Help Needed. 1935 Benjamin Franklin Air Pistol Repair

[Mobiasstrip]

Hi, I am hoping someone can help me as I am stumped.
I have a very early Benjamin Franklin (c1935) that needs a silver solder repair. The repair is relatively simple - reattach the bolt unit to the barrel. However before I can do this the air outlet valve needs to be removed as heating will no doubt ruin it.
It looks like it need a very special tool.

Anyone any advice on how to do this?
Photos attached.






Many thanks
Steve

[magicesperanto]

Looks like a standard Benjamin/ Sheridan valve tool is what you need, but that is NOT a "silver solder" joint, but ordinary lead based solder, easy enough to fix depending on what kit you have available.

[grieva]

Looks like a standard Benjamin/ Sheridan valve tool is what you need, but that is NOT a "silver solder" joint, but ordinary lead based solder, easy enough to fix depending on what kit you have available.

ped on here makes the tool you require and no doubt will explain how to use it.

[Mobiasstrip]

Thankyou. I am not familiar with these airpistols so this is very helpful.
I did wonder if it was lead based solder but thought it would not be robust enough. Should make it more straightforward to repair :-)
Next job - source the tool.

Thanks again
Steve

[magicesperanto]

Thankyou. I am not familiar with these airpistols so this is very helpful.
I did wonder if it was lead based solder but thought it would not be robust enough. Should make it more straightforward to repair :-)
Next job - source the tool.

Thanks again
Steve

Not that difficult to make, I made mine from square key steel, though I have read of folk grinding an old socket to suit.

Dimensions here: http://www.mcarterbrown.com/forums/s...ensions-2.html

[Mobiasstrip]

I dont have the tools to manufacture so will need to purchase the tool.
Steve

[Mobiasstrip]

Peds contacted and purchase made. MANY thanks. Steve

[DT Fletcher]

Yep. A pretty common occurrence with Benjamin pistols and rifles. Saw a lot of these at the local repair shop.

Years ago, I talked to a local airgun mechanic who repaired these. As I recall, he stressed the importance of getting all of the old solder off. Then, standard brass plumbing flux and solder. Used a standard propane torch.

Most of the conversation involved details about how the job had to be done right and.... I can't really recall much.. but, there was one bit about how the gun can be improperly soldered in such a way as to put stress on the barrel, which would cause the gun to flex with temperature differences. Vividly recall how he described how such a gun, soldered and left under tension, where he heated up the breech (or muzzle?) and that the gun eventually "popped" releasing the tension.

The Benjamin design, with both the muzzle and breech soldered hard to the compression tube, as we can see, fails. Not sure if there is any real data but I recall speculating either the gun being dropped or even being exposed to the sun. A gun with a barrel under tension (as above) exposed to the sun would seem to be an ideal candidate for this type of failure.

Crosman rifles and pistols of the similar design (109-120) the muzzle end sits inside a bracket brazed to the lower tube so this all but never becomes an issue.

[Mobiasstrip]

An afternoons fettling went well.

[Mobiasstrip]

Holds pressure well too. :-)

[ccdjg]

Very nice work! Did you sweat it on or use capillary action?

[Mobiasstrip]

[Mobiasstrip]

I thought they were the same?
Carefully cleaned off all solder. V carefully applied flux only where I wanted solder to flow. Assembled, wire wrapped and heated with blow torch and sweated solder into joint. Capillary action pulls the solder through the joint. Not tried before. So quite pleased with myself :-)
Beer deserved.

[ccdjg]

I thought they were the same?
Carefully cleaned off all solder. V carefully applied flux only where I wanted solder to flow. Assembled, wire wrapped and heated with blow torch and sweated solder into joint. Capillary action pulls the solder through the joint. Not tried before. So quite pleased with myself :-)
Beer deserved.

Sweat soldering is what they use a lot in jewellery making. It involves coating one piece first with a layer of solder, then clamping the two pieces together and heating to remelt to solder. Useful for gap filling if the two surfaces are a bit uneven, or if the two surfaces are so flat that there is no capillary gap, or if you just want to be sure that the solder has reached every bit of the two surfaces. Anyway, capillary soldering has obviously worked well for you.

[--ped--]

well done on bringing it back to life