2D Contour toolpath entry mark

[tomae]

I am cutting a hex on a part on an EmcoTurn 365mc lathe (live tooling, Y axis) with an axial endmill.  I am using a 2D Contour toolpath. On the last pass, when the cutter is fully engaged with every side of the hex the tool path very slightly dives into that first side.  You can hear it when it happens and you can see the line it leaves on the one side of the hex.  I am attaching the exported project that contains the toolpath.

In the first picture you can see the toolpath and I have a little red circle around the part of the tool path that I think is where it is happening, the lead-in to the last pass.  The second picture shows the line (also circled in red) on the actual part where you can see the endmill dipped down into the side just a little before cutting flat across. 

I cannot see or hear this happening on any of the initial 2 passes, but then they aren't fully engaged on the material like they are on the last pass.  I spent a long time tweaking various tool path parameters to try to get this to not happen, or to move the lead in back away from the part but had no luck.  It always shows this little swoop, and it always leaves a line.  Any ideas on what I can tweak?

Thanks,

-Tom

[Marco.Takx · Accepted solution]

Hi @tomae,

You can place your entry position to a position so it ends on a edge of the hexagon. 

Because you are using roughing passes you have to place the entry position a little bit away of the position where you like it to have. 
But you will see this in the results when are using it. 

You can also create a finishing overlap so it end not at the same position as where it starts. 
Also you can make your finishing pass much smaller than your roughing passes. 

If my post answers your question Please use Accept as Solution & Kudos This helps everyone find answers more quickly!

[rhdfmail]

Another approach is   having a separate finishing-op and only have a straight line as lead-in. Just make sure it's long enough, at least Toolradius + stock left from roughing + some safetymargin.
maybe set lead-in feed = cutting feed 

[tomae]

Thanks!  Moving the entry point did the trick.  

By the way, I was also going to try your suggestion on using a finishing pass but for some reason I can't seem to get a finishing pass to generate any toolpath.  I'm not sure what I am screwing up there.  I  set Stock to Leave at 0.010 and then duplicate the existing 2D contour, change to Rest Machining in the Geometry tab, turn off Stock to Leave in new path but it fails to generate a tool path.

-Tom

[seth.madore · Accepted solution]

Rest Machining here won't yield anything. In 2D Contour/Pocket, Rest Machining is only applied to internal corners.

In this case, we don't have any, so we just go with a simple 2D Contour. Easy thing to do is right click on your existing toolpath and create a Derived toolpath, or copy/paste and delete what's not needed