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hoffman
10-18-2005, 11:25 AM
My brother has a friend who needs a timing cover (I think) from an old motorcycle welded up. It just has a crack and is leaking oil.

Since the day he learned I MAY have the capability to weld aluminum he's been bugging me about it and has gone as far as bringing the part to the shop the same day I first welded with the machine http://bbs.homeshopmachinist.net//rolleyes.gif

I told him just to hang onto the part and not leave it with me and I'd think about it...

Normally I'd just do it for free as a favor to my bro but I've met the guy...and he's payin for it...

It'll just be a weld it up, grind it down and sand job.

Anyway I was thinking about $50/min for firing up the machine and $25/hr with a minumum of 2 hours. The guy says he can't find anyone else that'll fool with it.

I don't think that $100 for tig welding an aluminum housing is too steep. Some folks think that just because you work in a backyard shop you should do stuff for free but none of my tools were free...

I also realize that castings can be porous and full of oil or be some mystery aluminum or even be magnesium... From the glance I had of it it looked to be pretty high quality stuff from a Japanese bike.

Evan
10-18-2005, 11:40 AM
I suggest you try to find a similar junk cover and practice on it first.

snowman
10-18-2005, 11:46 AM
BEWARE!

magnesium!

-Jacob

3 Phase Lightbulb
10-18-2005, 11:59 AM
I'd fix it for free. I'm always looking for welding projects. Sometimes I break stuff on purpose just so I can weld it back together http://bbs.homeshopmachinist.net//smile.gif

-Adrian

Wirecutter
10-18-2005, 12:53 PM
<font face="Verdana, Arial" size="2">Originally posted by 3 Phase Lightbulb:
I'd fix it for free. I'm always looking for welding projects. Sometimes I break stuff on purpose just so I can weld it back together http://bbs.homeshopmachinist.net//smile.gif

-Adrian</font>

Sounds like you should live closer to ibewgypsie - I bet you'd get along great.

-Mark

Wirecutter
10-18-2005, 12:55 PM
<font face="Verdana, Arial" size="2">Originally posted by snowman:
BEWARE!

magnesium!

-Jacob</font>


Speaking of which... How could hoffman determine (safely) what material he's going to be dealing with here? I know of the "spark tests" for various steels (and the cautions about trusting them with "modern" steel), but is there such a thing to distinguish aluminum and magnesium, for example? Thanks.

-M

3 Phase Lightbulb
10-18-2005, 12:58 PM
<font face="Verdana, Arial" size="2">Originally posted by Wirecutter:
Sounds like you should live closer to ibewgypsie - I bet you'd get along great.

-Mark</font>

We would get along fine becuase there is no worm inside of my Gatorade bottle to fight over http://bbs.homeshopmachinist.net//smile.gif

-Adrian

3 Phase Lightbulb
10-18-2005, 01:06 PM
You can TIG weld aluminum/magnesium without any problems. The key is a good pre-flow and post-flow.

Evan
10-18-2005, 01:20 PM
It's easy to identify aluminum vs magnesium. Mix up a teaspoon of lye in a cup of water (Red Devil from the grocery store will do). Clean an area on an unimportant area of the part thoroughly. Put a few drops of the solution on the part. If it is aluminum it will react quickly forming bubbles of hydrogen, basically fizzing. If it is magnesium it will do nothing.

You can also identify using battery acid. Put a few drops on the part. Aluminum will do nothing and magnesium will fizz.

Wash the part with clean water and it will not leave a mark other than a slight dulling of a bright finish.

If it fizzes with both then you have an aluminum-magnesium alloy.

[This message has been edited by Evan (edited 10-18-2005).]

Wirecutter
10-18-2005, 01:34 PM
Thanks, Evan. Another one for the next tips book?

-Mark

Evan
10-18-2005, 01:49 PM
I forgot to mention that you need to be sure that you are down to bare metal. Some of those cases are laquered and you want to get through any oxide layer too. A bit of stainless steel wool or emery should do.

hoffman
10-18-2005, 02:14 PM
I'm going to practice on some old castings I have around the shop. I don't really want to fool with it but $100 would make it worth it.

Good tip Evan!

Tony
10-18-2005, 02:40 PM
hoffman,
welcome to the club! i weld about a dozen of those things every day. from casings to covers to oil pans. speaking from my own experience, 90% of the time they'll be aluminum casting. the only magnesium i've ever come across is on chainsaws and (once) a lawn mower deck.

this probably isn't as rock solid as Evan's tests, but if it feels a LOT lighter than it should, its magnesium.

for aluminum castings you'll want to get your hands on some 4047 filler. its not the easiest thing to find, but its your safest bet for a good sound weld.

4043 leaves a nicer bead (shiny!) but may crack when the weld cools, depending on the casting alloys.

try to weld it when he's not around. if he sees it only takes you 5 minutes, you won't get $100 for it.

start cold with your amps.. the last thing you want is that casting to droop and leave a bigger hole than you're trying to fix.

if its just a crack (and not a patch job), grind the whole crack out with a thin cutoff disk.. down to about 1/2 depth. scrub the whole area clean.. and weld away.

some people recommend drilling a small hole in the end of the crack to keep it from propagating. i've rarely do this with alum, and only seems to be an issue with harder steels (like stainless) and cast iron.

for what its worth, i charge about $20 for a weld like that. granted i'm not looking at what youre holding.. but $20 in 10 minutes for a 3" bead is good money no matter how you look at it.

thats the kind of word of mouth that spreads fast, too. next thing you know, you'll have a whole pile of those covers behind your welding stool.

clean it REAL good. like you'd eat off of it. if its well cleaned (no dust), and its magnesium, it won't explode. in fact your weld bead might even look nice laying on top of it. but a gentle pry with a small screwdriver will pop the whole bead right up.

have fun
-tony

Your Old Dog
10-18-2005, 02:49 PM
Isn't it supposed to be a good idea to preheat aluminum castings before welding? I'm not a welder but just asking if it's necessary to prevent further cracking of the weldment?

hoffman
10-18-2005, 03:31 PM
Thanks for the advise Knuck. Maybe I priced a little high but I didn't make out that great on my last job. It was nasty and everything went wrong. I did get a repeat job out of it though...

Welding aluminum is like voo-doo to some guys around here so there's NO WAY I'm doing anything with someone watching/waiting.

It's sort of moot at the moment because my welder isn't put together.

So do you ride a Knuckehead or are you one http://bbs.homeshopmachinist.net//biggrin.gif (or both)

I learned a lot working on a friends older brothers Knuck ('47 I think) when I was a kid.

[This message has been edited by hoffman (edited 10-18-2005).]

3 Phase Lightbulb
10-18-2005, 04:46 PM
<font face="Verdana, Arial" size="2">Originally posted by hoffman:
Welding aluminum is like voo-doo to some guys around here so there's NO WAY I'm doing anything with someone watching/waiting.</font>

If that is the case, then I bet some really clear videos of TIG welding aluminum might de-voo-doo it http://bbs.homeshopmachinist.net//smile.gif If I can get a good setup going, I bet a lot of people would want to see, maybe even buy full length videos.

-Adrian

Tony
10-18-2005, 04:57 PM
Ol'Dog is right. preheating is never a bad idea. but aluminum sinks heat faster than hoffman can build another welder.. so it should be ok.

the only time i preheat aluminum is when its too thick/heavy for my tig to handle. i'm working with a little 160amp machine.. but with a good preheat, its smooth sailing on 1/4".

rule of thumb says 1 amp for every 1 thou. 160 amp machine should do .160" (more or less.. usually less.

hoff-- i've ridden 'customised' rice burners all my life -- could never afford (or afford to maintain) an american bike.. but thats a story for a different post, right? http://bbs.homeshopmachinist.net//smile.gif

just a good old fashioned knucklhead,
-knucklehead

Evan
10-18-2005, 05:46 PM
Hmmm. Sounds like a marketable product now that I think of it. Two small bottles of juice, one colored red and the other green. One 10 ml bottle has lye solution and the other H2SO4. Special labeling as a "Magnesium Detector Kit".

Sell it for ten bucks for 5 cents worth of materials and 50 cents of packaging.

Last Old Dog
10-18-2005, 08:30 PM
<font face="Verdana, Arial" size="2">Originally posted by hoffman:
. . . . It'll just be a weld it up, grind it down and sand job.

The guy says he can't find anyone else that'll fool with it.
</font>

Random thoughts:
If no one else will fool with it, there may be a message there.

What happens if some of it ends up in a shiny pool on your table?

Grind and sand? Establish up front how much finish work you are to perform.

Whilst working on covers, if any welding would be close to a bolt hole, on a Dykem'd sheet of .065 aluminum, I'd trace around the part and with transfer punches locate holes for possible redrilling.

What is your responsiblity if the gasket surface is, or becomes warped?

Chemically clean as much oil as you can, it will stain.

Keep in mind filler rod alloy will polish out with a different 'color'

You'll do fine, I have confidence . . . . Lost Old Dog

Last Old Dog
10-18-2005, 08:33 PM
Oops

[This message has been edited by Last Old Dog (edited 10-18-2005).]

bob308
10-19-2005, 09:25 AM
wow a $100 for a little weld like that. around here they would try to hammer you down from 30. maybe i better move to ga.