[Jzerro]

Greetings from Argentina! A few months ago I began working in a mold making shop that has recently acquired a big 5 axis mill (Y=10m, X=5m, Z=2.5m) and we have more or less got it running and this forum has been tremendously helpful.

I am a naval architect with have little to no experience in CNC machining, however after some months of trial and error I have learned a lot, but some solutions I have come up with empirically may not be the most efficient way to use the machine and I now turn to you hoping to tidy up our work process. This is my first post

The machine has a Sinumerik 840D controller, and I program in Rhinocam. So far it has worked, but the post processor file was more or less concocted by the previous guy with some help from the machine provider and a few little additions of mine. It is far from perfect and I don´t understand most of it. Also the Sinumerik controller was never properly set up by a professional. The machine builder sent a programmer a few times and he was really helpful for setting up some parameters, but I believe there is a lot more to tweak. Aside from this machine, we have 2 small 3-axis mills, one of them with Syntec and the other uses Mach3.

What follows is part of an endles list of doubts so please bear with me and if anyone can help me with at least one of them I will consider this a success. Most of them are about Rhinocam and a few about the machine itself

1- When programming for the 3-axis machines, Rhino lets me place the Zero point wherever I want. But as soon as the machine specification is set to 5-axis, it always uses the cPlanes "origin" as Zero point and there is nothing I can do to change it. Is this normal in RhinoCam? (or in 5-axis programming for that matter)

2- I was only able to program very few 5-axis operations. Mostly I index the rotary axes and use it in 3+2. This is due to the fact that in 90% of the surfaces I have to machine, RhinoCam doesn´t generate a good toolpath. It may be because of the way they are trimmed or mirrored. Below are some examples.
Notice how it sometimes responds well to one surface but not to its mirrored "twin". And also it´s not always the same side that brings problems. I tried deleting and mirroring again, flipping normals, etc. to no avail. So far the only thing that worked is using MIRROR function in the gcode (which mirrors XYZ axes) AND changing the machine axes definition in RhinoCam from "+Z, -Y" to "-Z, +Y" which mirrors the rotary axes. This brings me to my next point...

3- There is no machine definition that allows for a straightforward programming of the machine. "+Z, -Y" Outputs a code that succesfully moves the machine in simultaneous 5-axis mode (that is on the few ocassions when I can produce a toolpath), However if I want to machine in 3+2 mode, I need to change it to "-Z, +Y". I believe this to be a symptom of a deeper problem involving the patched up postprocessor file.

4- There is another "glitch" that scares me from using simultaneous 5-axis in general. When the trunnion vertical rotary axis B reaches it´s software limit in the middle of an operation, it has to rotate all the way around in order to continue machining. When this happens the tool only moves a very little bit away from the piece, which is never enough to avoid collision. So far this only happened in tests machining styrofoam so the machine is ok. But I have not found any parameter in the controller or in Rhino to change how much the tool moves away when this happens, or in what direction. I have avoided collisions by extending the range of motion of the B axis and personally checking the code in places where I know it may reach the limit. This is very tedious and inefficient

5- Bonus question; I have not found a way to use the machine in "4-axis" mode, since rhino seems to interpret 4 axis operations as only suitable to rotary table machines, or lathes. Is this so, or am I missing something?