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Old 07-01-2021, 11:46 AM   #1
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Beginner Welding Questions

Per the recommendations I have seen on this sight I went ahead and picked up a Hobart 140 welder. I have attached some pictures of what kind of holes I am dealing with on the subfloor. My gf and I are working on stopping the windows from leaking before we actually move on to the floor but I figured I would get some ideas in the mean time.

#1: about the size of a lot of the holes in the bus. This bus was used to transport students with disabilities so it was outfitted with special rails on the floor that were really hard to get off. A ton of prying and cutting got them off but left little mountains that I have since grinded down.

#2: My dad while trying to cut out the wood sub went a little to far and cut into the bus.

#3: A bunch of rust has created a nice hole.

#4: Holes from the old heating lines.

#5: My first attempt at welding with an old welder my dad had. It is wire feeding but the wire feed assembly is messed up so it wasn't consistent. Hopefully the Hobart is a much better improvement.

I know to start off with we will have to do a bunch of sanding to get rid of the rust. I guess my main question is will the Hobart be able to handle all the things I have pictured? I imagine for the old heating line holes I will have to get some sheet metal and weld a patch over it.

Any other helpful tips and tricks I should keep in mind when I am welding would be very much appreciated (like how to see where I am welding! I can't see anything through the welding mask, which is for my safety but makes welding for a noobie like me hard lol)

Thanks!
Attached Images
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Secular_Sam is offline   Reply With Quote
Old 07-01-2021, 11:56 AM   #2
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um... back up a little

Is this using CO2 or CO2 argon mix welding gas?

Learn to weld on some scrap first.......

If you have not used a welder like this.... watch you tube university for four or five hours with videos from different people.....

get some sheet metal the same thickness as the stuff you want to weld/repair.

practice until you get what you are looking for...

then.... go weld on the bus

or

Find a weldor that is a decent teacher take about half an hour to an hour in lessons...


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Old 07-01-2021, 12:04 PM   #3
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An auto darkening helmet is the only way to go for welding.
That Hobart 140 is a gas shielding wire feeder so it should handle that sheetmetal floor no problem.

If the flooring is galvanized coated, make sure you pre grind it off the areas you'll be welding as it gives off toxic gasses when welding to it.
Or simply wear a forced air respirator...
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Old 07-01-2021, 12:12 PM   #4
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Is there an easy way to tell whether or not the floor is galvanized?
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Old 07-01-2021, 12:22 PM   #5
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A couple of suggestions:
1) If you have time available, take a welding class at your local community college. It will provide you with a wealth of information about doing it right.


2) Buy an LCD welding helmet. They auto darken when you start the arc. A welding supply will have them. Harbor Freight has them. Expect to pay $60-$200 for one. I use one made by Miller.


3) Get a text book about welding and read it. The welding class I went to used "Welding Principles and Applications" by Larry Jeffus. The ISBN number is 978-1-305-49469-5. There is a bunch of them on eBay.


It looks like you are using flux core wire. I would get a bottle of welding gas and change over to solid wire. I use a Miller welder, but I would guess yours has a chart like the miller. Using the chart as a guide current setting / wire feed speed will get you good results.



4) Practice on some scrap metal. Get to a point where you can get some reasonable welds on the scrap vs. learning on the bus.


Now for the large holes:


Cut some steel into slightly smaller disks than the holes. use a magnet to hold them into place while welding them in. Make several spot welds around the hole. after getting enough spots to hold the disk in place, weld to connect the dots so to speak.


Also Clean the weld area first. Lightly grind around where the weld bead will be.
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Old 07-01-2021, 12:23 PM   #6
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I guess I should have read previous posts as I ended up mostly repeating what other already said. Sorry
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Old 07-01-2021, 12:33 PM   #7
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Thanks flattracker! I will definitely look into the book and like the previous post said seeing if a local welder would be willing to give me some lessons.
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Old 07-01-2021, 03:20 PM   #8
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where are you at in NC?
if you are close enough to me then we can go to my companies shop and i can teach you mig, stick, and plasma in less than a day and send you home with scrap sheetmetal for repairs.
has anyone mentioned disconnecting your battery and computer before welding?
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Old 07-01-2021, 05:14 PM   #9
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First off, you don't need extensive welding knowledge to plug those holes. Just follow this technique (and this is just for spot welding in holes):

1) Set the voltage extra high, like to the point where the welder just starts to sputter when you try to run a bead. If you're running flux core (which is perfectly fine), you'll want the voltage set high anyway since that's what it likes. You'll want a nice wide arc that lays a flat bead, not a little pinpoint one. If you're running a little 110v welder, I'm guessing it'll be about maxed out. Do not set your welder on what you're actually welding. Get some similarly thick scrap metal.

2) Clean at least a 2" swath all around the joint on both sides of the material. You'll want it shiny, shiny. And wipe it down with a solvent like mineral spirits, paint thinner, denatured alcohol, something along those lines.

3) Steel won't fuse to copper. Get a chunk of copper or brass at least 1/4" thick and find somebody to hold it with pliers on the underside of the hole you're going to fill. You'll want it wide enough to cover the hole completely and then some. This helps for several reasons:
--It keeps the underside of the weld from being contaminated by the open air. This won't be too big of a deal if you're running flux core, but it certainly helps.
--It provides a heat sink to whisk the heat away from the thin sheet metal, keeping it from burning through.
--It gives you a conductive bridge to weld across.

4) With the copper on the underside, slowly tack in the edges of the hole. It helps if you aim your arc half on the previous tack and half on the material you're trying to weld. Your tacks aren't even going to be half a second long. Since your voltage is set extra hot, you won't have any issues with a sputtery start or getting proper fusion. Tack one right next to eachother, following around the outer edge of the hole and slowly work your way in. Just to be extra cautious, I'd recommend a count of two mississippi between tacks and waiting for the material to cool completely between full passes. The one issue you may find with flux core is that if the flux hardens before you make your next tack, it may insulate you from striking an arc. In this case, either chip off the flux and then do your weld, or arc right next to the previous tack on good clean metal.

That should at least get you started.

From the looks of your sample welds, you are way way way too cold with way too much wirefeed. Like I say, really crank that voltage up until it runs a bit sputtery. That works well for spot welding.
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Old 07-01-2021, 09:29 PM   #10
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Quote:
Originally Posted by Jolly Roger bus 223 View Post
where are you at in NC?
if you are close enough to me then we can go to my companies shop and i can teach you mig, stick, and plasma in less than a day and send you home with scrap sheetmetal for repairs.
has anyone mentioned disconnecting your battery and computer before welding?
I am up near the Wake Forest area, so it looks like about 2.5 hours away. I would definitely be down to make the drive over to you and learn about about welding! And yes I knew about disconnecting the battery. I haven't heard anything about disconnecting the computer, which I am not sure what you mean by that.
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