Solder / Brazing to connect spring steel

Date 06-23-2005 05:31

If this failed in service it is almost surely a fatigue failure. This means the metal in the area is almost surely fatigued also. This means the repair will most likely not last very long. Next heating to dull red is enough to mostly anneal a carbon steel spring so the attempts at repair so far have changed the spring (cooling rate had an effect too). If I were you I would find someone who repairs antique clocks and ask him what to do. Making a new spring would not be a great challenge to such a person and is the only repair I would have any faith in.
Bill

By stimpy Date 06-23-2005 05:50

Let me elaborate. The spring steel is flat stock that is about 1/8" wide by 1/16" deep and is about 1'-6" long, similar to what you would find at a hobby store. The connection is not where the joint broke. I am trying to completely replace one piece of the steel, of which there are three which fan out, sort of like fingers. This is actually the back tailfeathers of a bird puppet. The secondary joint was going to be a smaller piece of spring steel laid across all three pieces near the appex where they begin to fan out. This was to add some strength.

By billvanderhoof (****)

Date 06-24-2005 02:31

Suppose you build a mount consisting of three pieces of tubing (like auto brake line for example). This is easily welded or brazed or (use copper tube) soldered. Then each tube could be filled with something rubbery (like silicone gasket material) and the "feather" inserted. After curing the mount has some flexibility so the stress isn't all in one spot on the spring. If you want to stiffen the lower part of the spring the tube could continue up for some distance.

Look at a steel spring leaf rake. There should be some ideas there. All of those connections tend to be mechanical.
Bill

By MBSims

Date 06-24-2005 03:41

A couple of questions to help understand the problem:

- What type of solder are you using?
- What type of flux are you using?
- Are the ends of the spring steel pieces overlapped so that the solder joint is at the overlapped area?

By stimpy Date 06-26-2005 18:47

The solder is silver core and the flux we have is waterproof paster flux, white in color. We also have some amber gel colored flux which looks like tree sap. The spring steel is overlapped by about 3/4" on both pieces. I have ordered some flux coated 1/16" and 1/8" brazening rods because a metal fabricator friend of mine suggested that the coating might help. We are using a propane torch to heat the metals up. My welder friend said we were on the right track but that we needed to heat the metal up a lot more.

By MBSims

Date 06-27-2005 03:14

If you have silver-bearing filler material, it may be brazing material instead of solder. If that is the case, you'll need to heat the material to around 1100-1200 F for it to flow. That will be tough with a propane torch. There are some solders that contain low amounts of silver though. These will flow at around 430-530 F. The flux must be matched to the solder. I'm not sure what "waterproof" flux is. Did you mean "water soluble"? What brand and type is it?

As far as heating, you'll want to heat the piece to be joined until the solder melts and flows flat when it is touched to the metal. If it balls up, it is not hot enough yet.

By stimpy Date 06-28-2005 18:52

Thanks for the info. The solder or brazing rod is just balling up, not really flowing like I have been told it should. The flux says waterproof and it is a Benzomatic container that came with a spool of what I think is solder. My guess is this is for the home repair person working on plumbing stuff. The silver-bearing stuff I've been trying to us is very stiff but it is on a spool.
Are brazing and soldering the same or does the high heat differentiat?

By stimpy Date 06-29-2005 03:00

Here is more info on the flux and solder we have:

Flux is watersoluble lead free, not water proof as I had originally thought.

We have some different types of solder / brazing rod(?)

1. Lead Free Rosin Core
2. Silver Bearing Lead Free Solder
3. Easy Flo #45 Silver Brazing Alloy
AWS/SFA BAg-1
Argent 45% Silver

The Easy Flo is what I have been trying to use but it only balls up, doesn't seem to flow very well.

By MBSims

Date 06-29-2005 03:37

The first two are solders. Soldering is performed at temperatures of 800 F or less. The Easy-Flo 45 is a brazing wire that has a brazing range of 1145-1350 F. This is much too hot for a propane torch. I believe the silver bearing lead free solder is the best choice as long as it is strong enough to hold the parts together while the puppet is used. If not, you should look into one of the "micro torches" or use an oxygen-acetylene torch for brazing with the Easy-Flo 45. Be sure to use the compatible flux. Usually a temperature indicating flux is used that turns clear when the correct brazing temp is reached. Here's some additional data on the Easy-Flo 45:

http://www.lucasmilhaupt.com/assets/brazing_products/technical_data_sheets/EASYFLO.pdf

And technical data on brazing:

http://www.lucasmilhaupt.com/htmdocs/brazing_support/index.html#technical_msds_safety