On Saturday 23 April 2016 02:17:58 Nicklas Karlsson wrote: > On Sat, 23 Apr 2016 10:32:09 +0800 > > Thomas Powderly <[email protected]> wrote: > > ... > > in real work the tool is already at the discharge distance when the > > initiation voltage is turned on > > so the initiation still occurs, followed by the discharge > > I was thinking about this for the ionization voltage. Usually tool is > already at the discharge distance but in case it is to far away > ionization just a little bit above limit would prevent discharge from > happen to far away. > > > ... > > .75 amps never bothered me, that measure is of the supplied current, > > ( the current that would be delivered in a dead short) > > which is much more than delivered current > > It is the current delivered if I happen to touch tool that bother me, > to high current and I wont be there to machine another day. There is a > blue-green-yellow-red graph a bit down to the right on this page > https://en.wikipedia.org/wiki/Electric_shock and I prefer to stay to > the left of the yellow area. > > > tomp > > 10mA seems to be enough for ionization although I will try higher > later to check if it make a difference. Sparc distinguishing seems to > work at if short circuited there is no current. I however have some > problem to keep the process running manually.
I should remind everyone that the lethal electric shock range is between 20 micro-amps, and 20 milli-amps directly thru the heart muscle. In this range fibrillation takes place and that is the killer because it continues after the shock has been removed. Above 20 ma, the heart will freeze, and if the current is removed before you expire, it generally will start right back up when the current is removed. You may have some 2nd degree burns but they will heal. The thing to watch out for as an aftereffect is the shingles as the body's immune system will take a huge hit while repairing other damages and may not be able to keep the chickenpox viri under control. BTDT. Worst continuous, debilitating pain I have ever experienced, for about 2 months. I had no assistant at the time and finally at about 2 weeks, had to get up and go to work and take care of the tv stations technical problems & broken equipment. I wasn't pleasant to be around as I had an extremely low tolerance for the idiocy the News Dept can perpetrate on equipment already, and it didn't get any better, but I did catch up eventually. I would not wish the shingles on anyone, although I might make an exception for that pompous little twerp that runs North Korea. He will start the next war with his atomics. > Regards Nicklas Karlsson > > > On 04/22/16 22:29, Nicklas Karlsson wrote: > > > .75 amps is very dangerous as soon as voltage is high enough. Low > > > current and it should not be dangerous even for rather high > > > voltage. > > > > > > Preferably I want to stay at low current at least until prototype > > > leave desktop. > > > > > > Since dielectric breakdown strength only has volts and distance I > > > guess volt should be adjusted so that ionization is not started at > > > to long distance which would create a big crater. > > > > > > I however want to keep current low to stay safe but does the > > > current change how large a channel is created or will it grow > > > large enough anyway as soon as the real current start? > > > > > > > > > Regards Nicklas Karlsson > > > > > > > > > > > > > > > On Thu, 21 Apr 2016 22:03:32 +0800 > > > > > > Thomas Powderly <[email protected]> wrote: > > >> initiation ONLY depends on voltage > > >> i use .75 amps and its overkill > > >> but it was easy to make the circuit > > >> the equation for dielectric breakdown strength only has volts and > > >> distance but > > >> higher voltage makes ionization easier > > >> typical value are 100 to 300VDC > > >> tho for some paarungs ( stahl bis stahl, copper to crystal ... ) > > >> upwards of 1000V= are used > > >> hth tomp > > >> > > >> On 04/21/16 20:13, Nicklas Karlsson wrote: > > >>> I certainly discovered the need to back off. > > >>> > > >>> As is now I use only 10mA for ionization and 10A for cuts. I > > >>> want to keep ionization current down for safety reason, do you > > >>> know if it is harder to get process running at low current? > > >>> > > >>> Regards Nicklas Karlsson > > >>> > > >>> > > >>> > > >>> On Thu, 17 Mar 2016 15:15:10 +0000 (UTC) > > >>> > > >>> Pete_Gruendeman <[email protected]> wrote: > > >>>> Hi Nicklas: > > >>>> Did you set up and run the simple RC type EDM? It's a > > >>>> pretty simple proposition, using a filtered DC power supply, a > > >>>> capacitor in parallel with the gap and the gap itself. An > > >>>> electrolytic capacitor would work. A motor-run capacitor, of > > >>>> 50-100 micro Farads would work even better. Hands-on > > >>>> experience will answer many of you questions, especially in > > >>>> regard to the stability of the process. No matter how stable > > >>>> your process is, backing up is part of this artform. > > >>>> > > >>>> Pete > > >>>> -------------------------------------------- > > >>>> On Thu, 3/10/16, Nicklas Karlsson > > >>>> <[email protected]> wrote: > > >>>> > > >>>> Subject: Re: hands-on EDM experience > > >>>> To: "Pete_Gruendeman" <[email protected]> > > >>>> Date: Thursday, March 10, 2016, 8:49 AM > > >>>> > > >>>> > Hi Nicklas: > > >>>> > I wrote and sent this last > > >>>> > > >>>> night but it seems to have bounced instead of reaching > > >>>> you. I want you to get some hands on experience with EDM, > > >>>> even if it's a simple RC type EDM that you clamp onto a > > >>>> milling machine and flush with a turkey baster you borrow > > >>>> from the kitchen. Even though I had run commercial EDMs, > > >>>> it was eye opening to run the process manually. The whole > > >>>> process can be complicated but it doesn't have to be. > > >>>> Read below. > > >>>> > > >>>> > Hi > > >>>> > > >>>> tomp and Nicklas: > > >>>> > > >>>> Careful tomp as much of what you wrote is some > > >>>> pretty technical stuff. It might be over Nicklas' head > > >>>> since he is new to EDM. I barely recognize some of this > > >>>> but do recall that Agie offered auto-overcut compensation. > > >>>> I always turned that off as much of my work was something > > >>>> like a horizontally oriented cylinder and I typically > > >>>> orbited about the X-axis. > > >>>> > > >>>> > Nicklas: Have you done > > >>>> > > >>>> anything with EDM yet?, even with a simple resistive > > >>>> capacitive spark eroder?, perhaps set up on a milling > > >>>> machine or other platform? And I don't mean CNC. I > > >>>> mean with control being provided by your ears and your > > >>>> hands. And flushing with a baster from the kitchen. Much > > >>>> of the discussion here will make more sense if you have even > > >>>> a little hands-on experience with EDM. Being a beginner is > > >>>> fine. I really want you to know instinctively what a > > >>>> stable burn sounds like, and what gap contamination looks > > >>>> like, sounds like and how quickly you need to do something > > >>>> about it when the burn starts to become unstable. These > > >>>> various hands-on skills will be more confusing to you when > > >>>> you try to learn it with the complexities of CNC added to > > >>>> the mix. Let's get your hands oily and a little EDM > > >>>> crackling sound in your ears as soon as possible. It takes > > >>>> very little equipment to replicate Lazarenkos' > > >>>> experiments and that's all I want you to do to get > > >>>> started. You can get started with a copper or brass > > >>>> electrode. Let me know how I can help you get started. > > >>>> > > >>>> > Pete > > >>>> > > >>>> Well I am more interested in > > >>>> the CNC part and an EDM is what I could buy cheap. My first > > >>>> sparcs will be coffecup EDM with food oil, it is still a few > > >>>> days away since I have to spend a few days on others. > > >>>> > > >>>> > > >>>> Nicklas > > >>>> Karlsson Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Find and fix application performance issues faster with Applications Manager Applications Manager provides deep performance insights into multiple tiers of your business applications. It resolves application problems quickly and reduces your MTTR. 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