Silver Soldering

[Deanofid]

Dan, if you are buying a torch, get one for MAPP gas. They look much the same as a regular hand held propane plumbers torch, and will take the same propane canisters, plus they will take MAPP gas canisters. That's what I use for any larger pieces I need to hard solder. It puts out more heat, which you find very handy.

The link I put in my first post takes you to the silver brazing section of that company. Get 45% or 56% silver wire. It will be specification BAg-5 or BAg-7. Doesn't matter what brand, if you buy using those spec numbers, you will get the right stuff.

I like thinner wire because it's easier to wrap around pieces to make a preformed ring. I use mostly .031" wire, and I've been doing this for some time. Harry has made a lot of boilers, so he knows his soldering. We just differ on this thing. I consider the smaller wire easier to use.

For bricks, I've used fireplace bricks for a long time. They work well for me. Stack them up like Shred shows and they will hold the heat around your work piece.

Dean

 

[trolley199]

Hello from the USA

I bought a PM research vertical boiler kit on ebay - excellent kit - it comes with everything - even the raw materials to make the tools. It came with more than enough silver solder and flux which soldered very well with a common Home depot type propane torch. I am pretty much of a beginner and this was my first boiler.

Lloyd
New Hampshire

 

[mklotz]

I bought a PM research vertical boiler kit on ebay - excellent kit - it comes with everything - even the raw materials to make the tools. It came with more than enough silver solder and flux which soldered very well with a common Home depot type propane torch. I am pretty much of a beginner and this was my first boiler.

If it's the vertical boiler, that's not true silver solder. The vertical boiler gets its strength from rivets and the silver-bearing solder is just used to caulk the joints.

 

[Deanofid]

As Marv said. The stuff PMR sells is Harris soft solder, 96% tin, 4% silver. Just soft solder with a tiny bit of silver in it. It melts at 430F, which is definitely soft solder territory. True hard solder has to melt above 840F to be considered "hard". That is the definition according to the AWS, who classify such things for the U.S. gubment. Most hard solders melt between 1150F and 1405F, depending on the alloy.

 

[sunworksco]

I'm finding that cadmium silver solder flows better than cad-free solder.
I have used cadmium silver solder for over 20 years now but use lots of ventilation.
Anyone else having the same experience?
Kind Regards,
Giovanni

 

[dnp101677]

Well, I've been practicing but it seems that I am cannot get the brass hot enough. I am just using a propane torch. Should I be using a differnt kind of gas? I can get the capilary action - the solder won't flow.

 

[shred]

Propane will work so long as you aren't trying to heat up a big chunk of brass or do it outside in the wind or something.

 

[picclock]

Hi

Propane will easily get you to the correct temperature provided you are using refractory bricks to reflect the heat back into the work area. If I remember correctly, propane burns at 1900C, brass melts at 900, and silver solders liquefy at a range of temperatures around 6-800. So if your silver soldering brass your getting quite close to its melting temperature.

Even with this setup, more bricks on the top make this 'hearth' better for larger items. The size of the item being heated will not affect the final temperature, only the time taken for the item to reach it. The trick is to minimise the heat losses as the final temperature is directly dependent on them (ratio of heat input, heat losses x flame temperature).

I only use a small propane torch but have successfully brazed quite large items, a 5" 10mm thick steel ring is my current record using a small propane torch. (http://www.machinemart.co.uk/shop/product/details/fc109-gas-torch-with-nozzles).

Hope this helps

Best Regards

picclock

 

[peatoluser]

Picclock, I think you've confused the melting points of what i would call brazing rod with the silver solders.
silver solders (silver tin alloy) have a melting point of about 600 - 670 degrees centigrade depending on the grade.
It's brazing rod (basicaly a copper zinc very much like brass) that is in the 850 range.
yours
peter

 

[sunworksco]

You might need oxygen/propane/butane to achieve the higher temps.
I use this with really good results.
I use oxygen/acetylene for large pieces.

 

[picclock]

@peatoluser
your quite correct in that I gave the impression that all silver solders melt at 800C. I get mine from

http://www.cupalloys.co.uk/popular-silver-solders-leads-to-prices-c26.html

and they list the highest temperature silver solder at 780C, with the lowest at 610C. I think the range of temperatures is so that parts can be soldered in several stages so the first joints don't melt.

According to Wikipedia, brass melts between 900 - 940C depending on mix.

I've altered the original post to reflect this.

I really must try to read what I post before I post it ;D

Best Regards

picclock

 

[steamer]

I find Oxy/gas to be too hot. You need heat for silver brazing. But you don't want extreme temperature that will burn flux.

A BIG propane torch works best for me.

Dave

 

[sunworksco]

I find Oxy/gas to be too hot. You need heat for silver brazing. But you don't want extreme temperature that will burn flux.

A BIG propane torch works best for me.

Dave

Oxy/Propane can be adjusted with the mixing valves for precise heat requirements.
It is infinitely faster than only using Propane.

 

[GWRdriver]

Giovanni,
It's a matter of experience. The reason why model engineers continue to be warned away from the use of oxy/acetyl gear is that in the hands of the typical amatuer, who might only build one boiler in a lifetime, it can be too powerful. It will, as you certainly know, deliver the goods but too much oxygen and an instant of inattention can easily result in a burn-through. Even though I have many boilers under my belt, while soldering a boiler I still need to pay close attention to a few things other than "Am I overheating and about to burn through a sheet?" For the less experienced person this is inviting disaster, hence the recommendations away from Oxy/acetyl. And yes, years ago in a moment of inattention I burned one through and once was enough. I now use both propane and oxy/acetyl, depending upon the specific demands of the job. Also, oxy/acetyl does not burn flux per se, as I occasionally see mentioned, boiling or burning flux is purely the fault of the operator and is the result of applying too much heat too soon, but then again that is much easier to do with oxy than with propane.

 

[sunworksco]

I'm always thinking that everyone is in the hobby for for life.
I use my 3 different torch set-ups for many different uses, including full-scale tubing soldering and brazing.
I just like to have all the tools, just like the tool freak that I am! LOL!
I'm guilty!LOL! I don't mean to be misleading.

 

[steamer]

Hi Giovanni,

As GW said, it's a matter of experience. GW....I tend to get inpatient...which I have tempered in the last twenty plus years....but I need to keep telling myself to keep the flame away from the joint, but to put it next to the joints....as you know, some setups and assemblies are harder than others to do, and I have used OXY with success, but I've also seen first hand the pitfalls of the inexperienced...and as you said, I try to steer them clear. I also speak from KOZO's teachings....which I've read several times, where he suggests staying away from OXY as it's too hot.....but...can't argue with success right?

Giovanni...if your successful silvering by rubbing two sticks together...it just means you did it right! ( LOL) ;D

Blaze away!

Dave

 

[sunworksco]

Good Write!
I'm considering using a kiln to solder with paste and solder wire.
I have seen this used and it looks very easy and precise.

 

[GWRdriver]

Giovanni,
There have been a number of times when a small brazing or heat treatment oven would have been just what I needed . . . but my workbenches are full, and my wallet is normally empty.
;D

 

[sunworksco]

I know that feeling!
My son and I are planning to join TechShop for learning more about tools.
They have low and hitech machinery.
I'm very interested in using their 3-D laser scanner and printer.
[ame]http://www.youtube.com/watch?v=V2M9h1cPNBo[/ame]

 

[shred]

Good Write!
I'm considering using a kiln to solder with paste and solder wire.
I have seen this used and it looks very easy and precise.

It's easy, but slow unless you keep the kiln hot. :-\