Joint preparation and welding; mitre cut vs notched joint in angle iron

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Hi allI've heard it said that a notched joint stays squarer with less distortion when you weld it than a mitre cut joint.The picture below is of different ways to prepare a notched 90 degree joint:In the plan views further below of the top and underside of a square frame, the holes identify which joint:a) Diamond to blank is vee'd underneath and is easiest to align for weldingb) Blank to circle is has gaps to get good penetration but has got to be hard to align before weldingc) Circle to Triangle is a mix of a) and b) d) Triangle to diamond has no preparation - I realise this is no good, but couldn't think of any other variationsThe gaps are drawn at an arbitrary 1/8" and the vee's drawn1/8" deep which may not be the best for either.My questions are:1) Is it actually true that the notched joint stays squarer than a mitre cut joint when being welded?2) Which (if any) is the best way to prepare the joint and why? 3) Where would you tack it, and then what order/direction would you weld each part of that joint in, to be most distortion free and stay square?Thanks - jv
Reply:Seems to me like this type of joint would require more cutting, more welding , more filler material and require more time all together.  with more welding would come more heat and as I understand it heat is what causes most concern when worrying about warping.  Interested to see what others have to say.Lincoln, ESAB, Thermal Dynamics, Victor, Miller, Dewalt, Makita, Kalamzoo.  Hand tools, power tools, welding and cutting tools.
Reply:What you are talking about is a coped joint. Copes often allow a bit more adjustment when setting up vs miters. Mitered joints are off 2x the saw error. so if your saw cuts 42 deg instead of 45 deg, your corner is automatically out 6 deg ( 3 deg error times 2) if you hold a constant gap/tight fit. On a  miter, it's a bit easier to make small adjustments to jig up square and not create huge gaps.The other thing on pulling welds is that some times you have to "over compensate" when jigging up so the welds pull straight. This can get back to the issue with miscut angles. If your cut is already 6 deg off to get to 90 deg just sitting there, and you need to add say 3 deg more to allow for shrinkage of the weld, this can cause you to have a very wide gap. 2nd thing is how the metal pulls. In a coped joint it's possible to have the welds pull parallel. to the material as it shrinks if you choose to weld in the correct order. Shrinkage this way distorts the angle less than on miters..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Originally Posted by N2 Weldingwith more welding would come more heat and as I understand it heat is what causes most concern when worrying about warping.
Reply:A picture of how mitred angle iron joints warps during welding, and in what direction based on direction of the weld. They recommend the notched joint as it warps less (no explaination why). From a 1937 welding handbook.
Reply:I see and stand corrected.  Thank you Lincoln, ESAB, Thermal Dynamics, Victor, Miller, Dewalt, Makita, Kalamzoo.  Hand tools, power tools, welding and cutting tools.
Reply:Originally Posted by G-sonA picture of how mitred angle iron joints warps during welding, and in what direction based on direction of the weld. They recommend the notched joint as it warps less (no explaination why). From a 1937 welding handbook.
Reply:I made many of angle brackets without cutting separate pieces. We used to layout the corners and cut a 45 to left and right and right of center , heat and bend. It took some thinking and practice but worked fine. Some jobs required brackets to be made from a continuous piece of angle.   I do both depending on what the finish piece will look like. Personally like to cope the joint.
Reply:Originally Posted by BD1I made many of angle brackets without cutting separate pieces. We used to layout the corners and cut a 45 to left and right and right of center , heat and bend. It took some thinking and practice but worked fine. Some jobs required brackets to be made from a continuous piece of angle.   I do both depending on what the finish piece will look like. Personally like to cope the joint.
Reply:[QUOTE=JasonPAtkins;7346341]That's what the Roper does, but without the need for heat (up to 2"x.25" thick angle), or having to lay out the 45's. Another awesome advantage of that method: no sharp outside edge to have to blend.I tried to buy one from craigs list . I called about it and left message said I want to come and buy it. It was CHEAP too, $100.00 and posted about a hour. Guy didn't call so I called again and was told it was now $400.00   .I guess he got so many calls he raised the price. I didn't want it that bad.
Reply:[QUOTE=BD1;7346551] Originally Posted by JasonPAtkinsThat's what the Roper does, but without the need for heat (up to 2"x.25" thick angle), or having to lay out the 45's. Another awesome advantage of that method: no sharp outside edge to have to blend.I tried to buy one from craigs list . I called about it and left message said I want to come and buy it. It was CHEAP too, $100.00 and posted about a hour. Guy didn't call so I called again and was told it was now $400.00   .I guess he got so many calls he raised the price. I didn't want it that bad.
Reply:Originally Posted by JasonPAtkinsI weld that joint a lot, and if you back step the weld, you can all but eliminate the movement.Also, I don't know if the existence of this tool is common knowledge, but if you do many angle iron frames/rectangles, one of these tools is totally indispensable.http://www.roperwhitney.com/combination-angle-iron.html