ali boat mods

[raazorj]

Hi every one, happy new year.This is my first post and I am Just putting out some feelers I am rearranging my aluminium boat moving console etc new fuel tank.I have just started to ally weld with my mig and ran into some feed problems but slowly working it out.If anyone is interested in throwing in their 2 bobs worth on welding aluminium and boat building it would be nice to hear from you.
Man is it hot today!
Thanks Ray (raazor-j)
I also dabble in timber will post some pics in album soon.

[tlbsg]

not that i am an expert welding ally with my mig as far as wire feed goes my welding lead is short approx 2 metres and keep it as straight as possible check that u are running the right feed roller for the wire this works for me no feed problems yet

[Grahame Collins]

Aluminium welds so differently to steel and though the manufacturers who sell the mig unit say their unit will weld aluminium there are so many factors one only has to get one wrong and it will likely cause problems.

What are the factors?

• Matching the filler wire to the base metal .In this particular case 5356 filler wire to match the marine grade aluminium.one reason is it is the correct metallurgic match,the other is that it is a stiffer wire.
  
• Wire diam size is another.In most wire feeders which are push units any thing below .9mm diameter and you are asking for wire feed problems as it will birdnest at the slightest problem.
  
• A teflon liner is a must to avoid friction which creates a load at the feed wheels and again a likely birdnest.
  
• To minimise friction further keep the cable straight when welding, so friction is not generated when the wire rubs against the liner.
  
• If you are really fair dinkum you may choose to cut the Mi g gun cable back to a minimum length.
  
• I have seen feeder units also hung up and the gun cable allowed to hand downwards.
  
• Not forgetting the contact tip.The wire expands in cross section due to heat.If the wire jams in there- guess whats happens next- birdsnesting.
  
• This is all before we even think of cleaning. Note those that use and form of stickum on their boat and then expect a good weld job, won't even get a look in in my shop. GRRR!!!!
  
• Cleaning is a must as a badly oxidised sheet will cause problems as it takes more current (heat) to melt through the oxide.
  
• Ordinary grinding wheels (aluminium oxide ) just add to the oxide problem .there is a special one that can be obtained.

This is off the top of my head so I may have further brainstorms and post a bit later.
Edit See Illustration below to understand.

Twice the temp to melt parent metal and it will turn to soup before you burn the the oxide.this is why you must clean it away.

Grahame

[rogerbaker]

If you havent welded ali before I would suggest that you get some scrap ali and have a bit of practice first. Welding ali is a bit like welding solder or lead. One second you have solid ali, the next second you have a big hole.
Aluminium has a very narrow temperature range between solid and liquid and when it is liquid gravity is stronger than its molecular attraction. (forgotten the right word for it)
My experience is that ali welding is an aquired art. The more practice you do the better you get at it.


Roger

[raazorj]

thanks all for replies, excuse typing and spelling but i am not really interested trying to master the keyboard, anyway have been replacing floor in boat after having to remove fuel tank which had small leak in hose but had to cut it out,cause of the way they had installed it.Also had to remove centre console.Now all that is done I have decided to modify the console which was good pratice at aluminium welding. I since have found that the main problem has been the wire feed has not been consistant probably due to the fact been a push feed.
Have been using both .9 and 1.2 wire. get into some tight posistions and it tends to burn back. I am gradually picking up on the extra speed required compared to welding steel, having a good supply of tips has helped, all I need to do is drill the tips out and reuse which I don't think will be a pushover, but not far from the welding shop for supplies.
Bought a sheet of 5050 marine ally that hurt $245.00 but have been collecting new scrap from recyclers to use for bracing from stringers to floor supports much cheaper option at around $2 kg compared to about $15 kg new. will post a couple of photos when I work out all the correct pixel size etc for this forum. any way thanks again.
Ray.