Re: HSM Express+Tormach undersized holes
 

If it's thin as aluminum foil, it is likely just the variation in the material wall thickness. As suggested, machine to a lower depth.

I wouldn't be too worried about the thin layer if it happens again. Poke it with a punch and run a deburring tool to trim the leftover and you'll be fine.

Edit: I missed the bottom height offset. That will work as well.

Now, test out some higher speeds and feeds and post some videos of the tests!

Re: HSM Express+Tormach undersized holes
 

Bottom offset is the setting you want. Just make sure you get the sign right.

Re: HSM Express+Tormach undersized holes
 

On the first question, I'd be willing to bet your running a roughing process for the bearing hole and it needs a finishing process to remove the remaining material.

In the second scenario, I've experienced this quite a bit on my tormach. I would either use a deburring tool to remove the foil, or set my zero for the Z axis a tad bit lower than actual zero. This happens sometimes based on how the workpiece is clamped down, which can cause the material to bow in the center, or pick up on one end.

Re: HSM Express+Tormach undersized holes
 

Maybe this is a function of how HSMExpress works, but I don't really understand why this is even a problem. Aren't you hand entering a depth to cut to? Or is it selecting that depth based on the depth of the chain you selected?

If it's the former, just put in -.1875 or -.250 for a .125" wall thickness tube.

Re: HSM Express+Tormach undersized holes
 

HSMExpress selects the depth of cut based on the contour/profile you select. So, if the part being milled is modeled with a wall thickness of .125", but in reality has a wall thickness of .127", in a perfect world, the milling operation leaves .002" of aluminum at the bottom of the hole.

What I have found is that if I just set the "Bottom Height Offset" to a value of .010", then the end mill will extend .010" beyond the selected profile. This will cut the hole cleanly as long as the material being milled is less than .010" thicker than the expected .125".

Re: HSM Express+Tormach undersized holes
 

Odd when I use MasterCAM for solidworks it does a similar thing by picking the depth of the chain selected. But like Cory I just over write the value and add .125 more to the depth. Especially in tubing. Is this not an option in hsm?

Re: HSM Express+Tormach undersized holes
 

Chains? Haha, you MasterCAM folks are funny. ;) :)

Re: HSM Express+Tormach undersized holes
 

It should be covered with the "Bottom Height Offset" option.

Re: HSM Express+Tormach undersized holes
 

It's still a chain, even if it's selecting the feature.

Re: HSM Express+Tormach undersized holes
 

I like to create a few planes in SW model for depths/clearance heights and set the toolpath to use those planes, rather than entering a bunch of offsets. This way I only have to figure out depth and clearance/retract plane locations once. The default clearance plane is a little excessive.

For depth, I would try to go as deep as possible. You'll get more rigidity and you'll use the part of the end mill that's likely used less, so you'll get more tool life.

HSMWorks calls them contours.