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Solid thicken and Electrodes.


MotorCityMinion
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Boss has been annoying me for over a year to start making electrodes. He tells me to make the finishers smaller by .0015 per side, rougher's smaller by .0085 per side. "Just put in a negative stock to leave" He uses Smurfcam. That approach doesn't pan out so well in MC. Not sure that it does in SC either. Anyway, I converted solids to surfaces, removed a few faces, back to solid, then thickened it in the direction I needed, back to surfaces again to delete the outer skin and sides. Create curves, do some analyzing and it looks good to me. The process is quicker than the time it takes to type this.

 

Here's my question: Is this how you guys do it using MC? Am I headed in the right direction?

 

I did some searching over the weekend and can't fine anything on the actual process of making the electrodes. I know nothing about electrodes and if anybody could point me to some tutorials on machining them, that would be great.

 

Thanks in advance, MCM.

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I use SolidEdge Mold Tooling and use to have Mold Plus until we got SE. I have done it before like you say using negative stock to leave on walls and floors using waterline and horizontal paths. I still do this occasionally on rush jobs.

 

Never have done solid thicken though,

maybe you could scale your solid??

 

HTH

 

edit: I also use an air spindle (60,000 rpm) with graphite specific tooling from Fraisa all bull and ball mills and we have an old Bridgeport VMC 760 stashed over in the corner for trode cutting. (Its MESSY)

Use POCO-3 grade carbon, its a little higher priced but worth the difference when it comes to polishing.

We make a lot of molds for small air cooled engines, so I make a LOT of fin shaped trodes.

I prolly dont even need to tell you to climb mill as I assume you already know this

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I thought about scaling also but wanted to get some feedback before barking up the wrong tree. I tried using blend and parallel path's using negative stock and got nothing but grief. I also have a trode plugin for SW that looks good, but I'm trying to get this down in MC if I can.

 

I know absolutely nothing about machining electrodes, so any tip is great. I usually climb cut every chance I get on all materials, but on the electrodes I did today, I ran the finisher with a zigzag, no chipping at all. I was told not to make jewelry with these relief trodes.

 

Is that air spindle also used on a Machining center? (Bridgeport VMC 760 ?) What type of feeds and DOC do you get at 60k, in graphite?

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DO NOT scale an electrode model. Things change that ought not to be changed. Picture if you have a "boss" feature on the electrode... Scaling will cause the position of the boss to be incorrect.

 

Lying about the cutter diameter (i.e. "scaling the tool") can be used but some features end up less than perfect. (usually where a small radius blends with a face.)

 

The most accurate way to do it is with negative stock to leave in MC toolpaths followed by spherical orbits at the EDM. I almost never modify the actual geometry unless it is so simple that I can move a couple faces along the X-Y plane then machine "to size" and burn with 2-D orbit.

 

The process of thickening up your electrodes will produce accurate results but holy crap that has to take some time ! In the past few years I used that strategy only one time IIRC. If you continue to work this way I think you could benefit from some type of parametric design software (i.e. Solidworks, Topsolid, etc.) to go along with MC.

 

Is there a reason that you don't want to just use "negative stock to leave" ?

 

Edit: Just re-read your post... When you say that method doesn't work so well what do you mean ? Done correctly, negative stock to leave can give extremely accurate results.

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I'm with Henry and Matt on this one. Never Ever scale!

 

Any of the other options work well. Either lie about the cutter size or just leave negative stock.

 

It always seemed easiest to me to just leave negative stock. When the entire electrode is done the Z stock on the entire electrode is all relative to itself which basically nullifies the z negative stock in the first place.

 

it sounds to me like maybe your overthinking it a little, MotorCity

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quote:

I'm with Henry and Matt on this one. Never Ever scale!

 

Any of the other options work well. Either lie about the cutter size or just leave negative stock.

I see a few of us have gotten "burnt" on the scaling biggrin.gif

 

quote:

One other thing:

.0015 ps and .0085 ps. isn't very much overburn. We almost always use .015-.030 on roughers and .003-.005 on finishers.

I have to agree with you I would bet it would cut your burn time in half if you do as Beej suggested. Specially on those finishers... small orbits will restrict the amount of power it can use. Even allowing the .005 on the finishers would help speed up the time tremendously. cheers.gif

 

JM2C cheers.gif

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"Edit: Just re-read your post... When you say that method doesn't work so well what do you mean ? Done correctly, negative stock to leave can give extremely accurate results."

 

Had problems with it. I'll post some pics later and we'll delve into negative stock some more. I'm sure it's something that I'm missing as quite a few of you are agreeing that this is the best/safest method.

 

Yes, I have access to SW with Electrode works. Why would I want to struggle? Well, someday I may not have that software at my disposal and I want to get it down in MC first. Also, I don't always get solids, so for the simpler stuff, I'll just make it in MC, and make the trode there as well.

 

I'm also going to mess with scaling a few parts and see how they compare to solid thickening. If the same results appear, I'll stay away from thickening.

 

Thanks for all the tips, I'll check back later, MCM.

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Don't scale your parts. wink.gif

 

Listen to Matt above.

 

 

Have made a ton of trodes here the way Matt is telling you..........Easy stuff with Mastercam.

 

Don't know what kind of work you are doing.

 

I have probably uses all the different tool paths making trodes.

 

Do you use orbiting on your edm????

 

 

sounds like you may not.

 

 

Usually with orbiting you only make 1 size/overburn.

 

 

cheers.gif

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quote:

Is that air spindle also used on a Machining center? (Bridgeport VMC 760 ?) What type of feeds and DOC do you get at 60k, in graphite?

I only use the air spindle for cutters smaller than 3mm and the feed on the ol bridgeport maxed out at 300 ipm. It is an old machining center from about 1994 or 95....still a good ol trode machine tho.

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quote:

DO NOT scale an electrode model.

quote:

Matt is correct:do not scale.

quote:

I'm with Henry and Matt on this one. Never Ever scale!

quote:

I see a few of us have gotten "burnt" on the scaling

quote:

I'm also going to mess with scaling a few parts and see how they compare to solid thickening. If the same results appear, I'll stay away from thickening.

cuckoo.gifbanghead.gif

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I've been using negative stock to leave for electrode making for the last 15 years or so. I have not had any problems whatsoever. The only time you need to fool Mastercam is when using flat bottom endmills and negative stock on a surface toolpath. You either need to program a corner rad that is the same or slightly greater than the spark gap, or, lie about the diameter of the tool and adjust the length offset of the tool by the spark gap.

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Types of EDM work done here: All.

My experience with it: ZERO.

Do the EDM guys orbit? Yes.

 

cuckoo.gifbanghead.gif ???

 

I get it... NO SCALING

Does solid thickening and scaling produce the same geometric results?

 

"The only time you need to fool Mastercam is when using flat bottom endmills and negative stock on a surface toolpath."

 

Bingo, that was problem #1. I used a square cornered e-mill to pick out a corner, then attempted to surface the rad adjacent to the corner with the same e-mill to pick out what the ball wasn't capable of reaching. Wasn't gonna fly with negative stock, so I redrew the profile.

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Sorry for the confusion MCM, I've never ran an EDM with (or knew how to use?) 3D orbit, I've always just used 2D and forced the diameter. I must have gotten something mixed up from what I remember from my training.

 

I guess screwing something up here is a heck of alot better than on a piece of steel. LOL!!

 

Thanks everyone for clearing that up, including you beej. biggrin.gif

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It's all good. I guarantee there's a ton of folks out there doing simple burns any way they can, scaling included, right or wrong. We do quite a bit of P/M .0004 burns at work and I'm just trying to get off on the right foot.

 

OK, I got the negative stock to work. My beer goggles must have been wearing beer goggles.

 

Thanks again guys, I'm sure I'll be back with more trode questions as long as Beej doesn't start shooting that thing at me.

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