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CNC Milling


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.

DSC06345What I have in my left hand is six pounds of  brass engine parts. It doesn’t quite look like it yet but it will get there.  I examined my brass stash for the A3 project and it wasn’t as complete as I thought it was. The stash is good but a few things had been “borrowed” and/or are otherwise missing, or I didn’t figure materials as close as I could.

Actually this is probably 300% more than I needed but with projects like this there are minimum amounts that can be ordered. That’s OK as it will all get used at some point in time. I often cut down stock on hand that is too large rather than make a special order for a tiny quantity. If I look close enough at certain stock I can see smaller parts hiding inside, that my tools help me cut out.

That’s the nice thing about metal milling machines and metal lathes. Excess material is not much of an issue. The hard part is when you have to put some back on…

I churned out 6 more of my 1” aluminum wrenches late Sunday afternoon. I am offering them for sale in the Ramblin’ Dan’s Store website. I have been selling them quietly but decided to go public this May. Price. $7.50

That’s the same (new) list price of the Taig flat wrench and I think the aluminum is better suited for the collet adjustment on the mill. The flat wrench is still great behind a chuck on the micro lathe.

I have optimized speed and feed according to GWizard (CNC Cookbook). I just received a new update to GWizard and now it shows me how to grab a bit more time performance if I sacrifice a quality finish. Speeds and feed didn’t change much but now it indicates I should be able to make much deeper passes. That will then require less overall time. I am down to 6 minutes 40 seconds per wrench now and I am pleased with that

BTW here is a hint for you GWizard users out there. I had to uninstall the old GWizard before the new one would install. That happens if you do not upgrade very often. I didn’t lose any of my old data.

As you can see 6 wrenches generated a lot of swarf. Nice fat chips. I was running 19 IPM with a 0.0377 DOC. The GWizard now says 0.083 DOC is possible in a roughing pass at twice the speed, but I am happy where I am… I have a great edge when done. Far better than the pokey 20 minutes I was running long ago.

I have found a good project for my 4 Axis CNC mill and also my Rhino 5 software. If you have read  recent posts I have mentioned I am pursuing carving some small bells from wax for lost wax casting. Here I am re-configuring my original Taig micro mill back into 4 axis operation.

I need the tailpost to be able to slide into any length position I need. The stock Taig slotted table is perfect for that. I don’t need the multi hole set-up table for 4-axis. I set the rotary table up so I can just slide the tailpost against the back of its slot and it is in perfect Y alignment. The height is taken care of by the shims and the small adjustment in the tailpost itself.  After this set up it will be a very quick reset for the tailpost.

You can see I have placed a Chuck adapter in the middle of the table. I will use that (with a chuck) to hold the wax cylinder as I mill out the center of the bell.

I have a few seconds of video I made of a dry run of the 4-axis profiling run. It makes some interesting sounds as the X axis is moving very slowly and sometimes “jiggling” a bit. Not sure why, but it is playing that CNC music. You will have to imagine all the missing parts. Hey! Just do it!  🙂

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