New tig welder??????

[schellmaple]

I need to buy a tig welder to weld my SS 304 2B pans. I'm looking at a Lincoln V-155 with the TIG torch. I have seen alot of cheaper welder on EBAY and I was wondering if I should stay with a brand name or do you think I could get away with a cheaper model?

[Mark]

Check to see how low a current it will start at. I have a Lincolin 185 with Micro Start that I like and I think it goes down to 5 amps. I think the new model is a Lincolin 225.

[schellmaple]

The book states that the V-155 will go to 5 amps. From what I have read I need to be at 20-25 amps to weld the 20 gauge SS.

[Mark]

The book states that the V-155 will go to 5 amps. From what I have read I need to be at 20-25 amps to weld the 20 gauge SS.

I had a Miller that went down to 1 amp but was hard to start without burning a hole because you could never start at a low current. The Lincoln with the Micro Start works real nice.

I have built a few pans with flues before and it is a lot of work. Also I am using a 6500 gallon tank that I built. After spending a lot of time learning how to do a good job I appreciate the quality of factory equipment. Welding is not that hard but the evaporator companies have a big advantage in cutting and bending for a perfect fit that is required to do a good job of welding. I buy everything now, the time saved is put into the woods instead and I get a much better return.

[schellmaple]

Well I guess I,m a gluten for punishment, I went and ordered the Lincoln 155 with the tig package. I have done some tig welding in the past but I'm figuring I will need some practice.

Mark.... Did you have any problem with sugaring on the back side of your welds? And if you did what did you do to prevent it? I'm using 20ga. type 304b SS.

[Mogli]

You can prevent sugaring by either having the perfect weld temp/penetration or back gassing the weld seam. It is really hard to do the first in thin stainless so I would suggest back gassing.

[Mark]

Well I guess I,m a gluten for punishment, I went and ordered the Lincoln 155 with the tig package. I have done some tig welding in the past but I'm figuring I will need some practice.

Mark.... Did you have any problem with sugaring on the back side of your welds? And if you did what did you do to prevent it? I'm using 20ga. type 304b SS.

I used aluminum bars and clamps on the corners, you have to have a perfect fit. You just want to fuse the metal without filler. If you use a filler rod it can go bad fast.
On the inside aluminum heat sink I filed off the edge and drilled a hole to it so I could put argon on the back side. If it is in a hard spot I use Solar Flux.

At the factory they don't back gas. Their fit is perfect and only requires a small quick weld and it is hardly noticed on the back.

[Mogli]

Whats the isssue with using rod. I have welded a fair amount of stainless, and I agree fusing a near perfect fit is easier, but if 316ss rod is used I dont usually see a sugaring issue unless too much heat is used.


I used aluminum bars and clamps on the corners, you have to have a perfect fit. You just want to fuse the metal without filler. If you use a filler rod it can go bad fast.
On the inside aluminum heat sink I filed off the edge and drilled a hole to it so I could put argon on the back side. If it is in a hard spot I use Solar Flux.

At the factory they don't back gas. Their fit is perfect and only requires a small quick weld and it is hardly noticed on the back.

[Mark]

Whats the isssue with using rod. I have welded a fair amount of stainless, and I agree fusing a near perfect fit is easier, but if 316ss rod is used I dont usually see a sugaring issue unless too much heat is used.

I have not much luck with filler rod on 22 gauge stainless, maybe I am just too picky with my welds. The smallest rod I could get locally was 1/16 but have not tried anything smaller.

On a corner I try to have one side a sheet thickness long to give me a little metal to work with.

I was welding some surgical tools for a locale machine shop and I had them do the same. When they machined the pieces they left a tiny ridge in the area to be welded so I could do a pretty job. Filler rod would have worked but would not have looked perfect.

I also did some parts for a machine that was for taking air samples. The part was round so I ended up making a motorized table to turn the part so I could do it in one weld. I was told they were going to be gold plated after being welded, wish I got to see one plated.

The only way to learn is to start welding. Make something small first before jumping into making a pan, stainless is expensive. The hardest part of making a 5x10 flue pan was turning it over. You have hundreds of pounds of stainless and not much strength.

[schellmaple]

Thanks guys for the help. I fired up the welder on some practice stuff and things are looking a little grim. The problem I'm having is on a lap joint, the top piece wants to melt away before it will melt with the bottom piece. This is with no filler rod. I would think you should be able to melt the two lap joints of ss together with ease. Well, I guess I was wrong or I'm missing something.

[Mark]

Lap seams are the hardest to weld, do you have it clamped tight with absolutely no gap? Heat sink on the back and one on each side of the weld? Tack weld every couple inches so it won't walk on you.
Where on the pan would you have a lap seam? One solution is to turn up each edge so you can fuse the two edges together.

[Big_Eddy]

Cut about 40 small strips 1" x 4" of your material of choice and practice practice, practice. Build a staircase and keep adding a new piece to practice your 90 degree corners. I hope you got a pedal with the TIG. As soon as you start moving you need to ramp down the power. If the puddle gets too big - stop then start again - don't try to continue as that will just make things worse. It's easier to go back and fix a tiny pinhole than it is to fix a blow-through.

For filler - buy a roll of 0.024" stainless MIG wire. It takes a lot less energy to melt than 1/16" rod.

Not sure why you would want a lap seam. Go with butt joints and 90 degree corners. Fitup is important, clamping is important and back-gassing is a must on your actual product. (But skip it during practice)

If you really do need a lap joint - focus all the energy on the lower piece and wash the puddle to the upper piece - that should reduce the burn back. Tack 1-2" apart then use a ball-pein hammer to close up any gaps between the tacks and fill in the middle.

Thin stainless is fun. It burns away, warps, and sugars on the backside. After you've used up your 40 coupons, you should be about ready to give something important a try.

[schellmaple]

I was doing the lap joint because I thought it would be easier than the but weld, just melt them together. I'm starting to see that this is not the case. I don't have a foot pedal with this welder and I know this is part of my problem. I think I'm going back to my Lincoln dealer and see what their tech guys have to say. I want to thank you guys for the help. I was talking to a guy at work that tig welds full time on .06" metal and he said hot and fast, do you guys agree with this?

[Big_Eddy]

I have a thumb control instead of a foot pedal. Foot pedal would be easier but you use what you have. You do need to decrease the energy as you get moving. That Lincoln should support a pedal - but expect them to ding you for it.

I agree - hot and fast is better than cool and slow. You want to form the puddle, let it flow together and move away fast so it can cool. If you take your time the heat affected zone increases and then when the puddle forms it's too big and you end up with a hole.