Weld prep 3/8", 1/2" plate ?

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I've worked mostly with thin stuff like square tubing, sheet metal etc, up to 1/8" thick with the occational 1/4" or so. And most of this stuff doesn't require much of a bevel or anything like that and when needed I've just used my gut feeling on what to do.Working with thicker stuff like 3/8" plate or 1/2" plate I feel that I need to know a bit more. Are there any rule of thumb when it comes to this? Or do you use tables to look this up or is it by experience?I guess for doing code work you have a WPS that specifies what process, weld prep and how it should be done. But what do you do when you don't have that?
Reply:What are you fab ing with it? What type of weld joints?JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720
Reply:3/8” and 1/2” is a little thin in my line of work. Normally when I splice plate, I would put a single 30-degree or 37-degree bevel on each plate. Or a double bevel, (one on each side of the plate). Remember when welding plate like this, back stepping your welds, and skipping around a lot is your friend. Other wise you'll warp the plate. Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:If your job requires full pen welds with this material, you will have to bevel at least one side. I like 37 degrees myself.JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720
Reply:Need some more info, Pete. Joint type, process, machine available, etc.GravelThe difference between theory and practice is that in theory there is no difference.
Reply:Most likely you'll do a close to 45degree bevel if done by eye.  It's good enough, except that it will use more filler, and tend to add to distortion because of the wider gap to fill at the the top of the bevel.  More filler = more distortion.  But it's a good close approximation.  Do something less than 45, and you'll be safe.  (37 degrees if you use a protractor or bevel gauge )In the real world, it's mainly about getting heat to the root.  If you're confident you're getting heat to the root anything in the somewhat 40 degree range is cool.Just remember that a bevel is a means towards good mechanical connection of the adjoining pieces.  It allows the weld filler to cover the full face of the joint."Any day above ground is a good day"http://www.farmersamm.com/
Reply:The other week I welded some plasma cut 3/8" flanges that were going to be machined. I beveled those. So that would be a type of lap joint I guess. I got a little porosity in those welds unfortunately.Now I'm going to do a height extension to raise a lathe about 5". Its going to look a bit like a box so outside corners and tee joints.I use mig when I can but only have access to a 200 Amp machine, 0.030 solidwire ER70S6, C18 gas. Stick also 200 Amps. Also lift tig but only 150 Amps. Also have access to O/A so can preheat if needed.Last edited by Pete.S.; 11-18-2014 at 04:37 AM.
Reply:With C18 are you able to get that machine into spray mode?Tiger Sales:  AHP Distributor    www.tigersalesco.comAHP200x; AHP 160ST; MM350P,  Spoolmatic 30A; Everlast PowerTig 185; Thermal Dynamics 60i plasma.  For Sale:  Cobra Mig 250 w/ Push-pull gun.  Lincoln Wirematic 250
Reply:With the correct joint prep, I wouldn't have any concerns welding 1/2” material with a 200-amp Mig machine. I did a 1/2” side bend test with this Mig machine. Attached ImagesDon’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Originally Posted by soutthpawWith C18 are you able to get that machine into spray mode?
Reply:Originally Posted by CEPWith the correct joint prep, I wouldn't have any concerns welding 1/2” material with a 200-amp Mig machine. I did a 1/2” side bend test with this Mig machine.