2D Contour Spring Passes

[zwelsh91]

I have never asked before. But why is there not an option in the 2D contour to do Multiple Spring Passes rather than only multiple finishing stepovers and a check box to "Repeat Finish Pass"? could the Autodesk team shed some light on why they have set it up that way? I have in my experience preferred multiple Spring passes over multiple stepovers. As a work around I have had to duplicate toolpaths removing roughing stepovers and then if, say I want 3 spring passes, set multiple finish passes to .0001 and the number to 2 then check the box for repeat finish pass. this feels counter productive. It seems more productive to give us the option in the passes tab the option to add spring passes then a box to define the number of passes. That way you can define all of the rough, finish and spring passes in one toolpath.

[Richard.stubley]

Hi @zwelsh91,

I wasn't there when the code was written but a spring pass is actually undesirable, but a fact of life that we have to live with.

We do give the option as you say to repeat the finishing pass, this is to in effect give a spring pass. Its not that common to need multiple spring passes, that is hinting to me that there is another factor that is causing the issue for yourself.
I would look at the roughing passes you have leading upto the finishing pass.

In an ideal world you never want to use a spring pass, and if you are needing more than 1 then there is most likely something causing this that can be rectified in other ways other than keep running the cutter round at the same coordinates. 

I would be looking for, backlash, play in the spindle bearings, play in the vice jaws, incorrect mating of the spindle taper, adjusting previous passes to reduce load and therefore reduce "spring".

Hope this helps.

[zwelsh91]

@seth.madoreCould you shed some light on this? Have you thought about this at all?

@Richard.stubleyThough your statements are correct, I also find them to be based around perfect world conditions rather than everyday operations in a machine shop. In the greater picture of things we the users of fusion do not all have brand new equipment that has very low hours and is super tight with little to no following error in machine motion followed closely by a full compliment of top of the line tool holders and premium cutting tools. We also need to consider that, yes, under the perfect cutting conditions that a single finish pass should do it.  But in many cases your users are using tooling in sub optimal conditions for example: an extended reach reduced shank short flute end mill in the bottom of a deep pocket. That tool is going to deflect no matter what you do and in effect it may take 2 or 3 spring passes to clean up the contour that you are trying to finish. I just think it would be nice for users to have the option (like in many of the other major CAM software's ) to add multiple spring passes without having to copy and paste operations with two passes each (finish pass+Spring) to accomplish that. Desirable or undesirable the fact of life is that Spring Passes are a daily necessity for many manufacturers.

[DarthBane55]

I'd like something different on this topic:

enable different speeds and feeds on the spring pass.  I find that if I need more than 1 spring pass, I am simply going too fast, so I'd like to reduce the speeds and feeds on the spring pass, instead of having to copy the operation and change it in there. 

I personally don't need more than 1 spring pass, but I can see some might, specially is very small hard to reach features where the tool is almost the size of the feature, that even slowing down the feed is still fast (1 ipm in a circle 0.010" diameter is still very fast for that feature).  But in those cases I use what you said earlier, enable multiple finish passes with a stepover of 0.0001" or less (I think setting it to 0.00001" would then output normal spring passes, although cutting is better than rubbing for tool wear).

[zwelsh91]

Agreed! you make a great point @DarthBane55

[daniel_lyall]

@zwelsh91 It would be good I know my machines limit and having a finishing toolpath option in the tool path so it does a spring passes or 2 at what you want would be handy and then a finishing toolpath after, then I could cut at 2000mm/min not 1400mm/min what has a direct effect on costs to run the machine.

[seth.madore]

I agree with the idea behind these suggestions, especially the reduced speeds and feeds. I know one of the concerns with doing so would be increased menu options in the dialog, which is already getting quite bloated. I can open a task on this idea and see if it gets any traction

[seth.madore]

I've opened up CAM-31208 to investigate changing the speeds and feeds of the finish pass

[ixenn1]

How is this coming along? 

Also, want to point out that "a spring pass is not optimal." is not the case in every environment. Whenever we've machined Inconel 625 or 718 and need to hold +/-.005" or better, then we must do at least 1 or 2 or even sometimes 3 spring passes to get things in tolerance. It's either that or replace the finish tool entirely too early. 

[seth.madore]

There has been no movement on this ticket, sorry to say.