Proper technique for welding round tube

[Racer81]

I have been playing with some round tubing and I am wondering what is the proper technique for welding either a butt joint where the tube is welded to a flat piece of plate, or when welding round tube to round tube after being properly notched. Is it best to weld on contiguous weld, or can the joint be welded in sections as you work around the tube? If done in sections, how many sections and would you weld opposing sides to keep the tubes aligned?

Thanks

Greg

[H80N]

Hope this FAA manual helps

https://www.faa.gov/regulations_poli...a/ama_Ch05.pdf



TIG...MIG...or... GAS.....??????????????

[Racer81]

Mig welder, welding steel tube (DOM or ERW)

[H80N]

Mig welder, welding steel tube (DOM or ERW)

and..??? more detail....???

[Racer81]

tube is 1.50" OD with either a .095 or .120 wall, using a Millermatic 212 with 75/25 gas mix, .035 wire. right now just cutting material and welding together, trying to get a feel for the material and how to work the gun around the material. Idea is to be able to weld roll cages at some time in the future.

[ryanjones2150]

Not much chance of welding it without repositioning unless you're some sort of magician or have it chucked up in a welding lathe. You weld as much as you can, re-position and weld some more. Continue as required. Welding small diameter tubing is about the hardest way to learn to weld. I tig weld all of my roll cage work, mostly because I want to see the root fuse. What kind of cars are you working on?

[Ltbadd]

Your going to weld in sections, impossible to do otherwise, how many sections depends on the skill level and welding conditions, such as comfortable in a shop to in the field under less then ideal conditions.

If you're butt welding 2 tubes and are able to rotate then one weld.

Ryan you answered while I was typing

[Racer81]

Working on production based sports cars, Mazda MX-5's, rules require 1.50" OD DOM tubing, with .095 wall, we had a stick of the tube in the shop so, I have started to play with it, right now we farm out all final welding. Looking to become competent in welding this stuff together

[H80N]

tube is 1.50" OD with either a .095 or .120 wall, using a Millermatic 212 with 75/25 gas mix, .035 wire. right now just cutting material and welding together, trying to get a feel for the material and how to work the gun around the material. Idea is to be able to weld roll cages at some time in the future.

take your time ..... practice and learn a LOT before you ever weld on something that your life or somebody else's may depend on

make sure you have good penetration and sound welds

[FusionKing]

And make sure to learn proper technique...... not using the trigger making a bunch pretty craters to look like a tig weld.

[ryanjones2150]

Yup. MIG-like-TIG? Why not just tig it if you want it to look like tig?

[Forced_Firebird]

More importantly, what organization is the car competing in? SCCA, NASA and other club type organization will have different scrutiny when it comes to more advanced sanctions that rely on FIA rules.

In club racing situations, the weld technique will rely heavily on the tech inspector, and as stated above, don't ever pulse the trigger. Nothing worse than your racer showing up to an event and being sent home without a log book, or stamp on his cage.

Seeing you mentioned it's an MX-5, I'm gathering you are talking club type racing and rules. I am a track official and/or driving coach and competition license holder for NASA, FARA, Hooked On Driving, The HPDE, and a few others. I working towards my shop becoming an authorized off-track tech center. I have built/bent/welded numerous cages personally (both TIG and MIG). Familiarize yourself with the CCR, and read what it says about welding. Almost all say the same thing verbatim, right down to car weights, tube notches and full penetrating welds.

Being in the car environment, you will not be able to make the welds in one shot, even if you are a 3' tall contortionist with two elbows on each arm, caging a mini van. Best advice I can give is to weld as log a single bead as possible, and plan your welds according to comfort/reach-ability. Dry run everything prior to pulling the trigger, or starting your arc, #1 importance being full 360 degree welds. Sometimes you will have to get creative with the torch, or drill holes/cut notches in the chassis, and close the holes back up after. I'm a small stature guy and have welded (and driven) those "hairdresser" cars, and they aren't easy lol.

On both .120" and .095 tubing I prefer to use .025" wire and leave a little gap. Often after notching, I re-grind the pipe "square" to the face, leaving the fish mouth so that the pool will fill the void and it's easy to see full penetration. On the inside of the mating angles, there will be plenty of meat, specially when they are over 45 degrees. All too often I cringe at the caterpillars on the obtuse side because the notch was almost "too" tight.

Seeing you have been farming out, guessing you are buying the pre-bent kits, pre-fitting/tacking, then towing the chassis to the welding shop?

[H80N]

More importantly, what organization is the car competing in? SCCA, NASA and other club type organization will have different scrutiny when it comes to more advanced sanctions that rely on FIA rules.

In club racing situations, the weld technique will rely heavily on the tech inspector, and as stated above, don't ever pulse the trigger. Nothing worse than your racer showing up to an event and being sent home without a log book, or stamp on his cage.

Seeing you mentioned it's an MX-5, I'm gathering you are talking club type racing and rules. I am a track official and/or driving coach and competition license holder for NASA, FARA, Hooked On Driving, The HPDE, and a few others. I working towards my shop becoming an authorized off-track tech center. I have built/bent/welded numerous cages personally (both TIG and MIG). Familiarize yourself with the CCR, and read what it says about welding. Almost all say the same thing verbatim, right down to car weights, tube notches and full penetrating welds.

Being in the car environment, you will not be able to make the welds in one shot, even if you are a 3' tall contortionist with two elbows on each arm, caging a mini van. Best advice I can give is to weld as log a single bead as possible, and plan your welds according to comfort/reach-ability. Dry run everything prior to pulling the trigger, or starting your arc, #1 importance being full 360 degree welds. Sometimes you will have to get creative with the torch, or drill holes/cut notches in the chassis, and close the holes back up after. I'm a small stature guy and have welded (and driven) those "hairdresser" cars, and they aren't easy lol.

On both .120" and .095 tubing I prefer to use .025" wire and leave a little gap. Often after notching, I re-grind the pipe "square" to the face, leaving the fish mouth so that the pool will fill the void and it's easy to see full penetration. On the inside of the mating angles, there will be plenty of meat, specially when they are over 45 degrees. All too often I cringe at the caterpillars on the obtuse side because the notch was almost "too" tight.

Seeing you have been farming out, guessing you are buying the pre-bent kits, pre-fitting/tacking, then towing the chassis to the welding shop?

EXCELLENT Post.....

Thank You...