welding C channel and rect tubing

It was noted on this forum that C channel should not be welded vertically. What is the maximum angle at which it can be welded , assuming horizontal (along side lengthwise) is 0 and vertical is 90. Does the same apply to rectangular tubing and/or boxed C- channel? What about welding on the top/bottom of C? Is is also only parallel to the length and not across? If welding a piece to the end (across at right angle) of a C channel I assume all 3 edges would be welded , 4 in the case of tubing? Thanks

Reply to
Ken Hilson
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There are all kinds of channel shaped material. If you are using structural channel which is rolled in a mill it is just mild steel, it can be welded anywhere you wish. Structural channel comes in nominal sizes commonly starting at three inch and exceeding fifteen inches . Channel shapes that have been formed out of flat material can be unknown compositions and often they are low alloy steels. An example is the formed channel that is used for truck frame rails. Often you will see decals on the truck frames; " Do Not Weld or Drill on Flanges" When you run a weld joint on a diagonal it is because you want to avoid a stress riser or stress concentration when the member flexes. If the channel is not being flexed hundreds of thousands or millions of times as it travels down a roadway you can generally ignore this concern. Can you be more specific about your application? Identify the kind of channel section and where it will be used. Randy

Reply to
Randy Zimmerman


I generally read all your posts even when I'm not particularly interested in the topic. And I've never read a single one that wasn't a masterpiece of lean, mean, spot-on informative welding erudition.

Except for a few hundred extra calories of good humor.

P.S. We just got home with my latest 4 wheel acquisition. A 1982 Volksie diesel wabbit. A hundred abdullahs! Is this a great country, or what?

Woo hoo!


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"Vernon" wrote

The United States is the only country where you can put a two thousand dollar set of tires and wheels and a three thousand dollar stereo in a hunnert dollar car.


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So exactly how many Rabbits have you owned in your lifetime???? Own up now! At seventy a barrel on the horizon...... Hmmmm If anyone has any inclination to make money the place to be is Northern Alberta in the Tar Sands. Welders, heavy duty, open pit operators. Fast food people are making ten an hour and a cross word from a supervisor, they are gone. Randy

Reply to
Randy Zimmerman

You about answered it. Application is car frame , model a , boxed plus structural rectangular addons, specifically placing a 2x3 rectangular on top boxed frame rail for kickup with fishplates on side of this so assume keep fish plates welds on horizontal only . Curious about the no drill on the track flanges as the model a has many body mounting holes in the top flange or were they made by process other than drilling finished channel? Also seems to be standard practice to V-notch the flanges and draw channel in to narrow the rear and weld closed notch and of course box it.

Reply to
Ken Hilson

Well, let's see. Randy, I don't think I can count that high!

But I'll try. Let's see if I can remember where I left 'em...

Diesels. An '82 four door. An '81 two door. An '80 two door. An '83 pickup. An '83 jetta. An '84 golf. The "new" '82 four door. An '82 Quantum 2 door sedan; An '83 Quantum station wagon; An '84 Quantum "Syncro" station wagon (has nearly 500K on the clock!);

Gassers. An '82 rabbit 2 door; An '83 rabbit GTI (my son's first car!); An '83 Cabriolet convertible (my second son's first car to be);

I think that's all of the "A1" rabbits or similar and perhaps an A2 or two. Some of the above are wrecked or otherwise just scrap metal on wheels. Some of 'em, while they're not on the road at the moment for one reason or another are in various stages of running order. Several of the "runners" have well over 200k miles on 'em. The king of the high milers is the Quantum Syncro.

During the early 80s oil crunch both VW and all the Japanese manufacturers came out with small diesel automobiles. People lined up to buy 'em and paid an extra grand or more for the diesel option.

Another year or two later people lined up to sell 'em. They took a grand or three less for 'em just to get rid of 'em. Only VW continued to market small diesels.

The car I just bought sat in a field for nearly 10 years. When we opened the hood we were greeted by a wood rat's nest SO BIG that you literally could not see anything in the engine bay except the top edge of the air filter box. Yet the car still has significant traces of that "new car" look, if not the smell!

On the way home we stopped at a car wash and I blasted out the rat's nest. This car shows 118K on the ticker. Of course it may have broken

800K miles ago. But the signs make me believe that's the original mileage.

I started driving these cars in the early 90s when we moved to a small Texas town (Brenham) about 80 miles from my job (Houston). Except for the pickup, which has nearly 300K on its original engine, all of these cars have reliably delivered not less than 42 miles per gallon. Provided you change the timing belt and water pump every 50K miles, don't let the engine overheat for any reason, and change the oil with reasonable frequency, they are capable of from 400 to 500K miles between rebuilds.

I've never found a car more effortless to drive. Once, on a late night trip on Interstate Highway 10 west between Houston and San Antonio I drove nearly 110 miles without touching the steering wheel. The car had the slightest tendency to drift to the right.

Whenever it did so I would roll down the window and stick out my hand. This would feather the car back onto a straight track. Whenever I'd come to a curve I'd stick a canoe paddle out the window. By "feathering my oars" I could navigate the curve. I finally got bored doing it.

But probably the only worse car to be driving during in a wreck would be a Volksie beetle or perhaps an MG midget.

Due to these safety issues I had a brief, and similarly intense fling with Mercedes Benz diesels, also from the early 80s, these being the famed "240Ds". While one of the safest cars ever made the 240D is perhaps also the pokiest. For that reason, although my wife and kids continue to drive the Benzes I'm beginning to cast loving glances back toward the rabbits. The rabbit diesels will run circles around a 240D.

My son's gasser rabbit GTI is downright exhilarating to drive. His GTI is white. I plan to get him customized plates if they're available:

ML8 ML8 ML8! (for a very important date!).

Welding content. I'm gonna have to do some mig welding to repair some slight rust damage on some of these.

Welder Wabbit

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The cautions about welding across the frame come from dealing with the HAZ (Heat Affected Zone) If you weld a piece of steel with some reasonable carbon content, there will be an area near the weld that has been heated and cooled rapidly. The weld itself cools more slowly, the area away from the weld never gets to the critical temp. This means that you have a band of hardened steel just outside the weld area that concetrates the stesses you see in a vehicle frame. Result is that is fractures next to the weld some time in the future.

The big truck frames are formed and riveted or welded together, then the entire frame is heat treated. Welding is obviously a no no, drilling may cause a stress concetration that the mfg does not want to deal with. ie no warranty.

You can deal with it by various tricks: going diagonally (moves the stresses to much larger area) , preheating the weld area, big fish plates, annealing the whole area, using low carbon steel in the first place, etc.

Sounds like you are do> You about answered it. Application is car frame , model a , boxed plus

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Reply to
Ken Hilson

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