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Why do I not get a helix with open pockets?

Message 1 of 5
357 Views, 4 Replies

Why do I not get a helix with open pockets?


I have already milled quite a bit with success in Fusion 360.

But now I have problems with open pockets. Partly I don't get a helix and the cutter do a plunge full into the material. I have attached a simple example. While everything is fine with the closed pocket, there are problems with the open pockets.
Why do I not get a helix on open pockets?


Or is there a better way to mill such a part?


Thanks for any help

Message 2 of 5
in reply to: janus2



2D toolpaths are not "Model aware", you have not removed any material around the example part, to have the open pocket start outside the stock then under the Links tab select "Plunge Outside Pocket" instead of Helix and the toolpath will start outside the stock, see images below and attached file. Would usually be best to remove all the excess stock first IMHO

Open pocket-1.jpg


Open Pocket-2.jpg


Message 3 of 5
in reply to: engineguy


Thank you for your explanations. That makes sense.


Although I can't understand why there is such a difference between open and closed pocket.
The Helix option is selectable, although it does not work on open pocket.


I have found 2 other solutions in the meantime:


1. Create a sketch with the desired milling area and use this sketch as a closed pocket.

2. Use 3D pocket.


As always: There are many ways ......


Thanks a lot

Message 4 of 5
in reply to: janus2

If you enable Stock Contours the pocket will be extended to the edge of the stock.



Or where you hoping to fully machine the pocket and stay within the stock, then yes 3d pocket is really the only option. 






Mark Hughes
Owner, Hughes Tooling
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Message 5 of 5
in reply to: engineguy

Sure this can work in this example but what if your clamp is there.   In my case that is where I have to clamp, not enough material on the sides.   Fusion is lied to about how much Stock is actually there.    As of now, April 2023 there is an option as a closed Boundary when selecting Geometry but that was no help, I thought that would Contain the tool.   I think I am going to try the next solution adding a closed pocket by the OP, sounds hopeful.    As it is, 1/4" 2 flute endmill doing about 3/8" deep into hardwood is not a problem, it's just the first move after the plunge, oh my. 

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