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Nov 21, 2009. 7:35 AMtwenglish1
says:
i have another question about the transformer: do you think modified microwave transformers much like these(http://www.instructables.com/id/Build-a-Microwave-Transformer-Homemade-Welder/) will work? what does the output voltage have to be? and i know that it needs to be DC
Nov 18, 2009. 5:17 PMtwenglish1
says:
what are the voltage requirements for the plasma cutter(going to the torch)? i really want to make one of these, i actually already ordered a torch head thats how confident i am
im using 12 volt dc for the trigger, electrode gets around 325 on 120 volt and tip wire is running 50 k offf chevy coil.
Jan 20, 2009. 8:36 AMjmastersinc
says:
but yesterday i saw the complete directions on how to build the thing with a parts list and a bunch of pics what happened to them?
Jan 19, 2009. 4:14 PMjmastersinc
says:
why can't I access the directions? I was reading them earlier but not there gone.
Schematics please? Your diagrams are interesting, but too confusing for me to actually build this...
Jan 19, 2009. 5:24 AMexpansion
says:
Okay...well, one more question: in your homemade torch, what material your electrode was? And i think that your tip was copper?
Jan 19, 2009. 12:19 PMexpansion
says:
Oh yeah, that is very smart swirl ring :P How about your tip, how did you done it?
Jan 16, 2009. 9:29 PMelb
says:
Read else where to use two step down transformers back to back ( 120 to 24 - 24 to 120 or what you require.) to create a isolation transformer. I believe this requires a break between the grounding wire as well. The heat dissipation on the rectifier can be reduced by the use of the suggested heat sink; further drive the temperature down by adding a dc power line to a peltier junction (Thermo Electric Heat Pump) mounted cold side to the heat sink on the opposite side.
Jan 15, 2009. 11:07 AMjimwig
says:
two transformers - one @40:1 and one @20:1 windings ratio. parallel the primaries and series the secondaries to obtain your 36 volt working voltage. can we put up small graphics here the comments? anyone know? accoding to the diagrams the AC working voltag (before rectification) is 36 volts. right? so instead of stepping down from 120VAC then you will be coming down from 240VAC (single phase?) right? so just get the proper transformer primary to secondary windings and there you are.
Jan 16, 2009. 6:56 AMjimwig
says:
i totally missed the caps hookup. not to mention other most relevant details. so i will start over iow -"---------- NEVERMIND!"
Jan 16, 2009. 6:44 AMjimwig
says:
i just got here about two days ago., downloaded the pdf and on the same there ;was no repeat -NO- ref as to how the plasanator works. i never read the line version and never saw the how it work section until about three minutes ago. the only circuit i saw was rectfication after the step down transformers - i must be off in ga ga land again. so i will backstep and try for another take. be right back
Jan 14, 2009. 5:14 PMLT
says:
very interesting and resourceful as far as design and parts go. The fact that the work is at or above line potential with no isolation transformer is to big a risk for me. Someone mentioned a welding transformer. Strip off the secondary and wind another same as the primary. I'd Remove the circuit breaker from the nuetral also. Just my thoughts. jay-
Jan 15, 2009. 10:53 AMjimwig
says:
yes remove the brealer from the neutral. The NEC speciically says not to fuse the neutral. the reason is just common sense. if in the event of a fault resulting in the neutral being deengerized and the hot leads remaining hot then you have a very dangerous situation. the answer to all of this is a ground faul interuptor circuit device.then any overcurrent is detected no matter what/where the phasing might be. and all power is removed from the load. the double pole GFCI (in this case) is not cheap but then how much is your life worth. also do not put the work at high potential in relation to ground because you are probably grounded yourself and do not want to become part of the path. and for that matter how can you both ground and energize the work? `
Jan 13, 2009. 6:35 PMelb
says:
How much is left to do on the step 13 version? Is this included in the plan set? Do the plans include the torch you built?
Jan 13, 2009. 5:22 PMdarwinwandler
says:
NO it will not split. Use 240 to 24 or 240 to 12 volt transformers. I am sure they are common in Australia.
Jan 9, 2009. 3:02 AMteddlesruss
says:
Eeek! No! No! A thousand times no, it will not "split!" Be safe, talk to someone in Australia that's done something like this. Please. I don't want to read an obituary.
Jan 8, 2009. 11:22 PMmacsimski
says:
that is not necessary so. here in Europe one wire of the 240 is always on gnd level, due to the 3 phase way of doing things. between phases lives 400Volts, between phase and neutral lives 240volts.
Jan 11, 2009. 8:58 PMpraxis180
says:
The way power is supplied over here in Australia is that the mains coming into a home is 240V there are usually just TWO wires plus and earth wire (AKA single phase). These two are active and neutral (I think it's what has been referred to previously as ground). Occasionally a home might have three phase, but in that case you have three wire plus earth, where two are 240V active and one neutral.....
Jan 12, 2009. 1:14 AMsamuelchrist
says:
yes here we do have what U say how ever the two coming in is Active an neutral the earth is a link the rod running from the ground, three phase is like u say but working in rotation red, blue and white plus neutral earth does not come in from the power pole ever...i install airconditioning systems for a living from small 1 kw units to 200 kws.
Jan 13, 2009. 8:45 AMundinstructable
says:
Congratulations, man! Very interesting though I didn't get the whole picture... It would be nice attached to a CNC machine... Thanks for sharing! A
Thank you, I think that would be cool too. Im gonna work on that next.
Jan 12, 2009. 10:22 AMjimwig
says:
i have been cogitating about a plasma cutter for years.. i couldn't get a handle on the frequency part. but now there it is. i am so grateful. i will build this one. only in a higher power to cut 1/2 inch steel. (i hope) right!!!! thanks again sir.
Thanks Jimwig, add a couple of coils to reduce the resistance and it will cut 1/2 inch with know problem.
Jan 13, 2009. 9:37 AMjimwig
says:
okay so now you know i sound good but that is about it. tell me about the series coils. what are we talking in terms of size and inductance. i have some spike limiting coils from some stage theatrical dimmers. the dimmers went belly up sorta so the parts are available for this great attempt. they were 2kw dimmers with the coils in series i think so number 12 wire on a laminated core. inductance i do not know. if someone could verbalise theory of operation that sure would be swelll and excuse me if i missed same. great project.
Jan 7, 2009. 10:59 AMtercero
says:
Pretty much what I was told. I searched for plans back in the fall for making my own plasma cutter and came across these very ones, and the forum found on yahoo.
Tom Caudle over at CNCZONE wrote a frank reply to my inquiry if this was safe to build and use. In his words "Plasma has lethal voltages even without a transformer isolated primary. The workclamp on a cutting plasma is not at ground UNLESS you physically ground the table! You can get a nasty shock if you touch an earth ground and the ungrounded plasma table at the same time. The voltages are higher than TIG and MIG welding and there is plenty of current to kill. I know plasma cutters are expensive but building your own could result in heavy expenses to your family for the funeral. Half of the secret to plasma is the structure of the torch (with the arc start method) and the safety and control electronics in the unit. All plasma torches and units have sensors that if you are changing consummables and accidently hit the torch button you don't fry yourself.
I have years of experience in power electronics design, high voltage systems and control electronics. I would not attempt the design my own plasma power section.
TOM CAUDLE
www.CandCNC.com"
I got the same answer from weldingweb, Miller Welding discussion forum, http://www.mig-welding.co.uk
They all replied that I was taking a stupid chance building and using this. So. I left it. I want to go on to build new things. Not die by building unsafe ones.
Oh well.
Tom Caudle over at CNCZONE wrote a frank reply to my inquiry if this was safe to build and use. In his words "Plasma has lethal voltages even without a transformer isolated primary. The workclamp on a cutting plasma is not at ground UNLESS you physically ground the table! You can get a nasty shock if you touch an earth ground and the ungrounded plasma table at the same time. The voltages are higher than TIG and MIG welding and there is plenty of current to kill. I know plasma cutters are expensive but building your own could result in heavy expenses to your family for the funeral. Half of the secret to plasma is the structure of the torch (with the arc start method) and the safety and control electronics in the unit. All plasma torches and units have sensors that if you are changing consummables and accidently hit the torch button you don't fry yourself.
I have years of experience in power electronics design, high voltage systems and control electronics. I would not attempt the design my own plasma power section.
TOM CAUDLE
www.CandCNC.com"
I got the same answer from weldingweb, Miller Welding discussion forum, http://www.mig-welding.co.uk
They all replied that I was taking a stupid chance building and using this. So. I left it. I want to go on to build new things. Not die by building unsafe ones.
Oh well.
Jan 9, 2009. 11:10 PMbassbindevil
says:
There's at least one other person who'd agree. He built a DIY plasma cutter, forgot to power it off completely, then accidentally touched the tip. When he regained consciousness, he was very badly burned and lucky just to be alive.. I really don't like the idea of the work clamp being hot. I'd hold out for some surplus transformer that can be rewound, maybe the transformer out of an old arc or MIG welder if they aren't suitable as-is.
Jan 13, 2009. 7:13 AMdrboostv6
says:
You could get around that with a contactor activated by the trigger...
Jan 13, 2009. 7:11 AMdrboostv6
says:
I'm currently building one...to get around these problems I'm using a huge isolation transformer, a contactor (activated by trigger also), and two heavy duty carbon pile load (HD car battery load testers) (to control resistance)
its no different than with welding when you have the reverse polarity swtiched on, its the same thing and just as deadly. Welding and plasma cutteing is not a toy and if someone touches the tip while using it then he or she is just being careless, who would get that close to the tip anyway? I wouldnt and maybe thats why after about 500 cuts with it so far im still alive. Your bathroom recepticleby code should have a gfi in it but I wouldnt take a bath still while blow drying my hair niether.
Jan 10, 2009. 12:58 PMbassbindevil
says:
Well, with most welders, reverse polarity maintains the work clamp at ground potential, and just changes the polarity of the electrode. Otherwise it wouldn't be possible to weld on large items which are at ground potential. It's great if you can use it safely, but, $400 for a Harbor Freight unit is peanuts compared to the inconvenience of lawyers or medical bills if something goes Horribly Wrong. You only need to turn your back on it for a moment with it hot for a friend/family member/pet to walk in and touch something they shouldn't...
Thats funny, my lincoln changes at the clamp, I guess anything in life can happen if your careless.
I appriciate your input. but would you weld something while standing in water? I wouldnt and with all welding equipment there is inherent danger in volved that can kill you. The breakers will blow fast if any thing goes wrong before any major problems. When I cut for 10 minutes straight it will blow my breaker on q. I just put a fan on it and now cut for 25 minutes before it gets to hot, then let it cool for a couple of minutes. As for as affecting anything in the house, short of pouring water on it while its in use, its not gonna happen.
Jan 8, 2009. 7:40 PMteeps
says:
I think a ventilation system would be in order, no? great instructable btw. stuff like this thrills me despite my complete lack of intention to attempt such a feat. really makes one wonder how many things CAN'T be hacked together that normally cost oodles of money, though. cheers
Thank you for your input, also remember now that if you touch the tip of the torch you wont be touching the electrode because it is insulated from the tip and only transfers to the tip when you power the high voltage arc start and come in contact with the metal. I can see some folks get to relaxed around welding equipment after awhile or any power tool but its all about being safety conscience about what where doing during these few minutes of operation.
Jan 11, 2009. 9:31 AMtsm3rdz
says:
This may be a stupid question but I've got an old lincoln stick welder (up to 225 amp)that I don't use since I got the mig. What are the chances as could use this as my dc power supply? Than it would be isolated, correct? If so how would I go about adapting your plans to this old welder? Thanks in advance for you help
Its not a stupid question, interesting to say the least. I'm not sure but I am going to investigate this because I also wonder about that.
Jan 11, 2009. 11:22 AMtsm3rdz
says:
Good deal! I will certainly keep checking back to this. What an ingenious thing you've done here. Very nice work!
Jan 13, 2009. 7:07 AMdrboostv6
says:
probably won't do it.. plasma cutters are high voltage/ low amperage - welder are the opposite.
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