Need welding help

[GSpreeman]

Okay guys, I picked up a new 100amp MIG welder and got all the parts for my P-Car. I've practiced, practiced and practiced but I'm turning my project car into an abstract piece of art. Any takers on helping me weld on a rocker? Will trade for food, beer, carpentry, even money! I live in South Orange, NJ if that helps.

PS, I would take it to a shop to have it welded but I have yet to drop in the engine. Anybody want to help drop in a 912 engine?

[MotoSook]

Are you using gas? If not, I have found that flux core wires are not all the same...quality...

Small sections at a time (~1 inch) to prevent massive warping is what I have heard...

I've got a $250 harbor freight gas mig that does a pritty good bead with practice..heat and wire feed settign is critical so it seems.

[GSpreeman]

The welder works okay. My problem is with cutting out the old pieces and getting the new ones in so they fit right.

[911r_parts]

One easy way to do sheetmetal work is to use cheap mat board and make templates.Mat board is waaay easier to work with then steel. When the mat fits good trace it on the steel, cut out and it should fit fine.

[Zeke]

Originally posted by 911r_parts
One easy way to do sheetmetal work is to use cheap mat board and make templates.Mat board is waaay easier to work with then steel. When the mat fits good trace it on the steel, cut out and it should fit fine.

Or tar paper. What many do is fit the piece as close as you can and scribe around the perimeter. Cut out on scribed line and the new piece should drop right in.

Edit: This doesn't read right. The tar paper/ mat board is for a pattern to cut the metal. The scribing is for metal to metal. If you could see what I meant, good. If not, now you have clarification.

[dean]

Originally posted by 911r_parts
One easy way to do sheetmetal work is to use cheap mat board and make templates.Mat board is waaay easier to work with then steel. When the mat fits good trace it on the steel, cut out and it should fit fine.

This is a good idea that I use all the time. For really cheap matt board I use cereal boxes.

[cstreit]

Why not cut the flares to their approximate size, lay them out on the fender, then scribe a line on the fender. Cut and then grind to this line to get a perfect butt weld...

[RickM]

Greg, rockers or flares or both?

[techguy]

Who is able to get a good bead on 18 guage sheet metal without burning a hole in it with a mig and still maintain strength? Maybe 16 gauge or heavier but 18 and 20 guage sheet are paper thin. You may be better off making several small tacks a few inches apart to allow the heat to disperse and then go back in fill in the line. To polish it all off go back and grind out the exta material so its nice and smooth.

Good luck!

This is what I was able to do with my mig:

Rockers, what do you think? Dotorg, your thresholds reminded me!

[RickM]

Techguy,

It's not easy but the welder can make a big difference here as well as the wire used. The more you spend the more infinite the adjustment gets for current and wire feed rate. The typical low cost MIG welder is General Purpose and doing delicate work can be challenging but not impossible.

The free roll of wire you get is usually too thick for thinner metal applications. There is wire available with stabilizers and deoxidizers that will give a sounder weld in less than perfectly prepped metals.

Also, a high Argon percentage (to CO2) is desirable...up to 90%. Straight C02 will weld hotter and with more spatter.

[RickM]

Here is an excellent PDF on Welding basics including Gas mix and a chart on selecting the proper wire diameter for metal thickness.

It also states that "pushing" the wire into the weld will afford you less penetration (and narrower bead) that "dragging" or "pulling" the wire.

http://www.hobartwelders.com/pdfs/MIG_Welding_Tips.pdf

[techguy]

Its all practice and patience thats for sure. I did buy a really high end MIG, it was a Lincoln..around $900 CDN with infinate heat and variable wire with 90% argon mix. I have been very happy with the unit but of course only spent about 2 days playing with stock then decided to bite into the car. The car turned out very nicely after all was said and done but I must admit I need to sit down and play a lot more. Great hobby, just don't weld over 12x12 ceramic tiles...it does a nasty job of pitting it...next Q is why the previos owner put ceramic in my garage but thats another story.

[andycook]

I have completed many successful panel replacements with a non-gas flux core welder. I "stitch weld" my panels working from the outside edges in. This elimnates the concentration of heat in any single area. Only do a very little bit at a time. Less than 1/4". This also eliminates panel warpage and burn throughs. Another good investment is a panel flanger. They are like a pair of vise grip pliers that form a flange on to the sheetmetal. They can be bought for around $30. Allows panels to be welded flush instead of overlapping them. Good luck to you!

[atlporsche]

tech guy...

I can do 20 gauge with .035 flux wire. it's all about controlling the heat. flux only upsets me because it's soooo messy to clean up...otherwise it's a pretty strong weld. a couple hints for the thread starter...

1. watch the puddle, not the arc.
2. on sheet metal, stitch it...pull the trigger, start the arc, just as it gets hot, let go for a second, then .5-1 second on, and 1 second off. work along like that.

I have a lincoln 100hd...4 heat settings, gas convertable...

i've also got access to a miller 250 at work...it's just plain awesome.

sjd

[Porsche_monkey]

1. smallest diameter wire
2. tack, dont do long stitches
3. copper back up block as a heat sink
4. Argon gas, not CO2
5. grind and repeat where necessary

[GSpreeman]

Yeah, I'm catching on to the welding part but here is what happened. I bought the part that is the rear part of the front quarter panel (right in front of the driver's side door.) I marked on my car where the part should go, cut out the old rusty part and started stitching in the new one. Now, instead of a nice straight line along the body there is a ^ type rise where the weld is. I could cut it apart and re-weld it but I'm afraid I'll just ruin the part. I've tried to grind it down but it's the actual sheet metal that forms the rise and if I were to grind it flat I would go through it. Guess I've gained a lot of respect for the guys who are able to do this.

On a positive note, it sounds like one of the Pelicans might be able to come over to rescue my handywork.

[markwemple]

For the inexperienced, lap is soooooo much better than butt welding. Start with that notion and don't be afraid!

[Porsche_monkey]

Don't think that professional bodymen don't use hammers.

[Series900]

and we play with dollys, use them with hammers!

What you are up against now is the heat of the welding has expanded, warped the metal. you can grind the weld flush, more heat= more warp. now its at least level but warped. get out the oxy/acet, set a flame for brazing, not to big with two feathers, less o2, heat a dime to nickel size dot at the high point of the warp, drop the torch, grab the hammer and the dolly, the spot should have risen higher, dolly right underneath, start tapping all around the spot , working into the circle center while still red, do not try to get perfectly flat yet, let cool, or better yet grab an air gun or wet rag, metal contracts. repeat as needed till flat. this is the basic SHRINKING of metal. what is really happening is the molecules are all in a stretched/free form from the heat of the weld, by reheating a concentrated spot, the molecules are allowed to compress into the circle, tapping of the hammer forcing the molecules tighter in the heat spot, thus tightening the overall panel, reducing the extra material, and getting back to a flat panel. same process for big dents, once pulled out the metal has been stretched, and an "eyebrow" exists around the perimeter, or the dent is now an outtie( is that really a word?) , basically to much metal. careful heating and tapping, and cooling shrinks the metal back. We also use slap files,which kinda grab the metal as it is slapped into a center high area, reducing the warp. all this takes practice...