Attn: Mold100

[Jammer™]

Hey, I was reading through the electrode topic conversation that you were having, talking about "negative stock". We cut alot of electrodes here, big, small, simple, and complex. We all lie to the cutter, everytime. I was wanting to know some more information on this method that you are talking about. If you could please e-mail me and give me some details and how to go about using the "negative stock" method. No rush, whenever you get time. I sure would apprieciate it very much. I am running V8.1.1 Thanks

[mold100]

Not a problem,it will be sometime this week,or weekend.

[Mark H]

Not wanting to step on any toes, but its really simple and I couldnt resist. All you do is set stock to leave to a negative number. For example -.003 will give you an electrode that is .003 per side smaller.

 

[ 06-06-2002, 03:00 PM: Message edited by: Mark H ]

[mbuster]

when you lie about the cutter you get a xy orbit or a flat orbit. when using negative stock you get a spherical orbit or a 3d orbit.

[mold100]

mbuster,lying,and negative stock are not going to change your burner orbit,lying is sort of

the same it is still a ball nose cutter following the same surface,only the diameter of the tool is differant,and your

your z axis is compensated differntly.

 

[ 06-07-2002, 08:18 AM: Message edited by: mold100 ]

[Jammer™]

mold100: I understand the "negative stock", but does that have an effect on z axis. When lying to the cutter, I get my overburn on sidewalls and the depth is left alone like it should be. If I use negative stock, will it cut my z depths the overburn amount deeper?

[mold100]

Z- stock takes stock off of all your surfaces ,z included if you have detail that is .25 deep,its gonna be .25 deep,because lets say our overburn is .01,you cut that off the top and the bottom of your detail,everything is cut relative.TRY IT,thats the best thing I can tell you,nothing bad will happen,your not going to scrap something because of side walls and z depths having differant overburn.Take a set of trodes when you have some machine time and run them both ways.Take note if you pick up on the top of your trode the one you use neg. stock on will be shorter by your overburn,BUT all the z depths will.

[Jammer™]

Got it! I was just trying to understand the pros/cons between the two methods. I can see where using "neg. stock" will give you the exact part shape whereas lying to the cutter in some cases wouldn't. They would be close but some contoured shapes wouldn't be exactly right. Thanks alot for all your input guys. I will use this knowledge on my next set of electrodes.

[mold100]

Let us know how it goes.

[kyle]

I agree cutting useing negative is great, but the

only problem that I had with it is the fact that it does cut the -z also, to get around if I have a .010 overbut I set my geometry so it is .010 above 0, then when I cut the trode I do not lose my known z height on the trode, the main reason I do this is say all the trodes in a job work with say 5/8 think poco, then when I mount them on my erowa tool holders all my electrodes offsets in my edm machine will be the same, only need to reference one trode. I agree with mold that the negative is great and makes so there is no surface or geometry manipulation.

[Lucky]

Cutting electrode with negative stock:

 

1. For simplicity it is easier to surface everything and specify negative "stock to leave" with surface toolpaths.

 

2. If you use 2D paths (pocketing and contouring) specify negative stock in both XY and Z. Your 2D and 3D paths will be relative this way.

 

3. If you must hold a depth relative to an existing surface (such as a ground top surface), shift the Z-Axis datum at the machine upward by the undersize amount. If you are cutting ALL surfaces, this is not necessary - ALL depths will be relative.

 

4. To produce a cavity with correct form at the EDM machine, you must use a spherical orbit. Agie calls this EQUIMODE, Charmilles calls it 3D-ORB, etc. Producing an electrode for other orbits such as circular, 2D vector, 3D vector usually requires complete remodelling of the part.