[cj737]

I tried welding thin to thick today. It's HARD.

Now you’re learning! Understanding how hard it is to get right is a critical part of the learning process.

Hard as in there's a very fine line between getting it to weld, and blowing big holes into it. Unlike TIG you can't really see where the metal's gone (because the slag covers everything).

What I've found works best so far is weld alongside the thin material, and every so often (but not too often), weave into the thin material. Then chip the slag off, and see if it welded, if it did not then another pass and hopefully you do not blow holes into it.

Something to understand, whenever possible orient the thick piece below the thin piece. That way you aren’t fighting gravity with the weld pool falling down. It’s easier to whip up to the thin side, then drop back to thick, linger, then move forward, whip up, drop down, linger, move, etc…

If you must weld thick above thin, it’s critical you point the rod at the thick piece. Don’t point into the joint. Gravity and fluidity will draw the weld pool down, and when you drop and whip up, you should have enough weld left behind to fill the root and the toe. This is the really hard part of stick welding; seeing through the slag and understanding what the puddle is doing.

And you’re right, TIG is much easier to weld when two surface are very different thicknesses. But master this with Stick, and your TIG welds get so much better so much faster. And it’s cheaper because no gas… Skip welding stainless altogether until you’ve got your Stick game on mild steel down. Just pad beads in flat position. Then overlap them. Then work on a fillet or T joint with Stick. Keep at it, 1 month down, only 80 more to go

[taiwanluthiers]

A little context though...

The object I'm welding is actually a weld table I built. I built the weld table using those metal shelves, and a 3mm thick piece of mild steel on top. I've welded some support out of scrap metal under it to stiffen it and not have it sag under weight. I've also welded some steel tubes to it that keys into the very top of the shelf unit so that it does not move around on me.

Turns out the support under the table was kinda coming off because sometimes I had to hammer and pound on it, and so had to weld it back on as well, and I figure I might as well try and practice stick welding thick to thin. I had it laid horizontally. I didn't want to try vertical or anything.

I've tried using a much thinner stick at low amperage (40 amps) and I can weld onto the thin piece, however it doesn't weld to the thicker piece well (it gets cold welds) and it will still blow through the thin piece, so best result has been 3/32" rods at 80 amps, welding alongside the thin piece but pointing the stick down into the thicker piece and weaving very little into the thicker piece. I only welded about an inch, I don't dare to weld more than this because it blows through.

Thanks for the vertical up advise, maybe I should just weld this vertically with the thin piece below and simply weld alongside the thin piece and see if this will work.

[cj737]

Don't do vertical up. From your description, turn the table upside down (top of table on ground) with legs sticking into the air. Then weld the table in a "flat" position. The thinner material being above will easier for you to run the rod along the thick with 80+ amps and the weld pool will fill to the leg. Much easier this way.

I did the same on my fab table: 0.750 thick top welded to 0.187 legs. Stick rod, 3.2mm at 122 amps. I realize my material is much thinker than you're working with, but the orientation and principle is the same. The only hard part for me was turning the table back over onto it's legs after welding it (it weighs about 750kg).

[tweake]

Now you’re learning! Understanding how hard it is to get right is a critical part of the learning process.

[taiwanluthiers]

I'm using 1/8 inch top for the welding table because it's thick enough to have structure but thin enough to not weight half a ton since it must go up 5 sets of stairs. Expense is also another consideration. Steel is cheap but when the top weights more than 100 pound, it adds up very quick.

The bottom stiffening support is thinner, maybe 1/16? Not sure what 1.2mm is in inches. It's thin because I got it for free. It was literally some clothing rack of sort that I found thrown out by a neighbor, and the support is a tube of about 2.5 inch in diameter with perforations to allow you to hang brackets into along the length. I split the tube in half down the middle and welded it to the top to stiffen it.

I always thought stick was supposed to be easy, but not when you're trying to make something that don't look like dog barf. I'm embarrassed to show you my attempt because I know welders can be judgmental as heck and mine don't look good. Like by the time you struck an arc you've burned a 1/2 inch hole into it already.

The top snaps right off the base, and there are 1 inch ID tubes welded to it which keys into the shelving unit. The shelving unit is exactly 1 inch OD so it fits perfectly. I had it fitted up by slipping the tube over then tacking it into place. I then tried to tack it better but I don't dare to full weld it, as I risk burning holes in it (I have already done so in places) and it doesn't need to be strong. The tube is to prevent the top from sliding around.

Most the practice is on the stiffening support. At least stick weld practice is cheap.

I saw a video by someone who builds fences, he said not to use 7018, use 6011 or 6013 because 7018 needs more heat. He said he used backing plates sometimes when he needs to weld something really thick to thin tubes. Saw him weld a 1/4 inch hinge plate to a tube that must have been less than 2mm. He placed a plate, 1/8 inch thick bent to conform to the tube and he had the electrode right on the thick backing plate, then the melted metal just falls right onto the thinner tube.

[cj737]

Stick is not easy. The margin of too long an arc and snuffing the arc because you’re buried is very small. And let’s remember, your machine is NOT specifically designed for Stick welding, you’re hacking it. So expect challenges.

A typical cause of blowing through is too long an arc. With 7018 rods, I literally “just scratch” the material while welding so I am digging in and letting the rod fill behind me. I run hotter than others, but it’s a technique I’ve learned. I can also adjust the arc force (DIG) on my machine to help with the outcome.

6011/6013 are decent rods here for general purpose. They can be run on most inverter machines too that don’t support 6010. You can even run some on AC which can be an advantage. But this all comes down to the machine (you have a TiG box, keep remembering that). Your results will be very different than what you see on YT.

Last bit: when you weld unknown thin metal, expect terrible results. It may be “mild steel” but have large amounts of zinc, galvanizing, manganese, etc. All these little mystery materials affect its weld-ability. Not all steel is steel as the saying goes…

[taiwanluthiers]

If it's painted, it's probably not galvanized. They have a certain look to it, and I won't weld galvanized, the fume is very bad for you.

Does Chrome moly weld any harder than anything else?

It's almost Chinese New Year and I'm going to see how much 7018 rods cost here... I bought most of them from China because it's way cheaper (and before you ask, stuff I buy from shops here are all made in China, but with a 300% markup compared to ordering directly from China), this goes with stick electrodes too, says "made in China" in big letters in fact.

I always thought it is easier to rig TIG for stick than the other way around, and I've seen plenty of examples of people rigging stick to TIG. Stick welder is cheap anyways, and I'll probably get a plasma cutter later on that have built in stick function.

I think the only thing I'm missing is hot start, I have to long arc a little bit when starting, then I can bring the arc back down to start welding. I've only buried a rod when I traveled too slow, otherwise if I'm traveling normally, the rod feeds itself with moderate pressure, I think the flux coating keeps the arc where it needs to be.

The stick welders I've seen only have a dial for current, and nothing else. It probably have a VRD to prevent you from shocking yourself though.

As to why I want a plasma cutter, well let's just say cutting sheet metal with angle grinder is really tedious, and it hurts my ears too (I do wear earplugs). Having a plasma cutter is like Obi Wan thinking how to cut this piece of steel into pieces...

[cj737]

Straight Stick machines do cost less. But using a Stick/TIG hack is unreliable. That’s all.

Long arcing to start is because you’re using the TIG box, again, it’s a workaround for your equipment. Long arcing intentionally with a Stick is used in some circumstances, but it’s a technique not a good “practice”.

Once you have a true Stick box I think you’ll see better results and easier welding. It’s not all about dialing the amperage. The voltage and current control going on under the covers inside the inverter is where the magic happens.

I like plasmas too. I’ve got a very good one. I use it to cut stainless sheets for kitchens so I can very precise, fast, and control the warpage. And they are much quieter!

[taiwanluthiers]

I used to have a Andeli CT520 which is a TIG/Stick/Plasma machine. I loved the plasma feature, even though they can't really cut anything thicker than half inch (it struggles even at that), I don't really encounter anything that thick in my everyday life. Most of it will be sheet metal less than 1/4" thick. Basically it zips through stuff like that like it's not even there. The only downside with that machine is that their TIG is DC only meaning you couldn't weld aluminum. I can't find an AC/DC TIG machine that has plasma built in so I figure I'll just have to save for a plasma/stick later on.

They do have a model with LCD screens and all that that is AC/DC/stick but I didn't get that because it was a lot more expensive. The cheaper model also has stick mode but for some reason mine doesn't. I'm not sure what cost cutting is involved in removing stick function (it's all software anyways). I opted for this model because it has higher welding capacity especially for aluminum, and it has spot welding function for aluminum (for when I want to weld very thin aluminum panels).

The plasma/stick model I'm looking at (in fact all their standalone plasma cutters) have integrated air supply. It means I won't need a separate air compressor.

[taiwanluthiers]

I can't find any 7018 or 7016 locally at all. All they got is 6011, but it's around 15 dollars for a box of 5kg which doesn't seem all that expensive. It's 10 pounds in freedom units.

So I'll have to look online or order from china if I want 7018. In china they're about 30 bucks for 50 pounds in freedom units, but I'm also paying about 10 rmb per kg for shipping by sea. So all in I'm going to pay about 60 bucks for 50 pounds of 7018 if I order from china. That a good deal?

[cj737]

It is. Order it in 3/32 or 2.4mm if they have it

[taiwanluthiers]

7018 only exists in 3/32 or 1/8 as well as 4mm size. Everything thinner is either 6011 or stainless.

[taiwanluthiers]

Can you suggest how I can maintain a straight line absent a guide (such as just laying beads onto a flat piece of metal)? It feels like trying to draw a straight line with a long pencil but holding the far end of the pencil, and it turns out exactly how you'd expect. When welding fillets you can use the joint as a guide, but being able to draw a straight line with stick might be far more useful doing outside corner joints. And keep in mind said "pencil" becomes shorter and shorter as you lay down the bead, so it's actually quite hard to do. Even for TIG it was hard for me to maintain a straight line absent an actual joint to weld.

The problem is once I lay down a bead that isn't straight, that bead just ends up making future beads just as crooked because now that bead becomes a guide.

[cj737]

Welding straight takes practice. Lots of practice. And when you are padding beads on a flat piece of material with no guidelines, it’s darn near impossible (as you’ve correctly discovered).

The workaround is easy though: use a straight edge and a scribe/awl/scratch tool and make scratch lines in the base material. You can make them single lines to follow, or you can make them parallel tracks to declare how wide you want your weld bead to be. Then as you weld, you look and follow the scratch. If you’re welding between two scratch lines to aide you in developing a bead width, watch the weld puddle fill to the edges and move just as fast as necessary to keep the weld within the lines but filled to them.

If you make these parallel sets with space between the tracks, you can come back and weld between your welds to learn to “overlap” and fill. This helps keep the padded beads straight. You can even weld the first layer with stick, clean the welds really well, then weld the next layer with TIG. These pieces become perpetual training material. TIG build-up the edges of the plate for more practice.

Never overlook how many ways you can reuse the same piece to get practice. It makes practice less expensive (not buying as much material). That’s a big part of why we encourage using thicker material for practice when available.

[taiwanluthiers]

I tried to TIG weld over stick beads and they often sputter like crazy and ruin the tungsten. It doesn't like it for some reason. Yes this is after grinding all the beads flat and welding over the cleaned portions. I think it's because of oxides or flux that got into the metal during welding. Not sure what I can do about it Perhaps I can grind one side until clean, use it only for stick, and use the other side for TIG.