Xform Roll

[DavidB]

I'm machining a shaft in a Vertical machining centre with a 4th axis rotating around X.

I'm trying to machining the grooves in the below pic.

 

 

I create edge curves off the solid model and Xform Roll them and select the diameter in the xform dialog. The above pic shows the unrolled curves for this groove.

 

When I backplot the toolpath the position of the toolpaths contour does not match up with the solid model.

Am I doing something wrong?

 

If I use the edge curves of the solid model and in the toolpath select "unroll" the toolpaths contour matches the solid model.

 

I'm substituting the Y-axis

 

Thanks in advance Dave

[Glenn Bouman]

When you do the roll operation you need to set the Position Angle in the Roll Dialog to -90

[DavidB]

When you do the roll operation you need to set the Position Angle in the Roll Dialog to -90

 

 

Thanks Glenn why is this so?

I'll try it tomorrow at work, Thanks. Maybe CNC should put that info in the help files. I read them to see if I was doing anything wrong but didn't see what you are saying.

[B.D.]

I've tried cutting grooves with an 4th axis in a vertical mill before and it didn't work out. The walls of the groove where tapered when X moved along the part for some reason. Didn't have time so figure it out so someone else had to do it. Have you cut stuff like that before?

[Elmer Fudd]

I wonder why you can't just chain the 3d geometry.

[CJep]

You can chain the 3D "wrapped" geom, you will need to know the dia it is wrapped around. Then in the rotary axis control you tell the toolpath what the actual dia the wrapped geom is and check the box for unroll.

 

I see from the screen shot that you have a closed boundary, are you cutting this as a contour or a pocket?

 

As a contour the geom can be wrapped 3D or unwrapped 2D, if you're using a pocket it must be unwrapped 2D geom.

To index the geom I typically work from the 12:00 position which would be Y 0.0

[Chris Rizzo]

Yeah I've wondered why the -90 is needed. Big mystery in my book.

 

Use peel mill for this part, works great! Clean up the walls with 5x swarf. I've cut something very similar out of 4140 with about a .375 width slot. How big is your part there?

 

Using stock posts getting inverse time to output with the hst toolpaths does not work. Email me (or better yet qc!) and I can show you the post mods needed.

[Glenn Bouman]

The reason for the -90 is you are looking in the top view when you are doing the unroll. A0 would be the centerline at Y0. However the actual rotation takes place in relation to the side view where the A0 is at 3 oclock. The angle difference between the two is -90 degrees.

[DavidB]

Well using -90° in the Xform unroll has solved my problem Thank you