I've got to weld up a valve cover and fill in some big gaps. Any techniques on how to make it look nice? I'll be preheating the cover to try to get any oil out of the casting and it's already stripped of paint. Do I build up the gap first and then make a 2nd pass over the whole thing?

 

I have had 0 luck filling large gaps in aluminim

Can be a very frustrating endavour.

 

Luckily this isn't a high load or pressure application. I know I can do it but i'm not sure how pretty it will turn out. I'd like it to look nice obviously :D

 

You should post some pics of before and after to see how it goes. Only thing I can figure is to direct the heat at a "high" side and let gravity and some torch movement pull it across the gap.

 

I did it! I filled about a 1/2" circular hole. It was not all that pretty to start with or easy but I got it done. I added plenty of material so I can work it down and blend it in how I wanted it with the base metal. Now that I practiced on this one I will try one that I have to do too that is a small gap but still a gab and more important to look nice.

I didn't have my camera or I'd have taken pictures. I'll try to take pictures on the next one.

 

Tig and gaps don't go together. If there's a gap where there shouldn't be one, practice on fitting the parts up correctly, not on how to fill the gap afterwards.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by backpurge &raquo;</TD></TR><TR><TD CLASS="quote">Tig and gaps don't go together. If there's a gap where there shouldn't be one, practice on fitting the parts up correctly, not on how to fill the gap afterwards.</TD></TR></TABLE>

I think he's talking more of "repairing" holes, not welding improperly fitted pieces, like piping.

I was going to suggest just cutting some scrap metal roughly the same size as the hole and welding it up since it's a low load piece. Then just sand it down to blend it in and throw a few coats of paint over it.

 

if its a hole, just build up the outside edge; KEEP the puddle flowing and KEEP the filler in the puddle, ie, dont dip. COntrol the heat, if it starts to sink in, obviously let off a bit. If you need to, stop and let it cool down, then continue. Should be able to fill a 1/2" hole in under a minute with some cool-down time in between.
Oh ya, 1/8" filler helps too

 

Good tips, Tinker. I will practice those tonight.

And yes this wasn't a bad fit up but a hole that existed that needed to not exist in the future. It was a factory hole in the valve cover that couldn't be enlarged without busting through the baffle. Instead I closed this hole and made 2 other holes to weld the -10AN bungs onto. My other option was to cut a little disk the same size and weld it in but I knew I could do that and I'd never just filled the hole before. I worked around the edges and filled it all in and then smoothed it all over and into the base metal once it was cool with some sanding. Very low stress application, ducttape could practically work here if it wasn't ghetto I would definitely treat a more structural application or even something like IC piping much differently.

 

actally with tig and aluminum you can fill some pretty serious gaps. When i was just learining, i would constantly burn through on my corner welds, about dime size...easily filled as tinker said, keep the rod in the puddle.

 

I totally agree with backpurge. No matter what, TIG machines are for PRECISION work...not filling gaps. Not bashing you or anything just stating the facts. If you want to fill the gap, get your Mig to go aluminum, fill it that way, then just smoothe the bead out with a flap disk. Or, as stated before, welding a smaller piece in it, to somewhat fill the gap instead of trying to fill it all with filler rod...MIGHT work. GOOD LUCK!
Kyle

 

Ummm, a TIG is a tool like a hammer or a wrench. What you do with that tool is up to the owner/operator. Just as a wrench makes a great makeshift hammer in certain instances, I think a TIG does just dandy filling gaps in one off situations. And to boot I don't have an aluminum spool gun for the MIG. You may choose to only use your TIG for precision work but I just get the job done using the tools I have.

 

I don't care if you have a 1/2" gap in something, provided it's not something like .0005" thick, you CAN fill the gaps.

The advantage to tig over mig, for filling gaps, is that you can adjust the heat and amount of filler metal added on the fly.

Yes, tig is better for precision...but soetimes you need precision to fill a gap...the precise control to add exactly the amount of heat and wire you want can be important to keep from blowing a bigger hole or just melting the base metal away.

I wouldn't say that one process is better than the other, but in different applications, they each can have advantages.