cast aluminum side cover ? tig/mig/stic??help

[fun4now]

help please im looking to repair a crack in my motercycle side cover (engin part) i know first thing is get all oil off it but dont know if it can be done with my mig or if it neads another machine? could be a good excuse to buy more miller stuf dose anyone know if i could use my mig millermatic 135 on it with proper gasses i know you can get extra heat.and what gass would do it?
thaks james

[aametalmaster]

James, The most important thing is to get out all the grease. If you don't when you start welding on it it's gonna come out from nowhere. I don't know much about the welder you mentioned but you need Argon gas...Bob

[HAWK]

fun4now,

TIG is the way to go here, but...

This may be more project than you want. Bob is right about the cleaning! Acetone or toluene are both good degreasers. Acetone is much more readily available. If possible "v" out the crack with a die grinder and carbide tip. Then drill a small hole at each end of the crack. This will help stop the crack from spreading. Now use a clean SS brush, not one that has been used on steel or other materials, and brush the crack and surrounding weld area. Once again wipe with acetone. Some preheat with a MAP gas plumber's torch will go a long way. It will boil off the oil and heat the material to where it will more readily accept the aluminum wire from your mig. I would not go past 300 degrees. Use a heat pencil temp stick. Let your acetone evaporate before pre-heating!

If I had a choice I would TIG the cracked piece once it was prepped as described. Either way, TIG or MIG, on aluminum is a new ballgame and not easily learned on a part that is important to your daily life. Whichever method you choose pratice on scrap first. If you go with MIG, use argon as Bob said and try to push the MIG torch on a steep angle ( 75 degrees off the horizontal ) rather than pull the torch. This will produce much better results with aluminum.

If you go with your MM135 a teflon liner sold in the aluminum kit is a good investment to help the wire feed easier. Keep your torch very straight. I think a small spool of 5356 wire is included in the aluminum kit. Don't try to use a 4043 wire as it is very soft and won't feed well.

TIG is the way to go. You may want to pay a good shop to repair this one until you learn the process and acquire new skills. You may be like me and some others and have a true desire to learn a new process, such as TIG, and invest in more "Blue" equipment. Let us know.