Carbon Arc Cutter
Kolas, Mon May 08 2006, 02:23AMhi guys
while working on my homeade pole pig, I realzied a steel box would be needed to hold the oil. Thus many hairy situations arised, like welding (properly), feed throughs. and how to make the holes for all this.
With the help of Chris(not Russell) I settled on a way to kill two birds with one expensive, and over heated stone. Carbon arc cutting is very similar to welding, but instead of a stick, a carbon rod is used. Blah blah blah...
Now to the real reason for the post. Pictures of the full wave rectifier under construction.
The transfromer I will be using (not photographed yet) suplies about 30V, and is rated 500A continuous. so here is the subsequently sized device for rectification...
Yes, yes, I apologize for eh poor qaulity photographs.
Re: Carbon Arc Cutter
Dr. Shark, Tue May 09 2006, 09:41AM
Your telling us that you've got a 15kVA transfomer standing around? Wow, that must be a hell of a beast and easily be capable of tripping some breakers. Why do you want to rectify it, should an AC arc not be just fine for cutting?
Dr. Shark, Tue May 09 2006, 09:41AM
Your telling us that you've got a 15kVA transfomer standing around? Wow, that must be a hell of a beast and easily be capable of tripping some breakers. Why do you want to rectify it, should an AC arc not be just fine for cutting?
Re: Carbon Arc Cutter
Kolas, Wed May 10 2006, 02:46AM
Yeah, the tranny is a beast alright. I'll be sure to make a video, and take plenty of pics. The reason I rectify is because alternating current wouldnt cut well. also I'm told that when the cutting electrode is -, it pushes the molten steel out of the way.
Anyone with thoughs on how to put a pilot arc on this, so striking the arc is more easy?
oh, and i will ahve to patch directly into the main breaker with this operation. of course current shoudl successfully be controlled by the saturatable reactor i have.
Kolas
Kolas, Wed May 10 2006, 02:46AM
Yeah, the tranny is a beast alright. I'll be sure to make a video, and take plenty of pics. The reason I rectify is because alternating current wouldnt cut well. also I'm told that when the cutting electrode is -, it pushes the molten steel out of the way.
Anyone with thoughs on how to put a pilot arc on this, so striking the arc is more easy?
oh, and i will ahve to patch directly into the main breaker with this operation. of course current shoudl successfully be controlled by the saturatable reactor i have.
Kolas
Re: Carbon Arc Cutter
Hazmatt_(The Underdog), Wed May 10 2006, 08:54AM
striking an arc would be similar to mig or tig with a HF HV source. The HV HF source is coupled to the LV side with an inductor. Or there are also very large 'trigger coils' that do the same job. Its a fairly large inductor of heavy guage wire of about 20T #8 square magnet wire on a ferrite or heavy rod, overwound with 5 or 6 turns of a very heavily insulated silicone wire where the HV pulse is discharged through, like a camera flash circuit, except that you are modulating a HV pulse onto the LV side.
You should be able to pick one up from a welding supply I think, although the replacement cost may be really prohibitive.
The first time I saw one of these tig 'trigger coils' I didn't know what the heck it was for, but a good friend of mine told me the whole story behind it. Its pretty neat stuff. I would look to Lincoln Electric and ask them for the part number. Their staff is excellent with technical questions. They helped me when I needed Tungsten electrodes.
So, there ya go.
Hazmatt_(The Underdog), Wed May 10 2006, 08:54AM
striking an arc would be similar to mig or tig with a HF HV source. The HV HF source is coupled to the LV side with an inductor. Or there are also very large 'trigger coils' that do the same job. Its a fairly large inductor of heavy guage wire of about 20T #8 square magnet wire on a ferrite or heavy rod, overwound with 5 or 6 turns of a very heavily insulated silicone wire where the HV pulse is discharged through, like a camera flash circuit, except that you are modulating a HV pulse onto the LV side.
You should be able to pick one up from a welding supply I think, although the replacement cost may be really prohibitive.
The first time I saw one of these tig 'trigger coils' I didn't know what the heck it was for, but a good friend of mine told me the whole story behind it. Its pretty neat stuff. I would look to Lincoln Electric and ask them for the part number. Their staff is excellent with technical questions. They helped me when I needed Tungsten electrodes.
So, there ya go.
Re: Carbon Arc Cutter
Plasmaniac, Wed May 10 2006, 10:52AM
I'm also buiding a welding machine right now. Unfortunately, the 1mm thungsten electrodes are too thin though they are rated for 10-60A. I think I'll try a carbon rod later.
here some pics:
Argon
my pilot arc transformator (around 2kV and a few 100mA output)
here you can see my high curernt source
I'm looking for some MOTs right now, so I can make a better high current suplly. Right now, I'm using 60V 20A/120V 10A
This is how it looks like if you forget turning the argon on...
I made the nozzle from a 12cm piece of 8mm brass rod with my drilling machine and a dremel. It took half an hour and everything in our basement (including me) looked very shiny...
Plasmaniac, Wed May 10 2006, 10:52AM
I'm also buiding a welding machine right now. Unfortunately, the 1mm thungsten electrodes are too thin though they are rated for 10-60A. I think I'll try a carbon rod later.
here some pics:
Argon
my pilot arc transformator (around 2kV and a few 100mA output)
here you can see my high curernt source
I'm looking for some MOTs right now, so I can make a better high current suplly. Right now, I'm using 60V 20A/120V 10A
This is how it looks like if you forget turning the argon on...
I made the nozzle from a 12cm piece of 8mm brass rod with my drilling machine and a dremel. It took half an hour and everything in our basement (including me) looked very shiny...
Re: Carbon Arc Cutter
Kolas, Wed May 10 2006, 02:42PM
oh, that pilot arc is mighty cool!
is your HV source HF?
how can i do this with my 500A source, i assure you, i dont have the ferrite for such a core.
also, how does the HV not overcome the breakdown voltage of your rectifiers.
kolas
Kolas, Wed May 10 2006, 02:42PM
oh, that pilot arc is mighty cool!
is your HV source HF?
how can i do this with my 500A source, i assure you, i dont have the ferrite for such a core.
also, how does the HV not overcome the breakdown voltage of your rectifiers.
kolas
Re: Carbon Arc Cutter
G^3, Fri May 12 2006, 02:36AM
To stop the HV a choke and a capacitor like this guy is using should do the trick. http://www.geocities.com/CapeCanaveral/Hangar/6160/welder/arcstarter/hf.html
I don't understand why a ferrite core doesn't saturate or something like that when used like this.
G^3, Fri May 12 2006, 02:36AM
To stop the HV a choke and a capacitor like this guy is using should do the trick. http://www.geocities.com/CapeCanaveral/Hangar/6160/welder/arcstarter/hf.html
I don't understand why a ferrite core doesn't saturate or something like that when used like this.
Re: Carbon Arc Cutter
Marko, Sun May 14 2006, 03:20PM
Doesnt' seem like something lou'l like to hold in hand like a pencil.
Marko, Sun May 14 2006, 03:20PM
my pilot arc transformator (around 2kV and a few 100mA output)
Doesnt' seem like something lou'l like to hold in hand like a pencil.
Re: Carbon Arc Cutter
Plasmaniac, Sun May 14 2006, 03:48PM
The insulation is about 2mm thick, so this is no big problem. If I touch it I'll get some neat HF burns and that's all because of its relatively high frq of 20kHz (yes conditional I -> "It is possible and also very likely that the condition will be fulfilled." why? because I'm stupid and never managed to not touch a HV supply...
).
Plasmaniac, Sun May 14 2006, 03:48PM
The insulation is about 2mm thick, so this is no big problem. If I touch it I'll get some neat HF burns and that's all because of its relatively high frq of 20kHz (yes conditional I -> "It is possible and also very likely that the condition will be fulfilled." why? because I'm stupid and never managed to not touch a HV supply...
).Re: Carbon Arc Cutter
..., Sun May 14 2006, 06:45PM
I would really hate to touch the output while connected to that battery pack... Why in the world do you need it to start that far away?
In any case, this looks like once it is done it will be quite a beast... Just out of curiosity, why did you use SCR's for the rectification instead of normal diodes?
As to the ferrite core saturating... It probably does; but it doesn't matter since once the lv ark is going you don't need the hv any more, so it doesn't matter what is going on with the ferrite core...
..., Sun May 14 2006, 06:45PM
I would really hate to touch the output while connected to that battery pack... Why in the world do you need it to start that far away?
In any case, this looks like once it is done it will be quite a beast... Just out of curiosity, why did you use SCR's for the rectification instead of normal diodes?
As to the ferrite core saturating... It probably does; but it doesn't matter since once the lv ark is going you don't need the hv any more, so it doesn't matter what is going on with the ferrite core...
Re: Carbon Arc Cutter
Kolas, Mon May 15 2006, 03:24AM
I usualy buy my parts form a surplus CB radio tech here. And he didnt have diodes that woudl be large enough, so SCR's were almsot as easy to use.
Heh, only reason. Though the SCR's do allow me to play around with phase modulation and such.
Well this project is actually only a side to my more major project. A self wound plate transformer for arguably one of the larger VTTC's ever. However, that will be far down the road.
Kolas
Kolas
Kolas, Mon May 15 2006, 03:24AM
I usualy buy my parts form a surplus CB radio tech here. And he didnt have diodes that woudl be large enough, so SCR's were almsot as easy to use.
Heh, only reason. Though the SCR's do allow me to play around with phase modulation and such.
Well this project is actually only a side to my more major project. A self wound plate transformer for arguably one of the larger VTTC's ever. However, that will be far down the road.
Kolas
Kolas
Re: Carbon Arc Cutter
G^3, Tue May 16 2006, 05:57PM
Ok so I am building an arc welder out of 4 rewound MOTs and I was wondering a few things. First off what open circuit voltage should I be looking for? What size rods can I use? Is an HF HV arcstarter necessary or just very useful? Should I remove the shunts? Is it alright to have more turns on one transformer than on the others?
Thanks
Graham
Edit: few more questions made it a lot of questions.
G^3, Tue May 16 2006, 05:57PM
Ok so I am building an arc welder out of 4 rewound MOTs and I was wondering a few things. First off what open circuit voltage should I be looking for? What size rods can I use? Is an HF HV arcstarter necessary or just very useful? Should I remove the shunts? Is it alright to have more turns on one transformer than on the others?
Thanks
Graham
Edit: few more questions made it a lot of questions.
Re: Carbon Arc Cutter
Desmogod, Wed May 17 2006, 01:47AM
G^3, Might be an idea to start a new thread on this instead of 'jacking.
Desmogod, Wed May 17 2006, 01:47AM
G^3, Might be an idea to start a new thread on this instead of 'jacking.
Re: Carbon Arc Cutter
Kolas, Thu May 18 2006, 07:30AM
Weee, I dont care, my project is done, I juut dropped the pilot arc idea. I was told; at my current, estabilishing an arc will not be an issue. This weekend I'm going to cut a lawnmower frame in half to get some much needed practice with this thing.
G^3 there are many things to consider. Most consumer arc welders rise to about 40VAC when unloaded. Were you to use MOT cores, you would be limited in a few ways. 1: 40V's worth of wraps might be hard to get on one MOT with any serious current handleing ability. 2 MOT's are rather easy to saturate to the point to being overly lossy.
So, with that in mind. If you're going to try to get 40V you may find putting two MOT's in serise, and then a set of those in parralell might suit you best. As far as your number of wraps goes. unless you want one MOT, or pair of MOT's doing all the work; I would defiantly not sujest having more then 1/2 wrap differnace between the 4 MOT's.
Welding rod size depends on two things: the type (and thickness) of material you're bonding to, and the number of RMS amps.
I think the final thing to consider here, is that welding works much better when your using DC. AC causes poor deposition of molten iron, but DC will have a very obvious direction of flow. (durr)
All in all, I would sujest a single transformer, with one set of high current windings. therefore paralelling secodnaries; and thus inductance, isnt an issue. Well that's about all I ahve to say.
Kolas
Kolas, Thu May 18 2006, 07:30AM
Weee, I dont care, my project is done, I juut dropped the pilot arc idea. I was told; at my current, estabilishing an arc will not be an issue. This weekend I'm going to cut a lawnmower frame in half to get some much needed practice with this thing.
G^3 there are many things to consider. Most consumer arc welders rise to about 40VAC when unloaded. Were you to use MOT cores, you would be limited in a few ways. 1: 40V's worth of wraps might be hard to get on one MOT with any serious current handleing ability. 2 MOT's are rather easy to saturate to the point to being overly lossy.
So, with that in mind. If you're going to try to get 40V you may find putting two MOT's in serise, and then a set of those in parralell might suit you best. As far as your number of wraps goes. unless you want one MOT, or pair of MOT's doing all the work; I would defiantly not sujest having more then 1/2 wrap differnace between the 4 MOT's.
Welding rod size depends on two things: the type (and thickness) of material you're bonding to, and the number of RMS amps.
I think the final thing to consider here, is that welding works much better when your using DC. AC causes poor deposition of molten iron, but DC will have a very obvious direction of flow. (durr)
All in all, I would sujest a single transformer, with one set of high current windings. therefore paralelling secodnaries; and thus inductance, isnt an issue. Well that's about all I ahve to say.
Kolas
Re: Carbon Arc Cutter
Kolas, Mon May 22 2006, 05:38AM
hi again.
well for some follow up, i took some video of the cutting device in action. so here is the link
my thanks to Rev for hosting these videos
first is me, secodn is a buddy of mine.
Kolas
Kolas, Mon May 22 2006, 05:38AM
hi again.
well for some follow up, i took some video of the cutting device in action. so here is the link
my thanks to Rev for hosting these videos
first is me, secodn is a buddy of mine.
Kolas
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