Welding Rod Dia?

[914pete]

I perused several posts and it seems the preferred rod is RG-45 or ER-70S2 for O/A welding.  I've never gas welded before and will enjoy learning a new skill.  One thing I didn't notice (or missed) was the preferred diameter of rod.  Can anyone chime in on what diameter rod works best for the LE?  I'm sure a skilled O/A welder can use any diameter but I'm wondering if there is a better choice for the thinned walled tubing used in the LE fuse and for someone whose never gas welded before.

[Hugh Sistrunk]

Just my two cents here - I used 1/16th and most others I know of have used the same dia.  The one way to look at it is,, if your fishmouth fit up with the tubing needs a larger diameter, you probably need to spend more time on getting that tighter.  A few practice pieces used for getting the fit right and some welding practice will put you on the path....
Info.... your last weld  on the fuselage will be the weld you wish you had at the beginning.... But other than John Bolding, I think we all felt that way.... Hint - Watch the Puddle, it will tell you what you need to do after a little practice.....Good Luck, Build one piece each day if you can, and have fun.

Hugh
NightEagle

[Dan_]

 Can anyone chime in on what diameter rod works best for the LE? 

Pete,

See if you can get some .045 diameter filler just to try it.  The larger the rod the more it cools the puddle.   

Like Hugh says, you want good fitting joints... The better the joint coping fits, the less movement during the welding.   

If you hear a loud pop while welding, a joint probably moved a microscopic amount...

You will go looking for something being broken somewhere, but not find anything.   

The bigger the gaps the more stresses can be present from the puddle shrinking while cooling.  (mig and tig mostly)

The Oxy-Acet process, and post weld normalizing should keep this to a minimum.

You may be able to talk a local shop into cutting off some pieces .045 mig wire so you can try it out.  If you like it you can buy a small spool...

The ER -S2 filler has less chro-mo and manganese, than S-6.  It mixes with the parent metal though and is said to be more ductile.

[scottiniowa]

914 Pete
    99% of the time you will be able to use 1/16th rod as stated..  I would avoid using run of the mill (or often used mig wire) as it is very often of tensile type that we don't want in our aircraft builds. Please note that I say often. It could be exactly what you need- depending on your shop/location/supplier.

Having a tube of fill rods, is far easier to keep track of, than a cut off piece/pieces of mig wire. Plus you can store for nearly forever in your cheap home made fill rod tubes. You shouldn't go over two pounds on the legal eagle size aircraft, as I build far larger ones and almost always end around 3# rod used. And often you can buy in 1, 2 and 10# containers.  (you could buy two 1# er's.)

That was a new one on me, about hearing a large pop- then relating this sound to a micro movement in the frame- I suppose, but almost for sure if your gas welding, and your getting popping sounds, your tip is dipping into the puddle and the welding gas, is getting snuffed and then relights, milli-second later. This will improve with your skill.  There are fantastic welding lessons on youtube.  Welding tips and tricks would keep you busy for days watching.. Pick the ones that are most helpful to your project.

Often covered but not stressed, is the simple fact of making several tack welds, always keeping in mind the next tube coming in. But you will want as many tack welds as you can do- This keeps everything in place for your final welding. (always a good thing)  I figure a properly tacked up frame probably could make a flight or two.. without being welded complete. Thus you be assured that when you have them fully welded, you will be in good shape. 

Best of success.

[Dan_]

I would avoid using run of the mill (or often used mig wire) as it is very often of tensile type that we don't want in our aircraft builds. 

Scott,

Mig wire has the same metallurgical properties as TIG wire.  

When they have the same designation they are EXACTLY the same animal.  

One comes off the extruding die in cut lengths, one comes on a spool.

The "ER" in ER70S-2 means it can be used as an electrode or filler rod.  

The "70" in ER70S-2 means it is 70 thousand psi tensile minimum.

The "S" in ER70S-2 means it is solid wire.  Flux core or dual shield wire is tubular, it has to contain the flux.

The - 2  in ER70S-2 designates the alloy of the oxidizers used, usually silicon and manganese, and to a lesser extent titanium, aluminum, and zirconium.

Mig uses it as electrode,  tig or gas processes use it as rod.

Perhaps you should try some ER70S-2 .045 MIG wire for your filler, you might like it.  

http://www.airgas.com/product/Welding-Products/Filler-Metal/MIG-Wire-%28GMAW-%26-SAW%29/MIG-Wire---Carbon-Steel/p/ESA1042F07


http://www.esabna.com/euweb/awtc/lesson6_10.htm

[scottiniowa]

I would avoid using run of the mill (or often used mig wire) as it is very often of tensile type that we don't want in our aircraft builds.

Scott,

Mig wire has the same metallurgical properties as TIG wire.  

When they have the same designation they are EXACTLY the same animal.  
 

I'm totally good with this, IF you know what MIG wire you have.. I have found that many, new tig welding or gas welding folks, just assume the wire they are using is one of the call outs you listed. If the coiled wire is one of those, no problems in my book.  So yes, with the added words, "if they have the same designation" I'm all for it, if you want the smaller dia. wire. And of course you can get the smaller wire in rods/tubes as well. 
   I probably have 50#'s of fill rods, of perhaps 10 different designations. All serve a certain purpose. But that would be muddling the waters.
cheers
Scott

[914pete]

Thanks for the info fellas.  I'm going to start with 1/16" to practice with and see how that goes.  I take my time with the copes so they are pretty good.  As far as the type of rod I'll have to see what the local welding supply house carries.  Ideally I guess a pound of each RG45 and ER-70S2 would be good to practice and get started with.

[Dan_]

Ideally I guess a pound of each RG45 and ER-70S2 would be good to practice and get started with.

Have fun Pete, it's a trip...  Soon you will be able to weld up the crack of dawn...

[JohnB]

Hugh, Thanks for the kudos but believe me, the fuselage I'm welding now is better than the one before it.  I have a 5 tube cluster I cut out of an old Piper or Champ I was parting out and the welding (gas) is pure art. Done most likely by a 60 yr old guy (or gal) that was welding tubes together since childhood.  Every time I think I'm getting pretty good I look at that cluster to bring my ego back to reality. It's 98% PRACTICE. 

By the way , I have used 1/16" rod from the get go.   I have read a couple of accident reports yrs ago where a contributing factor was too small a fillet on a weld.  I use a little less than 2# on an XL fuselage/gear

John Bolding

[Dan_]

It's 98% PRACTICE.

By the way , I have used 1/16" rod from the get go.   I have read a couple of accident reports yrs ago where a contributing factor was too small a fillet on a weld.  I use a little less than 2# on an XL fuselage/gear

John Bolding

Try it JB and let us know.  That will settle it once and for all...

You have to feed the wire more, according to what the puddle needs...

I saw a video of the Cub factory weldors  gettin after it...  They were fast.  

It looked like they had the torch up really hot.  (no .045 mig wire back in the 30's)

It appeared as though they had 3 motions.  Pause, run the heat up the wire, and back the torch up to burn it in good.

I have seen some Oxy- Acet welding that looked like it grew there...  Mine looks like I picked up a dog tird and hammered it on.

[Dan_]

I found the video...

Skip it to 4 minutes in...  Looks like about a 1/8" rod,  but they keep whipping it with the torch flame...  Sparkles like RG 45.

[914pete]

I found the video...

Skip it to 4 minutes in...  Looks like about a 1/8" rod,  but they keep whipping it with the torch flame...  Sparkles like RG 45.

[https://www.youtube.com/watch?v=Q6q1VKsTeKQ

Great Vid!  Almost look like an LE at 4:00.  Thanks for sharing.

[914pete]

My first OA weld, yikes!  OK, this is going to take some practice.  (1/16" dia ER70S2)

[Hugh Sistrunk]

Pete,
My first one looked just as bad.  Don't worry about it, don't get discouraged, just burn up some more rod... I found practice at laying a bead along the length of tubing helped me in the beginning.  I was not having to worry about the edges of the fishmouth burning out and I could put more attention into watching the puddle.  I watched for little sparks coming off the metal, which usually was a sign that I was about to burn through, just lift the torch a bit, then back on the puddle. Start with thicker wall and move to thinner.  If it happens a lot, you maybe be running too hot or too big a tip, sometimes adjusting speed will compensate - You will need more heat at tube cluster, the more clusters the more heat or slower speed - You will develop a rhythm with your torch and rod feed, actually, it is magic as it happens without you realizing it :-) -  keep the flame in a neutral state.  Hope this helps, there are a lot of pros out on this site that will provide tips as you go along.

[Dan_]

My first OA weld, yikes!  OK, this is going to take some practice.  (1/16" dia ER70S2)

You're on yer way dude...

It's like computers... everybody starts at the same place.  

Try not to ever leave yourself a joint like that to weld on your airframe.  

You left yourself 2 cut edges at the end of that joint... Best practice is to leave one tube long, weld it and cut the extra length off.  

Rudder pedal joint cut on a 45 is one place you can have this and may want to cut the heat way down and go to .045 rod.

Be sure you have a neutral flame just coming off the feather.  Leave a little blur or out of focus-ness on the inner cone.

If you see the puddle getting too hot, lift the heat off of it enough for it to keep from making a hole, but keeping the puddle and rod in the flame to protect them from oxidizing.

One dab at a time...  You don't start out welding like the guys at the Cub factory.  

Think -- heat, puddle, dip, move.  A string of tacks.  

You will learn how far to keep the rod away to keep it hot, but near enough for it to be ready to dip without sticking.  

When you stop, just raise the heat enough to stop welding, but keep the puddle and rod protected until they cool some.

Tilt the torch 45 degrees down the weld line, and tilt it away from that cut edge enough so that both pieces are taking the same amount of heat...  Hold the rod 90 degrees to the torch.

How do you know they are taking the same heat..?  Trial and error.  

Try a particular angle and apply heat.  When the pieces turn red take the heat away.  

You have the right angle when they both loose redness at the same rate.

2 attachments.  Disregard fig. 3  (back hand)  

Practice, practice, practice.