Parallel Tool Path with Ballnose Endmill

[richardsalzman]

I am using a parallel tool path with a ball nose endmill for the first time.  Here is what I tried:

1.  I used a 2D adaptive with the ball nose to rough out the stock where I want to use the ball nose for finishing.  Is there something wrong with how I setup this 2D adaptive?  It looks like it should be removing more stock:

2.  I followed with a 3D adaptive with a normal endmill to remove additional stock for the rest of the part.  It incidentally removed more stock where I want to use the ball nose:

I then used the parallel tool path to finish the curved area:

Does this approach make sense?  Is there a better way to handle this?

Richard

[a.laasW8M6T]

Hi See vid, I did mention in it that adaptive with a ballnose isn't a great idea, but you may have success with it in Aluminum.

You said it was a 2D adaptive but you have a 3d adaptive there, 2d wouldn't work.

Your approach is mostly sound, just needed some refinement

[a.laasW8M6T]

Hi

It's because of your selection of bottom height, when you select an edge the Height is set to the top most extent of that edge which in this case is equivalent to the model top.

For flow you dont normally need to select a bottom height to contain the toolpath, if you leave it at the Fusion default of Model Bottom it will work.

This will prevent the toolpath from going below the model bottom so in some cases where the tool needs to go lower to contact the whole surface you may need to make the bottom height lower again

[a.laasW8M6T · Accepted solution]

To answer you question about only going one way, the reason is typically to maintain Climb milling as you get a much better and more consistent finish.

For that shallow curve, going along that direction one way will inevitably switch from Climb to Conventional so its not too much of a concern.

Both ways will be the easiest, I'm just very picky about my surface finishes so I always like to try and optimize things even if its not needed(all the aluminum parts I make get anodized so that hides a lot of imperfections anyway)

[richardsalzman]

Thanks again for the clarification.

Funny that you mentioned surface finish.  I converted my mill to CNC using a conversion kit.  The kit uses a belt drive for Z axis, resulting in a bit too much too much back lash (about .00045 before compensation).  Some time ago you helped me with a ball nose end mill with a curved surface.   The resulting surface finish was not great due to the sloppy z axis. 

This is kind of funny because the project I am working on now is a new direct drive z axis.  I am eager to see how it improves the z axis backlash.

[programming2C78B]

That sadly may not do anything since the backlash is most often a cause of the clearances between your screw and nut.

[richardsalzman]

That is what I thought. But I took apart the assembly and put an indicator on top of the screw... No matter how hard I tugged up and down on the ball screw, I couldn't get the indicator to budge at all.  I think the belt drive system was very poorly designed and couldn't develop enough tension and used the wrong belt type.  Unfortunately, the gentleman who sold it to me unexpectedly passed away just after I received the CNC conversion kit. 

[richardsalzman]

Wow.... That came out amazing... see attached.  The flow tool path worked great!

Two questions:

1.  I tried to tell the 3D adaptive tool path to avoid the left side... but no matter what I did, I could not make it happen.  It is a waste of time.  Is there an easy way to do this?

2.  I learn most of the CAD/CAM on Youtube.  Is there a good reference that I can use, so I don't have to bother you folks with all these little questions.

[a.laasW8M6T]

Fantastic, a direct drive servo is always better than belt, less vibration and noise too, be aware you probably will need to re tune the servos as the dynamics of the system have changed and you may end up with harmonics as its now stiffer.

For avoiding the surface you can use the Avoid/Machine surfaces.

See vid for how to do it

As far as learning resources on Youtube etc, I don't really have any current recommendations.

I learned mostly From NYCCNC when I was starting out(Fusion Fridays) but he doesn't really do Fusion stuff anymore

The software has advanced a lot so some of the videos may be less relevant now.

Everything else I've learnt by trial and error and a HUUGE amount by just following along with other peoples dilemmas here on the Forum and seeing how they were solved, then adding that to my memory banks

[richardsalzman]

Andrew... Thanks again for explaining that Avoid feature.   I had tried to use it, but you are correct, not exactly intuitive.  I also like your idea of making another model without that feature... that is actually just as easy.  

For what it is worth, I have a word document with all the links to every video/explanation you have sent me in an easy to find indexed fashion.

Many thanks for all your help!

[richardsalzman]

Thanks for all your help!  I replaced the old belt drive with my new direct drive and reduced the back lash from .00045 to less than one thou!  Couldn't do it without you guys!