Ron
Fournier
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During
the course of workshops, correspondence and phone queries, we receive
a variety of questions from metal workers from around the country. This
page highlights a few recently received questions, with our suggestions
as well as some selected from past issues of Metal
Crafter's News. We hope you will find some of them helpful. --
Ron |
Q
--
I have a question about 2024-T3 aluminum (.063 alclad) minimum bend
radius. My manuals show many different recommendations like 3 to 5 times
thickness for minimum bend radius. I would like to know: what is a good
number to use that will not cause cracks or weakness in a 90 degree
bend? I was going to use the 3 times thickness recommendation (or about
3/16" radius) to keep things tight. Will this be okay? This appears
to be the radius on the parts I am replacing. Also, will standard box
and pan brakes be able to give a different bend radius?
A
-- Your
reference materials sound trustworthy, and we agree with their general
recommendations. Just keep in mind that if a tight bend is what you
are trying to achieve, then the materials you are using are not the
best choice. We prefer to use 3003 H-14 .063 aluminum for practically
everything - from fuel tanks to body work. And yes, a good brake has
an adjustment that will allow you to "back-up" the top clamping
jaw enough to produce different radii.
Q
-- I am building an English wheel and I'm having trouble
locating the material
for the anvils. I have a supplier who is offering 4142 cold drawn (3"
dia. x 24" long) for the small anvils and 4142 hot rolled (9"
dia. x 3" long) for the large top wheel. My question is: are these
acceptable substitues for 4130 / 4330? If not, can you suggest a supplier
who carries the right material?
A
-- You
can use 4142 cold drawn 3" dia. material. In fact, anything that
is in the '41' family will be fine as long as it is "cold drawn"
material. The 9" dia. material is not suitable due to the fact
that it is "hot rolled". This is too soft and you will be
very disappointed with the results. Most steel suppliers in the metro-Detroit
area carry this type of material.
Q
--Your
description of the Henrob Torch indicates that a 2-stage regulator
is required. Do you think that it is absolutely essential? The Henrob
website doesn't say anything about this and I wonder if the torch is
problematic when used in conjunction with a single stage regulator setup.
What sort of problems have you experienced using a single stage setup
with this torch?
A -- A two-stage regulator
is not absolutely necessary, but if you plan to weld sheet aluminum,
we highly recommend it. This recommendation is not due to using a Henrob
torch per se, but has to do with the fact that gas-welding aluminum
requires the use of very low line pressure ( 2 - 4 p.s.i.). If a regulator
fluctuates just 4 or 5%, this makes a very large difference in the flame's
mixture. A two-stage regulator is much more stable than a single-stage
unit. If you are using higher line pressures on steel ( 10 -15 p.s.i.),
that same 4 or 5% variance will have very little effect on your flame
setting. After the investment in that awesome torch, you owe it to yourself
to buy the regulators!
Q
-- In
your video, Blocking and Smoothing, the top wheel and lower anvils of
your English wheels have a mirror-like finish on them. I would like
to know how you achieve this finish and how to maintain it.
A -- We polish our
wheels with a "D.A." sander. It's best to start with a 350
grit paper and then work your way to 800 or 1,000 grit for a beautiful
final shine. It's a good idea to use a light oil, like WD-40, to protect
the wheels from corrosion.
Q
-- I
am building a new work table for my shop and want to be sure
it is well-built and will endure for many years. In one of your books
you recommend a minimum of 1/2" thick steel plate for the table
top. Do you think it would be a good idea to upgrade to 3/4" or
1" thick steel plate instead? The table is 4' x 8' and the upgrade
would not be cheap, but I want to do the right thing. What do you think?
A -- I think you're smart
to think through the idea in the first place! 3/4" thick steel
plate would be a great upgrade, if you can afford it. There really isn't
that much more "value added" by going to the 1" plate.
Instead I would strongly recommend you spend the money on having the
surface of the table blanchard ground
so it will be a nice, true, surface
while working.
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Q
-- I am going to be buying an oxyacetylene set up. Is there a particular
brand you recommend? I will be using the equiment for automobile repair
and metalwork. I understand that you prefer oxyacetylene for welding
aluminum. Why is this so?
A -- MIG welding is a very good
way to do "patch panel" work, but it is not as versatile as
a gas-welding set up. If you are looking for a set you can learn with
and be able to do a very wide variety of things, oxyacetelene is the
way to go. We prefer to gas-weld aluminum because it doesn't work harden
the weld area. One of the many benefits of this process is that the
area surrounding the weld gets annealed by the relatively slow heat
up / cool down process. Gas-welding can be an effective way of joining
steel body work. As with any other technique, this skill is acquired
by practice, and you must be willing to invest some time practicing
this method.
As far as the brand of torch, we highly recommend the Victor as it is
a national standard and parts will surely be available if needed. For
a general overview of welding practices and applications, check out
the book "Welders Handbook"
by Richard Finch.
Q
-- I am trying to find Greenlee knockout hole punches. Do you know who
carries them?
A -- As a matter of fact we do!
One of our favorite suppliers, Irvan-Smith Inc., carries this handy
race and custom car tool. Follow this link to the page on their website
that details the specialized punch options they offer: Greenlee
Punches
Q
-- I
am in the process of restoring a '67 Shelby built Trans-am Coupe. I
have to re-form (flare) the steel fenders to cover the additional width
of the wheels and tires. I have standard autobody hammers and dollies,
but I am sure I will need a shot bag (size?) and maybe some slappers
and mallets. I know that starting with the proper tools and knowledge
will greatly increase my learning curve. Do you have tool suggestions
you could offer for my situation?
A -- Given your
project and interests, here is a list of suggestions to consider:
Q
-- I
purchased your Metal Fabricator's Handbook and have read it from cover
to cover. I don't have all the power tools you have but I do have welding
capability some body hammers and dollies. I am restoring a 1934 Ford
and have managed to find myself with an oil can in the left cowl side
outer panel. I tried using a shrinking hammer (one that twists when
it impacts the metal) both with a steel dolly and a wood dolly. So far
I have not been successful in removing the oil can. I also tried some
heat with a water quenching but that was unsuccessful also. I know that
the metal needs to be shrunk but, so far, I have not been able figure
out how to do it with hand tools. Is it possible to do with hand tools?
A -- The heat shrinking technique
should allow you to successfully shrink out the extra metal -- that
is, if you are doing it properly. I have used this technique time and
time again to take out "oil cans" / extra metal. The technique works
best when you have a helper to work with you. By having an extra person,
you can heat the spot to be shrunk and quickly hand the torch to your
helper. The dime-size spot that you heat to dull orange must be tapped
back into itself with a flat hammer while holding a flat dolly directly
below it. Then it should be quenched with cold water immediately. Be
sure the entire part is cool to the touch in between each "shrink".
Do not allow the part to build up any heat.
Several of
these 'shrinks' can be executed along the area or line that requires
shrinking. Always do new 'shrinks', never one over another. I have found
that the metal used in '30s Fords reacts very favorably to this kind
of shrinking because of its thickness and low temper. You should try
again, but not before a little practice. It's a good idea to practice
the technique on scrap metal before working the car. Remember to hand
the torch off quickly to your helper so the raised, heated spot can
be struck while it's still glowing.
If you want to improve the surface further, a quick way to find trouble spots
(highs and lows) is to use layout die on the surface and then lightly
file the surface to locate the trouble spots. Use a flat dolly and a
soft face hammer to lower the high spots. Use a bullseye
pick to raise the low spots. As a final step, some additional filing
or sanding will further improve the surface, but be sure not to overdo
this final step, as it can result in thinning of the metal. Good luck!
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Q -- I have a shrinker/stretcher (similar to
the US Industrial Tool part #TP395)
with a 7" reach. When bending a curve at a 90 degree angle, what is
the proper method to use when the flange to be shrunk is more than two
inches wide?
A
-- When shrinking more than two inches of metal, the
shrinking pattern should be in and out, rather than right to left.
Remember, It is important to concentrate the shrinking process toward
the outer edge of the metal. More shrinking needs to take place at the
edge, due to the depth of the metal.
Q -- When making a wood buck, do you
ever screw it together rather than using wood glue and nails?
A -- Using screws to assemble a buck is an acceptable
method, as long as you use plenty of attachment points. You must have
enough attachment points so that the buck remains very rigid. If the
buck flexes at all, the finished part will be less accurate. A common
way to assemble a wooden buck with screws is to use small, 90 degree
metal strips at the joints. This method is very effective at achieving
rigidity. Using screws to assemble a buck also allows you to easily
disassemble it for storage and shipping. Bucks that can be disassembled
are very practical when building a part with a right and left side, like
a fender. Just reassemble the buck to fabricate the opposite side!
Q -- I recently purchased a used
shrinker/stretcher set. It has a 1" reach and is the bench mounted
version. The shrinker does not work very well and I am wondering if you
have suggestions on how to improve its performance.
A -- What comes to mind first is the possibility that the
shrinker jaws are either dirty or worn out. First, try cleaning them
with a stiff-bristled stainless steel wire brush. After you've cleaned
them, feel the serrations with your finger. They should be sharp. If
they aren't, they're probably just worn out. If cleaning doesn't improve
the machine's performance, you should consider buying new replacement
jaws. They are moderately priced and many companies stock them,
including Mittler Brothers Machine
and Tool. Their replacements jaws run $75 for shrinker or stretcher.
Q -- What
alloy of aluminum should I use for a water surge tank?
A -- A water surge tank must be made of a durable alloy.
I recommend 3003 H14 alloy, 0.050" thick. This kind of tank has
internal pressure and the aluminum must be tough, yet formable. It's
also important that the alloy be easy to weld. 3003 H14 aluminum fits
all these requirements, and I use it frequently.
Q
-- Does aluminum welding flux spoil easily?
A -- We assume you are asking about flux that has been
mixed with water for use. Unmixed aluminum flux powder will not spoil
and has a very long shelf life, if kept clean and dry. It's important to
keep the lid of the container tightly sealed. Don't re-use flux that has
been contaminated by standing out in an open container. We make it a
habit to discard any unused flux at the end of the work day. By the way,
you must never use a metal brush with aluminum flux mixture. The flux is
corrosive and will pick up some of the metal, causing an adverse
chemical reaction in the mixture.
All contents of this page copyright
Fournier Enterprises 2003
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