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View Full Version : Improvised metal shop equipment. the $10 welder


johnn 99
October 10th, 2004, 05:06 PM
Hello. I see a lot of posts along the lines of "I could rule the world if only I could build a better zipgun."

So I thought I Might post some low cost, no cost ways to build or modify shop equipment from around the house supplies.

First up is a combination stick welder and carbon arc torch. The stick welder will allow you to weld steel up to about 1/4" with multiple passes, using the small 5/32 rods. I recommend (EZ strike) they are a bit more expensive but are easier to work with. The really nice feature however is the carbon arc torch. Which is a sort of poor mans oxy/fuel torch without the expense of tanks. With it you can fusion weld a variety of metals including iron/steel, brass, copper,and aluminium. Either with or without a filler rod. Or braze and siver solder disimilar metals together.

Parts list.

1 electric space heater preferably an old one without a fan. (everyone has one of these buried in the closet don't they?) if not I found 7 of them at the second hand store yesterday not one of which cost over $5.
1 small extension cord.
2 pieces of wooden rod 1/2" Dia. x 8" long (not critical).
4 small hose clamps.
2 alligator clips.
1 roll of electrical tape
a few screws etc.

Construction.
First lets get the electronic portion out of the way, then we will more on to building the electrode holders. Ready? set the space heater in front of you, find the cord and halfway between the body of the heater and the plug cut one of the 2 wires that make up the cord. Now take your cheap extensin cord and cut of both ends leaving you with a piece of duplex wire. Now take both wires from THE SAME END of the extension cord and splice one each to either end of the heatercord wire that you already cut, so that you have lengthened one leg of the circuit with the extension cord. There you go, a resistance welder power supply and lead cables. Now all thats left to do is to build the electrode holders. To start take the 2 pieces of wooden rod and put a seperate hose clamp around the middle of each rod with the extra metal tab sticking out about 3/4" on each. Now flatten the curl out of the tabs. punch or drill one of the slots in the middle of each of the 2 tabs to accept a small bolt and wing nut. now lay the rods parallel to each other with the tabs overlapping and the holes aligned and bolt them both together with the wing nut and bolt such that it makes an H with the long legs being the wooden rods and the metal tabs forming the crossbar and able to pivot on the bolt. Next insert one of the free ends of your extension cord into one of the alligator clip connector ends and smash it flat, then punch a small hole through both the conector and the wire now take another hose clamps and unscrew it until it comes apart and open it out a bit and screw through one of the slots of the hose clamp AND the hole throuth the alligator clip into the endgrain of one of your wooden rods with a short drywall screw or something similar. Then put the tab of the hose clamp back into the screw mechanism and tighten until you have about a 1/4 inch circle. do the same to the other wooden rod. Tape the insulated portion of each leg of the extension cord down the length of each wooden rod and you are done. ( Sorry, hard to explain but really easy to do.)
To use as a stick welder, unscrew the wing nut to seperate the rods, clamp one via the alligator clip to the piece of metal you wish to weld.(doesn't matter which as this is an AC system) and your welding electode in the other alligator, clip plug in the heater and weld. (SEE WARNINGS AT THE END).
To use as a carbon arc torch you will need carbon electrodes. these can be purchased a a welding supply store. The last time I bought some I paid abot $5 for a box of a dozen or so. Which will last you for ages. 1/4" is best but thicker rods can be used if you sharpen them like a pencil to a fine point. Or for the really frugal I understand that you can strip the rod out of a C or D battery.
Reassemble the handle into the H configuration and insert one carbon rod into each of the hose clamps on the end of the wooden rods. tighten clamps to hold the electrodes securely such that the points on the electrodes just touch and form a V with the handles parallel. Plug in the heater and squeeze the handles gently together below the pivot to separate the electrodes drawing an arc between the points.(don't separate them more than about 1/4 inch and you should have a stable arc with a very hot corona around it that is used as a point heat source to weld with.
WARNING!!! In both configurations this is basically a short circuit in a 120V system if you touch both electrodes or the work piece at any time with the heater plugged in it will shunt 120V into you!
WARNING!!! be sure to use at least a #10 shaded lens in your welding helmet and cover all exposed skin when dealing with these procedures. The arc rays will burn exposed skin and do really nasty short and long term damage to your eyes if you don't take proper precautions!
An questions or comments? If there is any interest in this sort of thing I will continue to put them up in this thread.

Ropik
October 10th, 2004, 05:50 PM
IF this works without shorting the whole electrical system of the house, then it is great. I am not sure about it, but I think that this is going to do serious damage to your electric network. Did you tried this?
Anyway, good idea, cheap as hell. I would be very interested in this "no cost metal workshop" if somebody would try procedures like this himself and report. Otherwise, I personally will not take the risk of shorting out my home, cremate myself et cetera.

Zerstoren Sie
October 10th, 2004, 06:13 PM
The space heater needs to be in series to current limit. If this is done wiring in parallel, this will short out the electrical system in your house. As long as thats done correctly, the home-made arc welder should work ok.

Actually many high current devices will work for this. For instance, 10 - 100 watt light bulbs can be ran in series. In that case, if you short out one bulb, and make the series circuit have 9 bulbs in it, it would limit the welder to 900 watts. Using that technique, one can adjust for the current level they desire.

johnn 99
October 10th, 2004, 06:13 PM
Yes, Ropic. I have built and tested this, I also have a comercially produced version that works exactly the same way. Also I should note that any properly wired house ciruit should trip the breaker or fuse before doing any damage to the wiring in any case.

Anthony
October 11th, 2004, 01:41 PM
There was a thread a while back about rewinding the secondary on microwave oven transformers to produce small arc welders.

There's also info on the web about welders consisting of a car battery constantly charged by a large automotive alternator belted to a lawnmower engine. A large battery charger could probably be substituted for the engine/alternator, although it wouldn't be truly portable then.

ProdigyChild
November 14th, 2004, 11:07 AM
Put two 500uF electrolytic caps in series to become bipolar and use this 300uF cap as resistor (Z=10Ohms roughly). Should be even less work, less power dissipation but 10A maximum current, too ;)

Will be more than $10, however....

Haven't tried, yet, but will do something similar, soon.

Jacks Complete
November 15th, 2004, 01:10 PM
It might well have 10,000 Amps output for the few microseconds it has any voltage across it...
Using caps as a welder isn't going to do more than a tiny spot weld.

Personally, although the idea of making a simple arc welder is a good one, I don't see why anyone would bother - a brand new one will only set you back £50, including the gloves and goggles/mask, and a few rods. The shop-bought one runs on about 5 volts, so is far less likely to pass large currents through your body and kill you horrifically. This alone is worth £50!

There are a few other things that can be home-made, such as an electric arc furnace, which mostly uses an arc welder for the power supply. You could perhaps use this technique to make one of those.

Actually, thinking about it, homemade gear, and a collection of plans and designs, would be a very strong contender for a separate section, rather than going in Tools and Techniques. I have several, lifted from the likes of Scientific America, for stuff from the simple (a displacement can) to the complex (laser systems, a gravity detector sensitive enough to see the tides in the ocean from 2000 miles, etc.)

---For fucks sake, do NOT EVER try welding without gloves and long sleeves and a full face mask. If you are only doing a few small welds, you can get away with just welding goggles, but you still might get sunburned. Yes, you can weld by lining it all up and then looking away, but your welds won't be as good, and you just might wreck your eyesight. Cataracts anyone?---

Edit:
Marvin, you are correct - my mistake. Yes, using the caps instead of a resistor would be far better from a power efficiency point of view!

Marvin
November 15th, 2004, 01:22 PM
He isnt suggesting using the pulse from the caps for welding, he's talking about wiring them in series to limit the housecurrent.

I think spot welders are normally about 5V and arc welders around 50V open circuit.

I agree, I think buying an arc welder is the better move as they are inexpensive, reliable and safe. Crappy welds may as well be glued together.

vurr
November 30th, 2004, 04:22 PM
caps do limit curent, but inductive resistance in series gives more stable arc..