Posts Tagged ‘CNC’

Everything came together for the first real use of the forth axis mandrel for ring carving. It’s nice when the plan comes together and everything works as intended. There was of course far more than just making the mandrel. There is the CAD design stage and the CAM (Desk Proto) for generating the G-code for the 4th axis. Then running the G-code on the micro-mill. I use LinuxCNC and I had to write my own metric post processor for Desk Proto. Not all that hard, actually. I made a USC (inch) version too. One tiny code change.

The first picture is the carved ring blank on the mandrel. I can accommodate a wide range of wax sizes. There will be much more experimentation and determination of the correct wax width for a project. This example worked fine.

The second photo is after the wax master model was hand finished and at this point is ready for casting. Sprue’s were added the ring put into a flask and the investment added. This post is not about the lost wax process. However, I thought it was interesting to show the wax carving and the final result the mandrel helps create.

The last picture is the finished Sterling silver ring shown on my hand (size 11). It really looks great. I will be doing a lot more wax carving on the 4th axis of the Taig micro-mill.

Using 4 axis milling, requires a CAM software system to create the necessary CNC G-code. It’s not something one can easily hand code when doing 3D designs. Simple level surfacing could be hand-coded on a 4thaxis, but probably lathe turning would be far easier.

Aspire, a three-dimensional CAD/CAM produced by Vectric can produce G-code for the 4thaxis. It is one of my go-to programs. However, I don’t design everything in Aspire CAD. Fusion 360 and RhinoCAD are also programs I use for design.

Both these programs have 4 axis CAM built in. Fusion 360 has a built in CAM, and with Rhino5 I have a plugin RhinoCAM 2012 w/4axis.  In Fusion the 4thaxis CAM is 2.5D and cannot produce 3-dimensional 4thaxis G-code. I added 4thaxis 3D CAM to RhinoCAM 2012 but find it extremely difficult to produce quality cut pathing. It seems to contain some very strange algorithms producing highly fragmented pathing.

This has led me to another 3rdparty CAM software (from the Netherlands) called DeskProto. It can take input (in the proper format) from any CAD software. (I won’t be getting into describing the process here.)

DeskProto’s claim is that it is CAM software for creative people and not the die-hard machinist. I find agreement to that statement. I find details missing with some lack of particular seldom-needed features perhaps needed by a high powered VMC machinist. For the rest of us common users, making things (on up to 5 axis milling systems), DeskProto gets the job done without micro-managing every single minor detail.

Having made that (limiting) statement, there remains plenty of useful variables that will insure getting the results a user like myself desires.

I will admit I put off choosing this program, as I had access to the “professional” CAM in my existing CAD programs (described above). I discovered I didn’t need all the hard-to-use and “understand” details of those programs. Pride goes before failure. I failed in easily getting what I wanted from the other systems.

I downloaded and installed the unlimited use DeskProto trial software. I had full access to creating 4thaxis output. It does imprint a large “X” (trial copy) in the output file and is seen on the visual display. But I was able to produce some very clean and sensible G-code pathing.

Since I am a hobbyist user, I decided DeskProto was an excellent value CAM addition for my 4 axis needs. It is an improvement of what I get from Aspire on 4 axis output. I paid for the highest-level version of DeskProto and (of course) the registration removed the trial edition “X” without re-installing the software.

Now that I have a full non-obfuscated version of DeskProto installed, I will run some real projects.

My first task is to machine a suitable mandrel to hold the wax I intend to 4thaxis machine. The picture is a 3D printed example of the mandrel I will make with 12L14 carbon steel. I will be posting 4thaxis cut wax examples sometime soon…  

 

CNC Milling

A CAD

S. Whiplash, Typical CAD

It’s been a while since I have run my original CNC Taig Micro-Mill. It’s the one configured for metal work and has the mist cooling installed. There is nothing operationally wrong with it as far as I know. Just haven’t had a project where I needed its services.

I have always used RhinoCAD (Rhinoceros) with RhinoCAM to generate the design and the Gcode necessary to run the mill. I am presently working with FUSION360 CAD with its built-in CAM. FUSION360 has become my go-to CAD for 3D printing because of the very good built-in STL generator. Rhino can do STL too but has some issues (for me) in producing first-time usable STL.

CAM is a whole new layer of complexity after creating the CAD drawing. Of course, the first challenge is the CAD, as what is drawn must be something that can be produced by milling. It is possible to draw parts that can never be machined.

The CAM requires the complete understanding of the milling operation and all the tools that can be deployed on the target milling machine. In the case of the Taig Micro-mill, tool size is limited to the machine’s abilities and speeds. I have no need for things like an automatic tool change. I am a hobbyist, not a manufacturing center.

CNC is certainly not “push the button and go”. The complexity is what I love about the process.

I use two different CNC controller software systems to control the movements of the milling machines. The older mill is using MACH3. The newer WAX cutting mill runs on LinuxCNC controller software. I was very pleased to see what is called a POST processor available in FUSION360 for both controller formats.

The POST processor is a function in CAM that converts the machine movements to the dialect of G-code the machine controller can understand. G-code is a standard, but there is a huge variety in how the actual code is written for the controller.

Every controller manufacturer does control in their own way. That is what a POST processor does. It puts the standard code in a format the actual controller program can understand. It is a patch.

I have a simple 2D CNC machining metal project to cut new wrenches to fit the ER11 collet holder on my new high-speed spindle.  The spindle  installed on the Taig mill used for 3D wax machining.

The design of the wrenches is simple, but the CAM details needs to be configured within FUSION360.

The “tool table” defines in exact detail, the milling bits and holders used. Next is configuring the speeds and feeds the Taig mill can utilize with those tools in the specific materials to be machined. Saving all those details so they can be reused later in a new project. I’m lovin’ it!

It appeared overwhelming when first looking at the tool table. It was huge, with A LOT of tools pre-listed. But I soon discovered how to easily make a personal table better suited to my needs.

The results will be posted when the FUSION360 CAM is used on the wrench project. For now, its all about getting a new system configured. It just needs to be done correctly and I foresee no major obstacles. Stay tuned.

The full article on the Taig 24,000 RPM water cooled spindle conversion is now available on The Hobbyist Machine Shop website. Follow this URL: 

https://thehobbyistmachineshop.com/cms/projects/high-speed-spindle-for-the-taig-micro-mill

The new spindle performance exceeds all expectations. It is not a low cost option / addition to an already  adequate micro-machine tool system, but it does provide a very good way to achieve more than double the stock Taig spindle speeds.

Some applications using very small diameter tooling are performed much better when running adequate SFM and cut travel speeds. High speed spindles and especially water cooled ones like this example are a joy to use because of their extremely quite operation.

The Taig spindle is known for its quiet operation and the water cooled spindle here is in my opinion just as quite or perhaps more so, even running at full speed. Tool cutting sound is the same but the spindle motor has none of the sound of a high speed router.

The parts arrived yesterday. Exactly as shown in the previous post. I placed an order for some four conductor cable for the wiring between the Variable Frequency Drive (VFD) and the spindle motor.

I needed to see the clamping size of the spindle’s electrical plug connector. I didn’t want to select and order a cable that would not fit. The cable is on they way to me, so I created the adapter I needed to mount the new spindle on the Taig Micro-Mill.

The picture shows the results of my work as the spindle is now nicely mounted on the mill.

After I am finished with all the mounting, wiring, and set-up… and I have the new spindle working, I will write a detailed report on the mounting plate and all the work required in making the conversion.

I think the spindle looks like it belongs on the Taig!

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