electrodes

[specprogrammer]

Anyone use any software that compensates electrodes for the appropriate overburn? I seem to remember reading about an add on.

[Lucky]

Simply specify negative "stock to leave".

[Müřlıń®]

quote:

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Simply specify negative "stock to leave".

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+1

 

Murlin

[Jammer™]

Doesn't selecting negative stock remove material on the depths of the electrode as well? I have always "lied" to the cutter and never had any troubles with sizes. It also makes a difference what kind of burning pattern you use in the edm. Does it not?

[specprogrammer]

What about when you have odd orbits? Wouldn't some surfaces get cut w/ neg stock and others not?

[specprogrammer]

Jammer, thats what I have been doing. Lately were getting some pretty complicated burns though. Designers are leaving it to me to figure out which faces to have neg stock on, And I'm not so sure.

[Jammer™]

Spec,

I think your right. We went through this sometime back, and found that since we use different orbit patterns for different parts, that the negative stock got us in trouble. That's why we just lie to the cutter now, and it doesn't matter what pattern we use. It's always right.

[MachineSMMC]

This can get very confusing. I don't think that there is any one piece of software that can do it all. I wish there was a software solution.

[Roger Peterson]

If you cut your entire electrode with surface toolpaths and use the same negative stock to leave value the relationship in heights will remain constant. When you lie about cutter diameter you are also lieing about the cutter radius. This will cause cutting past the surface a diffferent amount depending on the tangent point of the cutter to the surface.

 

 

HTH

[Jammer™]

Without looking at your trodes / part shapes, all I can say is that no matter what our shape or size is, it always works with lying to the cutter. Even if your doing side burns. We cut trodes from two different setups sometimes, (i.e. top setup, then side setup) You'll do the top setup as always, then on your side setup, you need to shift your x or y axis away from the trode to compensate for the overburn. We build complicated molds with alot of detail, and it has always worked with us. Could you put a sample on the ftp site?

[specprogrammer]

Mold Plus SA? Anyone using it? I found it on the products page. It says electrode creation.

[Jammer™]

Roger,

When I use a bullnose, say a 1/2 dia. with a .030 rad. And I want -.010 p/s overburn, I lie about the diameter, (.480) but still use the .030 rad. My dimensions still come in right.

[specprogrammer]

I've never sent something to the FTP. What do I do Email it somewhere or what?

[specprogrammer]

sending it to nc files on the ftp. called "slide pocket electrode for ej side"

[Lucky]

Specifying negative stock results in an electrode that is three dimensionally undersized. Yes the Z depths are affected, but they are all increased by the same amount. The relative Z depth from one feature to another is unchanged. Negative stock to leave means all surfaces are undersized normal to the surface.

 

To achieve correct cavity shape and size at your sinker EDM, you MUST use a spherical orbit. The radius of the shpere is equal to the electrode undersize per side. Various manufacturers use different names for this. Agie calls it "Equimode", Charmilles calls it "3DORB", etc. Bear in mind that the smallest internal radius possible in the sinkered cavity is equal to the electrode undersize or orbit.

 

Except for very simple shapes, it will be necessary to remodel the part if you intend to use a different type of orbit such as "circular", "2D Vector", 3D Vector, "Cylindrical", etc. This is too much work and often results is size/shape errors.

 

Using negative "stock to leave" combined with spherical orbiting at the EDM is the only rational/profitable way to make electrodes and burn cavities. I've been doing it this way since Mastercam ver. 3.21. It works every time.

[Roger Peterson]

Jammer, dimensions that you can measure would be correct. Draw a rectangle with the corner fillet option turned on with a radius of .03. One point -> .5 width by 1 height -> use the lower center point as the placement point and pick the origin. Now do the same thing with a .480 by 1 rectangle. You will see that as you cut a surface at different angles the tangent point changes along the radius of the cutter which will in turn cause the real cutter to cut past the surface a different amount.

 

I would post a picture but I don't know how...

 

HTH

[TREV]

+1 to negative stock. 95% of what i do is program and cut trodes. we use a 3-d sperical orbit and it works every time. if you do a 2-d burn you would have to adjust your radiuss the amout of final spark.then cut negative undersize minus final spark.

keep in mind overburn and undersize are two completly diferent things.

i.e. lets say i cut a trode to -.012/side that is my undersize. when it hits the burner the hottest setting can not be more than .012,but the final setting may be .0007/side.

 

do a search this has been covered in depth before on user board and the technical tips board.

hth,

trevor

[specprogrammer]

I sent it to all nc programs. I guess I should have sent it to mc8 files. If you look at it i was wondering about all the sloped surfaces .Will telling it the wrong size affect the geometry.

[mold100]

Did any one try a search this has been a well covered.One caution is if you cut 3D surface you gotta burn it 3D (sphere), if 2D you want all your radius's to remain what they actually are and move in your walls,Weve been experimenting alot with this lately, Also either way z steps should never change.

[Jammer™]

Roger,

 

I see how that works. And I just went to ask the edm operator about how our radius's come out when the part is burnt, and he says they are off a bit. Makes sense. I guess we are still in tolerance, or they would make us change the way we do it. I am gonna play with this on my next trode. Might as well do it right huh? This isn't my thread, but thanks for all the input guys!

[Midwest]

 

 

This is what you get when you lie about the cutter dia. The sides move in the amount of the overburn and the top gets a point or edge. Using neg. stock will take an even amount off everywhere on the trode. I use both methods it just depends on your part.

 

Hope the pic. shows OK

 

The picture above could be a sphere or a round shaft.

[specprogrammer]

Thanks for all the input. Its reassuring to know that most do it the same way I do.

[Roger Peterson]

Okay I played over lunch:

 

 

Hope this helps illustrate it a little more clearly.

[Anbu Lingappan - Moldplus SA]

Hi

 

Moldplus allows for extraction of electrodes, creation of surface extensions for the electrodes, preparation for machining and generation of the electrode report for burn hole location and other pertinent details. A powerful tool to make electrodes.

 

Moldplus does not apply negative stock offsets for spark gap allowance to the extracted electrode geometries. Creating offset surfaces is not an easy task and therefore we leave that upto the programmer to compensate for that during machining.

 

Regards

 

Anbu

Moldplus SA

[Henry]

Roger,

Thats not correct approach to compensate spark gap.You have to lie cutter diameter minus 2GAPS and cutter corner radius minus 1GAP