Direction of finish pass

[Gregore]

Does anyone know a way to control the direction of the finish pass

I am doing a 4 axis cut and it keeps starting the pass on the X - side as it moves back and forth in Y towards X+ thus it is vibrating like a diving board as it gets way out from the vice which is in X -

What would be best it is remove the last of the support material as the cutter moves towards to vice

I also have this problem when doing a a tilt cut in gem stone with diamond cutters it will randomly choose either to start Y+ and move towards Y- or Y-towardsY+ which is the way I need it .

I find it hard to imagine no one has had this issue with 5 axis cutting as everything is hanging way out all the time ,so I must be overlooking a way to do it .

Thanks

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[awerby]

It sounds like you've got your material cantitevered out into empty space. This, as you've noticed, is not conducive to smooth cutting. I'd suggest supporting the far end and clamping it down (or if it's on the fourth axis, providing a tailstock with a center point which fits into a hole on the end) to eliminate vibration. It shouldn't matter much which way it cuts first.

[Gregore]

Yes you are correct it is way out there in relation to the thickness and flex of the material and usually i have it well supported with material and this time is also the same but the problem now arises with the fact that the thing I am cutting is so thin that even supported all around it that the part its self is flexing . I am basically cutting a life size spider , thus the legs are thin . And even supported they flex .

If I could have it cut towards the vice then the material always has support from the cutting along the leg from the cutter tip to the vice.

5 axis machines do not have support for the end of the work piece thus they must also work towards the vice ..... and this is 5 axis software so one would assume it could be done in madcam, or at least I would hope so.

Thanks
Gregore

[JOM]

The direction is controlled by the active coordinate system. madCAM has 3 different kinds of coordinate systems. For 3-axis, it's the Rhino world coordinates. In 4-axis mode, it's a revolved coordinate system created from the the axis of revolution. The 5-axis coordinate system is created from a drive surface where the X and Y is the same as the parametric directions U an V of the drive surface.

1) For changing the direction in 4-axis, just reverse the direction of the selected axis of revolution. Make sure that the axis of revolution is pointing towards the vice.

2) In simultaneous 5-axis, you can reverse the U or V direction of the drive surface in Rhino.

Regards,

Joakim

[Gregore]

Thanks joakim

I think I understand what you are referring to in the drive surface but I am unsure how that would effect which direction it starts from and moves towards ... but I will play with it and see .

Fourth axis explanation I do not understand at all and same with 3 axis

[Gregore]

So I did some experiments with drive surfaces even though it seems like I can change the direction of the u&v it seems to make no difference in the start position for the planar finish passes , they still start on the left and move to the right

The model is too complicated to change its surfaces

Any other suggestions? Or examples of how to do it as I might still be doing it wrong

[Gregore]

Joakim , I have tried a few different things and nothing works can you be more specific about how to get this to work?

Thanks
Gregore

[JOM]

I have made a video about this at:
Please let me know if you still are having trouble. If you like, you are also welcome to send your part to madCAM and I will have a look.

/ Joakim

[Gregore]

Thanks

That’s got it working now, this is going to come in so handy being able to do it with a drive surface ..... I will be able to cut much finer stuff with this