Rotary Toolpath Bad Surface

[ege.gener]

I have a strange problem with rotary toolpath. Please have a look at the attached file. Program gives error "Bad Surface". I just want to machine canals on the outer diameter. Is there any way to fix this problem? Thanks in advance.

[johnswetz1982]

Was this mad in fusion or imported from another program?

[ege.gener]

Solid model came from my client. I tried everything but could not create a toolpath. Even Fusion 360's turning module refuses to create a toolpath for this part. How can we fix this problem? Is this about solid model?

[dylan_smith]

@ege.gener are you able to remodel the part in Fusion? 

Thanks,

[ege.gener]

Unfortunately no, I don't have the required dimension info. Customer did not give me those details. However after working on it a little bit, I figured out how to create a 4-axis milling toolpath. But the machining time is way over my expectations, so I did not run it on machine. Please have a look my updated file. Right now I am trying to create a toolpath for lathe because I think it will require less time to machine this part. If you can help me out for lathe toolpath it will be much appreciated. Thanks in advance.

[Anonymous]

Why do you thing this can be done on lathe faster then on mill? These are not concentric grooves, if they were you could use grooving on lathe,.... but they are not.

Using C axis on lathe to cut spiral grooves is same as using 4th axis on mill with big disadvantages, lathe rotary tools are far less rigid and have very limited RPM's compared to mill, you still have to use same tools and your cycle time will increase significantly because of it.

[mathew.hutton]

Hi @ege.gener 

Have to agree with Vic here, you would be far better off doing this on a milling machine with 4th axis than using the live tooling on a lathe. The only advantage i can think of is not having multiple setups where you need to re-datum the part (this is where inaccuracy can creep in from having multiple setups). The only way you'd be able to produce this on a lathe would be to have a special form tool made to the same geometry as the groove and try a screw cutting cycle but that would be a very difficult route to take. I'd probably stick to the safe option and mill the grooves. 

Mat 

[Anonymous]

One possible solution would be to make form tool that confirms to groove profile, start cut in X axis at point where groove is full width, then drive C and Z axis to the other end using pitch as driving distance of Z axis for every C axis revolution, stopping short of entering narrow groove area.

This would have to be repeated in several depths to avoid overloading and breaking tool, (material type !!!???).

Perhaps roughing with standard ball end mill then follow with form tool, you would have to create drive curve along middle of grooves with specific entry and exit points to avoid narrow part of the grooves.

Without releasing part from chuck, detail front and back narrow areas of the grooves using small diameter ball end mill and machine flat detail, bore ID, broach key way and groove ID.

If you do consider form tool, same thing can be done on mill faster.

[ege.gener]

Thank you for your comments. I did not realize the formed tool requirement of lathe operation, that's why I thought that it will be easier on lathe. 4 axis milling toolpath will run for 7-8 hours if everything goes smoothly. Is this a reasonable duration or I just use very conservative feed/speed values?

[Anonymous]

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@ege.gener wrote:

Thank you for your comments. I did not realize the formed tool requirement of lathe operation, that's why I thought that it will be easier on lathe. 4 axis milling toolpath will run for 7-8 hours if everything goes smoothly. Is this a reasonable duration or I just use very conservative feed/speed values?

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Well, to clarify, running rotary tool path on lathe's C axis is same as running it on 4th axis mill with mill having huge advantage in RPM, spindle rigidity and number of tools you have at your disposal compared to lathe.

I mentioned form tool as an option to speed up the process but you would have other potential issues like having to make the tool, wait for it, pay for it, .... and if it brakes or doesn't work as expected you have more problems.

With form tool, you can also do it on mill if you think gain in cycle time is worth the risk.

As for 7-8 hours cycle time, plus all the other work, I have no idea what material you are cutting, but if you charge enough money to run it for 8 hours, it's not a problem, grab some chips, pull up a chair and grow a bird while it runs.