3d pocket clearing not using roughing stepdown

[caddzeus]

 In the attached sample I have four parts each with a cutout at a different level (.1, .5, .75 & 1” deep). When I try to run a 3d Pocket Clearing operation on the low area of Part 4, without parts 1, 2 or 3 being selected, and with a maximum roughing stepdown of 1”, the generated tool path cuts down in 4 stages instead of the 1 required. The 4 stages also correlate with the other pocket depths of .1, .5, .75 & 1” deep.

When part 4 is the only part in the setup, as in setup2, everything works as expected with the exact same operation parameters.

Setup3 shows a separate pocket operation for each part and that all depths are cut even with a maximum roughing stepdown of 1” is in place for all toolpaths.

Now imagine I want to cut out a full 4’x8’ sheet of MDF or even sign foam on a large bed CNC router with dozens of pockets at different depths. If you have 6 different depths of pockets throughout the sheet, the deepest pockets will take 6 times longer to cut than necessary, the pockets at the second deepest level would take 5 times longer to cut than necessary and so on. Some pockets on large sheets can easily take over 10 minutes, and if they’re at the deepest level of a 6-level model, that translates to over one hour for a single pocket.

[jscott6SWZG]

Do you have order by depth on?

[jscott6SWZG]

Do you have order by depth on? In passes tab

[caddzeus]

No. In the file I've attached with this post, "order by depth" is not checked on. Order by depth would only come into play if you had more than one pocket selected for clearing, and a "maximum roughing stepdown" set to less than the overall depth of each pocket. In that case it would clear each pocket to the maximum roughing stepdown before before going lower. With the "order by depth" off, it should clear each pocket, by the maximum roughing stepdown, before moving to an adjacent pocket and clear them all,  one by one.

Yes, during the trouble shooting, I have tried "order by depth" both on and off. It makes no difference for this issue as the "maximum roughing stepdown" is greater than any of the pocket depths. I get the same result either way.

In the attached image the machining operation is only selecting the one, deepest,  pocket, but the resultant toolpath cuts the pocket in 4 depths that correspond with the levels in the adjacent components. This has nothing to do with order by depth and the "maximum roughing stepdown" is greater than the depth of the pocket. This should pocket in one pass. I've even noted that if you leave a material offset in the setup of .04", the toolpath will generate an additional pass for the level of the top of the model. The file is of course attached for anyone to verify the operation.

[HughesTooling · Accepted solution]

The problem is caused by Flat Area Detection, it is not limited to looking inside of the boundaries. Doing something like your example 2d pockets will work better because they have the option to set the depth using the selected contour (for each pocket). The 3d pocketing ops have always had this problem and on 3d parts with multiple faces parallel to the XY plane Flat Area Detection is pretty useless!

[caddzeus]

@HughesTooling 

In my "wisdom" I over simplified my example to the result of it changing the best machining strategy to a 2d pocket, which works great for the sample, but not for my actual part. My actual part is, as you said, a "3d part with multiple faces parallel to the XY plane", and unchecking "Flat Area Detection" does help. Admittedly, I can't understand why any machining operation would look outside of the "Stock Contours" for any calculation, but now I know, and can plan accordingly. Maybe someone from Fusion can look into that. Thanks for your input, it was helpful.

[oleg.tikhomirov]

Hi @caddzeus 

Thanks for feedback. @HughesTooling is right. It's a known issue in 3D Pocket and we have ticket about it. It's possible to workaround the problem by using 3D Pocket with disabled Flat Area Detection + Horizontal or Flat strategies to clean flat areas.