Soldering Advice

[Dick Pacini]

I haven't built a tank since drive-in movies were a buck a carload.

I have a couple of the Brodak uniflow tank kits.  My soldering iron and stuff is long gone.  I have a little pencil iron which is OK for soldering small electrical leads.  I am looking to buy the right stuff and would like advice.
Butane torch?  Electric iron?  Wattage? Resin core? Acid flux?  Silver solder?  What say ye?

I know, what is a drive-in movie?

[Tim Wescott]

I use a 16 inch long 80 watt iron that may have been used to put together the first drive-in movie sound system (it's got a fabric-covered cord and everything).  I use acid flux and solid solder, and I clean the snot out of my tanks when I'm done.

Brett Buck, who has more experience with soldering tanks than I do, reports using a pencil iron, and having good success with it.  I think he uses rosin core solder, to avoid corrosion problems.  I know that other people do.

Tinned steel, which is what those Brodak kits should be made with, is about the easiest thing in the world to solder.  Clean copper tube is about the second-easiest.  If you can't solder that, you can't solder anything.

So the first thing that I'd suggest is trying your pencil iron, with the rosin core flux that you have.  Then if that doesn't work, think about getting a bigger iron.  I wouldn't use a torch -- it's too much heat all in one spot.  Unless you really know what you're doing all it'll do is burn the tin off of your steel and leave you with an un-solderable mess.  I think I know my way around solder and torch, and I certainly wouldn't use a torch for anything other than taking the end off of an existing tank.

[Brett Buck]

Brett Buck, who has more experience with soldering tanks than I do, reports using a pencil iron, and having good success with it.  I think he uses rosin core solder, to avoid corrosion problems.  I know that other people do.

  You can certainly do it with a regular pencil iron, but it will take a long time and there is far more skill required. Ed Robbert produced miraculaously good tanks with a 25 watt pencil iron. But, since it is relatively cheap, I would get the biggest Weller gun (D550 I think).

   For solder, use 60/40 Rosin Core electronics solder. It's plenty strong enough for a fuel tank. I have many where the airplane crashed, the backplate bolts left deep indentations, and the water hammer from the fuel crashing to the front blew it up like a balloon, but the solder joints stayed together.  You should not be too concerned with  acid fluxes because they are unnecessary for tin, and will corrode the tin off the steel. Only for repairs will you ever need anything like acid flux, and then only if the tin has been worn or pulled off the steel.

    It's all about technique, of course. To get a good bond, the solder has to be hot enough to flow like water. When you do it right, the surface while heating it will be shiny and kind of bluish.

   Brett

[Steve Hines]

Get your solder from radio shack that has lead in it. Most of the solder you get now is lead free, this is for potable water. It will work but it is a lot harder to work with.

steve

[55chevr]

Solder that is used in stained glass fabrication is made with lead.  50/50 solders extremely easy.  Flux well and clean well after completing.

[Chris Wilson]

Adding to the above sage advice - cleanliness is all when melting two metals together.

Any slag or oxides present from grease need to be thoroughly removed beforehand and I use film cleaner or as its commonly called called 'Hexane.'

Or any spirit that dries without any residue.

Same at the end of the process, especially neutralizing acidic residues.

[Jim Kraft]

I use .022 rosin core 2% silver solder from Radio Shack and the Weller gun that Bret talked about. This stuff flows really well and leaves a beautiful silver look. It is small enough to go right along the edge of the joint. I use to use it all the time when I was doing electronics work as it works so well.

[Bill Little]

I am not going to add too much but will reiterate some of what has been said.  I use the big Weller gun and I also have a comparable Craftsman gun.  Both do a GREAT job!  Plain old "Irons" will work fine, also, but I like the fact that when you pull the trigger the gun heats up quick. 

Because of my Grandfather (Plumbing/Heating/Air/Electrical Contractor) raising me, I learned lots of things early on.  By 8 yo. I was sweat soldering water lines with an acetylene torch, and using a solder gun for other things.  Soldering is easy once you have done it a few times.  The parts have to be clean, the parts have to get to the right temp. (the solder will flow like water) with out over heating them, and you have to let things cool before moving them.  To cold and you get a very weak joint.  Too hot and you melt the tinning off the metal.

So, use the rosin core solder, clean especially the copper tubes where they will be soldered with light sandpaper, and get both parts up to the point the solder flows into the crack.  I keep the tip off the gun on the flap of the end caps so that the solder will flow under and give a tight, complete joint.

BIG Bear

[55chevr]

The only trick to soldering is that both components need even heat and that the least amount of temperature you can get flow and adhesion with is the best temperature.   Overheating solder burns the surface and results in bad adhesion. 

[Dave Hull]

An 80W Weller "pencil" sold for stainless glass works pretty well. Good heat reservoir. Mine gets a bit too hot, so make the joint and unplug before setting up the next joint.

McDivot

[Peter Grabenstein]

I prefer and trust "Stay Brite" silver solder
 
http://www.ebay.com/itm/Stay-Brite-R2000-Stay-Brite-Silver-Solder-3-64-inch-1-2-oz-/131112154068?pt=Radio_Control_Parts_Accessories&hash=item1e86e4b3d4
 
and my 150 Watts soldering iron.

In my younger days (70tees) I used to solder my own Combat tanks for my fleet of 6 or 10 models with
Radio solder and a 40 Watts soldering iron.
All my tanks did not survive because open cracks, broken solder joints,
after I crashed the model(s) the hard way .
Sure cleaning all them solder joints with Acetone before soldering.
The Radio solder I worked with had not enough strength to hold the tank together.
My hole fleet was soaked inside with Diesel fuel.
Radio solder is much weaker in strength compare with S.B. Silver Solder.
Since I use "Stay Brite", Tank leaks are history.
Excuse my american/english , still learning.

Peter G. GER-1223




 

[Steve Hines]

Remember in the old days when you had to keep the iron in the fire.

Steve

[RknRusty]

Wednesday, while making a control rod I soldered two 1/2" lengths of brass tube sleeves to music wire to fit into a cf tube for gluing. I used my dual heat Weller gun on low. I added a bit of flux before I tinned the wire thinking it would help the 60/40 flow into the joint better. It turned out to be a clean job. Was adding flux necessary at all?
Rusty

[Bob Reeves]

Wednesday, while making a control rod I soldered two 1/2" lengths of brass tube sleeves to music wire to fit into a cf tube for gluing. I used my dual heat Weller gun on low. I added a bit of flux before I tinned the wire thinking it would help the 60/40 flow into the joint better. It turned out to be a clean job. Was adding flux necessary at all?
Rusty

May have helped and sure didn't hurt as long as it was a rosin based flux.

[Bob Reeves]

I prefer and trust "Stay Brite" silver solder

The solder is OK but the flux that comes with it was formulated by the devil. Nothing we do requires acid core solder or acid based flux PIERIOD.

[Andrew Tinsley]

I don't much like Weller soldering guns, a bit too bulky for me! Use at least a 100 watt regular iron, I usually use a wedge bit as it gives greater heat transfer along the seems. Use regular electronic rosin cored solder and make sure everything is spotlessly clean. Once you have cleaned it, then do it again! Cleanliness is the secret of good soldering, everything else comes in a distant second, apart from having enough heat! The finished job is plenty strong enough for stunt tanks. You do use copper tubing? If not do so, it bends much better than brass. One final word. Do NOT drill holes for the pipes. Use a punch to cause a deep depression in the flat material of the tank. then drill to size, if you need to. The depression surrounding the pipe forms a beautiful area for the solder to sit in, giving a much more secure joint.
  You don't need acid fluxes, they just cause corrosion problems later. True silver soldering is far too high a temperature operation. Do NOT use it! As far as the 2% silver alloy mentioned, I have never come across it. Straight 60/40 rosin cored solder is fine and easy to use, so why complicate matters?

Andrew.

[John Park]

I do exactly what Andrew does, and it's always worked well for me: my iron's a 90W Henley Solon I inherited from my old man - it must be almost eighty years old.  I keep some acid flux, but use it only for soldering piano (music) wire: it needs a good scrub with water afterwards, or it'll corrode like you wouldn't believe.

[Jay]

Tower hobbies sells Staybrite

http://www3.towerhobbies.com/cgi-bin/wti0095p?FVPROFIL=&FVSEARCH=%3Cb%3Estay-%3C%2Fb%3Ebrite+silver+solder




 

[Brett Buck]

Tower hobbies sells Staybrite

http://www3.towerhobbies.com/cgi-bin/wti0095p?FVPROFIL=&FVSEARCH=%3Cb%3Estay-%3C%2Fb%3Ebrite+silver+solder

   I would strongly discourage the use of Sta-Brite flux for fuel tanks, or just about anything else. The corrosion problem is very serious and it cannot be effectively neutralized, but more importantly, it is not necessary. Also, do not use it for soldered washers on wheels, control horns, etc either, because the corrosion of the shaft will later wear out the bearings.

If you want to use 4% silver-bearing solder for its slight additional strength, the the Kester rosin-core 4% solder.
Regular old 60-40 rosin core is strong enough for tanks unless you do something strange and you certainly do not need to put any significant amount of acid flux on a tin-plated surface.

    BTW, while having clean metal is generally desirable, avoid anything like sandpaper, wire brushes, etc. You do not want to take a chance on removing the tin plate, then you *are* stuck with acid fluxes.

    For control horn construction, Sta-Brite is not adequate to hold the upright to the cross-bar unless you do something mechanically to reduce the load on the solder. Keith Trostle's method, fit up carefully, is adequate. For this you do have a chance to clean it up adequately, but don't just rinse it and hope for the best, you need to use scotch-brite or something to remove the metal surface, and lube it carefully  before putting on the bearings.

    If you want to construct a control horn with a conventional upright and wire, forget anything you can melt with a soldering iron. Get silver solder or braze and a torch.

    Brett

[ericrule]

What Brett says is very true.

Since I own GRW Tanks and am the person who makes all of the fuel tanks I have a bit of practical knowledge in the tank building area. When I took over GRW I continued to use everything that Glen Wells did.

Here is what I use:

Weller 100 soldering station which has a heat adjustment dial.
Weller 40 watt Solder Stick. Available from All-Spec.
.009 Steel sheet that is tinned both sides with 75# tin.
Fully annealed copper tubing.
Alpha Energized Plus .032 diameter rosin cored solder (part # 110170 63 SN/32PB). Available from Hisco.

The solder station is set on 4 for almost every process except the 6-1/2 & 7 oz tanks where I find a setting of 4-1/2 allows the solder to flow better (the steel robs the solder tip of heat as it runs across the 6-1/2 & 7" long seam so more heat volume works better).

Hope these data are of assistance.

Eric Rule

[Randy Ryan]

Just a few comments. I use a small Weller gun too, flux core electronic solder etc. Teaching soldering the simple truth is, once you've got it clean, clean it. One trick I haven't seen here but you will find very helpful is plumber's soldering paste. I use it no matter what no to much for its cleansing purpose but to aid in heat transfer. it was mentioned in an earlier post that the parts must be properly heated. This is correct and I've found that the paste really helps plus it cleans up with lacquer thinner.

Another thing to note , especially when making tanks, it fits. Make sure all your seams are in contact before you begin soldering. This can be done several ways, but I usually make sure the main shell is slightly underbent so the lap joint naturally closes. Then fitting the end caps make your bends sharp and perpendicular or very slightly over bent giving a very small area for the solder to fill.

[FLOYD CARTER]

I've had the best results using a small butane torch and 60-40 solder from Radio Shack.  The little torch has a flame only about 3/4", and is much faster than a soldering iron.

Floyd

[Dick Pacini]

I have ordered the Weller Gun that Brett suggested and a roll of 60/40 solder.  I should be good to go.

I need to assemble the tank for my Coyote that has the round nose and a tank pocket.  All the tubes need to exit on the wedge side since the tank is half buried lengthwise in the nose cheeks.

I will post pix of the finished product next week after I get the stuff.

[Bob Reeves]

I have ordered the Weller Gun that Brett suggested and a roll of 60/40 solder.  I should be good to go.

Smart decision, will serve you well.

[Joseph Lijoi]

  You can certainly do it with a regular pencil iron, but it will take a long time and there is far more skill required. Ed Robbert produced miraculaously good tanks with a 25 watt pencil iron. But, since it is relatively cheap, I would get the biggest Weller gun (D550 I think).

   For solder, use 60/40 Rosin Core electronics solder. It's plenty strong enough for a fuel tank. I have many where the airplane crashed, the backplate bolts left deep indentations, and the water hammer from the fuel crashing to the front blew it up like a balloon, but the solder joints stayed together.  You should not be too concerned with  acid fluxes because they are unnecessary for tin, and will corrode the tin off the steel. Only for repairs will you ever need anything like acid flux, and then only if the tin has been worn or pulled off the steel.

    It's all about technique, of course. To get a good bond, the solder has to be hot enough to flow like water. When you do it right, the surface while heating it will be shiny and kind of bluish.

   Brett

Your Ed Robbert probably built slot cars as well.  Nobody who does any serious soldering uses a gun.  There are no professional "gun" soldering stations.  Only torches or "pencils" are used by pros.  Maybe the gun is good for wire and keeping you from burning your house down.  You don't need a stand with a gun

You can buy a a 40 Watt Weller pencil soldering station with a sponge (very important) stand (variable heat} etc. for the same price.  You can get a chisel tip for this.  The tips on guns are pretty useless.

Silver solder is overkill on a tank. 60/40 is fine. I use solid wire.  No rosin core.  The trick is rosin paste flux.  Apply a nice bead of flux to the cleaned joint.  The temp should be set on high.  Put a coil of solder on the table with some wire sticking like a coiled snake.  Rub the tip in the moistened sponge. Come up to the head of the snake coil with your chisel tip like you were going to tickle his chin.  You will have a nice big drop of molten solder on the tip of your iron.  If it ball up and rolls off of the tip then you need a new tip.  Touch the tip to the rosin/joint bead.  The rosin will immediately sizzle up, heating the tin and sucking molten solder into every nook and cranny of the joint.

This technique was taught to me by a slot car guy.  Hang out at a commercial track or with your buddies who scratchbuild slot cars from brass (retro) and check this out.  You can make small tin discs with a paper punch to cover vent holes.  Slot car mail order houses are excellent sources os soldering stuff.

A lot of those slot car guys knew who Big Jim Greenaway was.  I guess at one time he was as famous in the slot car world as he was in stunt.

[Brett Buck]

Your Ed Robbert probably built slot cars as well.

   Not to my knowledge. In fact, I have never met anyone who did anything with soldering slot cars.

    I can assure you that the Weller gun works very well in this application, better than giant pencil irons or the like. Precisely because of the tip, and the lack of tip mass. You can locally heat the joint very quickly without heating everything else up.

   Torches are completely unnecessary for tank construction, and will make it much harder than a soldering iron because you end up ruining the tin plate in fractions of a seconds.

    Brett

[Jim Kraft]

One other thing I do is punch the holes for the tubing with an ice pick. It gives a lot more surface to solder to.

[Brett Buck]

One other thing I do is punch the holes for the tubing with an ice pick. It gives a lot more surface to solder to.

   Oh, absolutely. I use a sharpened 6p nail. It will leave a big dimple that the solder will flow into.

    Brett

[Dave Hull]

An alternative to the "flanged hole" via tapered punch, which I found to be a nuisance, is an undersize hole followed by a tapered reamer for just the right fit, and then one of the brass close-fit washers from Foremost. Plenty of contact area and less wrassling during assembly. Twist drills make triangular holes in thin sheet, hence the undersize hole followed by the tapered reamer to achieve the fit. I have a Whitney punch, but I like to put the holes into the prebent pieces which makes access a problem.

Absolutely agree on the 60/40 solder. Plenty strong when using a 3/32 seam overlap. I would not bother with a butted seam anywhere for reliability issues. A bit of scotchbrite rub and then lacquer thinner always seems to work. Most times it works with one or the other, but a half assembled tank with a dirty seam isn't worth the grief of saving a simple step.

Soldering can be done a dozen ways--some seem pretty strange to me, but the results look ok, and the builder always swore by his methods in public. I've seen some pretty ugly work that was doing the job at the time but always thought it a shame that someone didn't show them the technique. Making it that ugly had to take longer and be more frustrating.

The only place I ever needed acid flux and staybrite was on stainless steel. We ran solid .014 stainless F2C lines for a while.

McSlow

[Joseph Lijoi]

  Not to my knowledge. In fact, I have never met anyone who did anything with soldering slot cars.

    I can assure you that the Weller gun works very well in this application, better than giant pencil irons or the like. Precisely because of the tip, and the lack of tip mass. You can locally heat the joint very quickly without heating everything else up.

   Torches are completely unnecessary for tank construction, and will make it much harder than a soldering iron because you end up ruining the tin plate in fractions of a seconds.

    Brett

The 40 watt iron that I cite is 6 inches long,  The stand is temp controlled.  The iron is hot without pulling any triggers.

As far as tip mass or lack thereof, there is an abundance of tips available available for the Weller Iron.  Some with even less tip mass than the soldering gun.

[Chris Wilson]

Having semi professionally racing slot cars in a previous life (off topic I know) and having done my fair share of soldering in the past, I would want a matched source of heat to the width and depth of my intended joint.

If you want an overlap with tin tanks of say 6mm then I would use (ideally) a 6mm wide tip and could easily get away with a 40 watt iron.

The same job done with any thicker material and I would grab my 80 watt iron instinctively but still with that 6mm wide tip.

Having a tip smaller than the width of your work means that you will have to 'work' the joint more in order to heat the join equally - sure it can be done but its not the best way in my opinion.

Thanks.

[Tim Wescott]

An alternative to the "flanged hole" via tapered punch, which I found to be a nuisance, is an undersize hole followed by a tapered reamer for just the right fit, and then one of the brass close-fit washers from Foremost.

Dave, that works well for the style of tube entry that you show in your picture, but if you want to put a tube in slantwise, then an undersized hole and a tapered punch work very well, and gives a clean-looking result.