Soldering - how to solder brass - ADVANCED

A Knowledge base of basic and advanced topics
Locked
User avatar
Armortek
Site Admin
Posts: 2869
Joined: Tue Jul 10, 2007 10:30 am
Location: Winchester, England
Been liked: 3334 times

Soldering - how to solder brass - ADVANCED

Post by Armortek »

Armortek models offer a great opportunity to add extra detail, which often involves soldering. This Topic covers some tricks of the trade which make the difference between head-banging frustration and an enjoyable and trouble free build. Resistance soldering is covered in more detail in a separate Topic here:

http://www.armortek.co.uk/Forum3b/viewt ... 7759937b15 (to be updated).

Another ADVANCED technique involves aluminium brazing, which is covered here:

http://www.armortek.co.uk/Forum3b/viewt ... 423ce26c97

How do I get the patterns? Start with a maquette (a "rough draft" or preliminary design). That will give you the patterns and the fit. Best is to scale down the original measurements but judging by eye can be effective. A maquette can be made from card or plasticard. The ultimate is to model the assembly in a 3-D drawing tool and transfer the design to flat patterns. It can be as simple or complex as you wish.

DSC_0016[1] (4).jpg
DSC_0016[1] (4).jpg (38.48 KiB) Viewed 3183 times
DSC_0007w.jpg
DSC_0216.jpg
Flat Fold Pattern Trial 3D.png
Flat fold pattern trial.png
P1070973.jpg
P1080389.jpg
P1090863.jpg
P1090864.jpg

Materials- use tinplate or brass. Good sizes are .025" (.635mm) for the base and .010" (.25mm) for the rest.

Bending, Cutting/Shearing, Rolling sheet. You can use a vice for bending and aviation shears for cutting:

ae235.jpg
ae235.jpg (8.74 KiB) Viewed 3183 times
P1090869.jpg
P1090870.jpg
P1090871.jpg

but better still, invest in a "formit", which combines all three, such as this one:

https://www.warco.co.uk/sheet-metal-fab ... chine.html

Work Holding.This is key and will govern whether the job is easy or hugely frustrating. One good system is to use a piece of sheet steel as a base and rare earth magnets to hold and support the work.

P1020260_zpsc6e5356d.jpg
P1020258_zpseb4a8d7d.jpg

Spring clamps are also useful for the later stages


Soldering. This is likewise the source of head banging frustration or smooth operation. Cleaning joints is vital. I'd use a solvent cleaner first and then a fibreglass cleaning pen.

For the soldering, your biggest challenge is managing the heat. Silver solder (recommended) requires about 450deg C. That can be a challenge on a long seam. A butane soldering torch is a cheap option - such as the Dremel:

https://www.dremel.com/en_US/products/- ... tane-torch

You might also need direct flame:

https://www.proxxon.com/en/micromot/28146.php

The best (but expensive) option is resistance soldering, which is covered in a separate topic.

P1060975.jpg

With the work held firmly and clean, a flux is applied, the joint heated to the melting point of the solder, which will then run into the joint by capillary action. It's important not to apply the heat directly to the solder, which should be allow to come to temperature by contact with the joint surfaces. Seams can be soldered by running solder along the joint. To join surfaces, sweating is the best technique, covered here:

http://www.armortek.co.uk/Forum3b/viewt ... ?f=6&t=529


For assemblies such as bins, it's best to solder from the inside but this isn't always possible and sweating can be used.

Always beware of heat build-up. The whole assembly will absorb heat cumulatively, unless heat is allowed to dissipate. Nothing is more frustrating than to have the whole lot disintegrate as the last part is soldered. It's a good idea to invest in some small G-clamps and steel bars which can be attached to either side of the seam to act as heat sinks.

P1060978_zpswgqbnhpn.jpg

Cleaning. Flux will leave a corrosive residue which will colour paint if not removed. It can be removed mechanically with wire brushes and abrasives but a better way is to neutralise with acids, such as citric:

http://www.armortek.co.uk/Forum3b/viewt ... f=2&t=5486

You end up with something like this:

P1090877_zpsnzcfzwvs.jpg
P1090878_zpsuwh4ek9p.jpg
DSC_0016[1] (4).jpg
DSC_0016[1] (4).jpg (38.48 KiB) Viewed 3183 times

That's about it. The three key principles are: clean the surfaces, hold the work firmly and apply sufficient heat. It's great when it all works and hugely frustrating when it doesn't but worth every effort.

As ever, comments and additions always welcome.
Armortek

Locked