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  1. #21
    Join Date
    Feb 2006
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    120
    what would I do with it? hmm...
    Jet engine parts: diffusers, NGVs, turbine blades. I also experiment with nozzles, and high pressure equipment that use carbide parts. Other things are special gearing in robotics using hard material and slight helix. man I dunno maybe other things too. who knows but for the most part I want it because of the complexity. like my good German friend said to me one time "why make it simple when you can do it complex?" I think he was quoting someone else but anyway. a good challenge to hone my skills and give something useful to me in the end. If I crash and burn, it will only make me stronger in the end.

  2. #22
    Join Date
    Feb 2006
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    120
    oh yea, the frequency is still up for grabs, I haven’t found any definite data on it yet. I have been researching allot of machines, patents ect. But mostly they talk about wave form. I think the there needs to be time for the arc to extinguish which in my other projects having to do with high power High voltage discharges it would be somewhere around 20Khz but like I said I don’t know yet. Anyone able to lend an opinion on that is welcome. But on other facets of the issue the speed of cut would be theoretically proportionate to the frequency, the more sparks the more cut the more specific power. but there has to be a happy medium and since my hardware at the moment will do 100Khz with out to much of a problem I might just make it adjustable to that.

  3. #23
    Join Date
    Mar 2005
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    1136
    Quote Originally Posted by llilrex View Post
    like my good German friend said to me one time "why make it simple when you can do it complex?" .
    one analysis has them loosing war because of that

    you could do interesting shapes, not sure how many of those example would work....ie a helical tooth pattern doesn't have straight line to its form afaik. If you really wanted to push the envelope build a rotary electronic erosion machine like they use for PCD and run hobs on it. for me, a 2 axis wire and a sinker would capture 99.99% of it and be way down the curve from a 4 axis, but the fun of it we can build what ever the hell we want, right?

    keep posting on it, I'm interested to learn of your discoveries...i'm not as committed to a build yet but am enjoying learning and thinking about it

    PS, oh yeah, you can control up to 100kHz? doesn't the PC controller poop out before that?

  4. #24
    Join Date
    Feb 2006
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    120
    After allot of research I found that 100Khz is the low end of the spectrum. but before I reveal what I have found a word about the controller, yes I can control 100khz and with PWM my current max with this controller I am working on is about 410khz and the transistor switch is capable to much more then that. However I may have to abandon my current strategy, like I said I want a good power supply and here is where I found the modern standards to be.

    The generator voltage is 20 to 150V

    The generator frequency is 100Khz to 10Mhz

    The sense technology is separated and often even timed meaning the power is not monitored directly but rather as an observer. And often alternately used I.E. a cutting pulse of oscillations and a measuring period fallowed by a cutting pulse and so on.

    Now my current design cannot do this so I will have to try again. Fortunately I have a bit of experience in high power high frequency oscillators and with various coupling techniques. Heck the first time I witness electrical discharge machining was a continues breakdown in a 45,000 volt capacitor connection (that was cool... and very loud!).

    Anyway I am thinking of using a capacitively coupled class E oscillator running at about 2.4 Kw at 4Mhz up to maybe 8Mhz.

    or

    4Mhz @ 7micro amps, I would have to shield the thing so it didn’t create allot of interference but it is totally doable. Actually it would be a circuit very similar to a induction furnace I built a few years back.

    With that frequency capability very fine finishes are possible.

    One more thing… is it me or are EDM companies very secretive?

    Cheers!

  5. #25
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    Feb 2006
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    120
    Quote Originally Posted by Mcgyver View Post
    you could do interesting shapes, not sure how many of those example would work....ie a helical tooth pattern doesn't have straight line to its form afaik.
    It is true that you cannot reproduce a helical tooth pattern with a WEDM however but you can produce a pseudo-helical gear; it will not do some of the nifty things that a true helical will but it will get you a quiet-running gear. With the NGV and turbine blades I would not actually machine the blade profile but it will allow me to remove 90% or better of the material in a roughing cut, then I can profile the blades with a sinker or machining center. Otherwise that stuff is real painful to machine with the equipment I have.

    I am actually thinking of making a edm end mill like machine that I can use to produce more complicate profiles but I have to keep the simultaneous project count down.

    cheers!

  6. #26
    Join Date
    Feb 2006
    Posts
    120

    experimental circuit sketch

    Here is an experimental circuit. Rated at about 400W for this version.

    Here is the circuit theory:

    Stage 1. 4 MHz crystal oscillator provides a square wave.

    Stage 2. the 4Mhz get fed into a line driver buffer where it will get much more current capability to drive the next stage.

    Stage 3. the square wave gets fed to a push pull amp

    Stage 4. Through an isolation transformer and a DC blocking capacitor the 12V amplified current gets fed to a MOSFET that is the switch for the class E power amplifier. the principle for the Class E is understood and if anyone has any questions about it I will post what answers I can come up with. now the 400W rated 4Mhz current limited (through the DC blocking Cap) is delivered to the work.

    I will think some more on how to put a state sense circuit into it for "intelligent control"
    Attached Thumbnails Attached Thumbnails expEDMPS.jpg  

  7. #27
    Join Date
    Jan 2006
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    104
    not really sure where you get your generator info from, but all of the edms that i service do not run above about 50khz....never heard of anything running in the megahertz range......

    although the chinese have been making an edm system using low voltage and low current, (which may use higher frewuency) with a wire that spins back and forth off a steel drum. and it just flies back and forth....

    they call it fastwire edm

    what we normally think of wire edm they call slow wire edm.

    the machine does not cut in di water, rather some synthetic oil mixed with water....
    Registered Linux User #348337
    EMC2 Rocks!!!!

  8. #28
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    Feb 2006
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    120
    I got my information from patents, actually quite a few of them are high frequency, I just assumed that this is where the industry is at right now. It is nice to know however that the WEDMs that you worked on only went to 50Khz, this make things allot easier. But the Generator that I researched was and Agia unit.

    The patent used the term "prior art" to describe 100Khz to 10Mhz implying that their Generator is improving on others in a specific way, which was not in the frequency of it.

    But if you have more info for me I would appreciate it, like a manual or spec sheet... anything like that. it sounds like you have allot more experience in this field then I do

  9. #29
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    Jan 2006
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    104
    Quote Originally Posted by llilrex View Post
    I got my information from patents, actually quite a few of them are high frequency, I just assumed that this is where the industry is at right now. It is nice to know however that the WEDMs that you worked on only went to 50Khz, this make things allot easier. But the Generator that I researched was and Agia unit.

    The patent used the term "prior art" to describe 100Khz to 10Mhz implying that their Generator is improving on others in a specific way, which was not in the frequency of it.

    But if you have more info for me I would appreciate it, like a manual or spec sheet... anything like that. it sounds like you have allot more experience in this field then I do


    well i have never heard of an "Agia" edm machine.....you might mean agie...and specifically what model generator???? or are these "textbook" circuits...patents that will never be used...

    as far as genberators go, a simple 555 timer (or two) can be used to generate a pulse
    no secrets here just plain old electronic design.

    most taiwan machines do......now they use an atmel.....

    here is a typical generator spec:

    output voltage -200vdc yes that means wire negative and table at ground.

    variable ON TIME : 750ns to 2.25 us (use 100ns increments)

    variable PULSE RATE: 5khz to 52khz (variable with potentiometer)

    rise time < 20ns ("secrets" of edm...)

    OUTPUT CURRENT: 288 amps (peak current) variable in 16 increments
    hope you have a current probe handy, we must measure current peaks.....(more "secrets" of edm)

    why so much current, these are instantaenous currents, your front panel meter usually reads the straight line dc current, which will be quite smaller, say, several amps

    we would like to generate lots of very narrow(with lots of time in between) high current pulses....

    now i would build me a nice power switch circuit to switch -200v to the above specs.

    then only make them like 15 amp modules or so, and just using your favorie logic, t switch them in and out (parallel) (even more "secrets" of edm)
    try some IRF450 's

    but hey, if ya wanna build an rf machine, go right ahead, but i think the FCC would have something to say about that.....

    and cheap brass .010" wire will run fine on it, with properly desighed heads and flushing, i see 12 square an hour....
    Registered Linux User #348337
    EMC2 Rocks!!!!

  10. #30
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    Feb 2006
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    120
    Yea I did mean Agie sorry about the typo.

    This is all good news to me; I have found it very hard to track down the specs that you mentioned.

    If you would like to know about the patents hear is one of them "Method and apparatus for machining, 6,252,191"

    There are more but this is the only one I have handy

    So you are changing my mind yet again!
    Regardless I have resolved my self to making the machine first and then the generator after.

    And since I am argumentative I must rebuttal that an RF generator and work need only to be contained in a faraday cage and it will not radiate energy thus the FCC will have no problem with it. I have a RF switching power supply that produced 60,000VDC that runs at about 8Mhz. it uses air core transformers and hydrogen flooded gaps and a faraday cage is how I make it not radiate power. oh yea and good line filters.

  11. #31
    Join Date
    Jun 2005
    Posts
    32

    plans

    Quote Originally Posted by FRP View Post
    Hi,
    Happy new year to all.
    I'm working on an small homemade EDM switched mode pulse generator. I'm aiming for 0-15A (maybe more), 0 - 150V and 0 - 100kHz pulses (isofrequent and isoenergetic). The unit should be able to work at will in a pulse or relaxation mode). The electronic project is already in an advanced fase, but for the moment I'm lacking expensive measuring equipment for making good relevent load measurements, snubber adjustment and calibration of current limiters/controllers. The whole thing will be controlled with a microcontroller to set all kind of parameters for finishing result and speed optimizations. And above all it should be affordable for a simple student as me. The primary objective is to use it for a zinc EDM, but later on I plan another version for wire EDM.
    Dear Sir,
    Do we have the plans available for interested members. Please let us know.

  12. #32
    I would like to see your plans.

    jsologuren

  13. #33
    Join Date
    Jun 2005
    Posts
    32
    Quote Originally Posted by kulk_sd View Post
    Dear Sir,
    Do we have the plans available for interested members. Please let us know.
    Dear Sir,
    I would like to have the plans for my hobby shop.
    Regards
    kulk_sd

  14. #34

    Pulse Control

    I have basic circuit plans but I want to see different Project in order to add a bit more and the share my experience.
    My Yahho Mail is [email protected]

    ...Julio

  15. #35
    Join Date
    Jun 2005
    Posts
    32
    Dear Sir,
    Please let us know when you have completed your trials
    Regards
    S. D. Kulkarni

  16. #36
    Join Date
    Feb 2006
    Posts
    120
    I have been working on my circuit, found a good microcontroller, and good sampling circuits.

    I will keep it simple, but sophisticated. My prototype board has a RS232 connection and so I will use that for real time monitoring. It will stream things like the current sampled with a basic differential amplifier, average current, voltage and waveform; it has a maximum of 4 channels that are set up in this way. Because it is a microcontroller it will have the capability to change allot of parameters on the fly, with a connection to a PC, and also through simple voltage control via potentiometers.

    Although I have not been able to get the power end components together I think I am on the right track, thanks to the people here in this forum.

  17. #37
    Join Date
    Jun 2005
    Posts
    32
    I think that will be an interesting project to follow.
    Regards
    S. D. Kulkarni

  18. #38
    Join Date
    Feb 2006
    Posts
    120
    Although I sill have to program it, I have the pulse controller completed. I designed the board to be a universal controller CPU, complete with free bias resistors for switched inputs, and differential instrumentation amplifiers suitable for current measurement and thermocouples alike. It should work well. I am using a IGBT to drive the cutting element directly for now.

  19. #39
    Join Date
    Jun 2005
    Posts
    32
    Please keep on updating so that we are aware of the progress. I am very much interested in making a really good WIRE EDM machine.

  20. #40
    Join Date
    Jun 2005
    Posts
    32
    Please let us know the present status of the project.

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