The small bits of slag on the surface tend to throw things off a bit.
The red spot is a reflection from a gas jug sitting beside the axle.
Center brake line tab.
All things welding
- Thread starter AirborneTexasRanger
- Start date
The small bits of slag on the surface tend to throw things off a bit.
The red spot is a reflection from a gas jug sitting beside the axle.
Center brake line tab.
OP
Do you ever have issues with heat distortion or warping?
All welds shrink when they cool so they will pull no matter what. I just do a tight fit up where it matters and work around the rest. That truss you see bolted down has lots of tendency to move around. The truss that it comes with is 1" taller with a bent double bend tongue with the 4 front bolts in it. The bends start just behind the bolts, step up 1" and then back, with a down flange at the rear. Older version-
We lop that off level with the top of the diff casting or straight back from the bolt platform which leaves the two side legs with the 3 bolts at the base. Then we cut out that flat section the uppers weld onto as a platform and weld that to the two truss legs. I know it is going to pull and move so I tack it with the legs biased as far to the outside as possible so when it pulls, it will move them back to centerish. My goal is to not have to monkey with the bolts and a drift to remove and replace the truss.
I select which welds to do first and do the ones that will lock it down with the least amount of movement before I weld the ones with a higher tendency for displacement.
I'd love to understand this better. When I welded a receiver tube into a bumper it turned into a banana and I had to weld additional, otherwise unneeded beads in strategic locations to straighten out (I realize the same could have been accomplished with an oxy fuel torch, but some extra grinding time and a bit of wire was cheaper).
Seems like people around here weld on their axles with impunity, and I don't know if techniques are enough to prevent it or if they just don't care. I talked to an axle guy once that said every axle that's ever been welded on can benefit from straightening and that's been in my head ever since. I have some lower control arm bracket skids I'm waiting to install until I get a MIG so I can more easily do short beads and let it cool, rather than self shield and have to deal with a bunch of slag.
How do you handle welding brackets to tubes? Do you have to heat the opposite side of the tube to straighten it back out, or do you do anything special to keep it from warping to begin with?
I ignore it. I've never had an issue with the welds pulling it enough to matter. But, I get that from trying to straighten a bent front axle that I tagged a rock with. I tried heating and quenching first with almost no movement, so I started running beads that were pretty hot. That also had a very small effect. Only when I coupled that with a jack and chain through the inner Cs did I get enough stuff to get it back to straight. The downside to all of that is I now had a terrible weak spot with a giant HAZ. The next time I tagged a rock at speed, it cracked almost in half. I should have done a slice, bent it back, built a large curved patch that went out onto good tube with a large curved end and welded that over the straightened bend.
That said, I do at times run a chain and jack to the ends if I have a lot of weld in the middle area. Slight bit of preload to keep it from bowing up which I assume works since there have been no bowed axles after welding that way.
I see a lot of advice to "stitch, cool, stitch, cool". I tend to ignore that as well since I know that each inch of weld pulls the same amount given the same penetration. The weld behind you is cooling and pulling as you weld so I just make sure to put roughly the same amount of weld on something like the Savvy front mid arm stiffener. I don't weld it continuous and I swap sides with the welds. Some on the front, some on the back until done.
OP
When you heat up the metal the atoms become excited & expand. This puts stress on the cooler parts of the steel. As the heated area begins to cool, the stressed cold areas will push back forcing the heated area to "shrink". All of this depends on geometry of the part, the specific alloy of the steel, the amount of heat input & for how long. Also, heated steel will absorb more carbon & hydrogen which makes it harder but also more brittle & prone to cracking. This discussion could go really deep into the weeds with chemistry & physics talking about phases & crystal structures but that's boring.
The ideal way to minimize warping would be to preheat the steel prior to welding to around 400° which can be done with a small bottle of MAPP gas. Then slowing the cooling process after welding by wrapping it in a fireproof blanket.
Another way is like @mrblaine said & carefully plan out your weld sequence. You can also grab some scrap and tack weld a brace or a strong back in areas where you think it will warp & can be removed after the weld cools. Clamps can help to an extent but they will be under stress making them more difficult to remove. If I'm welding something that requires specific tolerances then I try to weld it in place if at all possible without causing additional damage to paint, fluids, grease, rubber, etc. Keep in mind I'm familiar with metallurgy but don't have first hand experience welding on an axle so I'd defer to @mrblaine expertise for that specific project.
The science part is the part I actually understand....it's where it comes to specific practice (such as an axle tube) where I don't have the experience to know when it matters, how much I can do without jackstands and a chain or straightening afterward, as Blaine alluded to, how much difference does stitching really make...
I studied up on it quite a bit when I needed to fix my bumper and got a pretty good grasp on at least predicting the direction something will warp...less so on the magnitude...
My previous place of employment was at one point the largest volume producer of ASME pressure vessels west of the Mississippi - shell and tube refrigerant to water heat exchangers, as well as refrigerant oil separators for large commercial and industrial chillers.
When welding the plate (called a "tube sheet" because it's full of holes that support the ends of the heat exchanger tubes) onto the shell, the plate would have a massive, several inches thick, chunk of steel bolted to it to control the rates of heating and cooling as well as keep the plate perfectly flat. It had to be perfect because the outside of it was a gasketed bolt-on cap that also had to retain pressure. The weld was continuous. I don't know if there was any preheating.
For scale, that water pipe connection in the cap is probably for 6" pipe.
All the long welds are done by robots. That's not within the scope of this thread but I find that intriguing, since a robot can't read a puddle. The guy that sat across the aisle from me originally hired on as a welding engineer and did that stuff. I need to have him tell me about it next time I'm in town.
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You have to watch the puddle because you aren't a robot so you need something that tells you that the feed rate of your electrode, build height, and placement are correct. The robot doesn't need that since it is able to keep all of that correct and consistent much better than you.
I do know that if I was deaf, my welds would be a lot worse since the buzz changes to the pop and spit that tells me to speed back up and stop trying to make it a "really good" weld which is when I get spatter.
And as you've seen me say, I tend to ignore it so I'm not much of an expert at that stuff at all.
A buddy of mine built a vise stand for a monster Wilton vise. He is also Mr. Overkill so he used a piece of 5" x 1/2" wall tube welded down to a 36" diameter circle of 1" thick steel plate. He ran several TIG passes around the tube until he had about 1.5" across the face of the weld. When he was done, the outer edge of the circle was up off of the floor by almost 3/4". He hauled it off to some place with a giant press and got it back to flat.
MudMirthMaven
New Member
OP
The weld puddle has been mentioned a lot on this thread, but I wanted to discuss what this is. Understanding this, I think, made me better at laying down solid welds even though they aren't all "pretty". I'll focus on wire fed/short circuit welding since this is what the majority of us use, but the principle is the same for the majority of arc welding processes. When the arc is initially struck it starts to heat up the base metal to a molten state creating a dished puddle. At the same time, it is melting the wire into little droplets that fall into the puddle & promote fusion. If flux is involved then it is also being melted and creating a gas pocket around the arc & weld puddle.
Essentially what dictates the shape/size of the puddle are the volts & amps. Higher voltage, sometimes called "heat" will make the puddle wider & shallower. I'd like to add that if the end of your wire gets farther away from the puddle then the voltage will increase. You won't be welding at the settings you think you have; the metal will get hotter & more fluid making it harder to control. On the other hand, if you increase your amps also called current or wire feed speed (WFS) the weld will penetrate deeper. Also, the increased wire going into the weld puddle will cool it down. I suggest finding some scrap to help you find the balance between amps & volts that works best for you.
When you look at the puddle you want to make sure that it is slightly dished in front & humped up at the back. You should also see the edges of the puddle smoothly transitioning to the base metal along the sides. At the leading edge of the puddle you should see both sides of the base metal melting into the puddle equally. Sometimes you will see a small dot floating around in the middle. This is the impurities floating to the surface & burning off which is normal. If it looks like its boiling or spitting out globs of molten metal then stop
Common puddle troubleshooting:
Essentially what dictates the shape/size of the puddle are the volts & amps. Higher voltage, sometimes called "heat" will make the puddle wider & shallower. I'd like to add that if the end of your wire gets farther away from the puddle then the voltage will increase. You won't be welding at the settings you think you have; the metal will get hotter & more fluid making it harder to control. On the other hand, if you increase your amps also called current or wire feed speed (WFS) the weld will penetrate deeper. Also, the increased wire going into the weld puddle will cool it down. I suggest finding some scrap to help you find the balance between amps & volts that works best for you.
When you look at the puddle you want to make sure that it is slightly dished in front & humped up at the back. You should also see the edges of the puddle smoothly transitioning to the base metal along the sides. At the leading edge of the puddle you should see both sides of the base metal melting into the puddle equally. Sometimes you will see a small dot floating around in the middle. This is the impurities floating to the surface & burning off which is normal. If it looks like its boiling or spitting out globs of molten metal then stop
Common puddle troubleshooting:
- If the wire feels like it is pushing you back: WFS too high or Voltage too low
- If small droplets are forming on the end of the wire & you hear a hissing sound: WFS too low or Voltage too high
- If the arc seems erratic: Base metal is not clean enough or your Ground Clamp is not connected to clean metal
- If it looks like the weld puddle is covering the end of your wire (typically occurs welding vertically downward): You’re moving too slow or your WFS is a little high
- If the puddle is not filling up as you move: You’re moving too fast or your WFS is a little low
OP
I could probably scour my books/notes for some graphics, but honestly the best arc shots I've seen are of Jody Collier's videos on you tube Welding Tips and Tricks.
https://youtube.com/playlist?list=PLp0pALmMwc6v2ScmEGbvNSpNKcYA8GiGA&si=7CwkhEy34kYyjkHf
https://youtube.com/playlist?list=PLp0pALmMwc6v0rpE0ekf8xDsn0IzTr6-E&si=jOWivu3Gk148LlyR
https://youtube.com/playlist?list=PLp0pALmMwc6spNGCkzQT9S3Tzim7_OwKa&si=bs_7-ssFQBoZityh
OP
OP
TLDR: This gets a bit technical, but the gist of it is that you should make your tacks & welds accurate & intentional.
My #1 pet peeve of welders is when they mimic what they see on TV. I can’t tell you how many times I’ve seen a welder tack something with no gear & just their eyes closed only to put the tack in the wrong spot, make a tack that’s too big or too small, or the part is crooked because they couldn’t see what they’re doing. The funny thing is that after they tack everything up then they go put their gear on anyway so they can weld. A lot of people are probably thinking what’s the big deal, it’s just a tack. Well, aside from all the safety issues, you’re causing more harm than you may think.
When you make a tack weld, you’re causing the steel to heat up & cool off very quickly. That part of the steel will become brittle which is why most welders will weld over the tacks. Continuous welding introduces enough heat so that the temperature changes are more gradual & introduce less stress. Also, if you arc strike the steel, basically a split-second arc that was most likely unintentional, there will be micro cracking. This can be easily fixed with a grinder & flap disc. Multiple heat cycles can cause the metal to become brittle
If the tacks are too small then they won’t hold very well. If you put a weak tack on one end then start to weld on the other end, odds are the tack will break & your part will move. On the other hand, if the tack is too big then you are introducing unnecessary amounts of heat into the steel. Also, these tend to pull or warp the steel more because the heat is focused on one small spot. When you try to weld over a big booger of a tack its not going allow adequate penetration of the weld which creates a weak spot.
What about when you stop or start a weld? I’m glad I asked. Whenever you first strike an arc to weld you shouldn’t start moving right away. I like to make a small circle which allows the metal to heat up relieving any stress from initiating the arc. I do the same thing when I stop the weld. The extra heat will help the metal cool at a more controlled rate.
My #1 pet peeve of welders is when they mimic what they see on TV. I can’t tell you how many times I’ve seen a welder tack something with no gear & just their eyes closed only to put the tack in the wrong spot, make a tack that’s too big or too small, or the part is crooked because they couldn’t see what they’re doing. The funny thing is that after they tack everything up then they go put their gear on anyway so they can weld. A lot of people are probably thinking what’s the big deal, it’s just a tack. Well, aside from all the safety issues, you’re causing more harm than you may think.
When you make a tack weld, you’re causing the steel to heat up & cool off very quickly. That part of the steel will become brittle which is why most welders will weld over the tacks. Continuous welding introduces enough heat so that the temperature changes are more gradual & introduce less stress. Also, if you arc strike the steel, basically a split-second arc that was most likely unintentional, there will be micro cracking. This can be easily fixed with a grinder & flap disc. Multiple heat cycles can cause the metal to become brittle
If the tacks are too small then they won’t hold very well. If you put a weak tack on one end then start to weld on the other end, odds are the tack will break & your part will move. On the other hand, if the tack is too big then you are introducing unnecessary amounts of heat into the steel. Also, these tend to pull or warp the steel more because the heat is focused on one small spot. When you try to weld over a big booger of a tack its not going allow adequate penetration of the weld which creates a weak spot.
What about when you stop or start a weld? I’m glad I asked. Whenever you first strike an arc to weld you shouldn’t start moving right away. I like to make a small circle which allows the metal to heat up relieving any stress from initiating the arc. I do the same thing when I stop the weld. The extra heat will help the metal cool at a more controlled rate.
question: I've had a tack or 2 break while welding, would it make sense to turn the wire feed down for the tack vs the normal weld? (I'm thinking a little more heat/penetration without ta big booger)
OP
That could work. Depending on the thickness I will sometimes ocellate the gun to get good fusion on both pieces of metal with thicker material. Mostly because I'm too lazy to walk over & adjust the settings.
Edit: Be careful not to turn the WFS down too much or you could end up melting the edges away instead of joining them together.
I bought a new hood as I really struggled with my old cheap one. Settled on a Lincoln 1740. All I can say is holy shit what a difference! I can see EVERYTHING now where I couldn't before. I opted to get some cheaters for it too and it really helps with my vision. Very first weld with it as a test to see.
