welding 4130

[sjt]

I am building a patrol but the question is about welding 4130 to various nuts and washers. The plans have nuts and washers welded in certain locations - for example the aileron push rod 1/4-28 nut.

To my knowledge there is no such thing as a 4130 nut. I was just going to weld on grade 8 nuts to the 4130 unless someone can tell me an alternative.

stan

[bestbearhawk1231]

I used "heavy" nuts. They are used in the building trades for putting up buildings. They are a bit thicker and have more "meat" around the treads. I welded 2 nuts together then welded them onto the tube. I doubled them up since experience told me that heating up the metal like that will take the temper out and I wanted the extra threads to keep the heim joint from pulling or pushing out. I got them from Fastenal, they were pretty cheap but they might have to order them in. Make sure you thread a bolt into the nut to maintain the threads and remove the bolt before it cools off or you will be starting over. Run a tap through the threads after it cools off and use plenty of tapping fluid.

[alaskabearhawk]

As an alternative, I've seen these, but never used them:

http://www.markwilliams.com/chassisClevises.aspx?CategoryID=162

Or make your own:

http://www.mykitlog.com/users/display_log.php?user=yeeeha&project=527&category=7248&log=180384&row=3

http://www.mykitlog.com/users/display_log.php?user=yeeeha&project=527&category=7248&log=180443&row=2

[fairchild]

Just an idea- take a coupler nut and cut the outside down in the lathe to fit inside the tubing. leave a little hex on the end which lies outside the tube to use a wrench on.
The coupler nuts are about an inch long- so plenty of threads...... not sure about the grade though - maybe only 3 - maybe less- (?)

[nichzimmerman]

If I may hijack this thread and turn it into another welding topic, has anyone had issues with sparks caused by filler rod? I have the Meco torch and bought some RG45, 60, and ER70S6 to practice with. I can move the puddle around the surface of the 4130 all day, but once I add the filler rod I get a lot of sparks. I weld half an inch before my torch gets hot spots and starts popping. I ordered some rod from tinman tech to see if my original batch was bad, but there was no change. Any welding experts out there? Thanks.

[alaskabearhawk]

You left out a bunch of information, like tip size, thickness of materials, how you set the flame, etc, etc. On the surface, it seems like it's way too hot. Also, those rods all react and flow differently.

[jaredyates]

I agree with Paul. Without knowing more, I'll share some of my experience. If I melt the rod with the flame instead of the puddle, I can end up with a little molten blob that will seemingly explode when I get to it. Or, if I'm using too small of a tip, the torch will pop. I speculate that this happens when the temperature inside the tip gets too high, and usually pushing a little more gas through the torch helps.

[JakeP]

I also agree, this is hard to say without being there. It can spark and pop from too much gas flow (i.e. heat), especially early on in the weld. But there are many situations that can cause it to do the same from too little gas flow as well. Tips seem to be very sensitive to the surrounding heat feeding them. Whatever the case, the cause is either too much or too little gas flow [edit] and/or corresponding tip size [/edit], and likely has little to do with the type of filler rod.

Or, if I'm using too small of a tip, the torch will pop. I speculate that this happens when the temperature inside the tip gets too high, and usually pushing a little more gas through the torch helps.

This goes along with my own experiences and everything I've learned as well.

[sjt]

Sparks can be caused by:
oxygen set to high
cone of flame touches metal

As a rule of thumb, the pressure and nozzle that are correct for welding should reach welding temp in about 3 seconds. If it is faster then 3 seconds downsize nozzle, and or pressure.

Unless you are trying to cut metal, do not let the cone of the flame touch the metal.

Do not use ER70S6 - that is for Tig. RG45 is correct for gas welding.

I took the gas welding sportair workshop class. I wrote up my notes for the local EAA newsletter.

http://www.958.eaachapter.org/Newsletters/2014/0614.pdf

[JakeP]

Nice write-up! I disagree with the not wearing gloves bit. It's just too easy to get burned. I'd rather fumble with the rod with gloves on, or else don't weld at all.

We used RG45 for our fuselage. I have not found anything that conclusively (or even convincingly) states that ER70S-6 is unsuitable for welding 4130 steel fuselages. I've seen an awful lot of opinions on it though!

[alaskabearhawk]

I have to disagree with sjt on some points, but this is not the forum for that.

When I adjust the flame for the tip size (and I have five different tips, two that are custom for my Meco), I do so at the regulator and not at the torch. I have never had the needles move on my O/A gauges when using any of my tips. Kent White does an awesome job explaining the choice of tips, and most importantly how to adjust the fuel/oxygen at the tip. He recommends ER70S6 for gas welding, but RG45 is just fine and has been the standard for many years. FWIW, the testing I did the ER70S6, using O/A, had the best tensile strength test.

https://www.youtube.com/watch?v=riYCLPhuq7c&index=31&list=UUJZsfzVIbZt78P78Uks8q-A

https://www.tinmantech.com/products/welding/meco-torch-accessories/welding-tip-chart.php

[nichzimmerman]

Thanks for all the input folks. This morning, I welded some beads down a foot long piece of 7/8 x .049 using RG45, ER70S6, and a thin piece of 4130 that I cut from .032 sheet. Lots of sparking. I used both the #2 and #4 tips. I will try all my other tip sizes and different pressures and see if anything changes.

[dedgemon]

sounds like its just too hot, boiling the puddle. possibly a bit contaminated. too much oxygen would exacerbate it. any of the rods should be fine, but wouldn't use 4130 rod. generally you want the filler metal to be under rated on modulus wrt the parent metal.

[nichzimmerman]

I tried several tip sizes, pressures, and thicknesses of metal, with no change in results. Unexpectedly, I discovered that if I cleaned the surfaces extremely well with a wire wheel before running a bead and did not preheat or tack weld anything, I had no problems at all. Normally, I clean, preheat, tack, then final weld the joints.

My only explanation for the sparks I have experienced is that they were caused by the scale left by tack welding and preheating. I suppose I will have to have a wire wheel handy whenever im welding. Does this jive with others' experience? I thought squeaky cleanliness was not as critical for gas welding. Thanks.

[whee]

Maybe what you see as a lot of sparks really isn't that many? I get sparks when welding but it isn't anymore that what I saw when others were welding. Only time I get a bunch of sparks is when I dip the cone into the puddle.