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Old 12-30-2012, 08:41 AM   #1254
9Dave's Avatar
Joined: Aug 2005
Location: Central Ohio
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So with all of the discussion on the size and placement of welds, I dug out "The Procedure Handbook of Arc Welding" from the JF Lincoln Foundation. I bought it when I was there for my class. I know, I risk losing "guy points" by actually reading directions, but hey, they use this in their extended class, so I figured there must be some good information in here somewhere.

In designing a full strength joint, both weld placement and size are variables to deal with. They have this handy table of recommended weld sizes

and this one to describe what the finished weld, the "w" variable looks like

There is all sorts of discussions of cost/benefit of bevel joints vs. fillet welds, etc. - but we are basically dealing with fillet welds here.

So what it says, is that assuming you are getting adequate penetration, and with the 3/16 material you are using for the outer tubes, "w" should equal 1/8", since it is at the minimum. They key is that you are achieving full penetration, which you think you are.

There is a lengthy discussion of designing welds where they talk about overwelding and cost/benefit. Basically, the cost is that you are using too much filler metal, and the there is no additional benefit since you have achieved the desired strength.

For me of course, more is better , and since I am working on small projects, and have huge spools of wire, I don't care about the excess cost. If I were designing and building commercial projects, then I would care because I would be losing money if there was more material being used than required to meet the design specifications.

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