School me on welding gas, please?

alfadog

alfadog

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alfadog
I bought my son a 1972 GMC Sprint for his first car and a father/son project. He is 15 but an "old soul" and wanted one of these (actually an El Camino was what he specifically wanted but the Sprint is close enough); I had no input into his decision (I am more a sports car guy). He is very excited about the car but it needs some serious rust repair and came with one quarter panel for the worst bit but not yet installed. We drove it from NC to Miami so it is mechanically sound.

I have been repairing and restoring cars for 45 years but never learned to weld or do any serious metal fab. I am an excellent mechanic and have prepped and painted cars but again, no metal work beyond bang and bondo.

So I took a short welding class in my A&P school and practiced almost exclusively gas welding but it was way too short a class to become proficient. I just ordered a MIG welder and an oxyacetylene setup from Eastwood.

What do I need in the way of tanks? I have been looking on Craigslist and have some questions?

1. The normal full size tanks are 125 cf oxygen and 75 cf acetylene, right? How much does it cost to fill them? How much to rent them? If I buy some off Craigs, how much to test them if they need a test?

2. I see small 20/20 tanks. How long would they last welding 1/16 steel for practice?

3. What about argon for the MIG, size and cost? How long does it last, welding sheet steel?

4. How does the gasless flux-core MIG welding compare in quality to gas shielded on sheet steel?

Any other advice?

Thanks!
 
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The sheet metal(what's left of it) is very thin on those cars. The moment you set Oxy-Acet to it, it's going to warp like mad. Don't even try.

Get a small Craftsman wire feed welder http://www.ebay.com/itm/Welding-Equ...51633339339?pt=BI_Welders&hash=item3a96840bcb or similar. You are basically doing hobby work here, you don't need a ginormous Hobart to tack up some Chevy sheet metal. Forget about gasless flux-core wire, and just get the small bottle and regulator. The welding shop will have C-15 or C-25 mixed gas, and either will be fine. Use .016 or slightly bigger wire, and make your welds short, and spaced about 6-8 inches apart so the panel doesn't deform. Fill in as it cools, and once you have the panel in, you can grind back the bumps.

The key is to keep it fairly cool, and not warp things. Sometimes you have to use a backing plate of sheet metal to stiffen the body where the panel doesn't meet exactly. It's more art than science. Practice on some cut pieces. Don't bother with gas welding, or flux core wire, it's just a waste of time for body work.
 
docmirror said:
The sheet metal(what's left of it) is very thin on those cars. The moment you set Oxy-Acet to it, it's going to warp like mad. Don't even try.

Get a small Craftsman wire feed welder http://www.ebay.com/itm/Welding-Equ...51633339339?pt=BI_Welders&hash=item3a96840bcb or similar. You are basically doing hobby work here, you don't need a ginormous Hobart to tack up some Chevy sheet metal. Forget about gasless flux-core wire, and just get the small bottle and regulator. The welding shop will have C-15 or C-25 mixed gas, and either will be fine. Use .016 or slightly bigger wire, and make your welds short, and spaced about 6-8 inches apart so the panel doesn't deform. Fill in as it cools, and once you have the panel in, you can grind back the bumps.

The key is to keep it fairly cool, and not warp things. Sometimes you have to use a backing plate of sheet metal to stiffen the body where the panel doesn't meet exactly. It's more art than science. Practice on some cut pieces. Don't bother with gas welding, or flux core wire, it's just a waste of time for body work.
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I ordered a MIG welder with gauges from Eastwood. I know that I won't be gas welding the body panels, at least at my skill level. What size argon bottle are you thinking and how long will it last if I am practicing an hour or so at a time?
 
Yep, a little MIG, or even better, a little TIG machine will do you much better. 72 is still heavy enough you could gas weld it but you'd want to bronze braze.

The best thing though is to cut the metal out to a good shape and make a plate out of some 12 gauge that is about 3/4" bigger than the clean hole. Now epoxy it on, use some pop rivets if you have to pull it around a bend. When the epoxy cures, you can take a hammer and dolly set and flush down the overlap. There is also a tool you can get that will squeeze a recess into the parent metal before you put the cover on.
 
I hate MIG for body repair. The weld has a hard rapidly shrinking quality, which tends to crack in service as well. For body panels I prefer gas or TIG. I know a lot of guys use MIG, but I just don't like the quality.

For Mig on Steel you need 75/25 Argon/CO2. I usually buy a big tank because the economy isn't there with the smaller ones, that and I always seem to run low on a Sunday. Using a large tank (125) I can usually run about half of a 33lb. spool. That's a lot of welding. I don't use cheap wire, generally Lincoln or Hobart brand (Lincoln L-56 preferably).

Don't use flux core unless you're working outside all the time.

Re: tanks. If the neck on the tank is clean (no name). Then the tank is considered privately owned. Rules vary by location, but in Texas you can exchange any clean neck tank just about anywhere. Buy one of Craigslist if you can and save a lot of money.

Look at this chart for tank sizes.

http://cholla.mmto.org/welding/bottles.html

Shielding gas is a little more expensive than O2 or Actylene. Maybe $50 for a 125. Not really a big deal for any of it.

If you plan to use your Oxy rig for cutting primarily then get an O2 tank about twice the size of your fuel. That way you run out about the same time.
 
alfadog said:
I ordered a MIG welder with gauges from Eastwood. I know that I won't be gas welding the body panels, at least at my skill level. What size argon bottle are you thinking and how long will it last if I am practicing an hour or so at a time?
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Gosh I don't know what size I have. It's about 3ft tall, and 8" across. It'll last quite a while if you keep the regulator flow down. You don't need much flow to keep the gas on the weld. It's a trial and error deal to get the feed speed and gas flow right. Once you do, it'll be a thing of beauty. Start with lower settings, and slowly work your way up in amps, feed speed, and gas flow as needed. Smaller is generally better. Surely it'll last 10-ish hours if you keep the flow down.

<edit; looks like I have an 80cu ft. >
 
For patching body panels I prefer to braze the patch into place instead of welding it.
 
Argon mix gas, .024 wire and tips, a container of nozzle jelly helps keep spatter from sticking inside the nozzle. If the panel has long, flat spans, it'll be easier to keep warpage down if you flange it. You can use cleco's then too. Your machine should have a chart for wire size, speed and heat that'll be pretty close to start. You want to hear a sound like frying bacon as you weld.

http://www.northerntool.com/shop/tools/product_14322_14322

If you're not proud and only need it for occasional use, you can find the above flanging tool at HFD for $30 or so. I have one, and it does the job, but you have to disassemble and lubricate it before you use it. Apparently the Chinese don't believe in light machine oil.

An auto- darkening helmet is the only way to go. Don't bother practicing on 1/16" for practice, your heat will be too high for body panels. Go to a junkyard and buy a fender or hood to practice patching. You're going to blow through a few times, you can fill those holes by backing up with copper.
Widely spaced tacks, then stitch. Take your time, and let the work cool!

TIG is beautiful for a lot of things, but the cost of the machine is a bunch. And find a real welding supply shop. The stuff at Tractor Supply and such is crap.

One last thing. Coarse flapper wheels work a whole lot better for dressing the weld, and stay cooler than grinding wheels.
 
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Oh, Chip is right on the money with the auto darken hood. Those things make life so much easier when doing light duty body work or small stuff. I bought the cheapo and of course it broke, so then I got the better one from Linc and it's just the cat's meow. I love it!
 
Before doing any work on key parts, head out to the local wrecking yard and pick up some bent fenders and hoods (essentially scrap) to practice on.

Better to learn your technique on something other than that valuable one off original part.
 
AggieMike88 said:
Before doing any work on key parts, head out to the local wrecking yard and pick up some bent fenders and hoods (essentially scrap) to practice on.

Better to learn your technique on something other than that valuable one off original part.
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Agreed. Make sure the scrap parts are at least 15 years old. The newer parts are HSLA and much more difficult to weld than the mild steel used on your project.
 
All welding takes a considerable amount of practice to become proficient at. In my opinion GAS and TIG give me the most control despite being somewhat more tedious. MIG is easier providing you have it adjusted properly for the job you are doing but the only control you have then is that trigger and once you pull it you have to follow it's lead. It's nearly impossible to create welds as "pretty" with MIG as those produced by either GAS or TIG because of that.

GAS has the further advantage of being more versatile as you can anneal, braise and cut with it. If you've seen the movie "The Spirit of St Louis" you'll know that you can even cook Sand Dabs with it. All bottles for MIG, TIG or GAS, although initially purchased, are usually handled on an exchange rather than refill basis so you don't worry about static test expiration dates. As to size - the bigger bottles last longer.
 
Why are you all still welding panels? You glue them on these days. Heck, whole Hyundais are glued together, actually I think it's double stick tape. Just get some after market panels already formed up and glue them on with a few rivets. Much simpler, cheaper, and no heat issues.
 
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After reading some of these responses I think the OP needs to find an auto body forum where people actually know the correct methods for performing a welded repair.
 
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3393RP said:
After reading these responses I think the OP needs to find an auto body forum where people actually know the correct methods for performing a welded repair.
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Spot welders are expensive and limited use. Welding body panels is ancient technology along with clay based bondo. Use glue.
 
Thanks for the input so far. Just to clarify, I am not so much looking for advice on auto body repair on an aviation forum (although there is some good advice here) but rather, as the thread title indicates, looking to pick y'all's brains regarding tank selection, cost, and how long I can expect the full tank to last.
 
alfadog said:
Thanks for the input so far. Just to clarify, I am not so much looking for advice on auto body repair on an aviation forum (although there is some good advice here) but rather, as the thread title indicates, looking to pick y'all's brains regarding tank selection, cost, and how long I can expect the full tank to last.
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What questions do you still have before this completely goes off the rails?
 
Many people go for years between gas bottle exchanges if it's just occasional / hobby use. A handfull of body panels won't put a dent in your bottles unless they are real small. (I know, not a very scientific answer, but...)

I would take the time to talk to your local welding supply - they are the ones who are going to fill / exchange your tanks.
 
Rent the tanks and everything from the welding/tool rental shop for the project, return everything when finished. There is no good reason for the person who has one use a decade for a torch set to own one, same for any welding machine. Just rent the gear for when you need it, return it when it's done; when broken you return it and get another. You'll rent way better equipment than you'll buy.

I still say glue it together. If you don't have good experience and training in welding, your result is going to be crap. You can practice for a week and get it figured out and good at it, maybe even figure out how to pull the wrinkles out with a torch and a hose, or you can rivet and epoxy it on and be done in a few hours. You can even countersink Cherrymax rivets in and make it airplane strong. Your joint will come out straight and flush with no heat wrinkles to deal with.
 
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Capt. Geoffrey Thorpe said:
Many people go for years between gas bottle exchanges if it's just occasional / hobby use. A handfull of body panels won't put a dent in your bottles unless they are real small. (I know, not a very scientific answer, but...)

I would take the time to talk to your local welding supply - they are the ones who are going to fill / exchange your tanks.
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Between my son and I, I anticipate a fair bit of practice. I did about 10 hours practice in my welding class and could use another 40 hours or so myself so figure 100 hours of use with the oxyacetylene.
 
Spent a year of my life as a young man working at a bodyshop under the tutelage of master craftsman.

Doing body work is an art, and takes a true artist. The money you spend on the welder, etc you could have paid to have the panel replaced by a pro.

<reality on>I get it, father son want to do yourself but a bad panel job will create about 5 times more finish work for you. I'm sorry but unless you plan on having a crap paint job or spending 20 hours alone on finish work on one panel you just have a bad plan bud. *

As an aside, Henning is right about the glue - not only is it easier to work with it is actually stronger, I've glued a bunch of panels on.

Lastly, <nitpick on> any time you join two metals together, you are welding - no matter the method. <nitpick off>

* - can an amateur do a great job ? of course, but again how much time you want to spend ? reality is it will take you 10 times longer than you planned and cost you twice as much as paying a pro.

PS - I have a professional grade autobody welder (read - it has programmable spot weld functions) and I got the little tiny tank for it(75%argon), that I've filled a total of one time in 10 years (after I lent it to someone else)
 
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If you can weld a good straight bead with an oxy torch, you can weld with anything. It's all about puddle control. If you can color with a crayon, you can MIG. 75% of the job is the joint prep and setup. I learned to weld from a old guy who was trained by the USN. One of the most valuable gifts I have ever received.

The only way to learn it is to do it. Once you learn, you'll find a multitude of uses.
 
Chip Sylverne said:
If you can weld a good straight bead with an oxy torch, you can weld with anything. It's all about puddle control. If you can color with a crayon, you can MIG. 75% of the job is the joint prep and setup. I learned to weld from a old guy who was trained by the USN. One of the most valuable gifts I have ever received.

The only way to learn it is to do it. Once you learn, you'll find a multitude of uses.
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Thing is, you can't do a 'good straight weld' on a body panel, you introduce too much heat. You do a little stitch here, a little stitch there, and you still have 2 hrs of dolly work before you spend 5 with bondo getting halfway back to fair.
 
This is the guy I've trained with:

http://www.tinmantech.com

Kent used to work full time doing restorations for the Harrah's car collection. We did a lot of work on thin aluminum (.032), steel, etc. This is real body work, no bondo. All of the work we did was polish grade inside and out. One of the first exercises is to take a 12x12 piece of new sheet metal. Then Kent (who is a big guy) comes around and smashes it with a large hammer about as hard as he can. Then you get to make it perfect, just like a new piece again. By the end of the course you could do it in about an hour.

Maybe something of interest for a project like this.
 
Alexb2000 said:
This is the guy I've trained with:

http://www.tinmantech.com

Kent used to work full time doing restorations for the Harrah's car collection. We did a lot of work on thin aluminum (.032), steel, etc. This is real body work, no bondo. All of the work we did was polish grade inside and out. One of the first exercises is to take a 12x12 piece of new sheet metal. Then Kent (who is a big guy) comes around and smashes it with a large hammer about as hard as he can. Then you get to make it perfect, just like a new piece again. By the end of the course you could do it in about an hour.

Maybe something of interest for a project like this.
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Maybe if it was an SS-LS-7 with cowl induction with all numbers matching parts, otherwise it's a crapload of work for marginal improvement in long term result. Better off buying new repro 'patch panels' and gluing them on then fairing.
 
Alexb2000 said:
This is real body work, no bondo.
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:rofl:

There is no such thing as a straight panel with no bondo. :wink2:

Seriously, it seems as if you just want to claim a giant e-peen. Watch American Hot Rod TV show, some of the best built hot rods ever made by some of the nations top talent, or Chip Foose on Overhaulin if you will. Chip has won the Riddler award - there is no higher award in the car building business. In all those builds (including the Riddler winner), plenty of bondo :eek: being used.

You seem to know what you are talking about with welding, but when you say stuff like "no bondo" body work on cars you prove how little experience you have.

Not meant to be personal, just correcting an incorrect Old Wives Tale but hey take it however. :) misleading information is a pet peeve of mine.
 
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Henning said:
Thing is, you can't do a 'good straight weld' on a body panel, you introduce too much heat. You do a little stitch here, a little stitch there, and you still have 2 hrs of dolly work before you spend 5 with bondo getting halfway back to fair.
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IF you do a good job of putting the panel on ! :goofy:

Henning said:
Maybe if it was an SS-LS-7 with cowl induction with all numbers matching parts, otherwise it's a crapload of work for marginal improvement in long term result. Better off buying new repro 'patch panels' and gluing them on then fairing.
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Amen :)
 
Alexb2000 said:
This is the guy I've trained with:

http://www.tinmantech.com

...

Maybe something of interest for a project like this.
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Nice! I've seen some of his videos and Ron Covell's also. Though I was thinking today that selling those videos is a bit of a scam. I mean it is like if Bob Hoover put out an instructional flying video and Joe Pilot bought it thinking he would gain even a 1/10th of Hoover's skill. Better yet, it is Joe Non-pilot that buys it. Like Joe Non-welder buying Covell's. LOL. I still like the metalworking videos. Just saying.
 
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jaybee said:
:rofl:

There is no such thing as a straight panel with no bondo. :wink2:

Seriously, it seems as if you just want to claim a giant e-peen. Watch American Hot Rod TV show, some of the best built hot rods ever made by some of the nations top talent, or Chip Foose on Overhaulin if you will. Chip has won the Riddler award - there is no higher award in the car building business. In all those builds (including the Riddler winner), plenty of bondo :eek: being used.

You seem to know what you are talking about with welding, but when you say stuff like "no bondo" body work on cars you prove how little experience you have.

Not meant to be personal, just correcting an incorrect Old Wives Tale but hey take it however. :) misleading information is a pet peeve of mine.
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I worked on a 32 Chevy, no Bondo, all lead for filler.:eek: That's old school.:rofl:
 
Henning said:
I worked on a 32 Chevy, no Bondo, all lead for filler.:eek: That's old school.:rofl:
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Got me ! :goofy: of course I'm sure you knew what I meant though I'm sure someone will be along to post a link from SAE and someone else will post a link from the dictionary about how wrong I am :rofl::wink2:
 
jaybee said:
Got me ! :goofy: of course I'm sure you knew what I meant though I'm sure someone will be along to post a link from SAE and someone else will post a link from the dictionary about how wrong I am :rofl::wink2:
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Feadship used to brag how little fairing filler they use and how straight and fair their hulls were. Then I had to cut through the sides of one to put in new generator sets and found 1 1/2 inches of filler. :rofl:
 
Henning said:
Maybe if it was an SS-LS-7 with cowl induction with all numbers matching parts, otherwise it's a crapload of work for marginal improvement
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Ummm, yeah, THAT's the car you want to learn the skills on...
 
jaybee said:
:rofl:

There is no such thing as a straight panel with no bondo. :wink2:

Seriously, it seems as if you just want to claim a giant e-peen. Watch American Hot Rod TV show, some of the best built hot rods ever made by some of the nations top talent, or Chip Foose on Overhaulin if you will. Chip has won the Riddler award - there is no higher award in the car building business. In all those builds (including the Riddler winner), plenty of bondo :eek: being used.

You seem to know what you are talking about with welding, but when you say stuff like "no bondo" body work on cars you prove how little experience you have.

Not meant to be personal, just correcting an incorrect Old Wives Tale but hey take it however. :) misleading information is a pet peeve of mine.
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Did you look at the link? At least do that before you start calling me a liar. This guy has hand built aluminum bodies for Ferrari's from photographs. How do you think a chrome shop repairs a bumper prior to plating? Bondo?:) Paint work is a much easier standard than polish, high build primer can cover a lot of sin without requiring bondo. Look at modern paintless dent repair and how much damage they can remove without bondo.

The real problem is people don't understand the properties of metal and how to work with it. That's the basis of comments that say this work is impossible when it is being done everyday. Look at this link Kent did repairing a P-51 wing root fairing. Compound curve made by hand from flat sheet. It has to match the other side perfectly AND the finish is polished.

http://www.tinmantech.com/articles/repairing-wing-root-fairing.php

Here is Boyd Coddington's Alumatub, no paint and hand made down to the frame.

http://www.streetrodderweb.com/features/0408sr_1929_ford_model_phaeton/?__federated=1

Modern autobody technique is designed for production repairs with a tough cost/value ratio. Nothing wrong with a little bondo on these, but that's not my point.
 
RotorAndWing said:
You must stay very peeved on this board then..........:rolleyes:
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ronnieh said:
You think:yesnod:
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