Sprutcam Lathe Help Needed

[mecheng10]

I have been trying to create a tool path for a lathe part for a couple of weeks now and no matter what approach I take, I cannot get Sprutcam to generate a tool path that doesn’t remove excess material from the convex curved section. Based on the part and tool geometry used, I cannot think of any valid reason why it would be impossible for the software to generate a path that would very precisely follow the, yet per the simulation it removes far too much material (up to .012” gouge). I have confirmed that the tool path does indeed take away too much material by actually running the generated tool path and measuring the resulting part. Are there some settings incorrect in my file that could be causing this?

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[TXFred]

If you want an answer, you'll have to post the .stc file. Otherwise, all anyone can do is guess.

Frederic

[mecheng10]

Attached is a zipped version of the .stc file I am having trouble with. I suspect some type of resolution or accuracy setting may be the cause, but I can't find one to change that appears to have any effect.

[TXFred]

I tried it out, and I'm seeing the same problem. And like you, I cannot find any reason for it. I've changed tools, machine definitions, job assignments, etc, and cannot get it to simulate correctly. As far as I can tell, you've done everything correctly. I think you've run into a bug in Sprut.

I'm curious, is the curve on the part an arc or an ellipse? It appears to be an arc. If so, the curve will be defined by one or two G02 or G03 commands in the posted code. You could manually edit those to correct Sprut's error. It's a pain, but it would get the job done.

Frederic

[Gerry Sweetland]

I have been interested in the fourth axis and lathe part of SC so I downloaded your project file just to see how you set up for lathe.
I got to looking at your part was wondering if it is the way the geometry of that arc was created. I tried to duplicate that section of your part in solid works and tried to make that arc with a segment of the circle at a 1.245 R, and as just two lines from edge to center point of the perimeter of the arch.
The former (see attached Follower Test 1 screen caps) method resulted in a wider interference cut but not as deep (only .005 rather than .012) and the latter (see attached Follower Test 2 screen caps) method resulting in no interference it seems.
You might be able play with the solid geometry or how you created it in your CAD. But that's weird how SC doesn't follow the geometry for the convex profile.
Gerry, who's glancing over at his 10X22 lathe and wondering how to CNC it

[mecheng10]

Thanks to those that are helping investigate the problem. I have not been able to determine the root cause of the problem yet. I am going to try to contact Sprut tech support and see if they can figure this out.

[MichaelHenry]

I have not been able to determine the root cause of the problem yet.

Did you see my reply to a similar message from you on a different forum? I changed to the insert and the arc profile then seemed to simulate correctly. I think I uploaded my version of your file there; might have been the Practical Machinist or SprutCAM user forum.

Mike