Stock to leave error

[Anonymous]

Hi, sometimes with thin wall features I "face" them by using a contour toolpath.

However, in this example, I was facing this one with a ball nose mill and thus needed to do a stepover slightly over the tool radius.

Problem is, I get this error.

Is this a problem of behind-the-scenes geometry and programming, or is this an arbitrary constraint imposed by HSM?

Aside from sketching an offset chain, is there another way to do this?

[jeff.walters]

Instead of selecting the outer edge can you select the hole edge?

[Anonymous]

I can, but what does that accomplish?

[jeff.walters]

you can then change the arrow to the outside and use a postive offset. 

[Anonymous]

That moves the tool off the thin feature.

[jeff.walters]

i just noticed that you have the 3D operations have you tried the 3D horizontal before?

[kb9ydn]

I'm sort of confused as to why you would want to face these parts with a ball mill?  You don't mean to deburr the edge?

C|

[Anonymous]

because with such a thin wall part you can do two quick passes and get an acceptable result without having to have a 2 tool operation. I'm stuck with manual tool changes 😞

[jeff.walters]

It sounds like in this case you’re better off using a sketch and trace then.  

[Anonymous]

Is this a problem of behind-the-scenes geometry and programming, or is this an arbitrary constraint imposed by HSM?

[kb9ydn]

Oooohhhh, ok  That makes sense then.

As far as I know it's a mostly arbitrary limitation, although I seem to recall that allowing it to be more than 1x tool radius negative caused some issue with something I forget.  This was brought up on the CAM forum awhile back by a particular user that REALLY wanted it.  I think everyone else was just sort of... meh.

I would (also) say try the horizontal strategy.  The settings work a little differently from 2D contour but should be pretty simple to make it do what you want.

C|

[jeff.walters · Accepted solution]

It’s not an arbitrary limitation I don’t remember the exact reason for it but it is by designee. I have attached a sample of doing your part using 3D horizontal.

[Anonymous]

Thanks Jeff!