I have also substituted laminated safety glass. It is heavier but it doesn't scratch (did mine to stop my boss sneaking up on me), don't know the specs on protection compared with the plastics. But they use it on car windshields.

We manage to get 4 axis output using 5 axis toolpaths on both VMCs and HMCs. Clearly the .MMD is important but it is equally important how you derive your vectors. For drilling 5x holes in 4x I first untrim the surfaces inside the hole. If it untrims as one surface then create an edge curve at both ends of the cylinder. This might create splines so you need to simplify to arcs.If it untrims as two surfaces then choose one and use "entity properties" to convert to a full arc. Then go into back or front C-view and set to 2D. Set z depth at bottom of hole and select lower arc center and pass the vector through the upper arc center. This process locks your vectors normal to the rotation plane you are using and prevents rotations in a direction that the machine does not support. Vector will pass through the center of upper arc when viewed from front /back but not neccessarily when viewed from left/right or top. What you want to see is perpendicular lines when viewed from right or left. If you have this condition already, then it is either .MMD or .PST file problems. For 5x vector driven toolpaths I would again use C plane front/back and project to the z value at the base of the vector in 2D. Again you are looking for perpendicular lines when viewed from left/right. All this works much better and is more stable if you are using Mastercam origin. Can be done with your own constructed WCS but you have to be careful if you edit anything as it has a habit of loosing the origin. Have done this now in all X versions Hope this helps.

Check your axis orientation in you views, you may have an x component pointing the wrong way.

+1 Waterline works great for this sort of pocket

Hi Yarn, 3D toolpaths do not have a 3D cutter offset function so trying to use them to do a surface is problematic, toolpaths will tend to gouge. I only use these when doing a 2D toolpath and I want to vary the Z value because the profile is on a slope. Try the surfacing toolpaths. Flowline is fairly simple. often helps to isolate the surface and untrim it. This allows a certain amount of overrun to make sure you cover the whole surface. Surface finish contour is also good but you should always use a containment boundary which is an extra step and you will also probably need depth control. Read the help files as you go (? box on every parameter page) to help with all the options Hope this helps

In my exprerience Dapra cutters are the most free cutting insert cutters. However as with everything in this game there is no free lunch. They don't ramp very well and have a 90 degree shoulder which causes problems when working a vertical wall higher than about 2/3 the insert hieght. Drilling a hole to plunge into and conventional cutting on vertical walls (the inserts are so "up front" there is only about a 5% increse in tool pressure) will overcome these problems. If you absolutely must ramp I too like the Mitsubishi cutters.....have used both with good success in different situations.

I have also used Pencil and HS Pencil in situations like this. Can be difficult to control so you might try project if you have problems

Thanks for the correction John, I'll have to look out for an opportunity to try it out. Blend works too. You can use different tool and construction planes.Just did one using toolplane as my rotated view and project lines from front/back construction plane. Not as easy to control as SFC but useful in certain situations

As far as I am aware flowline does not support undercutting (unless this has changed recently). Surface Finish Contour and Surface Finish Blend will support undercutting if you have a tool selected which is capable. SFC is probably the simplest in this case..... Mark is correct use direction tab to get you in and out

Also a "flip-flop" arrow arrangement in the direction box of surface toolpaths would be handy for all of the above reasons

You might also consider using plate rather than extrusion. The extrusion process tends to concentrate impurities and inperfections in the outer skin, so when you remove it assymetric forces "warp" the material. Skinning the part first mitigates this problem. Substituting plate can allow you to skip the skinning op as the material is more "stable" and consistant. Keep your chipload as high as you can to get as much heat in the chip as you can, Nick Eaton