Gas welding filler rod

Hey ya'll,
Is there a preference of which filler and size to use gas welding the basic fuselage. I plan on Tig to finish welding but the Onan twin on my machine gave up the ghost. Almost done the rebuild but I need the wife to be gone so I can paint the cooling tin. She doesn't understand it will make it run better. I do have a bunch of 70S2 on hand but mostly .045. I'm feeling like I should be using 1/16. The gaps on the Spraker fuselage are a bit wider than I would like but I'll make it pretty. Thanks, Dana

I use RG45 for ox/acet welding and ER70 S2 for Tig. 1/16th. On those .045 rods you can take safety wire pliers and twist two together for those gaps you speak of.

whats it matter?? just feed filler faster.... Tig filler is much cleaner than the old oxy stuff

RG45 for gas o/a hands down.

Like Bugs said........ RG45 for gas, 60-70 for Tig. The higher numbers dont "flow" well for gas but the weld is OK, just not a likely to get that "pretty" weld. Just grab a piece of each and see for yourself. The 1/16 rod does well for a lot of smaller welds but I use mostly 3/32 ......... easier to control. But the bigger the weld, the more it will try to move.......... try to keep the gaps to a minimum.

Interesting, I tend to the smaller diameter filler. I do allot with .032 and .045 but there are days the aging eyes will not focus well enough so the cooling power of 1/16th is handy.
You mention the gaps are wide, is this one wall thickness gaps or wider?

Charlie,
Some gaps are wider than wall thickness. Circumstance does not allow for refitting as I have plenty of dimensional correction to deal with. Not ideal but doable. I see you are in Vermont. Pretty place. I grew up in White River and spent 21 years in the Vt. Air National Guard after 5 years active duty. I miss some of the people but not the winters. Regards, Dana

It is an interesting place to live up here, I really need to get out though. Hard to earn fair money here.

The gaps are not that nasty but tension can be built up, a little at each joint. 1/32 rod for 95% of the work. Depending on wall thickness when working a BIG gap I build along the edge of the tube till it then can be flowed across. Some times multiple passes are needed to extend the tube till you can flow the joint over. Tig or gas it is similar but the flame feels different, both tools still just provide a flame.

For much of the work the rod does two jobs, fill and create the joint, any tiny rod will do that and the material in steel is essentially dripped in, but the rod will also cool hot spots, if a puddle is starting to sink the rod gets dipped to draw heat out. Not dipped deep, just touched to the edge so it flows in. This is where filler diameter makes a difference. A tight joint fills fast and a smaller rod provides the fill without much cooling. Rod should be not be larger than wall thickness, generally less. With gap there is the probability of overheating spots so rod diameter will be wall thickness or next size larger.
I do allot of .083 and .090 tube building roll cages in race cars, it is almost all done with 1/16 rod. I do not use 3/32 till I am with .120 wall or more unless I have made a mistake on joint fitting.
Aircraft work is almost always small wire bought on a spool when I can find the desired alloy that way.

Charlie,

I have good working knowledge of welding using TIG process. I defaulted to O/A until I get the engine for my Miller Trailblazer back together. I may start looking for a Synchrowave machine if I find myself doing more production here at home and not so much time spent on the road welding up punctured pontoon boats and such. I just finished a prototype tube space frame chassis for my next Sunday drive sports car. It's getting after market fiberglass for a 1965 Corvette and should weigh in at a bit over 1800lbs. There are several kit Cobras in the area that need a spanking.
Thanks for you input, it's always better to have more than less. Dana

The Syncrowave is much more stable at the low power used in Aircraft work. I expect most of the inverter Tigs will be smooth running down low. It is the 5 to 30 amp range that is important and most welders just pass by this in their control logic. My antique by today's standards 250 Syncrowave is my go to machine. I have a Thermodynamic GTS180 that has absolutely the best DC arc stability, again not a new unit but a sweet welder. The Lincoln 180 Tig sits waiting till a lightning strike blows out $1000 circuit boards, otherwise it never gets used.

I would recommend looking at some of the newer tech welders for light stationary work. Worth the money for ease of arc control at low power settings.

But an old Purox 200 torch or a more modern small body gas setup with tiny tips is very stable on this tube as well.

The last few years I designed and built a frame for an aftermarket early Vette coupe body, customer is in final phase of the build. Road course car. For front suspension I went with C5 bits on my own frame pickups, it is coming in a tad heavier than yours but still under 2K. Should be a hoot to drive.

When I first read your thread I got thinking I have an Onan twin around somewhere that never went into the Quickie Q1 I built in the 80s, I went with a Rotax on mine.