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Up Topic Welding Industry / General Welding Discussion / Converting stick to tig
- - By seagull369 (*) Date 11-23-2008 05:41
Evening, folks!

Hope this topic hasn't been discussed to death already in this forum. I tried doing a search but didnt come up with much.

Anyway, I own a DC TIG machine (with seperate high frequency box) and a Lincoln AC stick welder. Although I hear it's possible to do thicker aluminum with using my TIG in DC mode (which probably requires some religious metal prepping), it supposedly isnt adequate for thinner sheets.   

Given that, I was wondering if I'd be able to make a crude AC TIG machine out of what I have by connecting parts of my TIG to the stick. Specifically, I thought I might try attaching the TIG's foot pedal (or a rheostat capable of doing the job) to the output of the stick machine then pipe that output into the high frequency box. The output from that box would be the usual TIG torch as it's set up currently. I haven't quite thunk up how to manage the argon flow yet, but I thought if worse case I could just use a manual ball valve for the time being to turn it on and off.

I thought since both machine are supposedly constant current machines this might work, but I'm certainly not discounting the possibility there's more to it than that. Any thoughts on the idea or will I do little more than fry my foot pedal and frequency box by doing this?

So you know, I'm just a hobbiest here so there are no crucial welds involved. I know an adjustable squarewave (or beyond) would serve me better, but I'm just was curious what I could get away with given what I have already.

THanks!
Parent - - By DaveBoyer (*****) Date 11-23-2008 06:00
You could use the HF box on the AC welder and turn the argon on with a valve.

DO NOT TRY TO RUN THE OUTPUT THROUGH A FOOT PEDAL. The foot pedal controlls a small ammount of power that regulates the output of Your DC machine.

If the HF unit does not have a contactor You could add one, cheapest way would be to get one from a scrap machine. You could add a gas selonoid valve too.Most likely You will not be able to have remote amperage controll, that depends on how Your AC welder controlls amperage.

If You tell Us what equipment You are using You might get more specific information.
Parent - - By seagull369 (*) Date 11-23-2008 14:45
Hi, thanks so much for replying.

The stick machine I have is the venerable Lincoln AC 225 buzzbox. The high frequency unit is a Miller Snap Start from the early 90's. The DC Tig is a Miller Maxstar 151 220Volt from the same era.

Could you tell me what you mean by a contactor as you mentioned?
Parent - - By sbcmweb (****) Date 11-23-2008 16:06 Edited 11-23-2008 16:23
A contactor is a simple switch used to turn the weld current on & off. The AC 225 does not have one. You can get a contactor, or motor starter just about anywhere you can find a salvage machine or electrical supplies. You would need one with a 115 coil, so you can run it off a wall outlet, or you could run it off the input power to your machine off one of the 220 volt legs.. You would want to use a copper strip formed or cut into a shape that will allow you to connect all three terminals on both sides of the contactor. Then you can connect the coil wires of the contactor to a remote switch to manually turn your weld current on & off.

If you have your foot pedal connected to the HF box, without an output contactor & remote on the AC machine you are wanting to connect it to, all the pedal is going to do is turn the HF & gas on & off. You will have NO amperage control with out an input signal coming from a machine with a remote out & a contactor. I would HIGHLY advise NOT getting inside the HF box to hack attach wires going to a homemade contactor. Like Dave said, you could fry something. That foot control you have runs on a very LOW wattage signal.

One thing I do want to mention is that the Snap Start is a solid state device that uses solid state circuitry, instead of the conventional analog means to create High Frequency. These units were designed to specifically run with the Maxstar units that only produce DC current. You may want to do a little checking into whether AC current may damage it or not. I did not see anything about it in the technical manual, but I would call the factory before hooking it up to your other machine. It will most likely be jumper linked for 230 VAC inside & you would have to re link it to run on 115 if you wanted to plug it into the wall. It will not have but about a 175 amp rating (DC current) @ 100% duty cycle.

Truthfully, with all the messing around & after buying Dinse connectors & rigging up a homemade contactor, you would be better off buying a real TIG machine. I would consider that rather than a bunch of wires, monkeying around & rigging to make it work.

Good luck. S.W.
Parent - - By chris2698 (****) Date 11-23-2008 20:29
I was told you can tig weld aluminum on DC on thick aluminum useing helium but I assume you don't really make pretty dimes it probally just melts it into one big glob. Have yall every tried it??
Parent - By sbcmweb (****) Date 11-23-2008 20:40
I have heard of it being done on DCRP, but I have never tried it or seen it done for that matter.

Of course, there's probably someone on here who has & can give more insight. Allan Aveald, where are you?? :-)

ssbn227 (Henry) probably has & would know. I don't think there's too much of anything he hasn't. :-)

I think this dude with the Maxstar should buy that Syncrowave 250 I have. That would solve all his problems! :-)

S.W.
Parent - - By pipewelder_1999 (****) Date 11-23-2008 21:58
I don't know what you mean by "thick" but I have welded on 1/4" and 5/16" material with helium in the field on electrical enclosures. Also on thinner stuff such as boat pontoons using a thunderbolt 225 and air cooled tig rig.
Parent - - By seagull369 (*) Date 11-24-2008 00:41
Sounds like I should leave well enough alone. Rather not be cursing myself out because I decided to get creative.    

I have a department store special campbell hausfeld MIG I''ll probably give a try. Although I have the liner that handles the AL wire, I don't have a spoolgun (doubt if even one's available for it), so the results should be 'interesting.' Maybe if I keep the torch/ cable straight enuff it'll work out OK.

I appreciate the feedback youve all given.
Parent - By DaveBoyer (*****) Date 11-24-2008 02:40
seagull, everyone here has given You good information. The snap start You have IS NOT the right unit for AC for the reasons AEvald mentioned. A better alternative is a used old TIG capable machine as Steve mentioned. The old Miller 320 & 330 A/BP often go cheap on eBay or craigs list. They are good machines but are big & heavy. If You have the money, the Syncrowave or similar machines offer a newer generation of technology, but they bring more money.
Parent - - By chris2698 (****) Date 11-24-2008 09:28
I was thinking 1 inch thick 1/4 inch not bad so does it lay down a nice weld? I mean it isn't like dimes you see with ac is it more the looks of carbon steel when you lay a weld down??

Chris
Parent - - By pipewelder_1999 (****) Date 11-24-2008 13:50
It does lay down a nice weld. It is much less forgiving for cleanliness. On lap joints for instance you need to cleand not only the surface you are welding but also the underlying surfaces if you want the weld to stay clean. The welds I made were a little smoky around the edges.

I would imagine that thicker material is similar to the issues with AC. Patience waiting for a puddle to start. With DCSP there is more energy used in creating the puddle so I imagine it would be easier to form the puddle at the same amperage however I have not tried this side by side.

On the boat pontoon a friend and I repaired last year I think AC would have helped a great deal with cleanliness. The boat is still floating.
Parent - By chris2698 (****) Date 11-25-2008 19:59
thanks that is really nice to know, I have been told you could weld with DC I just didn't know how good it would be or if you could make a sound weld or what.. if i ever get a piece of aluminum i may have to give it a try.

Thanks,
Chris
Parent - - By aevald (*****) Date 11-24-2008 01:33
Hello seagull369, all of the folks have given you some great answers and precautions. I believe the hi-frequency unit that you have isn't designed for AC anyway, it is likely a start-only, hi-frequency type delivery system. AC welding uses hi-frequency as the carrier to keep the arc going through the 1/2 cycles of the two different DC sides/reverse and straight polarity. The reason for the hi-frequency that is delivered by your snap-start system is only to initiate the arc without touching the tungsten to the work and then it shuts off after a few seconds. If you opt to try to use your AC 225 to tig weld with you will want to find another hi-frequency module that is capable of continuous hi-frequency, likely it will also have the start-only capability as well, there are quite a few out there, I believe Miller, Lincoln, Airco, Midstates, and a few others manufacture them. As Dave mentioned you could use one of these units to provide the hi-frequency required and use an air-cooled torch with a manual gas valve. As far as amperage control goes, you wouldn't be able to have that option with your machine as it isn't a simple matter to make it capable of a control such as that. Instead you would need to set the amperage and try it and adjust it accordingly to make the particular weld you are trying to do, in a sense the same way that scratch start welding is done with DC straight polarity for welding a lot of pipe(only minus the hi-frequency).
     If you decide to try using the DC straight polarity method, you will indeed need to use helium and you will also have to clean your parts "really" well. Even then, you won't end up with the type of aesthetics that can be done using the AC current. You will be able to make a sound weld, however. Just a few more $.02's to consider. Best regards, Allan
Parent - - By sbcmweb (****) Date 11-24-2008 03:25
Didn't even stop to think it was only start HF. got too into the technical info & it blew right by. :-)
Parent - By pypLynr (***) Date 11-24-2008 14:36 Edited 11-24-2008 14:42
Chris2698, I have welded aluminum with DC & helium and it is slick. No globs and if it is thin, you better be movin' . It is a deep penetrating process used by NASA and many aerospace co.'s . It  uses the same 2% tungsten as carbon and S/S and sharpened to a point. It lays a smooth bead, no ripple. These other guys are right also, clean parts weld lots better. We used acetone to clean our parts and pieces before we welded.
Up Topic Welding Industry / General Welding Discussion / Converting stick to tig

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