When I am trying to match up two helm tops, I've been tack welding at the top, or point if there is one, then raising the two edges together on my ball stake. I still have to go back and re-weld in some spots after clean up on the grinder. Is this the best way to get the edges to match? Do I just need to practice more, wait that means I'd have to make more helmets!!!!
I like to make sure my helmet tops line up as close as humanly possibly before committing to welding them. This usually entails spending some time with the grinder or belt sander to get the edges nice and level. Sometimes I'll need to dish one of the tops out a bit more.
Im with chay on this one. Dress the edge till they match up flush before you weld. Often, if Im using an rsimmons top I have to cut a bit out anyway, and as long as I make the cuts nice and strait there is not to much grinding to do. Btw, if your edges dont match up nice, but you manage to weld the top anyway, odds are all that is holding them togeather is filler metal (ie your wire if a wire feed, stick if stick welder or whatever). The to halfs are not really fused togeather, just filler stuck to half a on one side and stuck to have b on the other. On a good weld (IMHO) the metal of the to halfs should me melted togeather. (IE fusion) But I admit Im a self taught welder so I might be off base.
Accdnt's assessment is more applicable to the flux-core, less so to traditional stick, and not really valid with mig, tig or o/a welding. This is because the filler metal itself is in no way inferior to the sheet metal of the top, but flux-core, and to a lesser degree stick, welding will have a far greater chance of gaseous inclusions than the other types.
Best way to reduce that, btw, is to weld with your flux-core rig set at the highest level you can, without blowing through.
For best results [with wire-feed types], you should weld the halves with a gap about 1/2 the width of your filler.
I'm also a self-taught welder...but I've been at it a while.
Oh yeah...I make sure the edges can meet without gapping too much, then line up the ends, then tack weld the mid-point and ends, then match the edges. This gives me the quickest, and best, results. If you try to weld from one end to the other, unless you have done some serious clamping, the halves will warp away from each other as you go.
If you are dishing into a dishing bowl of the correct size(ie dishing to fit the bowl) the two halves should come out pretty close. I always spend some time adjusting them so they fit neatly, using hammer and hands to adjust the shape and then grinding the two edges so they meet without gapping. This adjustment can easily take an hour or so. Once they're matched I get a guy in my club to oxy weld them for me. I clamp them so there is a small gap and he then spots it in 4-5 places and I help him make sure no misallingment occurs. Once it's tacked MINOR adjustments can be made. He then welds them up, does a good job too. Where there is no peak in the helm I can plannish out the weld so it's no longer visible from either side of the metal.
I think Gundo hit on what I meant, once I tack weld (I have been paying a pro to MIG my tops together) Looking from the inside, there is never more than an 1/8th of an inch of light between the side "A" and side "B", but if I set a strait edge across "A" to "B" I get one side higher than the other. Matching them up while duct taping them or trying to hold them together is an exercise in frustration. I usually have to have them welded a 2nd time to fill in the any small gaps, or I could grind them down to match, but I was afraid that would thin out the area to below the .0625 SCA min. Tonight when I go to work I'm talking to one of the maintaince men who is selling his 110V MIG to move up to a 220V set-up. Then I'll start welding my own tops together. Then I can weld a few inches and check the fit, weld more, repeat till I'm done, at leased that's my plan. Does this sound right?
I weld in sections. no spot welding at all due to always welding much hotter than really needed. spot welding with the welder set high can cause your lines to burn out fast when your welding from one spot to another. I start by setting both helm halfs together and matching the edges. if its a ron simmons top I set them on the table and mark where I need to grind to get them to fit perfect if its my own I take the flat peices after cutting out and grind them while their sandwiched together with a duckbill clap. this insures that if I dish the sides right the edges will match perfect all the way around. aka grind the edges, mark a big "O" on the outside of each sandwiched half and dish the "O" side in. once I get the dishing fairly even and nice I start with one end flush vs the other and weld a 1" strip. planish the next few inches over a ball stake taking care not ot hit heavy near the weld ( doing that will make the weld push up on the metal causing it to get wavy) and weld the next section. and keep doing that until Im on the other side.
BTW I always weld from the inside until the entire two halfs are welded then run a nice hot bead over the top.
I use a lincoln wire feed lil poop welder that has the abcd settings for heat on 18-16 im in between b and c on heat settings on 14-12 always on d with wire running fast and draging slow. once I figured out I could melt 12g fairly easy going slow I sold my stick welder . now I can manage a decent holding weld on stakes if needed by grinding a curf to the edges and welding a few passes over....
yea the flux core stuff sucks on cleanup but some cooking spray works wonders to kill splattering, just dont spray it IN your welding line.
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR><font face="Verdana, Arial" size="2">Originally posted by sedric: Looking from the inside, there is never more than an 1/8th of an inch of light between the side "A" and side "B", but if I set a strait edge across "A" to "B" I get one side higher than the other. Matching them up while duct taping them or trying to hold them together is an exercise in frustration. </font><HR></BLOCKQUOTE>
Yes, it can be frustrating. That's just where repeated adjustment is needed. It's best if you have a constant reference point. I use a totally flat table top to sit the two halves next to eachother which stops unwanted vertical movement. I then adjust one half, repeatedly sitting it next to the other one on the table to check my progress.
The problem you explained above, concerning one side higher than the other, is simply fixed by supporting the higher half against a wooden block about 1/2-1 inch from the edge and tapping it down with a hammer. This will make the heights line up but you now have a section of edge where you tapped it down which sticks out. Just grind that back till it once more matches the other half.
I just welded my first helm!!!!!!!!!!!!! I no longer have to go to the welders and wait till they find the time, pay shop rates, suffer threw all the "your crazy!" looks for somone else to weld my helmets together! Plus I took my time and got a great match! Now I get to find out what all I can make with my new toy!
For my tops, I dish into an oxygen bottle bottom that some how, magically fits perfectly for the helm tops. I just dish until the top is flush with the bottle. I usually have to grind off a little on the edge to line it up, but its not much of a biggie. I usually clamp the front together along the seam and tack it there, then use a large G clamp to tack the top, then go to the back and tack it, and grind off any edge on it. If I ever try a wierd shapped top, I will probably have a bigger problem trying to get it to line up.
