Rate my rookie welds, and a chance to say "penetration" - JeepForum.com
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post #1 of 18 Old 05-23-2020, 03:14 PM Thread Starter
hbar
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Rate my rookie welds, and a chance to say "penetration"

Since inspiration & excess free time have coincided, I figured I should practice some welding. The spots seem ok from the top, if a little bit on the high side. But what I'm really wondering is what should the back side look like? How much weld should I be seeing on the other side, and does this look ok? If not, can you diagnose what I need to do differently/better?

Specs: Lincoln Handy Mig, 0.030 wire, voltage is Low-2, speed is about 3.5...seems to be the sweet spot for this.

EDIT: having trouble uploading my images....





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post #2 of 18 Old 05-23-2020, 07:05 PM
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That's because you tried to post a link as a picture.

Fixed it for you, I hope.


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post #3 of 18 Old 05-23-2020, 07:07 PM Thread Starter
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Well I first did it as part of the upload bit, but that didn't seem to work. And since I last posted, apparently photobucket has decided to suck out loud....it's been too long I guess.
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post #4 of 18 Old 05-23-2020, 08:55 PM
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Not very much penetration. Ideally, you want to the gap to be fused together on the back side of the weld. Usually with sheet metal, you would grind the front weld off and without good penetration, you will have no weld left. You could use 0.023 as some people like it better for sheet metal. I have a roll but I have never bothered to take my 12 pound roll of .030 off my welder when I need to weld a little sheet metal. You can also try using a piece of copper as a backer. You can really turn out the heat when you do that and not burn a hole. A flattened piece of 3/4" copper water pipe makes a great backer.


Run it hotter and get on it and then get off quick


Gets interesting at 24:10

Good luck
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post #5 of 18 Old 05-24-2020, 06:56 AM
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A few ideas on welding. Every time you make a weld like you have cut the oxidized wire off, provided you're using gas as a shield. You'll find the arc much easier to strike as it takes less time and it's a cleaner weld. Also a 1/32 gap between the metal is better in my opinion that no gap. By the time you grind the weld flat there's not much of it left.
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post #6 of 18 Old 05-24-2020, 11:03 AM
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Just like the guy says in the second video at 27:25. Actually Jim was the person who first told me about snipping off the end of the wire when welding sheetmetal. It works great. Thanks Jim.

Unless your welder has a spot welding setting like some of the newer digital welders, running it a little hotter really improves the results. The settings for 18 gauge metal (for example) are really for putting down a continuous weld bead and not a spot weld. When you start a weld, it has to get up to temperature and not burn through the metal after the weld bead starts. When you spot with those suggested settings, it may not fully melt the wire into the weld because the metal has not come up to the required temperature and the spot just builds up on the surface. The copper backer can really help the home hobbyist get really good results with complete fusion without the weld puddle falling through the sheet metal.

There is also some debate as to if the patch should fit tightly in the hole you are filling or if it should have a gap. Some say tightly, but others say that as the patch heat up and the surrounding metal heats up, they both expand and if they have no gap, it will cause the area to distort. I think leaving a small gap like Jim said is probably best. It is also easier to make a patch with a small gap rather than carefully grinding a patch that fits perfectly. It you weld the patch with the small gap properly, you will never know there was a gap there.

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Originally Posted by Jim1611 View Post
A few ideas on welding. Every time you make a weld like you have cut the oxidized wire off, provided you're using gas as a shield. You'll find the arc much easier to strike as it takes less time and it's a cleaner weld. Also a 1/32 gap between the metal is better in my opinion that no gap. By the time you grind the weld flat there's not much of it left.
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post #7 of 18 Old 05-24-2020, 05:54 PM Thread Starter
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Quote:
Originally Posted by StoneTower View Post
Just like the guy says in the second video at 27:25. Actually Jim was the person who first told me about snipping off the end of the wire when welding sheetmetal. It works great. Thanks Jim.
I had already been trimming off the wire most every time to get the right-ish stickout.

Quote:
Originally Posted by StoneTower View Post
Unless your welder has a spot welding setting like some of the newer digital welders, running it a little hotter really improves the results. The settings for 18 gauge metal (for example) are really for putting down a continuous weld bead and not a spot weld. When you start a weld, it has to get up to temperature and not burn through the metal after the weld bead starts. When you spot with those suggested settings, it may not fully melt the wire into the weld because the metal has not come up to the required temperature and the spot just builds up on the surface. The copper backer can really help the home hobbyist get really good results with complete fusion without the weld puddle falling through the sheet metal.
I only have 4 heat settings (hi/low, & 1/2) so I maxed it and I did get it looking better on the back side. I realize I'm new at it, but I've watched plenty of YouTubes of other amateurs and for your basic butt joint patch nobody uses a copper backer, so I'm just trying to mimic them. I'm on a harbor freight welding table, so the table surface should be drawing away a good amount of heat, I would think.

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There is also some debate as to if the patch should fit tightly in the hole you are filling or if it should have a gap. Some say tightly, but others say that as the patch heat up and the surrounding metal heats up, they both expand and if they have no gap, it will cause the area to distort. I think leaving a small gap like Jim said is probably best. It is also easier to make a patch with a small gap rather than carefully grinding a patch that fits perfectly. It you weld the patch with the small gap properly, you will never know there was a gap there.
When I set that up I even thought to myself, "man, you should probably put a gap here because even if this is ideal, you're never going to fit a patch this perfectly so why practice this way?"
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post #8 of 18 Old 05-24-2020, 07:17 PM
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Most of the time when you weld sheet metal it is on a car. You cannot get your fender flat on a HF welding table. The backer does more than just suck the heat out of the weld. You can actually put a copper backer behind a small hole and weld on the edge of the hole and fill the hole up with weld metal. If you did that with a piece of steel, you would spot weld your work piece to the steel backer. Steel MIG weld will not stick to the copper so it makes a nice flat back to the weld. You can really turn up the heat. Try it. It does not cost much to smash a 4" piece of 3/4" copper pipe. Harbor Freight used to sell a "welding spoon: which was a curved piece of copper with a handle on it.

http://www.weldingtipsandtricks.com/...ing-spoon.html

Quote:
Originally Posted by hbar View Post
I only have 4 heat settings (hi/low, & 1/2) so I maxed it and I did get it looking better on the back side. I realize I'm new at it, but I've watched plenty of YouTubes of other amateurs and for your basic butt joint patch nobody uses a copper backer, so I'm just trying to mimic them. I'm on a harbor freight welding table, so the table surface should be drawing away a good amount of heat, I would think.
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post #9 of 18 Old 05-24-2020, 08:22 PM Thread Starter
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Quote:
Originally Posted by StoneTower View Post
Most of the time when you weld sheet metal it is on a car. You cannot get your fender flat on a HF welding table. The backer does more than just suck the heat out of the weld. You can actually put a copper backer behind a small hole and weld on the edge of the hole and fill the hole up with weld metal. If you did that with a piece of steel, you would spot weld your work piece to the steel backer. Steel MIG weld will not stick to the copper so it makes a nice flat back to the weld. You can really turn up the heat. Try it. It does not cost much to smash a 4" piece of 3/4" copper pipe. Harbor Freight used to sell a "welding spoon: which was a curved piece of copper with a handle on it.

http://www.weldingtipsandtricks.com/...ing-spoon.html
Sorry, I knew most of that from what I've watched/done up to this point; I don't expect to do much actual repairing on the welding table, I was just saying that I would have expected it to function similar to a copper backer in terms of drawing off heat. I have a length of copper pipe, flattening it is on my to-do list already.
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post #10 of 18 Old 05-24-2020, 08:46 PM
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hello

if you are leaving a small gap (thickness of the wire) then use that setting. if you are going to have the metal touching togethor you will need to bring the heat up some. if your metal is 20ga then try the setting for 18ga. i would practice with some copper as a backing and some without. you cant always get a backer so its good to know how to do without. i actually split a piece of copper then flatten it. it will work harden when working it. take a small torch and heat it up to temper it to soften it. the main reason you want the copper is to keep the o2 off the back side. we normally use a back gas but if cant i have used copper alot. depending on what you are doing. if the copper if softened its easier to get to fit tight against what you are welding. welding is practice,practice and more practice. once you think you have a good joint cut it in half where you can see both pieces then inspect it.

oldschool
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post #11 of 18 Old 05-25-2020, 04:57 AM
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Im more of a lurker here, but have some experience in this area, thought Id chime in here.

Another old school body welding tip:

Tap out the welds. As you are tacking, assuming you are tack welding, in multiple rounds, tap each one out. Start with a slight gap. Make your tacks. Then back them up with a dolly, bucking bar, something with some mass to it, and tap the welds with a hammer. Dont hammer them, or distort, but enough to relieve the welds. Youll see the gap reappear, up to the point you have enough tacks/welds it wont move anymore.

As above, all good advice, backers, inert gas to keep the oxygen away, gap vs no gap, there are multiple methods, each one for best for the job at hand, each area you do will be slightly different. Ie Butt welding a 24 long piece of 22g will be different then welding 6 around a reinforced curved area of 14g. Best advice I can give, is go to the junk yard, buy some old fenders, cut them up how ever you want. Make patches. Weld them back together. Practice. Practice. And prep. A good weld will come from a good prep. If you can, Try different disciplines too, gas, tig, etc.
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post #12 of 18 Old 05-25-2020, 11:44 AM
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As you look at the welds from the back side in the middle group the first (top) weld shows a little penetration with added weld metal. This is what you want consistently.

The third weld in the middle group (bottom) shows a little suck back which is what you don't want. Despite sheet metal being thin and easily getting holes in it you need to be aggressive when welding. It really needs to be pushed in from the top (front) so you don't have that void in the bottom (back). That being said difficult to be perfect all the time especially at first. The more you do it the better you will get at it.

So on almost all of the welds I am not seeing enough penetration, except for the one I mentioned first where you can see just a little on back side, which is just what I am looking for. I would say do everything the same except just a skosh more heat or a skosh less wire speed when making the welds. Possibly just a skosh longer on each weld as long as top appearance is not too heavy but you are close, try not to alter too much and fine tune.

Sheet metal welding is not my particular area of expertise, I have way more time with heavier structural welding and pipe/tube but there are several things in welding that are more or less in common and suck back is not good and should be avoided if possible.

There are many different codes for welding different applications but they frequently have similar restrictions on discontinuities. A discontinuity is not a rejection automatically, as long as it is within tolerance but should be avoided. I like to think that acceptable discontinuities are a sign that it could be better and would encourage the welder to tighten it up a little, as an inspector I may accept a weld that meets the requirements for an acceptable discontinuity but would ask the welder to try to fine tune a little more for more acceptable/better looking welds.
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post #13 of 18 Old 05-25-2020, 12:05 PM
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Just going by the code if the weld is acceptable even with discontinuities it is good. In a production welding environment it is common to require a little more than what the code does, in other words you are allowed a certain amount of visible porosity in a code weld but if I have to take out a measuring device and make a judgment that someone will later notice and question... it doesn't take as long to just have the welder fix the visible porosity.

The codes are minimum requirements and you can get something to work even if it is not "to code" but you should always strive for no visible discontinuities. No undercut, no arc strikes out of the weld zone(this is the one discontinuity all the codes share and is rejectable), no suck back on the back side. You can absolutely grind and machine the surface of a weld but it should look good (and be inspected by you at least) before that happens.
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post #14 of 18 Old 05-25-2020, 01:14 PM
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I thought I’d follow up with a few pictures to show you. Not a jeep unfortunately...
pickup truck I’m rebuilding right now.
These are replacing the lower rear box fenders with patch panels.
The only difference is, I’m tig welding everything. Different process, but same principles and goals. It’s all 22 or 20g that is showed here.

They are not in order, sorry just the way it turned out. I don’t know how to re order them.

One other suggestion. You were asking about how big your welds were. I understand that. You want it to be pretty. We all do. But, sometimes, it doesn’t work out that way with this thin stuff. Or big stuff either, for that matter.... If you are comparing it to laying dimes on 1/4” steel, don’t. That will all come later. Those will be easier to you after learning on thin gauge. I’d rather have a great big ugly strong weld, than some pretty, weak, and useless welding I’ve seen any day. Edit: the other thing to keep in mind, lots of this type of body work on cars, jeeps, what have you, is on old rusty metal. Yes, in theory you’ve cut away all that old rust, but sometimes, in my experience, you can’t get it all without throwing it all out. Those rusty areas do not provide you good welding material, and it can get a little ugly. Such as on this. There was still some rusting areas on this, not much I could do about it other than scrap the whole box. It’s just full of it everywhere. So, you do the best you can.

Forget about pretty for now. Concentrate on strength. Good penetration, no warping, and strong. You can cut your welds, or put the piece in a vice and see if you can brake it by bending it. Once you have welded, good welds, you can smooth them out as you wish to pretty them up.

On one picture here you will see where I have tacked it along the straight stretch, once that was done, I went over them with a light tapping to relieve, then the gap reappeared, I had not done that yet in this picture. Around the tail light you will see I had it fitted tight, I wanted it fit well around there, and I wasn’t worried about it puckering, strong area with the curve. In fact on that straight stretch, looking at the pic, I probably should have started with a bit more gap.

One other thing I like to do, once I’ve dressed the welds, is to use a little primer. Use the cheapest stuff, it all coming back off for body work. The primer will really accentuate any issues, and you can dress them before you get to using any filler or anything on it. The primer is also good to cover up the metal so it won’t rust until you get to the body work, which is what this primer is here for.

Anyway, I’m just a guy who picked up welding years ago, and has picked away at it for some time now, picking up little things here and there from other guys, and learned what I can along the way, usually the hard way! I thought a few of these might help you. I has some good welder along the years help me out time to time. Good luck, have fun. Don’t weld fuel tanks, and don’t get your current crossing a vehicle through the fuel system, it will ruin your whole day.
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2B6F43AB-C73F-4938-8EE5-BB27280DE920.jpg   CC6AA51B-FE02-4660-BA0E-D22197BCCF36.jpg  

Last edited by GR-CJ; 05-25-2020 at 01:37 PM.
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post #15 of 18 Old 05-25-2020, 04:23 PM Thread Starter
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I'm not super concerned with pretty at the moment, I want them to be good. And you rarely see people showing the backside of their welds (especially when it's a body panel they just patched in). I started to go hotter, and I may slow the speed down a bit as you suggested, and and spend a hair longer. I'll give it another shot tonight and post back.

On a related note, say you have a patch that is say 5" square. I get that you need to tack it in and just keep moving around tacking to distribute the heat until basically you've got the whole thing welded. Roughly how long should that take? I mean, I could probably tack the whole permitter of something like that in a relatively short amount of time (not rushing), but how much time do you actually have to allow for cooling? That long run you have on the inside of that panel....how long did it take to complete that? I assume at no point did you actually ever lay a bead down?

These sorts of questions remind me of my dad teaching me how to drive, and him telling me about when he was learning how to drive and he would ask really technical questions that nobody even thinks about, like how many turns of the steering wheel does it take to go around a corner? Great question. Nobody knows the answer, because in practice it doesn't matter. That's where I'm at with welding.
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