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Helical Ramp Starting Height For Cavities - How To Have Different Starting Heights For Different Parts Of Model

Message 1 of 6
190 Views, 5 Replies

Helical Ramp Starting Height For Cavities - How To Have Different Starting Heights For Different Parts Of Model

Looking at the picture, below, and the attached Fusion 360 file, can anybody tell me how I can get the helical ramping on the lower part of the model (the red spirals) to start at a lower height than the helical ramping (also red spiral)on the higher part of the model, if you see what I mean?   I feel like this is causing machining time to be higher than it needs to be and I am quite desperate to get the machining time for this job down.


I've used a model to define the stock, so cannot understand why it is starting all helical ramps at, I think, the same height, irrespective of where the metal to be machined is.


As ever, thank you for any help or advice you can provide.  This really is a very helpful community.



Message 2 of 6

Because your max stepdown(35mm) is greater than the step height(25.4mm) it wants to ramp from the top height down to the maximum stepdown



If you change the max stepdown to 25.4mm then it will rough everything down to that level and then start ramping into the lower pockets on the next stepdown

Screenshot 2023-09-05 093220.pngScreenshot 2023-09-05 093509.png


If you want to get better control than that you would probably have to break it up into multiple toolpaths and use boundaries and heights tab adjustments to force it to do what you want.

Message 3 of 6

Thank you very much for your reply.


That has certainly sorted out the issue with the starting heights for the helical ramping.  Oddly, however, it has made the toolpath 25 minutes longer!  Also, there is a period, towards the end of the toolpath, where it spends a bit of time seemingly machining air.


I'm not sure why.

Anyway, thank you very much for your answer.  It is always good to learn new things about Fusion and very useful for future reference.


I reckon I'll have to find another way to try to take some time out of this machining, this time, though.

Message 4 of 6

You do have "reduce air cutting on, so it shouldn't be air cutting in that large pocket, but it is.


So if you change the rest machining to "From setup stock"

and also remove the stock contour selection(you dont need these for 3d adaptive)


it goes down to 1hr17mins


I see you are machining relatively large flat areas with minimal stock on them, adaptive isn't the most efficient way of processing these areas

so you can use the Flat toolpath first with stock to leave, then switch to adaptive to do the rest(change rest machining back to "from previous).

that knocks the roughing down to under 50 mins


You can also use the flat toolpath for finishing that flat areas rather than face and/or 2d contour


see attached:


Message 5 of 6

Thank you very much for your, again very quick, reply.  It is really helpful to have an example file to refer to.


This has been very helpful.  I didn't think to use "Flat" as the menu says that it is a finishing operation but I suppose that is just what it is usually used for.  I shall do as you suggest, and probably also use it instead of the facing operations.


Thank you, again.

Message 6 of 6

Me, again.  Apologies for crazing you with more questions but I have just tried adding in the "Flat" toolpath and have come a bit unstuck.


My first question is: is there a way of forcing the "Flat" toolpath to start away from the stock?  At the moment, as you can see from the first picture below, it plunges right into the stock, right in the middle of the shortest side.  I would be less nervous if I could get the tool to drop to the required height off the stock and then enter the stock using the lead-in feedrate, before starting to cut at the cutting feedrate.  Is this possible?


My second question is: how do I resolve the "rapid collision with stock" problem, as shown in the second picture below?  I have tried all sorts of things  but just can't stop it.  I tried increasing the stepover and that just added in more collisions.  I tried reducing the stepover, to 8mm, but that didn't get rid rid of the collision.  Can you suggest anything, please?






Also, it takes a really long time for the adaptive toolpath to regenerate.  Am I doing something wrong or is that normal?




As ever, any and all help greatly appreciated.  I've not attached the Fusion file, as I can't get it to actually regenerate the adaptive toolpath: it just hangs up.


Thank you,



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