Air Gun Home :: View topic - Aluminum- solder?

AirGunEric · Site Admin

Anyone know what can be done to effectively solder aluminum? Regular solder that would be used on copper or ferrous metals is apparently no good- is there some sort of solder that will work on aluminum?

23ib0d0n · Moderator

For conductivity or strength?

Conductivity requires tin and silver with a specialized aluminum flux, while strength bonding has aluminum powder in the solder mix and melts at higher temperatures.

On the other hand, FWIW, a low power mig setup can bond aluminum alot easier than solder, and produces a much better joint.

AirGunEric · Site Admin

Strength and sealing is the primary purpose- this is to seal up a vent hole in a valve assembly for a Crosman- they have stopped using brass in most of their guns and aluminum is prevalent. I may try an epoxy first and see if it will hold. I would try a MIG weld- but the valve is small and (relatively speaking) fairly thin between the vent hole to be filled and the valve stem- and I'm concerned the quick blast of heat that would accompany a MIG would cause issues.

AirGunEric · Site Admin

After thinking about this for a moment- perhaps I can find a very narrow aluminum nail/rod that will fit the hole and epoxy that in place and see if it holds up.

BBGun Bob · Veteran Member

Eric,
Being a retired welder alum solder does not work.I tried it many times.
However there is a product called JB Weld that is nearly as strong.It can with stand 450 degrees of heat and be drilled and taped if necessary.
Or you could go to a hobby shop and buy alum or brass tubing that will fit your hole to down size it.Use Loctite 495 super glue to hold it in place.Just make sure it is very clean and oil free.I use auto break cleaner for this type of degreasing.
http://jbweld.net/index.php

Good Luck
I'll be doing the same to
the Chinese AK47 look-a-like
next week.Time for some more mods.
I have all the parts to procede.
Trying to make a Magnum out of that
Chinese XS-B3-1 I have.
MORE POWER as Tim Allen would say (Home Improvment TV Show)

BBGun Bob
I really need a Cronograph

23ib0d0n · Moderator

I would tap it for a set screw and seal it with tiny drop of green loctite {serious metal superglue} then file any high spots. Having diamond bits for the dremel is also very handy for these situations . . . Twisted Evil

AirGunEric · Site Admin

I considered all those options, thought I had some JB Weld around the house (I was mistaken), didn't have a tap small enough to work in this teeny little hole and didn't have alot of space to expand it. Thought of driving a very tiny self-tapping screw into it and holding it in with some Loctite 692 (red, high strength) and cutting the head off with a Dremel- couldn't find a screw small enough either.

So- I went with the best thing I had laying around- some of this "Steely" epoxy (this is one of about 10 different names for this sort of product). It's the rigid epoxy you need to knead (!) to mix the two parts. I'm letting it cure overnight before applying any pressure to it.

Here are some pictures of what I was doing:

This is the valve vent, unplugged

This is the valve, plugged with the epoxy

And this is the transfer port after I enlarged it and countersunk it slightly

AirGunEric · Site Admin

I'm going to try out the alterations in a couple more hours- but I thought maybe I should throw something in here. A few months ago, when Crosman changed their 22xx series valves from brass to aluminum, alot of people got all worked up about it and some who got replacement aluminum valves were saying they were poorly built and ragged inside.

Just for the record- this valve was A-OK. It was machined smoothly and evenly with no contaminants or shaving anywhere near or in it. The only rough part- which you can see in my first picture, was the vent hole which had a bit of an uneven hole at the very outer edge. All-in-all, no issue with it being aluminum or its quality whatsoever. Of course, if it was brass and could be soldered, that would have been alot easier, but whatever.