need help welding 2" mild steel roundbar to 1/4" mild steel

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Hi,i need to weld 2" mild steel round bar to 1/4" steel plate. the bar will go through a hole in the plate. I have a miller 180 auto set and a miller 212 available if i want to borrow it. the problem is my welder is too small and i think the 212 is too small. People say to make multiple passes but i don't think it will be strong with my 180. Can anyone recommend a proper size welder for this job? or is there a specific technique for doing this?thanks in advance for your help.
Reply:You'll def need to preheat the 2'' round bar...bevel the plate edge..  then you could use either mig welder to weld the plate to bar...it really depends on what this is being used for...?? Both machines are more than adequate for 1/4'' plate... can you run beads on both side of the plate??..Lincoln pro mig 180Lincoln Square Wave Tig 300/wp 20/home built water cooler Victor, Purox, Harris, O/A welding/cutting setupsVintage Craftsman drill pressVintage Craftsman/Atlas 12"x 36'' lathe7''x 12'' w/c band saw Everlast 140 st
Reply:I am welding a spindle in my rear bumper for a swing out arm. the spindle will support a hub with bearings and a square tube welded to the side of the hub. similar to this 4x4 labs setup     http://forum.ih8mud.com/az-copper-st...ml#post1936885   If I lean on the attached tubing in the swing out position, i would imagine there would be enough force on the spindle to break a weak weld.yes i can put beads on both sides of the plate.do i preheat to almost red?
Reply:I agree, the spindle would def be the weak point...is solid 2'' bar really necessary??  Could you add gussets to the spindle??Lincoln pro mig 180Lincoln Square Wave Tig 300/wp 20/home built water cooler Victor, Purox, Harris, O/A welding/cutting setupsVintage Craftsman drill pressVintage Craftsman/Atlas 12"x 36'' lathe7''x 12'' w/c band saw Everlast 140 st
Reply:Properly prepped I can't see there being any issue for something like a swing out tire rack if the person doing the welding can do his part. The MM180 maxed out or the MM212 up near max are certainly capable of making a weld that would hold if welded both sides even without preheat. You don't need to get it red hot, 300-400 would work if you wanted to do some preheat. The idea in this case is just to keep the thicker material from sucking out all the heat.If I had a choice, I'd opt to run the MM212 myself, but I'd have no issues welding that up with a MM180. With the bar going thru the plate, I can't see you ripping it out with all the linear inches of weld you would have. It would be a bit different if you were just going to sit the round stock on top of the 1/4" and weld it up. In that case the weld would take all the load. With it going thru the 1/4" plate, you would have to rip the 1/4" plate apart to get the lower weld to fail, especially if the 2" extended any distance thru the 1/4" plate. The upper weld would add to the strength. If you are really concerned about the strength, add a bracket under the 1/4" and have the 2" bar pass thru 2 holes and get welded. A chunk of C channel would make a perfect "bracket". I'd tack the bracket on, then weld the top of the 1/4" 100%, than grind off the tacks and weld the bottom of the 1/4" 100%, then reinstall the bracket and weld the 2" to the bracket and the bracket to the 1/4". Even if you only tacked the 2" in place, you'd have to rip the whole bumper apart to get the piece of 2" to bend out of the welded bracket. The bracket would also help keep things lined up when putting it all together. All this assumes you are capable of making decent welds and not bird poop..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:when you say gussets, do you mean grind vertical grooves into the side around the perimeter? sorry, i'm not a journeyman welder. would this because of the additional welding area?2" spindle probably not necessary, i'm guessing on the size in the photo. i'm starting from scratch. i actually need to locate 2 if you know of where i could buy a couple. it appears to be similar to a wheel hub and spindle with 2 tapered bearings, dust seals and cover.
Reply:i like the bracket idea. this will work fine. I've been at this for a couple of years now and graduated beyond the bird poop stage.
Reply:Thanks for your help. greatly appreciated.
Reply:Depends on how safety critical it is, Meaning, what are the damage consequences if the weld fails?If you consider it safety critical I'd recommend stick welding.
Reply:Just curious why 1/4" and 2" one element of this design is much stronger than the other? If you could up your plate to 3/8" then do a bevel on it one side it would be a much stronger joint.Even as original still do the bevel, do a full penetration root weld, then two pases on top of that. Watch your heat and undercut as the heat effected zone and undercut will make this susceptable to cracking under heavy load on the plate.I followed your link that's a pipe not a solid round?
Reply:Originally Posted by JoshfromsaltlakeDepends on how safety critical it is, Meaning, what are the damage consequences if the weld fails?If you consider it safety critical I'd recommend stick welding.
Reply:Stick welding burns in to metal of unlimited thickness, and you can tell it's doing so. Hardwire mig looks might like it is but sometimes it will break right off the thick piece.Preheat the thick piece in your oven to 400degrees and you'll be fine.Welding/Fab Pics: www.UtahWeld.com
Reply:Originally Posted by fredschromJust curious why 1/4" and 2" one element of this design is much stronger than the other? If you could up your plate to 3/8" then do a bevel on it one side it would be a much stronger joint.Even as original still do the bevel, do a full penetration root weld, then two pases on top of that. Watch your heat and undercut as the heat effected zone and undercut will make this susceptable to cracking under heavy load on the plate.I followed your link that's a pipe not a solid round?
Reply:" why 2"? because the spindle is sized to available tapered bearings. "Wasn't questioning the 2 inch I figured it was for a shaft or pulley, just the plate at 1/4.
Reply:2" OD solid steel bar?  SMAW aka stick.The 180 or the 212 just don't have enough power to melt into that big chunk of steel with short-circuit transfer mode.  You'll just end up with a weld that may look just fine and may have melted/fused/penetrated just fine into the 1/4" plate, but it will be just sitting on top of that thick solid bar of steel.  AKA cold-lap aka inadequate penetration aka inadequate fusion.It's not the weld into the 1/4" plate, but trying to get the weld to actually melt into that big thick solid bar of steel that will be sucking the heat out of the weld PDQ.300-400F preheat?  That's barely warm (for steel).    If I were going to try to GMAW that together, I would go for the 'get it red hot' level of preheat (all plain ordinary low-carbon mild steel) on that big bar.  And I would watch the puddle very closely to make sure I was actually melting a puddle into the solid bar and then 'wash' the puddle (and arc) over onto the 1/4" plate.  If I couldn't get a puddle melting cleanly into the solid bar, then stop with the MIG and go for some stick welding.  Again, getting a puddle into the 2" round bar and then 'washing' the puddle over (and into) the 1/4" plate.I've used some solid-wire GMAW with a 180-class machine in layering up some 1/4 inch thick steel bars about 1" wide to make a 3/4" thick bar out of them (three bars turned into one thicker bar).  First two layers together wasn't too bad (grind a bevel on the edges and run the bead down the V).  But adding that third bar really put some more mass into the metal and I had to rely on either working pretty fast and using the heat from the previous pass(es) as the preheat or putting some more interpass heat in there with a torch and getting the whole mass of steel bars up into the 500F+ range (dark rich blue oxide colors, almost a blue-purple gun blue color).Take your solid 2" OD steel round bar and try to get a puddle going on it with your MIG machine and not just be piling metal on top of the (cold) steel bar.  If you actually can get a puddle melting into that steel bar, great.  If not, preheat the heck out of it and try again.  If you can get a test puddle going on the hot round bar, then you are good to go.  If not, go with the stick welder (or a much bigger MIG machine with spray transfer (like the 250-class machines).  The best laid schemes ... Gang oft agley ...
Reply:Short answer to your problem.....don't use Mig.....use a stick weld and prep it accordingly.....chamfer BOTH sides, top and bottom of the plate, and bottom of the bar.Ian.
Reply:If the end of the spindle sticks a couple inches through the hole and is welded on the end, no problem.  All the weld will be doing is keeping the spindle in the hole.  Wouldn't hurt to warm it up first.My name's not Jim....
Reply:You're fine migging it with the mm212 if you preheat it.The begining of a mig weld is cold and the end is usually hot and washed in. The only difference is the heat of the base metal at the time. When doing a 2G pipe weld for example it becomes increasingly difficult to avoid undercut on the top edge as you fill in your hot passes. The part is usualy left to cool before capping it just to avoid undercut. During the hot passes, the part is only a few hundred degrees but this is when undercut happens. Unsdercut is a good sign that the weld is fusing, all the way out to the very edge of the puddle. A few hundred degrees most definitely matters.2" thick isn't very much if the part is only a few inches long, it's not a plate of unlimited surface area, it's just a small part which can only hold so much heat. A preheat of a few hundred degrees will be just fine; just grind off all milscale so it's shiney metal. Don't grind any grooves, just put in a 1/4" or 5/16" fillet weld to the roundbar on each side of the plate.Last edited by MikeGyver; 09-02-2012 at 07:55 PM.Welding/Fab Pics: www.UtahWeld.com
Reply:Thanks for the help!is there a way to be notified by email of new posts, can't find the option anywhere.