Hmm, didn't get any responses the first time ... not sure if the post didn't
go out, or didn't generate any interest! Here's my second try:
I'm needing to build a pickup truck rack; nothing too heavy duty; it is
mostly for carrying a canoe, maybe the occasional small load of wood or
steel. Probably 200-300 lbs. max.
I happen to have lots of bedframe angle iron, around 1/10" thick, in various
widths ... I've done a little experimenting joining two pieces of angle to
make a tube, as my ascii graphics below attempt to show: * _______
The asterisks show where the welds are made. I clamp the two pieces together
to make the tube, and then grind out a vee to allow full penetration. I've
welded the pieces together with 3/32" 6011 running at 65 amps; this seems to
work pretty well, giving a completely fused weld, which I can grind down to
create what appears to be a smooth rectangular tube.
What do you think -- would such a tube be sufficiently strong to make some
or all parts of my rack? Would I use up more money in welding rod than I
would just buying some steel tubing? (It takes about one 3/32" rod to run 6"
of the weld, filling in the vee groove completely.) Is there any reason I
would want to use a different rod to do this?
If your time means anything - buy tube.
If you do keep going, you do not need a continuous weld.
Continuous will create tremendous warping.
Keep the whole world singing . . . .
DanG (remove the sevens)
duty; it is
thick, in various
of angle to
this seems to
grind down to
rod than I
rod to run 6"
Thanks for the response ... but I still have the same questions. Are
you recommending buying new because it would be cheaper? Are you
recommending buying new because it would be faster? (Obviously it
would ... but welding is a hobby, so the welding itself is fun, not
just the completed project.) Are you recommending buying new because
there are safety or other structural problems with making tube this
way/from this material?
Dan, thanks for the response. You raise an interesting question for
someone whose welding is strictly a hobby. Does my time mean anything?
Obviously if I were making a truck rack for income, it would be
ridiculous to trade several hours of labor for a material savings of
maybe $20-30. (But then again, if I were worried about the time/money
equation, I wouldn't be making the truck rack in the first place; I'd
simply buy one.)
Welding is, for me, strictly a hobby -- a way to spend time relaxing
from the stresses of my real job, doing something creative with my
hands, just enjoying the time making sparks ... trying to improve my
technique, trying to make good, strong, useful things, but absolutely
not trying to make any money at all. (The last time that I accepted
money for doing something that I do as a hobby -- in that case,
woodworking rather than metalworking -- it nearly ruined the hobby for
So, for me the equations work out this way: Time spent welding = time
enjoying my hobby. Money saved on buying tube = money I can put into
this or other hobbies. However, if money spent on rod > money saved on
tube, then I lose some money that I could be spending on hobbies. (My
wife keeps me on a strict hobby budget ... or rather, we keep each
other on strict hobby budgets :) And of course, if in the end the
pickup truck rack that I build proves unsafe and hurts someone, then
no matter how much I enjoyed the welding or how much money I saved
over buying tube, it was not worth it!
So here are the questions I'm trying to answer:
1) Am I likely to spend more on welding rod than I save over buying
tube? (I should be able to answer this question once I get back a
quote on some tube, and count how many rods are in a box ... but I
thought maybe someone would have experience or instinct that would
allow a quick answer.)
2) Is the resulting tubing going to be sufficiently strong for my
pickup rack? Issues here include the original material -- bedframe
angle, 1/10" thick; brittleness or other factors introduced by the
welding; perhaps a better choice of rod; anything else I haven't
Your point about warping is well taken; I had given some thought to
that. I would prefer to have a fully continuous seam, in order to keep
water out (I don't want it rusting away on the inside where I can't
see it!), but knew that just running a weld from one end to the other
would be disastrous. However, what about running stitches of 2-3",
spaced a few inches apart, then coming back and doing another stitch
to fill in some of the gap, and so on -- would that keep the warping
down? Or, hmmm -- what if I did a full-penetration weld (vee-grooving,
etc.) only say 2" out of 6", and just did a butt-joint weld elsewhere
-- enough to keep water out, but saving some rod and putting less heat
into the tube ... ?
Perhaps I should add that the longest piece of "tubing" that I would
expect to make this way would be 5' -- I don't have any bedframe angle
any longer than that. I figure that I could make the uprights and the
side-to-side crossbars this way, but I'll *have* to buy some tube to
get enough length for the front-to-back crossbars. (So, yeah, instead
of buying two 20' lengths of tube, I'll only buy one -- definitely not
saving a whole lot of money, but if I save any, then I'm ahead based
on the equations of the hobby :)
Thanks again for the input; keep it coming -- this will help me think
through this project!
I am a beginner welder and don't have much experience in this field yet, but
as a former auto mechanic and home owner, I think I have fixed and built
enough stuff to answer this question.
You will be building something that will be supporting potentially dangerous
items if they fall from said support structure while in motion. You could
cause someone serious injury or death.
Now, if you were that person, the one riding behind your structure at 55
MPH, what type of material would you want it made from?
Buy New, and weld it together with every weld being your very best.
Weld the bedframe together for practice or for use in some stationary
Just my 2 cents worth of common sense.
I am a hobby weldor. My 2c: For a project such as this, buy new steel
_tube_ or, if you can get enough _tube_ for the complete job at your local
metal salvage yard, that would be okay too so long as you can get all you
need and it is clean of major rust and paint.
Why new? 1. Bedframe metal is typically made from scrap with very little
metallurgical control on the resultant angle iron. Consequently, there are
often sections where the steel is more like high carbon steel than mild
steel (i.e., you can get significant brittle sections--made worse by
welding--which would be awful for a safety-critical weldment such as truck
racks). 2. Most of the bedframe stuff I've seen (and used myself for some
simple projects) is painted. I hate to work with something that already has
paint on it because it increases the metal prep time. Angle iron sucks in
this regard because it's tough to get all the paint off the inside of the
angle. 3. Unless you got a load of bed angle from the same manufacturer,
it will have all different dimensions. On a large job like a truck rack I
would hate to deal with all the fitting problems. 4. I love welding as a
hobby but, making tube from angle just sounds tedious to me and, this added
to all the other issues simply adds up to the beauty of getting new steel
for this type of job. Don't get me wrong, I use a _lot_ of scrap/used steel
for my projects but for something like this I personally would only use new
BTW, rebar is also made from scrap with little interest in controlling the
uniformity of the output (i.e., cannot be counted on to be uniformly mild
steel and, therefore, should not be used for safety-critical projects).
Have fun and best wishes,
Well, if you cost your time and materials yes.
Structurally it will be banana shaped.
Look at it this way: if you buy new tube, you can weld up this neat
project double quick and get to use it. Then you can make something
else: you will have a pile of rods left that you didn't use up, and lots
of cool offcuts of RHS to make something else with !!
In the UK I can buy a 21 ft length of 2" x 2" x 1/8" RHS for around
First, the safety issue. You have decided to build a welded rack, so be
sure you know how to weld. If you feel you are good enough to join
purchased steel materials, then go ahead. I, personally, don't trust my own
welding enough to do critical welds (where failure could be disastrous.) So
I always design in enough redundancy to eliminate the problem.
Second, the question about "manufacturing" your own tubing. I suggest that
you look at your design, and try to build it as much as possible out of
angle iron. It doesn't HAVE to be tubing throughout. You will eliminate
the problem of water leaking inside and causing rust, and all that
distortion that is so hard to control.
A rack made of both purchased tubing and the angle iron you now have will
probably look good, and be lighter.
I predict that if you start making up tubing out of your bed rails, you will
end up wasting a lot of time and materials, and will end up buying more
material. Just my 1 1/2 cents worth.
An old friend of mine used to say, "You can't make ice cream out of
horseshit." You can, actually, but the result will not be satisfying
to anybody. That's how I feel about "saving" by welding angles into
tubes. Can you do it? Sure. But down that path lies building a
direct reduction steel plant in your back yard to save gas on trips to
the steel distributor.
As far as whether it would work or not in practice, I'd have to see
the design for your truck rack. Where and how you plan to use the bed
frame material -- and how the loads will be borne -- makes all the
difference. I would be glad to look at and comment on a plan if you
have one that's email-able.
If you try to make full seam welds, chances are you are going to use
close to the same amount of rod as the tube would cost you(cost-wise).
Steel is still pretty cheap.
Probably, if you do a good job welding. In reality, you are going to
end up with a stress area somewhere, and you will crack/break
something(probably at the most inopportune moment). Your welds(and
the HAZ) are going to very brittle. A lot of this will depend on what
type of loading you put on your tube(compressive, bending, etc).
I would actually question if you need to weld these into a tube. With
proper construction, I would think you could leave as is and build the
structure. This would save you time and money. Everything would be
open eliminating the rust concern. Years back, Dad and I built a
canoe rack with open angle iron and it worked very well. It was a
double wide rack so that we could carry two canoes at the same time(a
third could be laid in the bed if need be).
Doug, your point about safety is well taken (and I share it
wholeheartedly) ... but let's take it a step further. Some of the
commercially produced racks I've seen appear to be made of something
like .065" thick tubing. If I buy new tubing, .065" thick, and weld it
up, am I going to get something stronger and safer than making my own
tubing, .1" thick? Why or why not? I'm asking seriously, not trying to
be flip; part of what I'm getting at is whether commercially made
tubing is necessarily stronger than homemade, and if so, why. Would a
heavier thickness in the homemade compensate for the possibility of
some imperfections in the seam? Does the commercial tubing have a
different geometry in the corners than I can get by welding together
Of course, any rack, whether commercial or homemade, has loading
limits beyond which it would be unsafe. The normal load that I
anticipate carrying is < 100 lbs.; the maximum that I would plan for
would be 200-300 lbs. (Even with 100 lbs., I think I'll be more
worried about center of gravity and stability of the truck than about
the rack itself.) My goal, whatever material I use, is to try to
over-engineer it so that it will always have a large margin of safety.
Obviously, just buying new material will not automatically guarantee
such a margin of safety; not only does the material need to be
sufficiently thick / strong, but also the design needs to be such that
one single weld failure does not result in the whole shebang coming
down. (I'm still interested in seeing plans or pictures, if anyone
else has built a rack :)
Truth to tell, with some of the racks I've seen, I'm more worried
about the bolts through the thin sheet metal of the truck body than I
am about the rack itself. :)
I guess the answer to your question is, I might rather be behind a
rack that I've made out of bedframe, well and over-engineered, than
behind a commercial rack that attempts to squeeze out the highest load
limits from the least amount of actual steel. After all, bedframe
material is used to support 200, 300, 400 lbs. or more every night!
Again, I appreciate the input, and the chance to dialogue and think
through this. A disclaimer: though I probably appear to be taking a
hard-nosed, I'm-going-to-do-it-regardless attitude, that is actually
not my intention. I have no great objection to spending the money for
new tubing (though I don't mind saving the money either, if it really
is a savings vs. the cost of rod), and certainly may wind up going
that way. However, so far the negative responses have not really given
a reason why they are negative beyond the assumption that new is
better, so I'm arguing the other side in order to try to push beyond
that assumption :)
.> BTW, rebar is also made from scrap with little interest in controlling
I cringe a little everytime I hear this one repeated.
All grades of rebar are weldable with the proper procedure.
If a lot of welding is intended, A706 or Multi grade A706/A616 will usually
A615, A616 and A617 require more care (preheat, postheat, ect.) but are
AWS D1.4, welding code for rebar, goes into the subject in great detail if
anyone is interested.
Southern California (a high seismic area) probably has more rebar certified
welders than most locales. But they are everywhere.
Your friendly local Ironworkers or Pile Drivers welding school's are testing
and turning them out as we speak.
I don't think so.I'm not an expert on rebar specs but my understanding is
that carbon content can be pretty high in some grades.
I'm also not suggesting that home garage welders go down to Home Depot and
buy rebar to weld important stuff out of.
Just that reinforcing bars are not the "mystery meat" a lot of people make
it out to be, and that it's welded by the freight car load in a lot of
I've heard structural engineers, who haven't any experience with welded
rebar, argue strongly that it can't be, never has been, and isn't done. A
copy of the AWS D1.4 code book is all it takes to "show them the light" : )
The specs on standard grade 40 and 60 rebar do have a very high carbon
content, that is how they get the tensile strength. This does have bad
effects on many other properties, such as welding. The weldable bars
mentioned are closer to regular steel in bar form.
We weld standard dumb rebar a fair bit - use it for temporary sway bracing
and beam bracing in falsework, for example.
You can't just compare one steel hunk to another.
Your bedframe steel is (at best) 36KSI yield, with lots of carbon and plenty
of impurities to make it brittle, reduce the toughness and so on.
At least in the US, rectangular formed tubes conform to A500-B, which has a
yield strength of 46ksi. These bought tubes will not have residual stresses
trying to warp them out of shape.
As for the geometry, yes it is different.
Your tubing will have seams at opposite angles. Shrinkage across the welds
there can cause the cross setion to twist or to flatten out as if you took
two opposing corners and pushed them together.
Commercial tubing has one seam in the middle of a side. This is symmetric,
and any shrinkage will cause one side to shorten, but leaving the top and
Everything else aside, it's a tested and true configuration, known to work.
Your new geometry adds a little more risk. It all adds up.
A trailer, especially a small one, is a high impact weldment - bouncing
around and such. The crappy bedframe steel will not have toughness,
expecially after you weld it all up. Toughness measures resistance to
Reduced toughness will cause your trailer to snap sooner, rather than just
bend way out of shape. Bending out of shape is prefered, since you get to
see the problem before it is too late.
Yet, in an unwelded condition with supports and designed connections.
As an engineer, homegrown trailers scare me. Let's break down the risks:
1) Faulty Design
2) Poor Materials
3) Poor Workmanship
In general, Workmanship comes with lots of experience. During that
experience, you see the types of materials used and the typical design
details and processes.
In defense of homegrown trailers, many (most?) are done very well. If the
weldor has years of experience, the risks of faulty design and poor
materials can be reduced since he can tell when it 'just dosen't smell
Most of the rebar sold through the secondary suppliers as well as retail
suppliers (Home Depot, etc) is indeed 'mystery meat' The only spec on
the normally available C40 and C60 grades is 40kpsi and 60kpsi. Actual
carbon content can vary a lot but commonly runs in the .4% to .6% range.
These numbers are high enough to preclude quick weld joints. The rest of
the 'good' components like Manganese and the bad stuff like silicon are
not controlled to particularly tight tolerances. None of this makes for
consistent welding. I do a demo where I weld samples of 1/2" bar and
quench them after most of the red disappears. The whole weld area will
commonly shatter like glass when dropped from shoulder height.
The better grades of bar are more tightly controlled, if the specs say
they can be welded, have at it.
The local Northstar steel plant makes this stuff by the 30 ton ladle.
Quite impressive to watch them melting, pouring, and rolling rebar.
The bed iron tends to be very hard and brittle, feels like it is .4%
carbon range. The HAZ is likely to be quite nasty. This translates to a
much lower fatigue resistance for the welded up angle iron compared to
I'd suggest using new tube of whatever thickness you need. My local
supplier sells 10' lengths of the common sizes for around $.55 a pound,
take your choice.
New stuff also has the advantage of clean, no paint, no rust, long
lengths, all those nice things!
Andrew H. Wakefield wrote:
I would box it up leaving the edges to form a small vee for your weld. Weld
up your angle in lengths running a one inch weld every six inches along the
Now that you have you "tubing" cut it to the lengths you need. I would
weld at the corners of your structure so that there is a continuous weld at
least four inches from every connection of the tubing.
Since you figure your load is maximum of 300 put a six hundred pound
static load on it then pull and twist it to see if you have any permanent
deformation. You are looking for it to bend. Those are the areas you will
need to reinforce.
Paint your rack with a good quality enamel. Regularly look for failure
of the paint film which will indicate cracking or deformation during