Mig welding aluminum

[FieryFurnace]

I've done plenty of migging with steel! I don't mess with aluminum ever at all! Never had any reason to!

However, one of the things our family does is sing at churches. Six people in a full cab truck with all our instruments and baggage in the back is tight. Then you have to find a place to stay, etc, etc.

Motor homes are expensive.

School buses aren't! Imagination can do the rest!

So THIS is sitting in our yard.


In short we are doing a school bus conversion to a motor coach. One of the things in the conversion process is adding storage compartments underneath the bus.

If we went with 16 gauge sheet metal for the storage we would be adding aproximately 2000 pounds JUST in sheet metal. (I haven't figured weight in frame work yet.)
That's a lot of weight to add. During the conversion we want to keep track of weight changes: what we put in and what we take out. If we keep it about the same we know the motor can handle it and it's not going to decrease the gas milage!

If we go with 16 gauge aluminum we will be adding about 400 pounds plus framing. Aluminum is the way to go.

Now with that basis, let me get on topic. I'm going to need to weld a LOT of aluminum.

We have a Miller Matic 175 mig welder. It's in great condition and welds GREAT. I've done some pretty high-stress welds with it without a problem.

However, CAN I weld aluminum with it? Do I have to have a spool gun to weld aluminum? How well do spool guns work? What does a spool gun cost? I just saw one in Northern Tool for $500. OUCH! Anyway, for migging aluminum, what's the process?

Is TIG a better option? I mean if we were going to have to spend $500 on a spool gun, why not spend a thousand to buy a used TIG and worse case, sell it when we were done.

If TIG is the way to go, then what about the Plasma rigs that also do TIG and stick welding? Do those work well, and would that be a "bigger bang for our buck?"

Thanks!!!

Thoughts??? Besides the thoughts that are saying "these people are crazy!" :)

[HWHII]

Dave, TIG is the best way to go and will give you more capablities in your shop. Most all aluminum jobs can be done with TIG not so with MIG. Your Miller Matic 175 will run with a Spool Mate 100 Series Spool Gun and weld 18GA through 1/4". MIG or TIG you will also need to get a bottle of argon. Stay with the Miller spool gun if you decide to go that way. Short circut transfer MIG can a bit tricky and you will have a tendancy for lack of fusion but with some practice you can do it. There also are stick rods and Oxy-Fuel rods available also.

[macbruce]

My 2c worth........

Tig produces a better weld but is harder to manuver in tight quarters
If you're going to fabing directly to the underside of the bus, this could be an issue

You can use your 175 but you will likely need a shorter lead/gun, (10' max I think) on account of alu wire being softer than steel and harder to push through the liner. New lead/gun units aren't cheap. Spool is the way to go.......try ebay

If you don't know already, welding the 16ga will be touchy and will distort the frames . I'd use pop rivets to fasten the sheet to the welded frames

Hope this helps..............mb

[Spears]

Hello Dave,

I own a Millermatic 250 mig welder and at one time had an Aluminum spool gun for it. Aluminum can be welded decently with Miller spool guns but Tig is going to give you that amperage control to get the better welds on thinner material. I had trouble with “cold starts” making my welds look ugly and I would avoid Aluminum welding jobs because I found the looks of my welds with the spool gun weren’t satisfying. With the price of these economy TIG welders such as the Miller Diversion 165 (which I now own) not much different than the spool guns, I would definitely go with TIG. Running straight Argon gas, one can switch from Stainless to Carbon steel and back to Aluminum just flipping a switch and grinding a new tip on the tungsten so you gain that versatility. The less expensive TIG machines won’t have water cooled torches and will have duty cycles, but those issues aren’t bad to deal with on the home front, just in continuous production environments. Good luck. Spears.

[Quonset6015]

More than you want to know at:

http://www.weldingtipsandtricks.com/aluminum-properties.html

Henry Votel
Forest Lake, MN

[arftist]

Hey Dave. The TIG would be a great thing to have in your shop anyway, and NOT sell it after.

You can MIG aluminum without a spool gun, but it is tedius. You will have to buy; a new 10 foot pistol grip gun. A new nylon liner. New feed rollers. I highly recomend against this route. You will spend most of your time messing with birds nests.

Spool on guns work very well, but the wire in 1# spools is way more expensive.

Stick aluminum would be extremely difficult for 16 ga.

Learn a bit about sheet metal fab, before you start this project. Most of your seams should be bent, not welded. A man with a press brake can make a ten foot seam in under a minute.

You may not need to weld at all, aluminum is so easy to drill that bolts may be a good option.

Back to the TIG, you should have a TIG anyway, this is your chance to justify the cost.

[BIGGUNDOCTOR]

Back when I had my shop I did some frames for highway signs that were made from .1875, and .250 web X 1.5", and 2" square channel. I stared with TIG, but went to MIG due to the greater speed. Aluminum takes more oomph than steel does due to its better heat transfer. I believe the gun on my Miller MP-65E is 12', or 15'. Popped the nylon liner in, popped in the serrated wheels into the feeder, hooked up the argon tank, and got welding. With my MIG being a 650 amp unit I was able to spray arc the welds, so much nicer than TIGgin' them. Point, squeeze the contactor, and HUMMMMMMMMMMMMMMMMM, done. About as fast as it took to read that sentence the 2" weld was done. With spray arc you need enough arc density to carry the molten metal to the weld area, the wire doesn't touch like in standard short circuit welding with MIG. I was also pushing a .062" wire from a large spool, so I had to keep the gun lead straight as I could.

To run large spools a push pull feeder like the Cobramatic can be used.

Spoolguns are nice for some applications, but they are not totally necessary. I have a Miller spoolgun that my friend got at an auction for $150 with the control box to adapt to a Miller Bobcat. Haven't even hooked it up yet.

That MIG setup was also great for fixing the broken skegs on outboards when the boaters had a DOH! moment. HUMMMMMMMMMM, done.


For your situation I would look into making a box that slid into a rack under the bus. The bottoms will need to be braced somehow to keep them from bending under a load. The bad thing about aluminum is that it will crack from vibration if not braced correcly, and if it is not protected somehow it will corrode if kept wet, or used on salted roads. Like Arftist stated look into fabbing by bending the most you can. Overlapped seams, and rivets may be the way to go. Followed with a good sealant to cover them from end to end. Think ahead to worst case scenarios IE; how will you do repairs when the time comes?

I have 2 TIGS, and 4 MIGS. Each method has its advantages, and disadvantages. With MIG you get speed, and some versatility, with TIG you get more precise welds, and it is faster to switch from aluminum, to steel, to stainless, etc.

[BIGGUNDOCTOR]

Back when I had my shop I did some frames for highway signs that were made from .1875, and .250 web X 1.5", and 2" square channel. I stared with TIG, but went to MIG due to the greater speed. Aluminum takes more oomph than steel does due to its better heat transfer. I believe the gun on my Miller MP-65E is 12', or 15'. Popped the nylon liner in, popped in the serrated wheels into the feeder, hooked up the argon tank, and got welding. With my MIG being a 650 amp unit I was able to spray arc the welds, so much nicer than TIGgin' them. Point, squeeze the contactor, and HUMMMMMMMMMMMMMMMMM, done. About as fast as it took to read that sentence the 2" weld was done. With spray arc you need enough arc density to carry the molten metal to the weld area, the wire doesn't touch like in standard short circuit welding with MIG. I was also pushing a .062" wire from a large spool, so I had to keep the gun lead straight as I could.

To run large spools a push pull feeder like the Cobramatic can be used.

Spoolguns are nice for some applications, but they are not totally necessary. I have a Miller spoolgun that my friend got at an auction for $150 with the control box to adapt to a Miller Bobcat. Haven't even hooked it up yet.

That MIG setup was also great for fixing the broken skegs on outboards when the boaters had a DOH! moment. HUMMMMMMMMMM, done.


For your situation I would look into making a box that slid into a rack under the bus. The bottoms will need to be braced somehow to keep them from bending under a load. The bad thing about aluminum is that it will crack from vibration if not braced correcly, and if it is not protected somehow it will corrode if kept wet, or used on salted roads. Like Arftist stated look into fabbing by bending the most you can. Overlapped seams, and rivets may be the way to go. Followed with a good sealant to cover them from end to end. Think ahead to worst case scenarios IE; how will you do repairs when the time comes?

I have 2 TIGS, and 4 MIGS. Each method has its advantages, and disadvantages. With MIG you get speed, and some versatility, with TIG you get more precise welds, and it is faster to switch from aluminum, to steel, to stainless, etc.

[FieryFurnace]

Thanks for all the quick and informative responses guys. I have already looked at the idea of fabricating a metal brake and bending the aluminum. Seems like it would be pretty simple.

Let me get one thing cleared up. We aren't going for the "lime-green, I converted a school bus into a make-shift RV" look. There are a number of people around that have converted a true blue (or should I say true yellow) school bus into a sure-nuff nice looking motor coach.

With that in mind, you know on the big nice Prevost motor coaches, the storage boxes are a shiny stainless steel or aluminum! That is what the idea and goal is. Another part where we will be using aluminum is to raise the roof hieght aproximately 20 inches. A lot of conversion projects do this, because a school bus does not have much head room! I think ours is 6' 2" inside!

We are planning on putting several coats of a glossy clear coat over the aluminum as a protectant and to help retain the shine.

After mentioning the rivets and/or bolts to dad, we agreed that that is going to be the best way to go. If we can make our own metal brake then we can drill all the holes and rivet or bolt everything. We talked about running SS bolts along the underside of the boxes. I was already planning on bolting the boxes to the underside of the bus so that they could be removed if needed. The bus is already primarily held together by rivets so we could do everything else with an insane amount of rivets and leave both the tig and the mig alone.


Have any of y'all built your own brakes?

I was already thinking about trying to put some money aside to put into a Plasma, tig, and stick welding combo unit this year. Any thoughts on those? I think Miller makes one, so I'd think they'd be pretty good. I've only used TIG once but it sure was NICE! I've never done stick and I've only seen a plasma cutter in action once!

[Charles R. Stevens]

Their are plenty of plans for simple breaks out their. I suggest that you radius the bends, as it will cut doun on cracks.
Hand dollies and a new plastic deadblow hammer, for shoot edges and corners. Make up a "T" dollei weld a flat stock to a price of round stock that matches your bender radius. Round of the ends to smooth half sphears, and sand and polish smooth. Then a block dolly with radiuses edges.
Not a full component of sheet tools, but it will get you started. With aluminum we can use hard wood to good effect for dollies and forms.

[BIGGUNDOCTOR]

I would get separate units instead of a combo machine. We had a TIM, MIG, ARC combo Miller, and it was a pain switching all of the leads around just to do a small weld. I like having single purpose equipment myself. With anything like that they have to make some compromises to make it work.

Just a rundown of my welders , and what I paid for them at auctions.

Linde 350A TIG $250 with radiator, added a foot control $160, and new torch $125. Great welder, very smooth.

Miller MP-65E MIG/Stick 650amp (3 phase) $500, feeder cost $400, and it came with around $900 worth of silicon bronze, core, and aluminum wire.

Lincoln SP-100 110v MIG. Purchased new for around $500 I love this model as it has variable adjustments, not heat ranges. This welder has had a ton of trouble free usage. Highly recommended.

Miller 250amp TIG Dialarc HF w/radiator, welding rods, torch, and bottle $1,100

MillerMatic 200 complete $440

Lincoln digital display 200/250 MIG (forget the model) complete $400

Watch Craigslist, I recently saw a 300A Lincoln TIG for $300 that looked pretty good. Lots of welders for sale in this area.

[FieryFurnace]

I would get separate units instead of a combo machine. We had a TIM, MIG, ARC combo Miller, and it was a pain switching all of the leads around just to do a small weld. I like having single purpose equipment myself. With anything like that they have to make some compromises to make it work.

Maskes sense! Thanks! It'll be a while before I could get one anyway. I will keep an eye on prices though so I have a general idea of what I'm doing....instead of jumping in head first without research and getting ripped off! :huh:

[pkrankow]

On the aluminum, use a product like a truck bed liner for the under body areas that are not visible. This will deaden road noise and reverberation in the box, and it will protect from gravel and road debris.

Cold riveting aluminum is no trick at all. Get a chisel gun, cut a chisel off and grind the round shank to a slight hollow face. You have someone buck the backside with a bar of steel that weighs about 20# and has a dimple in it. When I was in high school I helped my Dad re-rivet a boat with several pounds of aluminum rivets. We replaces 7 ribs while at it too. I bucked about 25% of them. My oldest brother bucked most of the rest. Wear thick gloves, the vibrations on either end are harsh. Our buck bar was a 1x2 piece of steel about 18 inches long.

Welding is faster.

Phil

[Jacques]

If you want to go the solid rivet way you can look at the aircaftpeople, especially the RV series.

Anyway a good place to start is at http://www.tinmantech.com/ .

I've personally seen this guy welding aluminium with a oxy-acetylene torch with the right flux.

[Bryce Masuk]

I would suggest using something thicker than 16 gauge

the problem with aluminum is that is cracks from vibration and stress alot easier than steel using about 1/8th will be better or you could using quite a bit of cross bracing or breaking if you have a access to a press break
plus if your going to mig weld it its going to be easier to weld .120 with the spool gun your probley going to want .030 or .035 wire and you will need pure argon to weld aluminum

you may find that its easier to build a frame out of channel and angle and than use sheet to close it up depending on your access to a press break

[shoer]

Don't know if this will help, but here are plans for building a press brake. It could probably be super-sized without too much trouble.
http://www.vintageprojects.com/machine-shop/press-brake-plans.html
If you want to just buy one, www.summitracing.com is a great place for good quality tools at a reasonable price.
I have bought lots of stuff from them over the years and never been disappointed.

[Scott Hightower]

It takes some practice but you can weld aluminum with a mig. I welded tons of racecar parts and never broke a weld, even in a hard crash. You need 100% argon though for the sheilding gas. If you don't have a pull gun make sure you keep your lead as straight as possible.

Scott
welders360

[Old N Rusty]

Spool gun, the best way to weld aluminum M.I.G.. Any other method can be likend to PUSHING a cooked spaghetti through a soda straw. For your brake, see WWW.ASSET SALES .com. Lots of good stuf,i will check my lottery tickets now.

[Rhrocker]

I've wanted a "real" tig for several years. I had the aftermarket "add-on" that you can attach to a regular welder, but the welder wasn't made for that, so....
I got a really good buy on a Lincoln Square Wave 175 not to long ago. So far it's performed ok, but I need some more time on the tig to practice with it. I have some thick aluminum to weld (.250"), and was wondering if this machine would do it? In fact, does anyone have any experience with a square wave 175? Good, bad, or otherwise? I do need some new tig parts (ceramic nozzels, etc) and so far haven't located anything for that, but should just be a matter of time.
Robert

[Old N Rusty]

Sorry i cannot help, i dont allow lincoln (spit) equipment in my shop.Its the name thing, you know, yankees and all that. pax

[NeatGuy]

If your storage does not need to be private you could use perforated aluminum sheets which would further reduce your weight. Have you considered using rivets? you have a compressor and a rivet gun is cheaper than a new welder or a spool gun ... just a thought.

brad

[Dave Huntress]

I have been tig welding for 35 years plus... it's a great trade.. www.tanksbytigman.com this is my website... why not re-think the design process? I have a press brake as well and you will need some tonnage to bend anything in length. Maybe a steel angle iron frame and bolt the aluminum to the frame work then seal all the seams to keep the weather out. Just a suggestion.. I worked sheetmetal fabrication for 25 years before going out on my own and it would be worth it to find a local welder who is already set up to weld your aluminum parts.. probably cost a couple or few hundred bucks opposed to all the set up building a brake for bending and failing when it doesn't work, shopping and spending money on a welder to find out you have to add a bigger circuit breaker or hardwire the welder etc.... just my .02

[Dave Huntress]

oh and almost forgot, you need a constant voltage machine to mig weld aluminum properly....

[SmoothBore]

Sounds like a lot of work, to make an "apple" into an "orange".

Particularly when older "tour" buses are readily available, ... cheap, ... and already have the storage and head room that you desire.

Just because you can build something yourself, doesn't always mean that you should.

.

[peacock]

I would rethink the steel/aluminum thing. Alum. is lighter but you will need to increase the thickness to get the same strength as steel. Cost will be much higher, you will still have to protect from corision. Your bus looks like a 72 passenger. It's meant to haul about 7,500 lbs of passengers. properly designed steel boxes will not need framing.
I don't think the extra weight of the steel over the alum. is a big factor. I have done 2 bus conversions and they are a lot of work but can be very nice when finished. Raising the top that much will drastically decrease your fuel mileage.