Problem- Not sure if this is safe to build or not

[tercero]

Anyone ever build their own plasma cutter? I've been interested in the process for the past month or so, since having a go at replacing the lower rocker/sill plate in the back door of my '97 Saturn. I used a reciprocating saw and air wheel to cut out the offending pieces and then had to reshape the new parts. To make a long story shorter, I cut the pieces by a variety of methods but kept thinking I wish I had a plasma torch.
After looking on ebay and couple of other stores for a plasma torch I thought, I wonder if I could build one and a short google search revealed a couple of different plans.
The one I thought looked most promising was by Joe Eichholz. The plasanator. He gives the plans away at his yahoo site.

http://finance.groups.yahoo.com/grou...guid=290185747


I've been in contact with him and he's a nice guy. My only concern seems to be the fact this doesn't have a isolation transformer between the rectifier and the secondary winding. I'm worried about the DC OCV on this thing. It looks lethal and if for whatever reason I happen to short I'd be gone instantly.

So. I'm asking anyone with more experience than me (and that should be practically everyone). What's your opinion on this? Is it worth building? Is it even safe to build? Can I make it safer?

Thanks

J.

[tercero]

No one?

[Edwardo]

My opinion, if it looks lethal it probly is... and may be the reason why you havent received any replies from people who built there own plasma torch. I think i seen the same drawings you are talking about, and read the concerns of people alot smarter than myself regarding the safety of doing this. I was'nt searching for information on building a plasma torch, i already bought one, it just happened to be in a forum i was surfing through. I bought my factory built, engineer designed , safety stamped, licensed electrician installed plasma cutter to use with my cnc table in my garage at home as a hobby, i paid alot of money for that cutter and its worth every cent of it to know that its a safe tool to be using if used to manufactures specs and safety guidlines. Hope i dont sound like im preaching, i dont mean to, but you only live once and being dead is for a long time....
Plasma torches are a great tool, either cnc or hand held, depending on what you will use it for and how much you use it should determine what size and price range to look at. There are cheaper chineese imports all the way up to 40-50 thousand dollar High defination cutters, new/used, rentals etc....
I'm willing to dedicate my life to my hobby, but im certainly not willing to sacrifice it for it... Good luck on what ever you decide to do...

EDD

[tercero]

Thank you. I appreciate the honest reply. I just assumed no one had built a plasma torch and wasn't interested in making one.
I've been watching ebay hoping to pick one up in the $200 to $400 range. I'd only use it a couple of times a year, so it's not worth a heavy investment.

Thanks again for the honest opinion.

TTYL.

J.
Canada

[Torchhead]

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

[tercero]

Originally Posted by Torchhead 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

So, the voltage starts high and drops?