[TowerTalk] Tack welding rebar, need howto
patrick_g at windstream.net
Fri Jan 3 09:13:44 EST 2014
The little bent point tool for twisting rebar tying wire is called a "pig
tail" by many users. Definitely worth having. Makes the rebar tying go
much much faster and with far less work or wear and tear on you in general
and your fingers in specific.
Regarding welding galvanized: Grinding it off mostly smears the zinc on and
into the grinding abrasive and does not remove all the zinc, It does NOT
MAKE IT SAFE TO WELD. It may weld some easier but it is still NOT SAFE FUME
As regards having the wind or a fan at your back to avoid breathing the
fumes. Not a good idea. Not a sound idea aerodynamically speaking. Wind in
your face is not the best either. Take a look at the videos on YOU TUBE
showing welding. Huge plumes of fumes are generated. Wind at your back
generates eddies and vortices on your lee side (face and chest side) and
puts you in the position of breathing in significant quantities of fumes. It
is far better to have the wind or fan produced breeze blowing sideways left
to right or right to left to clear the fumes. Having the breeze come from
several degrees to the rear but I wouldn't exceed about 15 degrees. The
idea is to have the fumes blown away and not recirculated around your head.
Zinc poisoning is not a casual minor thing to be ignored. If you do breathe
some zinc fumes one of the symptoms may be a metallic taste I your mouth.
The non-ferrous foundry workers casting zinc and welders welding galvanized
material that I have observed always drank significant quantities of milk as
a partial cure. I did some Google searches and saw where milk was
recommended too. I am not a medical doctor and am not advocating a medical
procedure, just reporting what I have observed. YMMV
I frequently weld galvanized steel. It has been decades since I had "that
metallic taste" in my mouth from it. I do take precautions to avoid
breathing the fumes. P.S. auto-darkening hoods ROCK!!!
Good luck and be safe out there in this wonderful new year.
From: Jim Lux
Sent: Thursday, January 02, 2014 5:11 PM
To: towertalk at contesting.com
Subject: Re: [TowerTalk] Tack welding rebar, need howto
On 1/2/14 2:27 PM, Richard (Rick) Karlquist wrote:
> On 1/2/2014 11:02 AM, Grant Saviers wrote:
>> Tack weld the bolts together with #3 rebar when attached to the base so
>> they don't move when set without the base to make concrete work easier.
>> Grant KZ1W
My welding experience is distinctly limited, but here's my take on it..
"tack to hold in place" is different than "use as fastening instead of
> Can anyone refer me to a Dummy's guide to welding rebar?
> 1. I have heard that I have to use special weldable rebar.
> What do I ask for? I'm assuming that the common rebar
> at Home Depot, etc is not it.
If you're going to weld the whole cage, yes, you need rebar that is
"weldable"and the right rods and flux.
For tack welding, anything will work. Two car batteries, jumper cables,
and some coat hangers for electrodes, if you're desperate. You could
use copper wire as brazing rod.
> 2. Gas weld or arc weld? How big of an arc welder needed?
> Can I get away with a MAPP gas torch?
I would assume for "tack" you could use an inexpensive MIG: it's not
structural, really. For that matter, MAPP and hard solder/braze would
also work. I don't know that one of the cheap oxy/mapp kits at the
hardware store with the disposable bottles wouldn't work to just tack
some bolts into place. There's not a lot of gas in those little bottles,
but brazing half a dozen bolts in place is well within the capability.
And they come with some flux covered rods which would probably work.
I found oxy/acetylene and oxy/MAPP brazing/hard soldering more like soft
soldering plumbing or electronic soldering than stick welding (at which
I am terrible) or MIG (at which I am slightly better than stick welding,
but still terrible). I sure wouldn't trust any of my arc welding for
When it comes to destructive purposes, though, I'm a fiend with a
oxy-acetylene cutting torch or plasma cutter...<grin>
One aspect to arc welding is that it's worth it to buy an electronic
helmet. that whole "balance the hood up and as you strike the arc nod
your head so the hood comes down" thing is all well and good if your
living is welding, but for casual welders who have disposable income,
the electronic faceplate that automatically darkens makes life SO MUCH
EASIER (because you can SEE the workpiece before and after the arc is
struck) (one reason gas welding is easier than arc for a lot of people
is that the flame is bright BEFORE you get to the workpiece so you wear
the same goggles all the time, and they're not as dark as for arc welding)
Oh, and welding aluminum is a whole different story, because aluminum
looks exactly the same both solid and liquid, unlike iron and steel,
which conveniently changes color and glows before melting. It would be
a lot of practice before I can TIG weld two big hunks of aluminum, much
less gum wrappers or cigarette pack foil or even coke cans.
> 3. What welding rods to use?
> 4. What if the bolts happen to be galvanized? Grind
> off the galvanizing near the weld?
Do it outdoors with the wind and a fan at your back, and just burn the
zinc off. if you were doing production structural welding or working
indoors, or welding a big galvanized water tank, etc, then other methods
would be appropriate.
Don't breath the fumes. If you do, you'll be miserable for a day or two.
> 5. Can this be done by a novice welder? (I took a
> class on welding in college 40 years ago, so I know
> just enough to be dangerous). Any stupid rookie
> mistakes to avoid?
Yes. "tack" is non structural. All you care is that it sticks. I think
that stick welding would be fairly difficult for this, but MIG would be
easy. Brazing would also be easy. It can look really ugly, because your
sins will be covered by concrete and you won't have to explain it to anyone.
> 6. Alternately, if I go to a welding shop, are they
> going to know what to do or do I need to go to a
> concrete company that makes rebar cages all the time?
That's a good question. When I've gone to welding places, I have asked
"I want you to do X" and if they think they can do it, they say "sure"
and if they can't they say "naah,, you should call so and so".
> 7. I am mainly interested in using tack welding to keep
> the bolts from moving. The jury is still out on whether
> to weld or wire the rest of the cage. I just don't
> trust wiring as being rigid enough to fix the bolts
> in place.
Wiring, done right, is amazingly rigid. I've wired a medium size rebar
cage (5-6 feet on a side) and we loaded it on a flatbed truck, drove it
to the site, dropped it in the hole, and it didn't move.
That said, welding might be faster, and is certainly easier on your
hands. That twisting iron wire umpty gazillion times is really, really
tedious and my hands and arms hurt for a few days afterwards.
> Thanks in advance.
> Rick N6RK
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