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25th Feb 2019, 08:34 PM #16Most Valued Member
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Not sure, but I think the 56% stuff is really only needed for jewellery.
Chris
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25th Feb 2019, 08:45 PM #17Golden Member
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Thanks Familyguy, thats quite reassuring to know. Basically I haven't got a clue about solder and was running with the recommendations in the books that I have.
BOC have told me a couple of weeks to get in some high silver content solder .... will see what they manage to do. Will go to Bunnings 15% if nothing arrives.
Bill
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25th Feb 2019, 09:04 PM #18Most Valued Member
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25th Feb 2019, 09:15 PM #19Most Valued Member
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Good to know Kryn, but you NEED 56% for bandsaw blades? Does the lower melting point prevent ruining the temper of the blades?
Chris
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25th Feb 2019, 09:34 PM #20China
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The 15% rods are for copper to copper plumbing applications, I think for high pressure jobs such a the the boiler 45% or 56% would be the way to go, you will gain Better "wetting" of the joint
and achieve the required capillary action easier.
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25th Feb 2019, 10:14 PM #21Member
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I am a plumber and use 5% silver solder to join copper to copper or to brass from 10mm to 150mm.
I have used 2% but it tends not to run as easy.
I haven't seen a joint fail that was welded correctly, usually it is not heated enough to allow the capillary attraction.
I have welded a patch onto a 100mm fire main that had a tent peg put in it one xmas, the patch was another piece of 100mm cut about 30mm bigger than the hole and I heated it up and used a few sticks of solder and it is still there today. When I did the job I was not so convinced it would work but my boss said it would be fine.
I have seen plumbers melt the solder onto the outside of the joint but it does not have any penetration.
I would only use a oxy/ acetylene for welding soldering, I have tried mapp gas but it is too slow, okay on 1/2 but 3/4 you would be there a while.
I was taught to use a welding tip for heating not a No12 or 14, the welding tip is more concentrated and quicker to heat the job up, when the job is near the correct temp and the solder is flowing just pull the torch away by a few inches to not heat the job up.
When the job is at the correct temp it is almost red.
For what you are welding I would heat the tube up first as that will take more heat, then put some heat on the cap, if you touch the silver solder and the temperature is correct it will run around the joint, also to remember is the silver solder follows the heat of the torch.
I would weld it with the cap sitting on a brick so you can heat it all the way around, if you have dags of silver solder on the job use a wire brush to get them off.
Whilst the joint is red hot leave it to cool naturally or it may get a crack in the weld.
The only time I have used 45% is to solder stainless steel
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25th Feb 2019, 10:33 PM #22Golden Member
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If the boiler is for a mini engine like Jenny Wren then the heat source is a feeble metho burner and I doubt it will even make 10psi, getting these small engines to run on compressed air at around 10 psi is reasonably easy but getting them to run under steam power can be a bit of a challenge.
This was how my first attempt went and from this I guessed that the boiler was not even making 10psi, whereas typical mains water pressure is around 75psi so the Bunnings 15% stuff should be ok, there are commercial toy steam engines that use 'soft' solder for the boiler as opposed to silver or hard solder, this works ok in practice until the boiler runs dry and it then springs a leak, I've seen a few like this at car boot sales. With a tiny boiler like this I used map gas and found the wider spread flame made it a easier to heat the boiler evenly
The idea with these small engines is to make it so it runs with lung power alone which is typically 2 or so psi this then makes the boiler much less critical, to make it run at this sort of low pressure you need to be spot on with your machining - minimal friction, close fit piston and just the right spring pressure on the oscillating cylinder to prevent steam leaking but not so much that is causes excess friction - I was not quite there with my second attempt - almost but not quite. To overcome my not so good machining I made the boiler from thin brass tube (0.55mm wall thickness) to minimise heat loss and did succeed in getting it run under steam power. The boiler tube came from a discarded mop bucket the type that has a pair of brass rollers that squeeze excess water from the mop.
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27th Feb 2019, 01:09 PM #23Most Valued Member
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That is the problem with using 2% and 5%., one has to get very hot to get it to flow and then it might or might not...15% beats the 2&5% hands down, as it flows better and easier into the joint.
For the small extra cost I am suprised that plumbers dont use just 15%
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27th Feb 2019, 07:18 PM #24Most Valued Member
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28th Feb 2019, 08:48 AM #25Most Valued Member
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Silver Solder brazing Alloys
Silver Solders Brazing Alloys.pdf
(10 (x2) pages)
yeah...this now works also
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15th Mar 2019, 05:15 PM #26Golden Member
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56% Silver
Found this on Amazon. If you join Amazon Prime you get free postage on a lot of stuff plus various other benefits. I have found it quite handy.
https://www.amazon.com.au/Harris-Saf.../dp/B0713Y6V2F
My understanding is that the eutectic of the alloy blend occurs at 56% Silver content, and the eutectic will have the lowest melting point of all off the alloy blends. Therefore slightly better for folk with smaller torches.
I've been reading that experienced people doing complicated jobs will use different %age blends to do different joins in order to reduce the chance of a previously soldered joint melting. They will also deliberately add heat sinks to protect previously soldered joints from the heat of a later joint. Don't think I'll ever get that fancy.
Also found the sb245 at total tools last week, so if anyone is looking you can get it there, didn't have it first time I tried.
Bill
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