A Finishing Pass Was Skipped.....What's this telling me?

[apostM2K9B]

I had this working yesterday, and THOUGHT I was using the same settings.  I'm making a hole gauge and see that the generated tool path is not cutting the smaller holes.  Using a 1/8" bit (3.175mm and have holes starting at 3.2 mm and stepping up in size by .05mm.  The tool path starts at 3.85mm.  It was working fine yesterday.   I get the message "A finishing pass was skipped because the pocket collapsed for dependent roughing passes"

What am I doing wrong and what do I need to change?

[daniel_lyall]

Can you post the model To do this Go to File -> Export and save as a .F3D Archive File and attach it to your next post

[apostM2K9B]

Looks like what I really need is a good tutorial on what all the myriad options mean in the CAM settings.  I managed to make the original warning go away.  I THINK i did that by simply eliminating the finishing passes.  What I don't know is if that hurts me in this case.  I'm machining small holes in phenolic with a table top CNC.  So it may be that as I'm not powering into anything really, the standard milling is giving me just as fine a finish as the so called finishing passes that would be designed to clean up all the horsing around.  

Take a look at Setup2  there are two 2d pockets in there, one has finishing passes checked and returns the warning AND skips about 1/3 of the holes, the other does no finishing passes and cuts all the holes.  

I actually cut this gauge a few days ago, and thought I'd had finishing passes checked.  So not sure if I've just lost my tiny mind or have changed something else along the way.  

So I"m assuming there's something in the math that I don't understand...that somehow I'm asking it to cut a "rough" hole that is "x"mm smaller than the final, and then to cut away "y"mm to the finish size but that X+y is greater than the diameter of the hole????

Share your thoughts,

[LibertyMachine]

There just simply isn't enough room for the tool to move. Consider the lead-in/out of each finishing pass, along with the lead-out of the rough pass. Your hole size (the ones that are skipped) are little more than your tool diameter. Your smallest hole measures .1259. Your tool measures .1250. There is nothing there for it to work.

I don't really suggest going right to finish size, at least not if you have some desire for actual accuracy. Tool and machine deflection is quite real in the smaller machines, I don't suspect you are going to achieve holes that actually measure what they are supposed to measure.

Your best bet would be to split up the operations. The ones that allow the Finish pass to take place inside of that operation, go for it. The other ones? Leave a small amount of stock (or none) and come back in with a 2D Circular strategy. Just make sure your leads are small enough, otherwise it will fail

[apostM2K9B]

Thankfully none of the holes I"m currently cutting are the small ones.  It's just a gauge to help me work around just that issue...that the holes aren't as accurate as I might imagine them to be.  

If I DO need to cut the smaller holes, then I'd probably be best off using a smaller bit to do those?

Share your thoughts,

[daniel_lyall]

That would work you just need to make sure the lead in and out, readial stock to leave are all in total just less than the hole size

[daniel_lyall]

Have a look at the settings I used