Soldering brass

Advert

New Replies

Report Bug

Help/FAQs

Soldering brass

This topic has 12 replies, 7 voices, and was last updated 26 August 2021 at 17:04 by Keith Hale.

Viewing 13 posts - 1 through 13 (of 13 total)

Author

Posts
26 August 2021 at 06:40 #559856
Mark Wakelin
Participant
@markwakelin78336
I've just received the Bengs Modellbau kit Donatus, and there are lots of brass parts soldered together. Is there a solder that will give a reasonable colour match to brass? Do any grades of silver solder have a brassy colour without the melting point getting too close to the parent metal?

Or would I be better looking at modifying parts to be a threaded, bolted or press fit where possible.

Thanks in advance!

Mark
Advert

26 August 2021 at 06:40 #10940
Mark Wakelin
Participant
@markwakelin78336
26 August 2021 at 07:42 #559862
Keith Hale
Participant
@keithhale68713
Hi Mark,

This is probably the hardest question to solve. For example,

What colour is your brass?

What level of finish will you be aiming for?

The simple answer is to use a low silver content (20 – 24% silver) alloy. It has the colour of some brasses – even perhaps yours!

Best results will be obtained by using the correct brazing technique.

Check my personal profile.

Then see the personal message. It will,at least, point you in the right direction and keep the thread relevant.

I will be in touch.

Regards

Keith
26 August 2021 at 07:50 #559863
David George 1
Participant
@davidgeorge1
Hi Mark welcome to the forum. As to the soldering of brass parts the colour of the solder may not matter as much as you think. The method and use of the solder, it's strength and ease of use is more of a quandary to what colour it is. You should get a few scraps of brass and have a practice as the type of solder what flux you use will be better practised and will become more apparent with trying diferent solders for diferent jobs. Here are a few pictures of a small generator made from brass strip both lead and silver soldered in diferent parts. You can't see the solder easily after cleaning up.

David
26 August 2021 at 08:21 #559867
Paul Lousick
Participant
@paullousick59116
As mentioned, the lower % of silver in the solder is more brass coloured. The higher % grades flow better and has a lower melting temperature. The Donatus kit looks as though it is made with lots of turned parts and if finish machined after soldering, the small amount left will be hard to see.

This is a brass spindle that I am making, the large flange has been joined to the spindle with 45% silver solder. The silverish colour is hard to see because it reflects then colour of the surrounding brass.

Paul.
26 August 2021 at 08:55 #559875
Mark Wakelin
Participant
@markwakelin78336
Thanks for the very helpful replies. The Donatus kit looks like it's largely soldered after machining, and the instructions suggest this. Certainly some of the joints can't be machined after soldering.

The photos on the Bengs website show the finished engine with big soft solder filets, which look awful to me!

The brass looks like a common yellow brass to me. Perhaps Ms58? I have a Stirling engine kit of theirs with German instructions which lists the brass as Ms58. The Donatus has English instructions that just says brass.

Finish wise, I'm happy with a good standard, but not exhibition standard. Small, neat filets that don't look out of place.

Thanks for the pointers in your profile pic Keith. That is very useful! Now I have somewhere I can get a good range of solders, rather than just the odds and ends that some suppliers have left on their shelves!

Practicing with scraps roughly the same size and shape is also a really good idea.

I'll probably be starting the kit in November or December, once I've got my workshop set up again.

Cheers

Mark
26 August 2021 at 09:07 #559879
JasonB
Moderator
@jasonb
I suppose a fair bit will come down to how you want the engine to look and how much bright bling you like.

Myself I would probably paint or timber clad the cylinder so colour of joint material would not be critical, Not keen on brass running on brass for the eccentric so would make that from steel and can't see why that needs to be soldered up anyway unless they are assuming the builder does not have a 4-jaw..

Steam fittings would generally be left in the bare metal so a better colour match there may help and a lower silver content solder is also less likely to tarnish over time but you do need to take care holding the parts together as the melting point of the solder goes up as it is all too easy to clamp things a bit too tight and have them bend when close to melting point.
26 August 2021 at 09:27 #559882
Paul Lousick
Participant
@paullousick59116
An option for neater connections is to use silver solder paste. Jewelery makers use ground silver solder which is mixed with the flux and is not as messy. Comes in a syringe applicator and good for delicate pieces. Do a Google search for suppliers.

Paul

Edited By Paul Lousick on 26/08/2021 09:32:23
26 August 2021 at 09:47 #559886
Mark Wakelin
Participant
@markwakelin78336
Posted by JasonB on 26/08/2021 09:07:36:

I suppose a fair bit will come down to how you want the engine to look and how much bright bling you like.

Myself I would probably paint or timber clad the cylinder so colour of joint material would not be critical, Not keen on brass running on brass for the eccentric so would make that from steel and can't see why that needs to be soldered up anyway unless they are assuming the builder does not have a 4-jaw..

Not keen on brightly polished engines to be honest. I prefer them looking like working engines, not brightly polished.

I hadn't spotted that the eccentrics were soldered! I shall certainly make those from one piece. I get the impression that the kits are designed for builders with a minimal workshop. No milling involved, just turning and drilling as far as I can see. They do suggest a simple jig for holding square stock in a 3 jaw chuck.
26 August 2021 at 09:57 #559888
Keith Hale
Participant
@keithhale68713
Hi Mark,

See personal message.

If making your own paste, you will need alloy powder in a suitable mesh size readily available in 10kg lots. Contact any specialist supplier of silver solder.

You will need a binder that doesn't dry out. Water is not an option.

£22 sorts it. But why try to reinvent the wheel!

I am reminded of the occasion when a model engineer told me that he insisted on making his own special alloys (3!) to make a truly authentic samurai sword. My response of £1m was not what he wanted to hear!

Months later, he bought silver solder foil. He saved £999,985.

Keith
26 August 2021 at 11:25 #559906
Russell Eberhardt
Participant
@russelleberhardt48058
Posted by Keith Hale on 26/08/2021 09:57:49:

I am reminded of the occasion when a model engineer told me that he insisted on making his own special alloys (3!) to make a truly authentic samurai sword. My response of £1m was not what he wanted to hear!

Where would he use silver solder on a samurai sword? I have a 500 year old katana and I can't see where it would have been soldered.

Russell
26 August 2021 at 11:58 #559910
Rod Renshaw
Participant
@rodrenshaw28584
I'm with Russell. I don't have a katana but I have often read about them and their manufacture and also watched film of japanese swords being made

.The smith forges the blade and the tang in one piece and then passes the sword blank on to the sharpener and the polisher. The sword guard and other sword furniture just slide on over the tang as part of the fitting out of the grip process, there is no more heating involved, so where is the silver solder used?

Rod
26 August 2021 at 17:04 #559930
Keith Hale
Participant
@keithhale68713
I've got no idea about how they made a samurai sword.

I was simply asked about making silver solder that was to be used to make a sword! Having borrowed a lot of money to create a factory to make it, I thought that I had some experience that I could share with him. Similarly, I share my 51 years of experience in the brazing business with model engineers.

Apologies to Mark for an unguarded aside that has apparently led to his thread being hijacked with unrelated content.
Author

Posts