Gunsmithing Solder for bolt nose bushing

[cast1]

Trying my first m16 extractor install and not having much luck with hiforce 44 and comet flux. Any suggestions on an alternate product?

 

[Blue Sky Country]

(Use high temperature silver solder. They are app. 1700 degrees F and is commonly used with white flux paste which provides more aggressive protection to the workpieces as the joint forms.) DISREGARD THIS BRACKET. DO NOT USE HIGH TEMPERATURE SOLDER. DID NOT FULLY REALIZE WHAT PART IS INVOLVED AT THIS POSTING TIME. GO TO POST #4...

Make sure BOTH parts are thoroughly degreased and free from any solvent or paint residue and apply the flux to both parts. Do not heat the workpieces any more past the point where the thin wedge of flux protruding from between the joined pieces begin to bubble. If the flux burns, it will lose it's chemical properties and become useless.

 

[cast1]

Wouldn’t that soften the lugs and ruin the bolt?

 

[Blue Sky Country]

There are also lower temp silver solders that can be used. For best results make sure that it is a silver solder.

This one here yields flow at around 700F and may be more compatible for sensitive metal parts:

Silver Soft Solder & Flux Kit

TM Technologies: Tools, Sheet Metal Shaping Machines, Gas Welding Supplies, Articles & lWorkshops for Better Metalworking

www.tinmantech.com

ETA: Brownells has both med and 'high' temp Hi Force 44 solders, the latter which operates at the same temps as the Tinman Tech product I linked above. Before you proceed again with that bolt and bushing,

1. Make sure you are thoroughly degreasing the parts and they are not coated with a foreign substance such as black powder finish. Bare steel must show on both sides for proper adhesion.

2. Find some scrap carbon steel pieces and do a test run on them with your setup. Are you applying so much heat that you are burning away your flux? Are both pieces being heated evenly? If the heat is not even, liquid solder will be drawn to the hotter side instead of flowing into the joints where they should. As with welding, do some tests on scrap pieces before you move on to the actual project. Run your setup on the test pieces, then smack them around after they have cooled to see if you are doing the process correctly. The high-temp HF44 has a tensile strength of 38,000 PSI, and the low-temp product is rated for 28,000.

Hope that helps,

 

[colchester]

I have had good results with the hi force and comet flux. I abrasive blast the bolt and the ring and clean thoroughly with acetone. Once the parts are clean i flux and then bring each part to temp slowly so as not to scorch the flux, apply solder in order to tin each part. Once you have the parts tinned just heat the bolt and ring and join the two parts apply a bit more solder. Heres a vid a saw a while back I dont have a much trouble getting the parts tinned as it seems he does in the vid but his result looks good:
bolt nose soldering

 

[2aBaC̶a̶]

I have had good results with the hi force and comet flux. I abrasive blast the bolt and the ring and clean thoroughly with acetone. Once the parts are clean i flux and then bring each part to temp slowly so as not to scorch the flux, apply solder in order to tin each part. Once you have the parts tinned just heat the bolt and ring and join the two parts apply a bit more solder. Heres a vid a saw a while back I dont have a much trouble getting the parts tinned as it seems he does in the vid but his result looks good:
bolt nose soldering

I solder and braze for a living.

The description of how you do it sounds way better than how he shows in the video. Cringe worthy, I would say that is the wrong way to do it.

Clean/flux/heat/apply silver/ weld

 

[Blue Sky Country]

I have had good results with the hi force and comet flux. I abrasive blast the bolt and the ring and clean thoroughly with acetone. Once the parts are clean i flux and then bring each part to temp slowly so as not to scorch the flux, apply solder in order to tin each part. Once you have the parts tinned just heat the bolt and ring and join the two parts apply a bit more solder. Heres a vid a saw a while back I dont have a much trouble getting the parts tinned as it seems he does in the vid but his result looks good:
bolt nose soldering

Cleanliness of the workpieces is the KEY here. Good writeup... I have done brazing on pipes as well as epoxying them, and I always scruff the faces that are to be joined with sandpaper after degreasing the parts and then wiping and blow drying any solvent residue away with a Bernzomatic mini torch heat gun nozzle. With soldering, there is no "mud rod" equivalent that welding has so the parts must be 100% free of anything and roughed up for more surface area for the solder to flow into.

 

[LRI]

Use high temperature silver solder. They are app. 1700 degrees F and is commonly used with white flux paste which provides more aggressive protection to the workpieces as the joint forms.

Make sure BOTH parts are thoroughly degreased and free from any solvent or paint residue and apply the flux to both parts. Do not heat the workpieces any more past the point where the thin wedge of flux protruding from between the joined pieces begin to bubble. If the flux burns, it will lose it's chemical properties and become useless.

NO, NO, NO.

I STRONGLY discourage anyone from using 1700*F silver solder on a bolt head for any reason other than to ruin it. That is a heat-treated part. Remington bolt bodies are 4 pieces. The bolt head, bolt body, cross pin, and handle. The heads are furnace brazed using induction. Ever notice the seam and how far back it is from the lugs? Thats because distance and heat sinks prevent it (head/lugs) from annealing. Keep in mind the body is much thinner wall than the upper head portion. Takes far less heat volume to bring it to temp. The handles are also soldered.

You go blasting an O/C torch on a bolt head and get it hot enough to flow 1700* solder, you ARE annealing the bolt head. You cannot put enough concentrated heat into that part quickly enough for it to bring flux to temp, heat the area being worked on, and flow the solder without it also migrating into the surrounding material. (I've done the tests using a hardness tester.)

That is not a good thing. Not to mention the damage the torch does to the steel because there's no protective atmosphere. You can turn it down to an acetylene rich flame and it'll help, but it won't prevent it and then you have to deal with a bunch of soot contamination.

The better fix:

First, build your bushing so that it has a mechanical lock of some kind. Mine are threaded. Both male and female. The solder is merely the glue, the strength comes from the interaction. I know this is about an M16 extractor, but just to cover the bases:

You don't need to solder a striker pin bushing. A tapped hole is plenty sufficient. The trick is getting threads in it. I mill mine, I don't tap because a busted up tap in 42-44 Rockwell steel is a bitch.

Threading a bolt head recess is not a job for a tap and you better be "Karate Kid" to do it on a lathe. Again, thread milling is the better fix here.

For soldering the bushing:

Get a low temp solder. I use stuff around 400*F for bolt head work, make sure you have the appropriate flux.
Spend the money and buy a magnetic induction coil to heat your stuff. Far, far less risk of flame erosion this way.

Been there, done it, have the shirt. My staff and I have literally done thousands of these. Learn from my mistakes and keep your face, and your customers, attached to your heads.

C.


Last: Once your done, DO NOT quench the joint ever! You MUST allow it to cool on its own back to ambient temp. If you can't hold it in your hand comfortably, its not done yet. You have 3 different materials, the bolt, the bushing, and the solder. All three respond to temperature fluctuation differently. Rapid cooling results in what's called a "cold joint" and that will lead to failure at some point.

 

[Blue Sky Country]

NO, NO, NO.

I STRONGLY discourage anyone from using 1700*F silver solder on a bolt head for any reason other than to ruin it. That is a heat-treated part. Remington bolt bodies are 4 pieces. The bolt head, bolt body, cross pin, and handle. The heads are furnace brazed using induction. Ever notice the seam and how far back it is from the lugs? Thats because distance and heat sinks prevent it from annealing. The handles are also soldered.

You go blasting an O/C torch on a bolt head and get it hot enough to flow 1700* solder, you ARE annealing the bolt head. You cannot put enough concentrated heat into that part quickly enough for it to bring flux to temp, heat the area being worked on, and flow the solder without it also migrating into the surrounding material.

That is not a good thing. Not to mention the damage the torch does to the steel because there's no protective atmosphere. You can turn it down to an acetylene rich flame and it'll help, but it won't prevent it and then you have to deal with a bunch of soot contamination.

The better fix:

First, build your bushing so that it has a mechanical lock of some kind. Mine are threaded. Both male and female. The solder is merely the glue, the strength comes from the interaction. You don't need to solder a striker pin bushing. A tapped hole is plenty sufficient. The trick is getting threads in it. I mill mine, I don't tap because a busted up tap in 42-44 Rockwell steel is a bitch.

If you insist on soldering:

Get a low temp solder. I use stuff around 400*F for bolt head work, make sure you have the appropriate flux.
Spend the money and buy a magnetic induction coil to heat your stuff. Far, far less risk of flame erosion this way.

Been there, done it, have the shirt. My staff and I have literally done thousands of these. Learn from my mistakes and keep your face and your customers attached to your heads.

C.

I realized what part was being involved in this project later on, that is why I recommended the lower temperature solders along with a troubleshoot guide for improperly sticking solder. Going to bracket my original text with a disregard memo...

 

[cast1]

I realized what part was being involved in this project later on, that is why I recommended the lower temperature solders along with a troubleshoot guide for improperly sticking solder. Going to bracket my original text with a disregard memo...

Chad, where would one buy an induction coil?

 

[Maxduty]

Chad, where would one buy an induction coil?

You can actually build one fairly cheap. The parts are on auction and other sites and instructional videos are online. They are the same ones used for induction annealing and not that expensive.

 

[LRI]

I bought mine from a tool truck. Sold with the intent of body shops using them for removing stubborn body/chassis hardware. The little portable unit I have are hand held. They don't give em away, but we've had really good luck with them for years now.