Silver solder question...

[jbabb]

I have searched many times on this site and I think I have found my own answer, I just want to verify it. I am trying to figure out what types of hard/silver solder everyone is using. I am needing a siver solder to join pieces on a condenser and later on will be joining other fittings such as elbows with soft solder, thus wanting silver solder on the inside so my previous joint won't come apart. From what I can find, Stay Silv 15 is what alot of people are using. Is that pretty much what I need? I know it has a much higher melting point than soft solder which makes me think this will work. What do ya'll think?

[Usge]

That's a popular one. Some of the hard solders have different makeup and flux needs. The one with copper, phosphorous, silver is the one that doesn't need solder. Yes, they require intense heat to flow (your part will be glowing cherry red before it will flow). The biggest problem I've found is using them on larger joins. I just could not get enough heat through a 2" tube to make it melt. Smaller pieces that you can heat from all sides works fine. If you have oxy/acet you can probably get it to work well. If you are using standard propane or mapp/pro...you might get by for small parts that are exposed...but you will have a tough time doing anything on a larger or more enclosed scale (that was my experience anyway..others may have different experience). Some advised to pre-heat the part, or use a furnace like setup to keep the whole part very hot..while using mapp or propane to work the other parts. I will just say...it's not easy on non-exposed parts.

I hard soldered a few outside smaller parts, as well as the tubes inside my shotgun condenser plate. Those worked fine. But, trying to solder the seam of the plates inside the tube...was pointless. Even heating the outside of the 2" tube till it was red..would not get the inside hot enough to melt the solder at any one point. The other consideration is...I was working in a vice. When you heat the copper that much..it gets very soft and will start to deform. So, you have to watch for that as well. I looked for an "interim" heat solder, that was maybe a couple hundred degrees above soft...but not as high as the 1200-1500F of hard solder. Never found one.

[jbabb]

I am going to be soldering my tubes to the plate of my shotgun condenser. I have 5-3/8" tubes inside a 1.5" pipe. I was wanting to use silver solder on these joints because I am going to soft solder an 1.5" elbow on the top of the condenser and didn't want my previous joints to come loose and cause a leak inside the whole works. What silver solder would you suggest? I will be using MAPP gas but if need be, I can use oxy/acet but it is not as easy for me to get ahold of with the trying to be secretive thing. I will probably have to use the same technique on my dephlag when I get that far.

[Usge]

The copper I used was 15/80/5. Sta silv 15 I think would be the equiv. Yes, you can use this solder on the tubes with mapp IF they are out of the column where you can heat them back and front. You'll find it difficult to do once they are inside the column without using something with significantly more heat. I had no problem with 1/4" tubes I used in my 2". I have no idea how you gonna fit 5 3/8" tube (which are actually 1/2" OD) inside a 1.5" column. It will be tight for sure. and you'll have to be very careful drilling.

The other thing you have to be careful of soldering the shotgun tubes to plate outside the column is twisting. If its not in alignment...it won't go in the column properly. The bigger issue here is how to seal the plate to the side of the column. If you use soft solder for that...and have to put a fitting over it..you are going to undo that when you solder the other. This was the issue I had. I could not get the column hot enough or the inside hot enough once the shotgun plates/tubes were in place to hard solder the seam around the edge that holds the plate in. So, using soft solder there...I tried many tricks...some worked some didn't. But, it came loose/leaked 4 times. I finally ended up just filling the entire cavity with soft solder to try and seal it. Hopefully, you'll have better luck than I

One of the tricks you can try..if you have your plate/shotgun in....pour water over it..or fill the tube from bottom with water until it's just over the top of the top plate. Now..solder the fitting on above it. The problem with this..is it tends to keep the copper much cooler below...(what you want) but may prevent what you are trying to solder above from taking. So, you'll have to experiment. A very easy way to get your plate soldered up (from OD) is to flux the seam good..then bend a piece of soft solder around the inside diamter of your column. Slide that down till and fit it till it's up against the wall as close as possible. Heat from the outside...until it liquifies, then walk it around the seam from the outside. The problem is..if your gap is too wide...and any flux has leaked down..the solder will run out the seam into the cavity below. Just have to work at it.

[jbabb]

The more people tell me about hard solder the worse my chances seem to get it to work for me. The main area I am concerned about is the top of the condenser. What I am thinking now is to leave the tubes sticking above the plate about 1/8" and recess the plate into the column about the same 1/8". When I solder it, using soft solder, use alot more solder than I should need and fill alot of the 1/8" void in with solder. My thinking on this is that when I solder the elbow on top, anything that melts inside will reseal itself once it cools. Whatcha think? I might be shooting blanks here but it makes sense to me. Just trying to think my way around this problem out loud.

[Usge]

The more people tell me about hard solder the worse my chances seem to get it to work for me. The main area I am concerned about is the top of the condenser. What I am thinking now is to leave the tubes sticking above the plate about 1/8" and recess the plate into the column about the same 1/8". When I solder it, using soft solder, use alot more solder than I should need and fill alot of the 1/8" void in with solder. My thinking on this is that when I solder the elbow on top, anything that melts inside will reseal itself once it cools. Whatcha think? I might be shooting blanks here but it makes sense to me. Just trying to think my way around this problem out loud.

If you get it hot enough it can work as you have it pictured with hard solder. That's the general issue. The area you are soldering needs to be glowing red. If you can get it up to temp...it will flow.

Filling the cavity with soft solder hoping it reseals is hit and miss bet. Sometimes it opens "up" holes when it cools doing it that way. Plus you have to work on it standing straight up/level. It does what you say....the solder will melt again then harden when it cools. Whether or not it reseals itself...is another issue entirely. And then...once you've soldered the fitting on it..if it develops a leak...you are in for an even tougher time to fix it. Might have to pull it all off, clean it, and start over. I had to do this 3x on mine before it finally sealed. It "looked" sealed up every time..but putting some water pressure to it...would reveal leaks. I'ts just hit and miss.

I'd give the hard solder a go if you can. It's a better solution once it's done. Some people used a 2nd torch (propane, etc) with s "rosebud" (wide heat area) nozzle...setup inside a few bricks to make a "furnace" like thing. Put the part over top of that and heat the whole area...THEN use the mapp to work one spot/area at a time. The thing you have to be careful for here is...once you've heated it that far...it's annealed/softened and will bend/distort easy. This is why..although these methods work...it's better just to have something hot enough and small enough..to work a small area and bring it up to temp.

[jbabb]

Just had a thought after doing alot of searching on this site about silver soldering. Alot of people say to preheat the piece or even keep it hot while soldering the joint with a MAPP torch. When doing a run, right now I use a Bayou burner as my heat source. It is the big banjo style burner and that puppy gets HOTTTTT! I was thinking of putting a piece of expanded metal over the stand and lighting the burner. I don't know how high I would have to turn it up but I would be willing to bet it is going to get warm. While the piece is getting warm I could use my MAPP torch and my stay silv 15 to solder my dephlag. Any reason why this won't work? I will be using Stay Silv 15, Harris stay clean paste flux, and a Mapp torch.

[Usge]

Sounds like it's worth a shot. Use a couple bricks on the burner to stackup and make kind of a furnace that can hold the pice where you can get to it. The thing you have to remember is ...that's going to be "really" hot trying to work over. Just be careful with the piece once it gets that hot. Things start to expand and get very soft (ie, don't drop it and don't put a lot of pressure on anything). If you pick it up with pliers after you get it that hot...it will bend/warp whatever end you are holding. So, a little forethought and planning...should suffice.

I didn't need flux with mine....it was silver/copper/phos and just melted once you get it up to temp. If you burn the flux..might as well stop, clean it up, and start over (nothing is going to stick). You might want to throw a piece of scrap (if there is such a thing) copper on whatever you rig up..and just do a little test area to see if you can get the solder flowing. Once your test is good and you satisified you are safe (with the heat, etc)...then proceed to solder up your rig. You'll be glad you got it hard soldered after it's all said and done. Again, just be careful with the piece after you finish..it's going to be soft and remain that way once it gets that much heat in it (ie., annealed). In that regard...try and focus/limit the area you are heating as much as possible. Sounds like you are moving forward. Let us know how it turns out