5axis and dynamic fixture offset

[Jonah086]

anyone out there use "dynamic fixture offset" when machining using full 5axis motion? or is it more for positioning. trying to read up on this feature to make sure it dose what i think it dose before i ask my boss to drop the $$$ on it.

[christinandavid]

Surprised that this feature is not activated as standard on a 5-axis machine.

Saying that, I suppose your programming is done offline? In which case your CAM software will pump out the figures based on how you position the work offset at the programming stage.

I run merely a 3-axis with an indexing bed, and I find the feature indispensable for ease of set-up, reference checks and subsequent online programming.

All it does is recalculate the position of the work offset based on the position of your rotary axes. As I mentioned, I run a basic machine, so was able to create my own macro program to do the job. I suggest you get 'the real deal' for 5-axis work, plus whatever 3D tool compensation options are available for full functionality.

DP

[dacar1]

From my experience with post processor development, I can tell you that its best to use "Tool Center Point Control" feature, it you can have it, because it controls tooltip so that it always stays on the programmed path relative to workpiece.

Dynamic offset is also widely used for 5 axis simultaneous operations. But it only takes into account the final point of motion. So, for a 5 axis linear motion, the tooltip will not follow a linear path relative workpiece as it would with TCPC feature. The path will be more like an arc with only end point coordinate being correct. But If the rotary axes change in small steps (eg. 0.5 degree) this error can be ignored.

You can also handle 5 axis simultaneous operation with a suitable post processor even if you don't have these features. In this case the post processor would have to handle the compansation work using rotation center and workpiece zero coordinates. And accuracy would be same or better (if it generates proper middle points to improve accuracy) than dynamic fixture offset feature.

Regards,

Dinc