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Attempting to weld
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Totaly_Recycled
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Hi george the question you asked is a bit wide ranged it will realy depend on how old the welder you buy is ect as to availability of parts ect Most of the older types with huge transformers never give any trouble , i have one that is about 40 or more years old .
The newer compact types have some electonics and stuff and require a fan for cooling the smaller compact type transformers ect so might be more prone to break downs .

The real old types that ran electric motor /generators were great but did need some maintainance of brushes ect and are huge and heavy and most required 3 phase wireing so steer away from those unles you are thinking about welding 20 to 30 mm plate ect or thinking of useing a carbon arc torch lol Then they are in a class of their own an no matter what i get told they cant be beaten by the newer electronic gadgetry for relaibly suplying 300 to 800 amps cont ..


All i can sugest is iff you can already weld ask to try it first ... turn the amps up full and run a weld on some scrap if you cant weld take some one who can along with you to check it out .. you will soon know iff its any good or not ..
Check out prices on new ones as well before you go hunting .

the older CIG types are good , trans arc used to be a popular brand as well as Lincon welders were prety reliable .

If all else fails and you have a 5 to 7 hp petrol motor lying about I can send you details on how to make one useing a car alternator .These are exelant for welding as they are d/c

Post Fri Sep 10, 2004 11:39 pm 
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Nick
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Buying a secondhand welder is like anything there are good ones and dogs. Stick welders are pretty simple; hardly any moving parts and as long as the electricals don't look worn you should be OK. The electrode holders take a beating and are usually cheap to replace. Check all the switches and get the seller to demo it.

MIG / TIG welders are another matter. Unless it really looks like new, you could be buying either a lemon or its almost ready to die. These welders have many moving parts and they are hard to check. Feed motors & rollers liners, switches gas lines & regulators - all expensive to replace. I would specially stay away from a commercial place selling a used welder - its likely to be completely used up.
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Post Fri Sep 10, 2004 11:43 pm 
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timmeh
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Ok i am getting my 140amp ark welder tomor from bunnings for $98.

Any last tips before i start makeing plasma Laughing

So far what i have to do is were cotton clothes no metal in my pockets or on me\stand on a rubber matt and dont weld when its damp\if i stick the rod to the steel dont pannic as nothind bad will happen just yank the rod of or turn the welder of first which ever is quickest\dont touch the steel or the rod when the welder is on\were mask or my eyes will go Shocked

Ist hat all the safety i need to know?
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Post Tue Sep 14, 2004 6:26 pm 
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Totaly_Recycled
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lol you got most of it right----
metal in your pockets doesnt matter but dont have matches or cigarete lighters in them a hot metal spark can light up matches or melt through the case of a plastic cigarete ligher and you will be engulfed in a fire ball .....

Also dont touch the steel or rod as it will be hot!!!!!!!!! after welding ----- touching or holding the cold end while welding is ok as long as you arent soaking wet and holding the electrode in the other hand lol....go for it sounds like you are organised let us know how your first attempts go Very Happy

Post Wed Sep 15, 2004 8:00 pm 
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timmeh
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I just got my welder tonight but its too dark to play with it so i will have aggo tomorow and let evryone know if im still alive Very Happy

BTW if i dont reply i am probbebly not alive then Laughing
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Post Wed Sep 15, 2004 8:11 pm 
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Valen
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bah ya dont need light for welding
theres a reason they call it a welding "torch" yaknow


;-P
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Post Thu Sep 16, 2004 12:41 am 
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timmeh
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That was fun!!! Very Happy Very Happy Very Happy

I had a play with my welder and it was not as SCARY Laughing as i thought it would be.

I was expecting it to shower sparks and crap every where and make loud zapping noises but it was like touching the wires together on a 12v hawker batt which realy isnt that biger sparking and it was very quiet too and easy to snap the rod off when it stuck Very Happy

A rusty old galvanised bit o metal i practised strikeing on probbebly not the best thing to start with but it was all i had there at the time Very Happy

Most of the little dobs i made was because i had the amps too low and the rod keppt sticking but then i turned it right up and there is a couple of short runs there but not many cos i had to stop for dinner Rolling Eyes

http://robowars.org/forum/album_pic.php?pic_id=234
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Post Thu Sep 16, 2004 7:10 pm 
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ffej
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When welding gal steel, make sure you remove the galvinising before welding. Apart from the fact that you'll get a shatty weld, the fumes coming off it are pretty toxic, and its not a good idea to be breathing them in.
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Post Thu Sep 16, 2004 7:21 pm 
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timmeh
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It was a bit smelly lol Shocked

For some reason i felt realy happy lol Laughing
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Post Thu Sep 16, 2004 7:26 pm 
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timmeh
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Ok for some reason my welder is only letting me weld on 90 amps for 30secs before it cuts off to cool down?

Any ideas why?
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Post Fri Sep 17, 2004 7:47 pm 
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Totaly_Recycled
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The welder probaly has an over temperature shut down .Read the owners manual !!!and read up on what the rateintgs are most small hobby welders arent rated for continious duty you might find that your welder may have a 20 to 30 second high current duty cycle ect . so you might have to weld for 10 to 20 seconds then let it cool for another 10 to 20 and so on iff its one of those smal fan coled tol box sized welders and its a cheap brand it will probaly not be rated for continious duty

Post Fri Sep 17, 2004 8:50 pm 
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Totaly_Recycled
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most welders run at around 24 to 36 volts max

so even at 24 volts 90 amps thats about 2000+ watts going through the transformer

Small transformers arent real eficiant at disapateing heat so they heat up rather quick .
Some of the newer weldrs use electr0nincs instead of transformers a bit like computer power suplies .....but i doubt yours would for the price you paid price ...

Post Fri Sep 17, 2004 8:57 pm 
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ffej
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If your talking about the GMC CEN 140A arc welder, then at 45A, its duty cycle is only 25% at 45A, meaning that in every 10 minutes, you can only be using the welder for 2.5 minutes. 45A is a relativly wimpy current, so when you step it up, the duty cycle drops dramaticly. At 140A I would be suprised if it was rated at more than 5% duty.

http://www.onlinetoolreviews.com/reviews/gmccen.htm has some stuff on that welder
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Post Fri Sep 17, 2004 9:18 pm 
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Nick
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I don't think they actually make a welder that works at 100% duty cycle, but 30sec weld time kinda sucks! Most welders publish a duty cycle as a percentage of 10 minutes like Jeff mentioned, however the GMC seems to be playing with the figures - how long would the weld time be at 140A (if it really goes that high)?

Unless the unit resets itself pretty quickly, I would be thinking about taking it back and upgrading, perhaps $98 really is too good to be true...
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Post Sat Sep 18, 2004 12:36 am 
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timmeh
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It takes 15mins to reset so i will take it back Twisted Evil
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Post Sat Sep 18, 2004 4:15 pm 
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