No, they are not. Are they being serious? That little torch is a joke. I
have a couple and they will not heat anything unless it is very small. I
would not be surprised if the solder joint as demonstrated were rather poor.
The saw blade is going to conduct the heat away from the joint faster than
that torch will heat it even if you *can* keep it lit :-) Note that the
picture of the final result in the video was not seen well, if at all.
OTOH I wonder if using one of these pastes would be an option. I like the
concept of precise application to the joint:
Has anyone used them?
I have silver brazed ( often called silver soldering ) numerous things
using small propane torches. Propane is hot enough. It is no problem
to silver braze bandsaw blades using silver braze. I have done it.
Silver brazing larger objects takes some thought. Insulating fire
bricks ( IFB ) are useful. You can take some IFB's and build a little
corner that keeps the heat from being conducted away. Silver braze
flows at dull red heat.
I have purchased boxes of a half dozen alloys of silver solder.
Some are vary hard and require a hotter flame, others flexible
and a lower flame.
Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
"Our Republic and the Press will Rise or Fall Together": Joseph Pulitzer
TSRA: Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Charter Charter Founder
IHMSA and NRA Metallic Silhouette maker & member. http://lufkinced.com /
On 6/11/2010 9:12 PM, email@example.com wrote:
Silver soldering is sometimes referred to as hard soldering.
It's become more confusing because old style rosin core electronics
soldering is going leadless and slowly replacing the lead in lead/tin
solder with a percentage of silver. When I used to hard solder large
stainless steel vacuum components to copper and brass fittings, we
called it hard soldering and it was the "hard" high silver content
solder that came in long thin rods like brazing rods and required
oxy/ecetylene to bring up to useful temps. Of course I'm talking
heavy metal mass, not thin saw blades. Bernzomatic torches may be
enough for thin saw blades. The key is the flux. That Sta-Silv
flux is the best. Very forgiving of wide range of temps, even
The black is primarily for stainless steel, but we used both
interchangably. If I were buying only one for general use, I'd go
with the black.
The stuff is water soluble, so it will eventually dry out and become
crusted over in the container, even completely dry out. Even new jars
sometimes have a crystaline crust on the top. Not to worry. Just add
water and remix. Its normal consistancy is a paste, about right to
put on with a simple acid brush or small spatula knife. Don't be
afraid to lay it on thick. Better too much than too little.
When the joint is hot enough (dull red), the flux will bubble and boil
and then become like warm honey, flowing everywhere and filling and
whetting the joint. Add the solder to the edge of the joint and let
it flow into the joint. If it doesn't flow into the joint, it isn't
hot enough or you used too little flux. Try and use only as much
solder as needed. Too much and it will flow out the bottom and drip
and you will end up having to grind down the blade so it will fit in
Water will clean up the post solder flux crust. A good stainless
steel brush, the fine ones that look like a tooth brush or a small
wheel is good to dress it all up.
That's your mistake. You don't "think" you need the 'real' stuff.
Lead free solder has no tensile strength to speak of. It doesn't come
close to resembling silver solder, even if it *is* silver bearing solder.
Get the 'real' stuff and enjoy success, although you must have a greater lap
area if you don't want to experience joint failure.
Heh! I asked Ernie about reassembling my 10" chef's knife with
*Real* silver solder. He advised the use of the *barely* silver
solder rather than the real stuff because of possible temper loss.
Ergo, I figured that my Oatey 5% lead-free, cadmium-free would be
plenty good for bandsaw blades.
Now I'm confused. :)
Plumbing solder is a "soft solder". It's designed to melt at low
temperatures, is brittle when frozen, and is NOT designed to be
structural in any sense -- it's job is to seal a joint well against
leakage when sweated properly.
Your knife repair would have been better served by making the repair with
a good hard solder, then re-hardening and re-tempering the blade.
Aha! Thanks Winston, that's a nice site. He's using 1/2" on a .035
blade so 3/8" on my .025 ought to be in the ballpark. Now to figure
out how to do it - the Dremels out for sure. I've give it a shot on the
grinder or beltsander.
As Lloyd and Ted mentioned, the higher silver content solder
(ca. 45-50%) is probably what you really want.
Compatible flux is critical. Match the flux to your solder
WRT temperature or be very frustrated! DAMHIKT
Just thought I'd throw this in:
I wouldn't even attempt to weld/solder a NEW blade, much less a broken one..
WHY did it break? Old? Bound up? Bad weld?
If any of the above, I wouldn't reuse the blade anyway..
I buy good blades for less than $15 each (105") and if it's dull, bent or
whatever, it gets recycled.. Not worth the few bucks I might save to take a
chance on a bad joint popping loose and ruining the work or a body part, IMHO..
I've only welded blades, not brazed them, but I'm going to guess the
blade is cooling fast enough to quench it, making it brittle. After
you've made the joint remove it from your jig, shine it up with
sandpaper, then heat it gently by waving your torch flame around 'til
the steel turns blue. You've tempered the steel enough that it should
no longer be brittle.
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