Who uses what for chassis soldering?

[Randall]

I have to re-cap the multi can on a 70's Princeton Reverb. The tabs on the can are bent 90 degrees and soldered to the chassis. I know my Weller soldering gun isn't up to this, I've burned out a few. What are the best options for soldering on this level, and how did the factory do it? I imagine a flame heated 1" round iron like I used back in HS shop class, but that's just a guess.

[Leo_Gnardo]

Weller 80W "pencil" iron. Mouser has 'em, and some have found theirs on Amazon. Last price I saw was about $30. Big fat tip has a lot of "thermal momentum" unlike the typical soldering gun. There are also 120 and 160W versions if you need to solder really big stuff. 80W works fine for me, an old beat up one donated by a stained glass artist 28 years ago. I bought a backup in case it quits but not needed yet, "old faithful" keeps chugging along.

[Randall]

80W, really? My Weller 100/140w is a shrinking violet in these cases. How does this work?

[52 Bill]

80W, really? My Weller 100/140w is a shrinking violet in these cases. How does this work?

The size of the tip makes for a better transfer of heat.

I've had the same 80 watt iron for the last 45 years. Bought it at Sears. It doesn't get used all that often, but when you need to unsolder a filter cap or unsolder the transformer ground wires on a Twin it does it with ease.

In a pinch, I've used two smaller irons to get the job done. Like a 40 watt and a 30 watt used together to get enough heat on the chassis. Depending upon what you are doing, it may be easier with a third hand.

[Justin Thomas]

I use the 80W Weller, the One that comes with a stained-glass-making tip. I put the fattest tip it comes with on it, let it warm up COMPLETELY before touching it to the chassis. No problems whatsoever and basically used only for pot cases, chassis grounds, and cap cans. Keep it cleaned and tinned and you're good to go. A gun just doesn't have enough mass to retain & transfer heat. I thought most soldering guns cool off when the trigger' s not pressed, anyway?

Justin

[tedmich]

I just tried a Weller 75w gun type yesterday and it was worse than useless, wouldn't even flow Pb free solder at all, it said on side "1 min on max, 4 min off" LOL I returned it today

Is this the 80w Weller people like?

it has LEDs so maybe its not "old faithful"

[Justin Thomas]

That looks to be a pumped out version... Mine doesn't have the space-age case. Though it does have a light in the handle,near the heating element, to tell you it's plugged in. It only came with a folded aluminum cheapy stand, and it holds heat long after unplugged. It doesn't fir in my station at all. That's probably a newer version.

How about a "rule": if it's got a trigger, pitch it.

Justin

[SteveJ]

I use an old iron that's physically bigger than the 80W Weller. Not sure what it is, but it has a fat flat tip on it and gets the job done fast. I'm pretty sure it was never intended for use on electronics. If I'm to lazy to wait on it to get hot, my Weller soldering gun will get the job done.

[Mick Bailey]

For chassis jobs, such as re-soldering the brass grouding strips on Fenders, I use a trusty old flame-heated 'hatchet' iron. It flows the solder within a second and the high thermal mass gets the job done without the surrounding area even becoming warm. I have some old resin-cored solder used by the old British GPO - it has a much higher resin content than modern solders (ever noticed just how much flux there is around Fender chassis joints and 70s Peavey boards?). Additional flux makes for better flow and heat transfer.

For slightly more delicate work where actual componets are involved I use my 80W desolder gun with its largest tip. If needed I'll additionally use my bench iron which is also 80W, but has a fine tip so isn't up to the job on its own.

[drewl]

Aside from a couple giant irons at work, I have a couple Weller irons that the temperature regulator is bad. They will literally glow red eventually.
Those work with a large tip.
I also use a variac to control temp.

[Leo_Gnardo]

Here's a Weller SP80 at Amazon, still cheap, no frills, just works great. As drewl suggests you can use a variac to "slow it down" if necessary. A cheap SCR/Triac light dimmer works too. Whenever I use mine, straight into 120V mains, I'm looking for heat, get'r'done.

http://www.amazon.com/Weller-SPG80L-...ds=weller+sp80

Of course you'll have to listen to something while you're using your big iron. Heeeere's Johnny!

https://www.youtube.com/watch?v=vbThC9Dt1BQ

[Tom Phillips]

I use a Weller Model W100P with an 800˚F tip for most of my heavy duty soldering. Note that this series and the similar smaller wattage use replaceable tips that are available in 600˚F, 700˚F and 800˚F tip. They are shipped with either 600˚F or 700˚F tips so you need to verify when buying. I found that changing to the 800˚F tip significantly improved performance when soldering to a chassis. The 800˚F tip seems to only be available as a separate item. As has already been mentioned, it is helpful to give the solder joint a heat boost with a second iron in order to get a nice solder puddle flow.

Attached is a soldering iron family photo.


Note that as the wattage increases the mass of the heating element and the tip increases proportionally much faster than the power draw. It is that thermal mass that makes the heavy duty soldering possible.

The big Daniel Woodhead soldering iron was a $2.00 thrift store find. It took a bit of work to clean and tin the tip and it now works fine. I have seen old films of the Fender assemblers at work and this is the type of soldering iron they were using.

There is a Weller W100P on eBay for $39 BIN at Weller W100P3 Soldering Iron 100 W | eBay but it doesn’t specify the tip temp rating. That gives you an idea of the price range available. Current list price is ~$90.00.

Cheers,
Tom

[Randall]

Cool, I just ordered one. Thank you!

[tedmich]

I guess instantaneous power is important and is proportional to tip mass, and less so wattage. So the ability to heat a large mass of metal in a small area requires rate of energy transfer from tip->spot be faster than rate heat conduction from spot-> rest of metal mass. That's why metals with lower conduction are easier to solder to, everything else being equal.

A small tip on a high wattage iron might have little energy stored at tip and heat conductance away from spot can exceed the rate heat can be transferred from iron -> tip -> spot (= FAIL)

then there's this method

although hand on work piece at 1:00 makes me nervous, I know circuit is at gun but still...

[Leo_Gnardo]

I guess instantaneous power is important and is proportional to tip mass, and less so wattage. So the ability to heat a large mass of metal in a small area requires rate of energy transfer from tip->spot be faster than rate heat conduction from spot-> rest of metal mass. That's why metals with lower conduction are easier to solder to, everything else being equal.

A small tip on a high wattage iron might have little energy stored at tip and heat conductance away from spot can exceed the rate heat can be transferred from iron -> tip -> spot (= FAIL)

That's it. FWIW in college days one of my friends showed me his chassis-soldering technique with a big Weller solder gun: he removed the tip, and pressed the two tip anchors against the chassis, forcing current thru the chassis until it got hot enough to melt solder. I've tried it since & never found it to work well for me. Those who wish to, give that one a try. Clean chassis surface plus being able to hold the solder gun at a position you can put serious pressure on the chassis are required. So much easier with Big Bertha 80W iron.