Hobart 140 and Car Frame Questions???

[shipley031]

Hello I have recently got into welding. I am really enjoying mig and tig welding.I got a Hobart 140 on Craigslist for a pretty decent deal.. I am running .30 Mig Wire with 75/25. My question is I am going to be taking on a project with a total restoration on a 1969 Corvette and its going to need some welding on the frame. I would also like to weld in Gussets for extra strength.

Should I sell the 140 and get a little bigger machine or in everyone's opinion will I be good with the 140 ?

[DSW]

I see 2 issues with your post.

#1 that machine is probably borderline at best if the frame is 1/8" material. Most small machine top out at 1/8" steel under real world conditions, and it doesn't take much to drop performance below this level. Anything thicker and you really need a bigger machine. Personally for something like this I wouldn't trust a machine that wasn't 230v for structural stuff.

#2 is that you are a very long ways away from having the skill set to do any structural welding on a vehicle. You must be able to do code quality welds every time in all positions to do something like this right, and know exactly what the requirements are for welding on that particular frame. Older cars are more forgiving than newer ones as the weld requirements are not as strict as they are for today's vehicles with high strength alloy frames. Best bet is to stick to sheetmetal work on the body and leave any frame work to someone who knows what they are doing. If you don't, there is a good chance you can do more damage to the frame than you are trying to solve.

Keep in mind that chances are you do not have the insurance to cover any problems if something you do goes wrong. in the case of a serious accident or injury, you may find your azz hanging out in the breeze in todays sue happy society. Your vehicle insurance company can deny coverage due to a "bad" repair, even if you may not think it's directly related. The other party certainly will go after anyone who was at all involved in a "shoddy" repair if nothing else to try and grab insurance money from the company that did the work. That's just the way things go today. If you don't have insurance, you can find yourself on the hook for both criminal and civil penalties, especially if someone is hurt or killed.

Structural welding on vehicles, like frame repair, is NOT a "learning" project.

Also keep in mind for something like this to work well, you really need to clean everything extremely well. That usually means a body off restoration and having everything blasted to remove all the rust and grime on the frame. You can't make good structural welds on rust, and chances are if there is serious rot, it's much worse than you think. You really will not see the extent of the issues until you clean off all the dirt, undercoating and rust to see the bare steel.


I generally recommend at least a 230v 180-200 amp class machine as the basic hobby machine. It will greatly help with material in the 1/8"-1/4" range that many guy find they need to weld.That little machine is perfect for doing the body work though. It will also give you a nice machine that will allow you to practice on material up to 1/8" to learn the basics. If you are serious about learning to do this right, I'd strongly suggest looking into taking a night class at a local votech school. When you sit down and add up what materials, wire, gas, electric and so on will cost you, not to mention the instruction, a class is stupid cheap. Since you have your own machine, you can practice at home between classes and spend your class time working on learning new things and trying to work out problems rather than spending the time doing repetitive welds.

Many schools also run body shop classes as well. If you want to keep the value of a "classic" car, you will want to do the restoration correct right from the start. Nothing can destroy the value of a very nice car faster than a poor restoration attempt. Good luck.

[shipley031]

Thank you for the reply.. I am taking night classes. basically the reason for my question is because I have talked to a few experienced welders some of which say that 140 Amps w./ .30 mig wire will be good for a small frame repairs patching and what not..because the frame is roughly 1/16-1/8 in most spots. Its not my ability that I'm worried about I am not going to start on the Vette until 2015 so I will have plenty of practice before then.. and she will be going down to bare frame, blasted and back on the road hopefully in under 1 year. I appreciate the response!!!


Any one in the pittsburgh area want a Hobart 140 brand New!!!! ???

[BradTN]

I have a Firemist Maroon Big Block '69 Corvette convertible. I've had it since 1980 and it's been a lot of fun to own. I'm guessing your car has rust in the "kickups" in the frame based on your "saltbelt" location.
I agree with DSW that you need to be sure of your skills before welding on something that is mission critical. But don't let that stop you, develop those skills and go at it.
If I were you, I would keep the 140 for the small detail stuff you will run into during a resto. and get a 230v stick welder for frame work. A good, "hot", stickwelder, and the skills to use it, will do just fine on a frame and will have excellent weld penetration. I did a "frame off" on a '64 Impala Conv. years ago and did much frame welding using the old reliable Lincoln "buzzzBox", with excellent results. I used an AC machine back then, but would recommend an AC/DC machine now. Enjoy the restoration !

[shipley031]

hey thanks for all the responses..I think im going to keep the Hobart and pick up a nice tig/stick machine when I find the right used one for sale that way when something goes down I can still keep going.

Thanks guys.

[scottybaccus]

You will be just fine using your Hobart 140 on that frame. It's a collection of sheetmetal stampings that were assembled with far less sophisticated equipment.

I've been building hotrod and race car chassis for nearly 15 years. I've used a Miller 135 almost exclusively for the last 5 or so. Your Hobart is rated for 3/16 or better in a single pass. Nothing on the vette is any heavier than that.

As to your skill, it sounds like you are getting some instruction and open to advice. Just keep in mind that welding cracks is usually a temporary fix and preparation of the metal is key to your success.

Don't rush to add reinforcments to the chassis. It was designed to have a certain amoungt of flex. Eliminating that could lead to accellerated cracking of the chassis, or even the body. Fix what was there and save the engineering exercises for another day.

[shipley031]

Gotcha .. thank you for the tip!!!

[SuperArc]

Agreed, your Hobart 140 will handle the Vette frame, no problem. Vehicle chassis frames are incredibly thin stuff. My Silverado 2500 is probably less than 1/8" at the thickest part, and the rest is well under that thickness. I'd say about 3/32" last time I recall actually checking with old "kentucky eyeballing."

It's sad, but car makers haven't used thick steel in years.

[Corbinworks]

Originally Posted by SuperArc

Agreed, your Hobart 140 will handle the Vette frame, no problem. Vehicle chassis frames are incredibly thin stuff. My Silverado 2500 is probably less than 1/8" at the thickest part, and the rest is well under that thickness. I'd say about 3/32" last time I recall actually checking with old "kentucky eyeballing."

It's sad, but car makers haven't used thick steel in years.

I was going to say the same thing..all the frames I have worked on are so thin, The only thing you might run in to is the duty cycle, You might have to take alot of breaks...

[hseldon]

I've used a 140 for years on car thickness material, the quality is fine though I tend to use the .023 wire to get better penetration

Oh and here's a fun fact, a ships hull is mostly 3/8 mild steel

[6530]

Originally Posted by DSW

I see 2 issues with your post.

#1 that machine is probably borderline at best if the frame is 1/8" material. Most small machine top out at 1/8" steel under real world conditions, and it doesn't take much to drop performance below this level. Anything thicker and you really need a bigger machine. Personally for something like this I wouldn't trust a machine that wasn't 230v for structural stuff.

#2 is that you are a very long ways away from having the skill set to do any structural welding on a vehicle. You must be able to do code quality welds every time in all positions to do something like this right, and know exactly what the requirements are for welding on that particular frame. Older cars are more forgiving than newer ones as the weld requirements are not as strict as they are for today's vehicles with high strength alloy frames. Best bet is to stick to sheetmetal work on the body and leave any frame work to someone who knows what they are doing. If you don't, there is a good chance you can do more damage to the frame than you are trying to solve.

Keep in mind that chances are you do not have the insurance to cover any problems if something you do goes wrong. in the case of a serious accident or injury, you may find your azz hanging out in the breeze in todays sue happy society. Your vehicle insurance company can deny coverage due to a "bad" repair, even if you may not think it's directly related. The other party certainly will go after anyone who was at all involved in a "shoddy" repair if nothing else to try and grab insurance money from the company that did the work. That's just the way things go today. If you don't have insurance, you can find yourself on the hook for both criminal and civil penalties, especially if someone is hurt or killed.

Structural welding on vehicles, like frame repair, is NOT a "learning" project.

Also keep in mind for something like this to work well, you really need to clean everything extremely well. That usually means a body off restoration and having everything blasted to remove all the rust and grime on the frame. You can't make good structural welds on rust, and chances are if there is serious rot, it's much worse than you think. You really will not see the extent of the issues until you clean off all the dirt, undercoating and rust to see the bare steel.


I generally recommend at least a 230v 180-200 amp class machine as the basic hobby machine. It will greatly help with material in the 1/8"-1/4" range that many guy find they need to weld.That little machine is perfect for doing the body work though. It will also give you a nice machine that will allow you to practice on material up to 1/8" to learn the basics. If you are serious about learning to do this right, I'd strongly suggest looking into taking a night class at a local votech school. When you sit down and add up what materials, wire, gas, electric and so on will cost you, not to mention the instruction, a class is stupid cheap. Since you have your own machine, you can practice at home between classes and spend your class time working on learning new things and trying to work out problems rather than spending the time doing repetitive welds.

Many schools also run body shop classes as well. If you want to keep the value of a "classic" car, you will want to do the restoration correct right from the start. Nothing can destroy the value of a very nice car faster than a poor restoration attempt. Good luck.

Do yourself a favor & listen to what this man says.

[BD1]

more machine is better. Keep the 140 and look for a Miller 200 syncro. Now you'll be set.

[momofx]

Wow lots of mixed opinions in this thread (I'm an auto enthusiast as well btw). Honestly, I would go with the guy who has been doing frame / car restoration (scottybaccus) since its the actual subject concerning the welder choice and not just the welder in general - unless you plan on doing other stuff that is...

[Agape Guy]

I agree with momofx---scottybaccus is the one you should give the most weight too, since he has the specific-area expertise. I'm real big on listening to "e-mentors" with the specific-area expertise, even though the other general welding experts raise good points too. My2cents.

[WookieWelding]

another thing to throw in the mix is that machine will NOT put out 140 amps unless plugged into a 30 amp 110 volt circuit

[WookieWelding]

Originally Posted by hseldon

I've used a 140 for years on car thickness material, the quality is fine though I tend to use the .023 wire to get better penetration

Oh and here's a fun fact, a ships hull is mostly 3/8 mild steel

in fact using 0.23 versus 0.035 you are carrying less amps due to wire size being smaller and its ability to carry the amps resulting in less penetration

[tnjind]

Originally Posted by WookieWelding

in fact using 0.23 versus 0.035 you are carrying less amps due to wire size being smaller and its ability to carry the amps resulting in less penetration

Thats why I use .030 in my 135.

[Gamble]

That's good information. Any idea on how many amps less you carry ?

[jamesyarbrough]

Originally Posted by WookieWelding

another thing to throw in the mix is that machine will NOT put out 140 amps unless plugged into a 30 amp 110 volt circuit

I see this stuff mentioned all the time. Thing is I maxed my 140 out and never tripped a 20 amp breaker. So I know for a fact you don't need a 30 amp breaker to get the machine to its full potential because it won't pull enough amps to trip a 20 if your wiring is proper because as stated on the plate on the machine its maximum load is 20 amps. So if your wire is not getting hot from undersizing and your not running it continuously for more than 3 hours a 20 amp breaker will feed the machine and not trip.

I think you guys are mistaking voltage drop for load sizing. You size your breaker to the load and size your wire to the load and corrections for voltage drop and ambient heat deratings. If the load is continuous ( on for more than 3 hours at a time) you can only run 80 percent of the breaker rating. But your not going to have a welder maxed out for 3 hours straight. It will hit duty cycle first.
Just another bit of info. If you put a 20 amp recepticle on a 30 amp load it will melt down.

The proper thing to do is just keep a 20 amp breaker and size your wire correctly. Most of the time 10 awg wire will solve any voltage drop issues and breaker tripping.

For more info check the nec or you can pm me directly for voltage drop calculations and wire deratings.

So just to recap, a breaker is just a switch and doesn't effect voltage at all. It either trips or it doesn't. Loading a wire to it maximum amperage and/or stretching it too long will cause voltage drop which effects any kind of machines performace and trips breakers from over heating the wire