Ah, yes. CNC Zone is always fun. I quit hanging out there when this place got warm.
We will have a much more enlightening talk about this here so let me get it started;
When we talk about “true 4 and 5 axis milling” we are really talking about G93, G94 and to a lesser degree G95.
Does Mach4 support G93 “Inverse Timing?” Yes it does. And yes, we mostly mill in G94. That is pretty much the default. G93 is the magical secret sauce for true 4 axis milling though.
It isn’t so much an issue of support from Mach4 or other controllers as I found out, so true story time!
In 2010 I called the guys at CNCRouterParts and asked them if their machines could do “X.” They said no and directed me to Probotix who sold me an electronics and motor kit for the Sieg X3 mill. I got the ball screw conversion kit online and that was my first personal CNC machine.
It had a twist! I ordered the Sherline PN3700 rotary attachment and got an adapter plate and Probotix made the electronics package 4 axis.
I assembled a LinuxCNC based steel cutting 4 axis CNC machine for $3,600 in December 2010.
I still own the machine and use it in its original configuration, original electronics. Sweet little machine.
Where am I going with this? I paid $3,600 for my machine, right? I called around and started pricing software to output G93 based tool paths…
Yeah, many 10s of thousands of dollars Waaaaay more than I paid for the machine.
So I had to hand code everything. It was truly a pain too.
Anyways, so what apps generate true G93 tool paths? The only one I can afford is Fusion 360. And I buy credits to use it because its just too expensive to have full time access to it. Deskproto v7 does in fact use G93 BUT!!! It does NOT use 3D space for calculating tool paths. Its still a turkey on a spit.
The hard part is actually in Fusion 360, you use 5 axis milling paths BUT you set up your machine to only have 4 axis (you do that in your machine library). Some tool path generators will also have a “inhibit 5th axis” checkbox (that might be removed now in favor of machine definitions, it’s been a year or so). When you do all of that correct, the magic happens!
3 axis is really simple. You place the cutter using 2 axis (X and Y) and then you vary the Z axis as needed. Not much to it. Thus you will hear the term “2.5D” in reference to 3 axis machines.
When you get into 4 and 5 axis, oh boy! You are in 3D space now. Suddenly the model you are cutting and the cutter itself have to be calculated in 3D space. The approximations in 2.5D milling was very forgiving compared to true 3D. Suddenly the curved shape of the ball or bull nosed end mill really does matter! Even more scary, collisions are now in 3D space as well. Wow! That is a lot of math… makes my head hurt just talking about it
There is a reason this is so darn expensive! Hate Autodesk all you want, but you aren’t getting true 4 axis anywhere else as cheap.