Boring Finishing Pass = Crash, Bug?

[aherdman]

I was doing a test of an outside bore on a cylinder of solid tool steel, the roughing pass of the bore went very well, however the finishing pass crashed the tool into the stock in a way I don't believe it should have.  But did see if on the simulation... but let it go anyway, I was on the stop waiting to see what would happen.

Fusion 360 archive attached, for some reason, the CAM thinks the tool flute is more than the full length of the bore (25.4 mm) so tries to do the full height in one pass, however, the tool's flutes are only 10mm, and are defined as so in the tool.  So I would have expected some vertical stepping to complete the finishing pass (or maybe I don't understand what a traditional definition of a boring operation is... I'm new to this machining world).

Attached PIC of the grazed part as well.

Bug?  Or Operator Error?  (Operator error for letting it do it, I agree on that).

Thanks

  Andrew

[LibertyMachine]

While the flutes might have been defined as 10mm, the Shoulder length was not. They need to be the same value if you intend on checking for collisions.

That said, it will still only try to take a finish pass at final depth. You want to select "Multiple Passes" if you want two similar toolpaths.

The other option is to use the Circular tool path and define your stepdowns.

A bore ramp of .010 is a loooooong cycle time.....

[aherdman]

Hi Seth, thanks for the reply.  I guess the key item you mentioned is "it will still only try to take a finish pass at final depth", is that some industry "rule" or some other "everyone knows that"?

The simulation actually shows the whole 25.4mm height being cleared even with a 10mm flute, if I do set the shoulder to 10mm as well it does the same pass but only cuts 10mm from the bottom up, still not ideal but more accurate... seems to me fusion shouldn't be showing cutting with the shoulder since there is no cutters there.... 

I did some other tries, using multiple passes instead of finishing passes with a manual stepover and count performs the operation completely and correctly.  3D Adaptive also does pretty much the same thing but less manual as I only needed to set the optimal load and it decides the number of passes.

yes 0.010 depth of cut... took about 2 hours to complete...  it was tool steel and probably not the best bit to throw at it, I actually ended up doing 0.010 chipload at that depth and cutting really well.  Unfortunately you can't dynamically change the depth of cut on the Tormach (or any ?) and only Feed and RPM to adjust the optimal speed....

Thanks again!

  Andrew

[Steinwerks]

You set a .0546063" finish pass. That is a huge stepover and will, bare minimum, cause deflection issues and your part will be tapered with the larger diameter at the bottom.

As for finishing passes at final depth, @LibertyMachine was referring to how the toolpath works. It's right in the toolpath itself (that inside contour line around the part at the bottom):

If multiple helical ramps were needed, Multiple Passes would have been the option to choose on the Passes tab.