Category: General LinuxCNC Questions
* the post processor file is saved as .txt , not as .cps because .cps cant be uploaded *
** i attached a picture which i used to explain claude ai where where the 4th axis assembly is - it was for the python script and simulation screen that claude should add, but this helps to understand where everything is**
*** another picture shows how it looks when the end mill is is offset to the workpiece on my machine when starting the g-code
Hi, last week i build my rotary axis assembly and tested it with simple g-codes that are created from a python script that i build with the help of claude.ai . Its for surfacing square/rectangular timber, because i am planning to build some wood tables, etc. and i have a lot of stock material. The python script works perfectly and does what i needed. Its surfacing one side, then turning 90°, again surfacing and next side, until all sides are surfaced. I was really happy and thought that i can create my first solid wood coffee table and machine the first leg on Monday.
Unfortunately this didnt work out well.
*** the problem is described below the Blue text.
I am trying to make it as short as possible, but also i want to be as precise as possible:
First of all, the rotary axis is mounted in the Y-direction. My CNC router is a Moving-Gantry machine (XYYZ), 2500x1250mm table travel. My first plan was to mount the rotary table parallel to the X-axis so physically parallel to the Gantry, but this would give me only about 900mm of machining capacity and for the stock timber this was not optimal and if i want to build bigger table-tops by gluing together the surfaced/machined timber i thought it will be better to mount it along the Y axis, which is my long axis (2500mm), especially because i had a piece of 3meters of fake hiwin linear rail that i could cut in half and mount the tailstock on it (- which gives me about 1500mm of rotary axis lenght).
This 4th axis assembly is done and working, but generating a g-code that works same as on the Fusion 360 simulation seems to be a huge problem that i tried to fix since yesterday, for almost 20 hours without sucess.
I thought Claude.ai will manage to help me out, but since yesterday i think i have tried everything i could and everything what claude told me. I first had the rotary setup as A-axis, because i thought that it doesnt make a difference and claude told me that Fusion has the A-axis hard coded to be along the X-axis not Y-axis, but in machine configuration its possible to create a machine and add a A-Axis and choose that it will be along the Y-Axis. I did that and had still some problems, so claude told me that it can be tricked, so claude modified my Post processor, but the main problem was still there, so i setup a new Linuxcnc config with B-Axis isntead of A-axis.
Now to the problem/problems:
The End mill in Fusion 360 simulation is horizontally to the workpiece (sometimes tilted at specific operations and settings that i have tried), not from Z-axis direction, but from X-Axis and although i have set the origin correct.
I have choosed Multi-Axis Operation "Rotary Parallel" (Sprial mode or Line mode, but it is same for Rotary Pocket operation) and have set in the Multi-axis tab: "Rotary axis: Setup Y-Axis", but the End mill is physically not in the Center above the workpiece/rotary axis while air-testing the g-code on the maching.
I zero Z in the center of the rotary axis, same for the X axis, and Y-axis zero is on the Chuck side where the 4th axis is mounted. (as the origin in Fusion 360 setup.
So, the X-axis is somehow offset to X30 instead of X0 or close to X0.. I have checked everything i could, tried different settings to see what happens, e.g.: when using stock to leave axial 10mm it moves the X offest by that 10mm, so e.g. instead of X30 its X40 at the beginning and of course it is always offset. So for example the G-code starts, the rotary axis positions the timber to 133 degree, so almost 45° - which makes one corner of the rectangular timber to point almost exactly up towards Z axis, but the X-axis does not move in into that corner, like in the Fusion operation sumulation, but is offset by that e.g. 30mm, so the highest point of the timber is the corner, but the end mill wants to cut the tilted flat surface left or right of it. See picture below
Not only is that not like in the simulation, but also its a problem because i dont have much space in Z-axis and that corner touches my Z-axis plate. (i have even cut out a piece, but still had to stop the g-code at some point because it got too cloose while rotating).
Due to the fact that my designed table leg is a pretty complicated form compared to lets say a tapered wood leg, i designed a simple tapered model to test if the problem is my model (which i could not really believe). The problem is same - its not cutting in the center.
BUT i moved the X axis away from the rotary axis and carefully watched what is actually going on when using Rotary Parallel "Spiral mode".
I explain: Z Axis moves up, Rotary axis starts rotating and simultanously the Z-axis and X-axis are moving in a circle. So, there are like creating a Circle around the work-piece, but the Rotary axis stops at some point after i think full turn, then rotates back to position to start angle and when it rotates back the Z and X-axis circular movement stops, but starts again when the rotary axis rotates for maching.
But, why does the X axis moves and why is it offset by e.g. 30mm?
Shouldnt the X axis be on the center of the rotary axis and just the Y-axis moves parallel/along to Rotary axis while the rotary axis rotates and the Z-axis just moves up and down, depending on the form of the model? I mean, its a spiral operation where the main axis are the Rotary axis, Z-axis for depth and Y-axis for the lenght of the workpiece (timber, 350mm)
I could write and write - but i am already so confused that i am currently trying it again on my pc, without success. I am uploading pictures of the Machine configuration, Operation settings, How my Rotary axis is mounted on the machine, Post-processor and g-codes.
I really hope someone can help me out or at least point me to the right direction and sorry for the long text.
PS: The last thing claude told me is that i cannot get it to work with the B-axis, even he told me so on today morning. Claude said "lets go back to A axis" and tricking the machine by modifying the post processor and so on.
I cant imagine that its not possible with the B-axis along the Y-axis, but maybe thats true.