Who uses what for chassis soldering?

[Enzo]

My 140 Weller gun worked for me, Weller made a 200 watt gun as well. I don't know how to burn one out, it is nothing more than a big transformer with a handle. The 120v mains is in a primary winding in the center. Then those two pipes are really one pipe bent in a U shape with one leg of the U shoved through the center of the primary. The pipes are a one turn secondary. The commercial tips have a little mass block on the end, but over the years I mostly made tips from a bent piece of 12ga house wire. I can bend it and shape it to suit my needs.

[Mick Bailey]

That reminds me of the spot-welders that people make from microwave oven transformers; they have open windings and are easy to strip off the secondary and replace it with a single turn. You end up with about a volt at 800 amps (in the UK). That would get a piece of 12g copper pretty warm.

[Enzo]

And these are really pretty controllable, meaning where you put the flame on your work. And can be used.
Micro-Torch

[elipsey]

My 140 Weller gun worked for me, Weller made a 200 watt gun as well. I don't know how to burn one out, it is nothing more than a big transformer with a handle. The 120v mains is in a primary winding in the center. Then those two pipes are really one pipe bent in a U shape with one leg of the U shoved through the center of the primary. The pipes are a one turn secondary. The commercial tips have a little mass block on the end, but over the years I mostly made tips from a bent piece of 12ga house wire. I can bend it and shape it to suit my needs.

To think of all the years I've been paying for soldering gun tips like sucker!

[Wes]

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.

Amazon.com: Weller SPG80L Marksman 80 Watt Stained Glass Soldering Iron: Home Improvement

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

The Weller SP80 is what I use. Anytime I need to solder or unsolder on a chassis, this iron gets it done with no problem. I just keep it hanging
up next to my work bench for when I need it.

[R.G.]

I'll go with Enzo's suggestion. That micro torch thingie is where to put your $40.

Here's another trick I learned from using a propane torch for a similar job (the micro-torch was some years in the future yet). Do any of you know what the phrase "tinker's dam" really means?

It's come to mean something of no value, as in "not worth a tinker's dam". But it goes back to the middle ages in Europe when cooking pots were extremely valuable items, and the highest tech items many people ever saw. A cracked or broken cooking pot might mean semi-starvation. People saved cracked pots (hmm... there's another word origin!!) and waited for the roving tinkers to come to town. Tinkers were roving (doh!) metal repairmen who went from village to village repairing... er, metal. Especially pots.

To keep their repair work from messing up the rest of the pot outside their repair area, they made a dam from mud or clay, whatever was available, around the repair area to keep the damage local. When the repairs were done, the dam was broken away and left wherever it landed. It no longer had value other than as fill dirt.

There is still a case for using a tinker's dam. If you have water-based clay to make a curtain wall around the heating area, it can redirect the waste gasses away from other delicate stuff and keep the delicates from burning or being damaged. Tinker's dams have value right up until the job is done.

Machinists often use... a potato for soaking up heat. If some operation generates a lot of heat to be kept local, they will stick the object to be worked through a potato, whose water content acts as an absorptive and ablative shield that guarantees that the work temp at and past the potato will not exceed 212F/100C until the potato is used up.

But I guess that's another story.

Update: they're available cheaper if you're sure you want only a few uses. Here's one for $20: micro torch at Austin Homebrew Supply. Googling "micro torch" turns up a lot of possibilities. Probably also for water based clay.

[riz]

I think it's the starch in the potato that gives it the extra capacity to absorb heat...

I've used a big Weller trigger gun for the few times I've had to solder to chassis. It's worked fine.

[tedmich]

The crack/meth epidemic has lead to a wonderful increase in micro-torch affordability and availability!

Potatoes are good heat-sinks, piercing backstops and workable clock power supplies!

truly an uber tuber!

[Enzo]

I find the russets sound a little harsh, while a Maine potato tends to have a smoother response.

[Leo_Gnardo]

I find the russets sound a little harsh, while a Maine potato tends to have a smoother response.

Yukon Gold for me, pass the ketchup please. About time Chuck rang in on this, he's a potato head.

The gas torches give me the heebeejeebies. I know I'd forget to switch one off, start a fire. And if the cops catch you with one, evidence, "you're a crack head, who's your dealer?" Can do without that.

[SteveJ]

Enzo's idea of the micro torch got me thinking. I bought a hot air rework station last year. I haven't had a chance to try it on a chassis yet, but I bet it would work well. I paid around $115 for a Samsung Tech, just because it had good reviews, but there are some as low as $49. Just a thought, as it serves multiple purposes. Great for removing D.C. jacks from PCB's.
2in1 992DA SMD ESD Rework Soldering Station Iron Welder Hot Air Gun 5 Nozzles | eBay

2in1 852D Soldering Rework Station Hot Air Gun Solder Iron Welder ESD w Nozzles | eBay

[Alex R]

Yes I use a gas torch, it's an iron and you take the tip out to make a butane torch with a nice thin flame.

[Gingertube]

I occassionally cheat. Cut the old ground side cap lead right at the cap and solder the new cap to that lead rather than try to unsolder the old lead from the chassis.
Cheers,
Ian

[R.G.]

I think it's the starch in the potato that gives it the extra capacity to absorb heat...

Well, it's the starch in the potato that gives it the extra capability to hold a lot of water, but the heat isn't absorbed by the starch. Water has an insanely high heat of vaporization for common materials, and the water absorbed in the starches has to be vaporized before the starch does anything - think about boiling rice or oatmeal. The starch just gets softened by the water, doing nothing much until the water boils away. Then the starch burns.

[tedmich]

I have some 0.25" x 1" PCB traces which have to move 26-31A ~32VDC safely* so I'm planning on flood tinning them and dropping a piece of (also tinned) 0.05" thick copper bus bar over the top of them.

I'll try the potato heat shield and my butane torch to solder them down without BBQing the PCB.

I make bus bars with flattened plumbing fittings cut with my HF power shears


This calculator suggests it should work AOK
http://circuitcalculator.com/wordpre...th-calculator/

but I may need a 100w iron...

(*This will be part of a 24VDC battery equalization 3kW PS I'm building for my off the grid Dad, with 3 parallel TDK/Lambda FPS1000-32 making ~85A trimable from 29-38 VDC)