2 sides melting (and blowing holes) but not joining

[Seventynine]

short of some pictures i'll try to explain what's happening the best i can.

having a play with my new R-tech unit this morning, set it up running a few test runs along some sheets of alu, all seemed well, real nice smooth beads.

then onto some lap joints, same again, no problems to report.

when it come to doing some butt joints, i found it really difficult to get both sides "wet" to add the filler, either it wasn't accepting the filler wire and creating a chunk of the rod to sit on the surface, or it'd melt and blow a hole in both peices of metal.

occasionally i'd manage to get both sides to wet up and get the filler in quick enough so i could start welding and then i was getting really good results. it was just starting off that i found really difficult.

any suggestions? i'll get some pictures up tomorrow if that would help

 

[shenion]

Lots of heat to start out, to low and edges will just melt back.

I lay the filler in the gap, hit with torch. usually creates a ball on the joint. Keep heat on and it will finally melt into both sides.

Some alloys are more difficult. I have some 6061 that takes a lot of heat to get going.

Tight fit up and spotless metal makes it easier.

Aluminum is a lot harder than steel to get started. Never had any issues on mild steel.

 

[hotrodder]

What Shenion said i.e. get in hot and quick with a short arc length and the edges will fuse together, build the heat slowly and/or arc length is too long and you either get an arc that favours one side only (one edge melts back) and/or the edges pull apart.

If there's a gap and you lay the wire in it need to be hot enough to get a virtually instant puddle or the wire tends to just ball up and shrivel back. Other way of dealing with tacking gaps is to concentrate on one edge, add a dab of filler as it puddles and work it across to the other edge with the torch

 

[Seventynine]

that's EXACTLY what happens. ok i'll give that a go

thanks guys