Can 4th axis do offaxis undercuts ?

[lesd]

Do VM 4 axis toolpaths only cut with the tool axis pointing directly to the A axis , or can it cut 'off axis' to allow under cuts?

In other words, of the rotary table 4th axis holds a piece of bar stock, will the tool path always be restricted to pointing to the barstocks centerline?

Thanks,
-Les

[Carver]

You can use the rotary axis as a positioning function and machine in any region in the entire model you would like. This would make the under cuts you need. You can also accomplish this by simply rotating your model and workpiece the same amount and generating typical 3 axis path limiting your machining regions to the areas requied. I do this daily and it works fine. A typical indexing head works without having to have an active fourth axis on your machine.

Good luck, Phill

[lesd]

OK , I see what you are saying. By making a new toolpath for a new fixed rotation position, XY and Z would then take advantage of the revealed undercut areas and cut them out. One new manually created toolpath for each new rotation.
But as far as Visual Mill software and other similar, they don't have the smarts to get to the undercut areas. Am I right on this? They always point the tool right at the 'A' rotation axis, limiting the reach.

What software ( very expensive ? ) goes further ?

Thanks!
-Les

Originally Posted by Carver You can use the rotary axis as a positioning function and machine in any region in the entire model you would like. This would make the under cuts you need. You can also accomplish this by simply rotating your model and workpiece the same amount and generating typical 3 axis path limiting your machining regions to the areas requied. I do this daily and it works fine. A typical indexing head works without having to have an active fourth axis on your machine. Good luck, Phill

[Carver]

Les,
The simplest way to clean up undercuts in my opinion is to run the simulation of the path you have already machined and the un-cut material will be obvious. Then use these areas to define your new machining regions.
There is probably some high end software out there that does this for you automatically, but I have not been exposed to it.
If you have only a four axis machine ( 3 + a rotary) some variation of this will be the solution whether it is automated or not.
The few high end packages I have been exposed to ran in the mid to upper teens ($ thousands)
I cut wood primarily and there is a real need to keep control of each specific cut for a multitude of reasons, so I haven't researched much more. ANY program that automates all the decision making is making a lot of assumptions in the process, no matter what you pay for it. The assumptions can be catastrophic in many cases, so I prefer a " manually" created path for each operation.

Best of luck, Phill