Code with Vertical Arcs, and 3 axis travel help

[GTmike400]

Im not sure if this is the right place to post this, so feel free to move it if its not.

I need to machine some spindles for my street rod model out of aluminum. Im having a very difficult time writing the code by hand since the finishing moves are moving on all three axes at once. I can write the linear motions pretty easily since its from one point to another, but writing the codes for the arcs (the XYZ coordinates for the start point and end point are completely different) is where I'm having troble since they use relative positioning. Any suggestions?

I had thought about taking my AutoCAD drawings and importing them into MasterCAM but I have no experience what so ever doing that, so Im stuck there. What would I need to import into MasterCAM, and write it into a G-Code for a Fanuc?

Heres a basic wireframe I drew in CAD in 3D, but its not a solid model yet.


Can anyone help? Any assistance would be appreciated.

[samco]

normal gcode can only do arcs in the xy xz and yz planes. xy is by default (g17)
G17 – XY plane, X and Y [offsets I, J] [linear Z axis]
G18 – ZX plane, X and Z [offsets I, K] [linear Y axis]
G19 – ZY plane, Y and Z [offsets J, K] [linear X axis]

if your arc are not perfectly allinged to those plane they will have to be converted to short line segments. (can't imagine doing that by hand )

sam

edit add. You may be able to add the linear movement in the 3rd axis to get what you want (so you would be creating a section of a helical cut) - but I am not sure that would work for what you want.

[Paul_S]

G17 default XY plane
G18 is ZX plane cw (G02) and ccw (G03) is looking from the back of the machine to the front.
(some controls allow XZ format cw (G02) and ccw (G03) looking from the operators view)
G19 is YZ plane.

[Paul_S]

". . . is where I'm having troble since they use relative positioning." I assume G91 format.
The J, K and/or I, K are the signed distance from the start point to center. (Fanuc style format)(others, rare, from the center to to the start point.)
In quarter quadrant format (old NC type controls) the distance is unsigned.

[GTmike400]

Originally Posted by samco if your arc are not perfectly allinged to those plane they will have to be converted to short line segments. (can't imagine doing that by hand )

Well, the arcs aren't aligned to any of the axes. So this poses a rather large problem.

I need this part machined soon, so how hard would it be to take the 3D AutoCAD file in MasterCAM to write the code? I've never used MasterCAM before, I've only opened the software at school to see if it can import dwg's.

[ger21]

You might want to look at the demo of MeshCAM, www.meshcam.com Just export a solid model from AutoCAD as an .stl, and MeshCAM can do it very quickly and easily.

[Paul_S]

Originally Posted by GTmike400 Well, the arcs aren't aligned to any of the axes. So this poses a rather large problem. I need this part machined soon, so how hard would it be to take the 3D AutoCAD file in MasterCAM to write the code? I've never used MasterCAM before, I've only opened the software at school to see if it can import dwg's.

If you are going to use MasterCAM to machine those off angled arcs, use the finishing "scallop" feature for the best results (my opinion). Use .054 x the sqr(tool radius) x sqr(desired finish / 125) to get your scallop width. Then use the filter feature to get the file size down.

[wjbzone]

GTmike400,
If you are familiar with Autocad you might be interested in this:
http://www.wjbzone.com/wjbzone-mdt-gcode.html

Especially if you have MDT.

Bill

[Goat]

In MasterCAM you are going to have to import your autocad dwg, then turn those arcs into a surface feature. The you machine it by using a suface toolpath. MasterCAM's help library is pretty good if you are not afraid to play with it.