Beginner, filling material gaps

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Hi all.  I've only done a little welding before and wanted advice on two small projects.Material is 1-1/2" wide 1/8" thick mild steel.First fix is to fill a 1/2" hole.  I was thinking of clamping a piece of aluminum to the back side while I fill the hole with weld on the other side.  Or I could make a small disc and weld that in place.The other fix is to cut the material, separate the two halves by about 1/2", and then fill the gap.  Same two solutions come to mind.  I'm not sure of the size of this gap yet, but it will be between 1/4" and 3/4".I only have welding access to one side of the material in both cases.  And I'll be using my Titanium Flux 125 flux-core welder with Lincoln wire.  I do have bar stock to practice on.Any thoughts?
Reply:What is the intended purpose of these 2 small projects as that will most likely determine whether what you want to do is possible?
Reply:Both of the repairs are to the legs of a small, 7 gal, portable compressor.  All metal is in new condition.  I have no doubt the repairs will be strong enough, I just didn't know the proper way to do this.
Reply:In this particular case the easiest way to repair those legs is really to use a mild steel backer  ( instead of the aluminum that you suggested) and weld away. IMHO
Reply:Okay, hadn't thought of that.  I wanted this to look like new, but that works too.  Thanks.Just so I know...Does nobody use a non-weldable backer when filling a hole?  Is aluminum a bad choice?  A piece of copper better?
Reply:Aluminum and copper are both great choices copper being the better one, so you can definitely use those to fill a hole.  The reason I suggested this method is because It would make a much easier repair and less chances of making a weaker repair considering your lack of welding experience ( as stated by you in your opening post).  However if you are looking to experiment and learn something in the process you can try the repair you suggested in your earlier post.  This is a 7 gallon air compressor leg.  If your repair doesn't work out you can just retry again.
Reply:Is copper better than aluminum because of the melting point?  Or does aluminum do something to the weld?  ...I know that steel crucibles affect the quality of the contained melted aluminum, in addition to being less durable than, say, graphite crucibles.
Reply:Best would be a carbon plate, then copper, brass or bronze then aluminum. Aluminum would work if you concentrate on the edges and try not to focus on the center until you've reduced the size of the hole.
Reply:Here's what I'm fixing.  I want to raise the tank about 1/2" to give me enough room for the extended drain that I'm installing.  Even with the current drain valve I have to lift the tank every time to have enough room to operate the valve.  Relocating the axle holes down 1/2" will do the job.  (And fixing the front leg length.)  When I took the wheels off I noticed that one leg was incorrectly welded at the factory.  The bottom piece of metal should be perfectly horizontal and the side piece should be perfectly vertical.  I figured I would fix this since the wheel does contact the ground at an angle.  The other side was done right.  I may not actually need to add metal to fix this part...just cut, bend, and weld. Attached Images
Reply:But Wait,,, you're not planning on welding to the Tank itself - right? I would Not weld on ANY pressure vessel myself, just not worth it...
Reply:Correct, I'm not welding to the tank.I originally thought I would cut the lower horizontal piece and weld in a piece to stretch it out.  But then I realized I could make it easier by cutting where the vertical piece meets the angled upper piece, bend it, and weld.  And this way matches the measurements I took from the other side.Last edited by upand_at_them; 5 Days Ago at 04:19 PM.
Reply:Originally Posted by BaTuBut Wait,,, you're not planning on welding to the Tank itself - right? I would Not weld on ANY pressure vessel myself, just not worth it...
Reply:Originally Posted by upand_at_themHere's what I'm fixing.  I want to raise the tank about 1/2" to give me enough room for the extended drain that I'm installing.  Even with the current drain valve I have to lift the tank every time to have enough room to operate the valve.  Relocating the axle holes down 1/2" will do the job.  (And fixing the front leg length.)  When I took the wheels off I noticed that one leg was incorrectly welded at the factory.  The bottom piece of metal should be perfectly horizontal and the side piece should be perfectly vertical.  I figured I would fix this since the wheel does contact the ground at an angle.  The other side was done right.  I may not actually need to add metal to fix this part...just cut, bend, and weld.
Reply:Originally Posted by Weld_If you are looking to only raise this a half-inch.  Get yourself some half-inch flat bar and welded to the bottom of the existing feet and now you are up your half-inch.
Reply:Originally Posted by Weld_If you are looking to only raise this a half-inch.  Get yourself some half-inch flat bar and welded to the bottom of the existing feet and now you are up your half-inch.
Reply:Originally Posted by upand_at_themThe wheels have to be lowered in order to raise the tank.  See pic #2 in post #9.  That's the axle hole.  It gets moved down.
Reply:Originally Posted by Weld_what if you just drill the hole lower and fill up the existing hole?  is there enough room if it's only half an inch?
Reply:well then have at it. The experience will come useful in the future I'm sure.
Reply:Here's the dilemma.  With the extended drain fitted it is very close to the ground.  I was thinking that if I raised the tank (lowered the wheels) and also extended the front leg down, then I could run the drain through the front leg.  This would protect it as well as giving me the drain valve right in the middle of that end.  Now that it's fitted, I think I need 3/4" or even more.
Reply:Just weld on some flat bar and then drill the hole where you need it.Add spacers to the from rubber pad.Ed Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:Originally Posted by upand_at_themHere's the dilemma.  With the extended drain fitted it is very close to the ground.  I was thinking that if I raised the tank (lowered the wheels) and also extended the front leg down, then I could run the drain through the front leg.  This would protect it as well as giving me the drain valve right in the middle of that end.  Now that it's fitted, I think I need 3/4" or even more.
Reply:Just weld around the hole one time and let it cool. Second time around it will be closed up solid.  Grind it flat again.
Reply:Very easy to fill that hole with a MIG welder.  Just build it out from the edges towards the middle.  Like Daniel said................smoogie, let cool, and smoogie some more.  MIG  is made for this kind of stuff.
Reply:Or just weld an axle to the underside of that bracket, and install the wheels on it.  About the easiest solution.
Reply:There is really no reason to weld at all, just drill the new hole below the old hole. There looks to be enough room to drill a new hole far enough below the old one to not cause any issues. I have some carts that have a row of holes an inch apart so you can use different sized wheels. Other option would be to just slap on some bigger wheels, probably cost under 10 bucks.Chip out the concrete so the drain valve isn't hitting. Lol. I had to. There should be a few options that do not require welding the holes shut. Can a 90° be used on drain valve to solve clearance issue.
Reply:I went the "simple, no welding" route.  I got a little more ground clearance by tapping the drain hole a little more to run the drain elbow in further.  And I bent the drain pipe to put the valve closer to the middle of the tank end instead of sticking out the corner.  If I make a bracket to secure the pipe to the front leg I'll be satisfied that it won't get damaged wheeling it around.
Reply:A piece of 1”- 1 1/2” tube bolted on the bottom of the legs would work. You could drill new axle holes a accomplish raising it up. Zap used to say “we don’t have to weld everything “.Burt _____________________Miller Syncrowave 250Millermatic 211Miller 375 Plasma Cutter Hobart Handler 12010FtDrillBit.com