View Full Version : I'm a total failure! ( silver solder travails )
December 24, 2000, 16:52
At least I am at silver soldering. I was playing around with my test peices and it didn't go well.
I am in dire need of advice. Surface preparation and actual soldering technique are needed...
[ September 09, 2001: Message edited by: gary.jeter ]
December 24, 2000, 17:36
Originally posted by DriftPunch:
I am in dire need of advice.
Welcome to the club.
At the risk of sounding like the blind leading the blind, I'll say this.
Use plenty of heat.
What are you planning to join? I can only think of two things on a FAL where you would use solder: The joint between the muzzle device and the barrel; and the joint between the gas tube and the gas block.
You don't have any (legal) choice of solder at the muzzle. I has to be silver solder. Of course, you can skip the solder, and weld instead. If you use solder, the good news is that the joint does not have to be real well done in order for the rifle to function. The joint is supposed to be solid in order to be legal. I haven't done one of these yet. But, after THOROUGHLY cleaning the surfaces to be joined, I'd apply the correct silver-solder paste to the surfaces, screw 'em together, slap a big glob of heat control paste around the barrel between the gas block and the muzzle device, and commence to make the joint cherry red with the proper torch. MAPP is a minimum for this task. The trick probably is to heat the parts without blasting the torch right on the joint itself. There should be a little bubbling at the joint to indicate the solder melting.
I HAVE tried to join the gas tube and the gas block. I too am a failure (so far) at this task. I tried to do it with Brownells Hi-Force 44 wire solder. This stuff comes as wire on a coil. It melts at 650 degrees. I cleaned and fluxed the parts. The MAPP torch easily got the gas block to reach a dull red color. I think if I had held it on there longer, I could have achieved an overall cherry red.
Frankly I don't think my failure came from lack of heat. The solder melted on contact with the parts. I think the solder just wasn't willing to flow far enough into the joint. It only would flow about a quarter-inch into the joint. That is not far enough. The joint seemed solid at first. But, a little wiggling had it back to the sloppy condition it was in before the ordeal began.
A switcheroo of parts finally fixed that rifle.
I'm going to try the Swif 95 paste on the next job. It melts at a lower temperature, and I KNOW I can get the paste all the way into the joint.
I too would love to hear about the technique of other builders.
December 24, 2000, 18:28
Blind pin it!
In order for solider to work, it must be clean, real clean, no bluing, park. or oil. Use a quality paste made espically for silver solider and lots-o-heat, although it really doesn't need to be red hot, dull red should work, the solider will only flow where the heat is.
Second Place is Just the First Loser
NRA Life Member
December 24, 2000, 19:17
I'm no pro, but with soldering I have learned the secret. Flux, flux, flux! No I ain't cussin at you. And clean the joints real well.
Drift Punch, you comin' to shoot on the 21st?
December 25, 2000, 08:00
Yup, like Bubba said...Use a ton of flux around the surrounding areas and heat up that brake real good...the solder will walk right under the joint...it'll follow the heat...
If you have any stuff you can practice on, you'll see how you can make that solder go where you want with the application of the torch...
December 25, 2000, 15:48
Is there any benefit (or peril) associated with applying flux to surfaces when you are using a solder/flux paste?
December 26, 2000, 09:37
Yes I am planning on going. I'm hoping for dry weather. That will determine what I bring. I'd like to bring a friend if that's ok. He's a fellow shooter, so experience isn't a problem.
December 26, 2000, 11:11
I've found this works for me: Parts to be joined must be very clean---use sandpaper or bead blast. Flux using a borax type flux (white paste). Heat to a dull red (around 1100 deg. F), just so the solder flows-- I find using as little heat as possible works best. Too much heat can scale the surface and contaminate the bond. Use oxy-acetylene if possible because you can make a smaller, more managable flame , and you don't heat such a large area. Parts should be a snug "slip-fit" for best bond. Solder is not strong enough to bridge large gaps. Don't be afraid to add more flux as you go if needed. A sure sign is the solder "balling" up at red heat. You should be able to chase the solder into the joint with the cone of the flame, or, the solder will flow by capillary action when the work is hot enough and the flame applied to the opposite side of the joint. Hope this helps.
December 26, 2000, 11:14
BTW--- Above post is for SILVER or SILVER BEARING solder. Technique for low temp solder (i.e., Brownell's HF 44 or similar) is different.
December 26, 2000, 11:18
The above post is for SILVER or SILVER BEARING solder only. Technique for low temp.(Brownell's HF44 or similar) is different.
December 26, 2000, 17:06
Um, there is a better way. Brownells sells silver solder paste that has got to be the easiest thing in the world to do. Clean mating parts real well, use Brakeclean, etc. to degrease, put on a glob of solder paste, assemble and heat with MAPP gas torch. When you see the flux flow from the joint you are pretty much done. Takes less than 5 minutes. RT
December 28, 2000, 13:57
Grumpy and Bubba are pretty right on as far as my experience goes. I use silver solder,the kind jewelers use, as opposed to silver bearing. this stuff comes in three different hardeness which I won't go in to but it all melts around 1100 or higher. The borax flux is a must. and MAPP will work but oxy/acetylene is better. The only thing I would like to add is that you can "draw" solder into a joint or area by heating the metalto be soldered farthest from the solder itself. As the metal heats up it eventually reaches the flow point of the solder and the solder will flow towards the hottest point(which is farthest from the solder)and closest to the heat source. Hope this explaination makes sense.
December 29, 2000, 13:47
In reference to RThomas's post concerning Brownell's paste, I'm preparing an order and I wanted to ensure I'm ordering the right stuff. Referencing Brownell's catalog #53 page 143, I intended to order STL 1205 Silver Braze (322-100-650), its melting point is listed at 1145. The listing says the flux is mixed in. To go with it I was also going to get Heatstop heat control paste (083-012-100) from the same page. Am I on the right track? I'm a novice with welding and silver soldering but I've done enough circuit board work to understand the basic concept of soldering, this seems to be on a grander scale and not available through the Jensen catalog.
The nearest smith I talked to about permanently attaching a brake said it would take two hours at $60 an hour to tig weld one brake and he'd have it back within 90 days. Some consumers might find that acceptable but not me.
December 29, 2000, 15:35
Yup, that's the stuff I used. They only send you a tiny jar of it but I understand you can do 20-25 brakes with it. I didn't use the heat control paste, it isn't neccessary with the temps produced by MAPP gas. RT
December 29, 2000, 15:59
If there was ever an argument for the blind pin technique I think I've just witnessed.
December 29, 2000, 16:03
Another vote for the Brownell's paste. Also suggest you get some of their chalk crayons that will keep the solder from sticking to inconvenient locations. The chalk also seems to protect the color of your parkerizing.
I put my DSA short brake onto my STG barrel using TWO regular propane torches; one torch will not generate sufficient heat, but two did the trick. I propped one torch so that the flame hit the brake from below, and held the other to hit it from above.
December 29, 2000, 16:56
reiterating what others have said
SILVER SOLDERING A MUZZLE CONTROL DEVICE
Silver soldering is as much an art as a science. What is critical is that your solder, flux, and heat source are all appropriate for the temperature you will be operating at (>1100 degrees F.). Also critical is that your surface is absolutely oil free. I recommend sand blasting, then degreasing in alcohol, acetone, lacquer thinner or Methyl Ethyl Ketone (MEK). For most applications, a propane torch will not generate sufficient heat for high temperature solder. I recommend an oxygen-acetylene torch or MAPP Gas. Follow manufacturer's caution with regard to fumes. Most of the parts I have soldered turn a dull red at 1100 degrees, and cherry soon after.
In theory, you clean and flux the parts to be soldered, heat, then apply the silver solder and it will flow evenly into all the gaps in your work area, neatly and permanently attaching your parts. I have not been particularly successful with this method. I have attached DSA brakes using Brownells' "Silvaloy 355" (1/2 oz $15 #080-538-405) ribbon. I cut a piece of ribbon that matches the barrel circumference, flux the threads and barrel, wrap the ribbon around the barrel right behind the threads, then screw the brake on. Heat until cherry. Melts at 1145 degrees, flows at 1205 degrees.
My favorite is a product from Brownells called "Fusion" Silver Solder Paste. It is a paste that has flux and silver powder pre-mixed. It is excellent for attaching brakes. Simply apply the paste to the threads, screw the muzzle control device on, index it, and then heat with MAPP gas until it turns dull red. You will see the silver melt. Let cool, wire brush, and you're done. I have found it to be a little messy in the clean-up, but if the gun is to be painted or refinished, this is not a big deal. The STL 1205 Silver Braze melts at 1100 degrees and costs $26 for 1 oz. One ounce should do 10+ jobs. Stock number #322-100-650
T. Mark "Gunplumber" Graham
Arizona Response Systems
5501 North 7th Avenue, Phoenix, AZ 85013
September 09, 2001, 14:12
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