A center axis.

What results is still 3 axis movement. The cartesian Y axis on the mill is fixed and is converted to rotary A axis movement. X and Z remain the same.

True simultaneous 4 axis movement has little application. I can’t say “no” application, as certainly there may be one. The 4^thaxis can be programed for incremental flat surface positioning such as machining 4 (or more) sides of a cube or poly-sided shape, or flipping over a 2-sided carving for reverse side machining. Presently I can manually combine two separate flat (cartesian) g-code runs with manually coded A axis rotation between sections with Aspire

I plan to investigate that operation and find some other or additional CAD/CAM software that will support the 4^thaxis function.

I am revisiting RhinoCAD to see if I can get a reasonable update (cost) for the RhinoCAM 4-axis update software. I have the 2012 version but need the 2019 update for Rhino Ver 6.

Also undergoing evaluation is a less powerful solution called DeskProto. It seems capable of good 4 axis at first look. It’s a bit weak as a full house CAM system.

Machine Control

LinuxCNC provides 4 axis control. It’s up to the operator to provide suitable g-code. I discovered Vectric Aspire did not have a LinuxCNC post processor (PP software) for flipping the Y axis moves to the A axis with LinuxCNC. I edited my regular LinuxCNC post processor and now have a Y conversion PP in both metric and inch. I will post them on the Vectric form after I test them with actual operations. I have them working but not in cutting an actual project. (Things to do…)

Wax Carving

All this because I plan to CNC carve (rings) slices of round wax tubes with a 5/8-inch diameter center hole. The hole will be used to mount a slice of the tube of the width needed for the ring, on a rotary mandrel mounted on the 4^thaxis. I am currently designing and will produce the mandrel in steel. The mandrel is a lathe machining project all its own. I have produced a prototype mandrel in 3D printed plastic for testing before machining the steel mandrel.

The concentric round tubes are my first wax material of choice. There are some other shapes, including off center holes that could be used. I will be exploring the use of these alternative wax shapes. 

So many new ideas to explore! Stay tuned…