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Lathe CAM lead in and lead out issues
Hi y'all! I have an issue which I cannot seem to solve regardless how much I scratch my noggin. I'm trying to create something that is almost like a threading operation, but I'm not cutting a thread, but rather a helical groove using a form tool, and it needs to have a faded lead in and lead out. See the image below for the geometry I'm trying to achieve.
Now. I cannot get it done with a threading operation because the threading doesn't allow for form tools like I'm using, only tools with threading inserts. Even when I try it with a threading tool I can only fade the thread end, not the start, so the start ends up with a full circular groove before it starts the thread.
The threading operation automatically clocks into the thread with every stepdown, making it possible to achieve rather deep threads using multiple passes. I was thinking I could possibly hack a profiling operation to do what I need, but I can't figure out how to get it to clock into the same groove on each pass. So either way I turn I'm stuck.
So, you kings of Fusions, you princes of Autodesk, how would I get this done on my CNC lathe?
Many thanks!
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I don't think what you are looking for is going to be possible in any of the turning operations. It "may" be possible to accomplish this in a Mill/Turn with a milling toolpath, but it's not going to give you what you are fully after.
"Fade Thread Start" isn't a threading requirement that I've ever encountered...

Seth Madore
Customer Advocacy Manager - Manufacturing
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That is what I feared. Though, I cannot see why it shouldn't be possible. If it can do a fade out it should be able to do a fade in. I'm looking at the G code and it's a very simple operation to do a threading with, let's say, five passes to make that thread. It's just the start that ends up with a full circular groove without a fade in. Could this perhaps be done manually with a bit of G code rewriting?
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Fade out is normally only used to finish threads where there is no shoulder relief. I you are threading middle of shaft for some purpose other then engaging mating part your option is manual programming.
Use G32 and strait infeed, repeat passes, only changing X values.
Something like that.
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On the other hand what you are showing on your model is not faded thread, it is spiral grove that can be done on mil-turn.
Rotary tool enters from Y plus direction, at Y0 position drive Z axis and rotate C axis, at the end of Z travel tool exits in Y minus direction.
Entry and exit also need to include Z axis move of calculated value to confirm to pitch of spiral groove.
Fusion