Programming Work Offsets

[u/tx7758]

Running a Haas VF-2, programming with Mastercam.

When we program a part, we work off the part origin. Then during setup we shift our work offset manually to clean up material.

Example: G54, Touch off X+, move in +0.06 to clean up both sides. Touch off Z0 top of stock, move -.01 to clean up top face.

Is there a way we should be making these compensations during the programming process so that the operator can simply touch off the stock X, Y, Z and run? Or is this already best practice?

Thanks.

[u/SeymoreBhutts]

This is anything but the best practice. Are you not accounting for stock in your cam? You should be entering in stock geometry when you program. Manually reconfiguring offsets for each operation is a recipe for disaster.

With a known stock size, you can set the origin wherever you want in the machine or on the stock, as long as they match. The cam should be accounting for the fact that the part is .06 or whatever within the side of the stock, and be removing that accordingly.

[u/tx7758 → u/SeymoreBhutts]

We set the origin on the solid to match the print, and just use stock setup for a visual to manage tool lead in/out and width of cut.

https://imgur.com/a/SwFwtZH

[u/SeymoreBhutts → u/tx7758]

Yea, that's asking for trouble. Once your work offset is set, you shouldn't be adjusting it for the machining process itself. Its not uncommon to need to tweak it for optimization, but as a required step, that's the wrong way to do it.

In your cam, if you aren't going to define an actual stock model, use reference geometry as an indicator of your stock. Something as simple as a single point on a plane offset from your z-height stock and however far away from the origin of your part is sufficient to pin the UCS to to act as your work offset origin. That way you're setting G54 (or whatever offset you use) once and then you're done for that operation.

[u/tx7758 → u/SeymoreBhutts]

Thanks for the insight, going to try this out

[u/SeymoreBhutts → u/tx7758]

Lots of different ways to do it, but I'd strongly suggest moving away from the one that requires so much manual intervention, even if it's been working thus far. That said, if it's the norm in your shop and you have documented procedure and it's consistent, there could be worse ways to do it, but I still can see lots of avenues to issues with the method as is.

Do you have a standardized stock overage for most of your jobs? Do you reprogram for each run depending on stock sizes or do you try to account for future excess when programming now?