Newbie question on soldering Al chassis

[Voxbox]

I'm trying to make solder connections to an old Fender aluminium chassis.
My iron is a Weller TCP with a no. 9 bit that operates at 450 deg. and it is only just managing to partially melt existing solder on the chassis.

I've never had an issue with a steel chassis, and I guess Al is a better conductor of heat than steel, so what temp. does the bit have to be at to make a good joint?

A lot of irons dont seem to go higher than 450 deg. and I cant get a higher rated tip for the iron, so what Irons (or bit temp.) do folks use for joints to Ally chassis?

Thanks

VB

[HotBluePlates]

I'm trying to make solder connections to an old Fender aluminium chassis.

I'm not aware of any old Fender amps that used aluminum chassis.

But if you're gonna solder to an older Fender chassis, it's gonna take ~150w solder gun, or one of the really big iron used to solder pipes.

[Ed_Chambley]

If it is truly aluminum a magnet will not stick to it, check first. 

If it is there are aluminum alloy solders and fluxes specifically designed for this. You will most likely need a torch (like accetylene). The key is to clean the surface well (sandpaper, wire brush), flux it up, heat it uniformly but not enough to melt the aluminum, and apply the solder.
 
At 428 F Degrees is where your solder will bond with aluminum, so a propane torch with a tip will work, but oxy/acetylene is much faster.  The way to tell if you aluminum is ready with little experience is a wooden stick will smoke when touched to the area to be welded.  Bring the heat up slowly checking as aluminum gets whiter as it heats and takes experience to know when ready.  If to hot to fasr a big hole will fall through.

Now the best method if you do not want to learn to solder aluminum:

Now if this too much, put an electrical eyelet on the ground and solder it to the wire and drill a hole and sand the area inside and out.  Place a nice #10 machine bolt and a star washer.  It will make a ground that will last for many years.

[stratele52]

I'm trying to make solder connections to an old Fender aluminium chassis.

I'm not aware of any old Fender amps that used aluminum chassis.

But if you're gonna solder to an older Fender chassis, it's gonna take ~150w solder gun, or one of the really big iron used to solder pipes.

+1 Fender never use aluminium chassis . I use a 100 watts Weller iron , or two 60 watts worsk too

[Colas LeGrippa]

a heat gun is what I used in the past. Very effective in removing big chunks of solder off any kind of chassis. One minute and you're done.  Careful though not to melt close components.

Colas

[sluckey]

I thought WTCPT tips were only available in three different temp ranges, #6 = 600°F, #7 = 700°F, and #8 = 800F°. Never seen a #9.

Anyhow, that's the wrong tool for soldering to a chassis. Temp is OK, but there just isn't enough quantity of heat. I use a Weller D550 for soldering to steel chassis. It won't do aluminum. I've never seen a solder joint to an aluminum chassis.

[Colas LeGrippa]

forget soldering on an aluminum chassis, unless you own a TIG or MIG welding machine. It is so easy to drill a hole in aluminium, even 1/4 inch thick . There is NO DIFFERENCE between soldering or bolting a ground wire to a chassis. The only thing important to do is to scrape off aluminum oxide off the place where you wish to bolt on a terminal. Use a nylon nut or a nut with a star lock washer and screw it tight so that no resistance is read with your meter, between the terminal and the chassis.

Colas

[Voxbox]

Thanks for the replies folks.

Well it is indeed a steel chassis! My magnet does stick to it..... Its a Jan 1960 Vibrasonic btw. The metal is grey and looks like Ally, and is soft too, so I presumed it wasnt steel.

If dont buy a bigger iron, I'll just drill a hole and use solder tags for the PT centre taps. The amp is a complete rebuild so it doesnt matter about drilling a hole.

BTW, Weller do a PTBB9 tip that goes to 480 degrees, not 450 like I said earlier. Never had an issue soldering to a chassis until now! Maybe its not going to 480, though it is definitely hotter than the no. 8 tip.

http://cpc.farnell.com/1/1/63702-tip-round-sloped-2-4mm-pt-bb9-weller.html

The Weller D550 is a 110V unit and isnt available in the UK unfortunately. It does go to 593C, so at least I know what temp I'm aiming for.

Thanks again

Cheers, VB

[Willabe]

It's not just the temp, you need enough mass in the irons tip to hold the temp so the heat doesn't bleed off to the chassis all at once. The iron's tip has to have enough mass to be able to retain enough heat/temp while heating up the spot on the chassis to solder to before the chassis bleeds the heat away.    

The chassis will act like a big heat sink and disperse the heat before you can build up enough heat in the spot you want to solder too.

They used to have a problem with Formica as bar tops with cig burns. They fixed it by adding a thin layer of Al. just under the surface to wick away the heat before the Formica burned.


          Brad