Ok, I've been enrolled in a welding class for some time and doing well based on instructor feedback but have been told by a machine shop that a 3/16's gap was ok to start welding for spring plate gussetts and wanted to get peoples feedback. My skills are more around butt weld and fusing arena. With major concerns for undercut, under penatration, and other problem welding I thought that he was offbase. Anyone have feedback? He said its the best way to weld for strength and maybe if I was a professional welder that it would ok but given my current skills I prefer to use a butt weld or lap.

Butt welds are OK but the best way is gap it or V-notch the joint.



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---------------------- --------------------- Gap


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:D

I would imagine it depends on the thickness, and how much moxie your welder's got. With my holbart 135 (115 volt 20% duty), I like to bevel when it's thicker than 1/8", and when I get up to around 1/4", I gap it also, and probably make two or three passses. Also, I have found that beveled joints are more likely to warp than butt, or gapped joints. If you have access to both sides, beveling from both sides will help stop that.

Kinda on the same subject, I saw some pretty cooling welding yesterday at work. I was watching a crew weld some stop blocks on a large hydraulic actuator, anyway, the weld depth was around 1" they made probably 7 or 8 passes on it, with a 200 amp stick. when they were done, it looked like it was cast into the machine.

the strongest weld is one that penetrates clear thru the parent metal, if you can weld a gap so the welds look good on both sides then it is stronger than if you weld it and have no weld on the backside. this is only really a concern if you can't acess both sides of the weld joint such as tubing.

i prefer usin a


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a over lap..

Double V
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Or when you can only get to one side

single v with a root
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Ugly but strong

lap
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..........Lap ___________
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Weld joint geometry follows common sense to a great degree. If you have the physical space then a lap joint is just as good if not better than a full penetration v-butt that is ground flush. The cross section is the biggest factor along with under-cut which can lead to stress risers (cracks). The butt joint should be set up so that a full penetration Key-hole pass will leave a positive bead on the back side of the plate. 1/8" to 3/16" is about as thick as I would go without beveling. Joint fit up helps but it can be somewhat sloppy if you have good DC welder with electronic "DIG" so you can leave it somewhat cold and drive in the rod to maintain the key-hole. The AC buzz-box will be a pain here. A good wire system will do OK for the root also but I'm old school and prefer stick here. The wire works great for cover.