Question on butt welding 1/4" steel

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I recently made a stand for my drill press and for the top i got 2 12"x12"x.25" pieces of steel which I wanted to butt weld together to make a 12"x24" plate.  (I have been stick welding now for ~6 months, self taught and am trying to get better).My question is what is the proper gap to have between the 2 plates for doing this type of weld.  When I welded them I gapped them about 1/8" apart and tacked them and then ran a simple stringer with 7018AC at 135A.  I after I finished the weld I flipped them over and noticed that the weld had only penetrated about 3/4 of the way through.Is this to be expected?  Should I have beveled both pieces to make a V and then used the 1/8" gap?I ended up flipping the piece over and then welding another stringer on that side, but I am just curious as to what is the proper way to do this!Since its only to support the weight of my drill press (150lbs) I am not really concerned that the weld is perfect.  But really I am trying to learn all that I can to do things the proper way since i am just a beginner.  I can post some pics that I took tomorrow when I get a chance.Also, another question that I have is that I noticed a slight amount of undercut after I ground the welds off to make the plate flat again.  What is the best way to prevent this? Should I travel slower, move the rod with a slight whip? Really I am trying to pick up as many pointers and tips and tricks as I can so I can improve my welding skills.
Reply:Pick's would really help to see where you are going wrong. Preferably after the slag is cleaned and before it's ground. Undercut usually comes from not staying put long enough to fill.The rest of your settings would help. DC or AC? What size rod? If you gapped the joint a bit more or better yet beveled it, it would be easier to get complete penetration. More amps may also have helped possibly..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:Bevel the joint for full penetration.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:Use 6011 or 6010 for stringer. 7018 is more for fillet and caps. My 2 cents worth.
Reply:On his AC machine, he would use 6011 rather than 6010, as 6010 is a DC rod.A stringer (weld run straight along without weaving) can be done using any type of rod, as can a weave.  A weave is used when more filling or a wider bead is desired in one pass, good for fill and cap passes.  A stringer concentrates the weld along one narrow path, good for root passes, used in fill and cap passes as well. Whipping is the domain of xx10 and xx11, whereas dragging (no forward/back out of puddle action) is acceptable with other rods.A fillet weld (welding t-joints and lap joints) can also be done with any type of rod, as can a groove weld (butt joints and outside corners).A root, fill or cap can be done with any type of rod too.Basicaly, without a written WPS or code to follow, the rod choice is wide open, so long as the filler material is compatible with the base material and it's intended use and the rod is compatible with the operating polarity of the machine being used.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:Originally Posted by ggarnerWhen I welded them I gapped them about 1/8" apart and tacked them and then ran a simple stringer with 7018AC at 135A.  I after I finished the weld I flipped them over and noticed that the weld had only penetrated about 3/4 of the way through.  Is this to be expected?  Should I have beveled both pieces to make a V and then used the 1/8" gap?  I ended up flipping the piece over and then welding another stringer on that side, but I am just curious as to what is the proper way to do this!
Reply:another option you could do is to butt you peices with a small gap, weld on one side with 6011 or 7018AC, then flip it over and grind right down the center of the peices. grind all the way down until there is no slag inclusions, just clean metal. then fill will with 7018AC all the out. i've done this before and works great. you could carbon ark it too, but it doesnt get out the slag, so you would have to grind after too. this is what i do when i do this and  when i do this i run 7018 on both sides. its not that common to do this way, but there have been occasions when this is the best option
Reply:First off, thanks for all of the suggestions and the in depth explanations.  It sounds like to me I would have been best off to either do a single bevel or a dual bevel for the best results.  I will have to remember this for the next time that something like this comes up.One thing that I was happy about is that I did not notice any porosity at the startup.  I followed a suggestion that I got in another thread about striking my arc about an inch in front of where i wanted to start welding and then moving back to my starting position.I have some 3/16 6011 rod, and am now wondering if I had used that would I have wanted to whip that rod (my understand is that with that rod you need to do a fair amount or rod manipulation) or would I keep it pretty static as i traveled along. I have only used that rod a few times laying down beads on top of a steel plate.Here are the photos: Also I forgot to mention that i was using 1/8" rod with a 225A AC buzz boxThe gap before welding:Starting to weld:Continuing on:Almost finished:After grinding:You can now see the areas where there was a slight undercut Last edited by ggarner; 07-02-2010 at 05:10 PM.
Reply:Might as well post pics of the frame as well to see if there are any major problems with the welds on it.Here is the lower leg support, basically just to keep the legs straight.  This was done with 3/16" 6013 @ 120A or something around there if i remember correctlyThe frame of the stand:Here are the adjustable feet that I put on.  3/8" nuts and bolts.  The nut was welded in place and then the second nut is used to lock the bolt in placeLast edited by ggarner; 07-02-2010 at 05:05 PM.
Reply:I would just flip the piece and grind out the back side down to clean weld metal like Hammerwelder suggested. I would have also used about 10 more amps when welding plate this way for more penetration.Yeah, you can whip 6011 but you can also drag it just fine, especially in the flat position and get a pretty smooth bead doing it that way too. 6011 is a very versatile and forgiving rod, uphill it, downhill it, whip it, drag it, weave it, make circles, shoestring lace it, it will do it all.