OK, so we caved into temptation and ran a slightly sensationalized headline on the cover about MIG welding without the use of gas. Since it's true one can MIG weld without employing a typical mix of 75 percent Argon gas and 25 percent CO2 we can't get into hot water for lying and there are valid reasons for doing so besides just trying to save some cash (which isn't an honest reason because flux-core costs a little more). It's obvious not having to haul around a heavy gas bottle piggy-backed on their welder can make things a lot easier working out in the field, but that's just the tip of the proverbial iceberg. Starting out, a good reason to use a self-shielded flux-core wire is for those times when the job has to be done outside in a drafty environment where the wind will blow gas away and porosities in the weld will result. Beyond looking bad, structurally speaking, porosities undermine the bonding qualities of the weld, which translates into potential weakness. Since we were stuck out in the driveway and the Santa Ana winds were howling, this was a plus, but there was another reason we were using Hobart's self-shielded flux-core wire in our Miller 252 welder. The '56 Ford F-100 chassis that's going under our '53 F-100 came to us in pretty good condition, but there were a few problems. Amongst them was a big ol' hole hacked out with an oxyacetylene cutting torch in the crossmember that looked worse than that place where Satan lives. Our friend Steve Bentley is a master welder and fabricator who spends a lot of time welding with cars and semis flying by as a subcontractor working for Caltrans building new additions to California's freeway system. With this in mind, we asked Steve to share some tech tips with our valued readers. On the rear side of the patch Steve shows how to make a piece to bridge the gap between the top of the 3/8-inch steel plate he whittled out with a plasma cutter and the crossmember. As it turned out the filler piece wasn't needed. On the front side of the crossmember Steve demonstrates how well self-shield flux-core wire works with its larger ball-type transfer with better deposition (the amount of weld metal deposited in a time period, measured by pounds per hour) to bridge the wide gap with only one pass of the MIG gun. This is not to say flux-core works better than solid-core, but rather they have different properties which work better on certain applications. Pretty cool stuff, huh?
In order to switch our Miller...
In order to switch our Miller 252 MIG welder over from gas-shielded to self-shielded flux-core wire it was necessary to change the polarity to electrode positive by reversing the terminals with a 3/4-inch box-end wrech.
With the polarity reversed...
With the polarity reversed we moved on to installing a 10lb spool of 0.035 flux-core wire. The diameter of the wire was determined by the gauge of the steel we intended to weld. This information is easily acquired by logging onto www.millerwelds.com.
This is called a guide roll,...
This is called a guide roll, notice the .030 indicated on the outside. This side should face out for .030 wire, but don't be confused because the .035 groove is closest to outside face.
We determined we needed .035...
We determined we needed .035 flux-wire by referring to the chart on Miller's website. We installed the guide roll, and then connected the wire to the gear-driven wire feed.
We plugged the Miller 252...
We plugged the Miller 252 into a 220-volt receptacle and then adjusted the voltage and the wire speed. Ballpark settings are available on Miller's website.
Next, we needed to locate...
Next, we needed to locate a handy spot to establish a good ground for the Miller 252. This bracket on the framerail was determined to be a good location.
But the paint needed to be...
But the paint needed to be stripped off with a die grinder to reach the bare metal.
The ground cable was securely...
The ground cable was securely attached to the bracket with the ground cable routed out of the line of fire so that it wouldn't accidently get kicked-off while welding.
The crossmember on our '56...
The crossmember on our '56 F-100 frame had been butchered out with a cutting torch to clear who knows what, so we squared (cleaned) up the area and made a patch out of 3/8-inch steel plate.
We used a Miller 375 Extreme...
We used a Miller 375 Extreme plasma cutter to produce surgical-quality cuts on the 3/8-inch steel plate, and then used a die grinder to do the final sizing.
Look to the bottom left of...
Look to the bottom left of the steel patch and you will see one little tack weld. Steve made this one tack weld and then checked to ensure the patch was perfectly aligned.
Once Steve was sure it was...
Once Steve was sure it was a good fit, it was time to add some more tack welds. Notice the gnarly, smoky white traces around the tack welds; this is from the flux-core in the MIG wire.
With the patch solidly tacked-in...
With the patch solidly tacked-in Steve moved on to welding the top and bottom. Notice the top weld is cleaned off thanks to using a wire brush.
To demonstrate for readers...
To demonstrate for readers two different methods of filling a gap Steve left an overhang of steel that he cut flush with a die grinder to be used as filler in the gap.
Here's the wire brush Steve...
Here's the wire brush Steve was using to clean the flux off with as he welded the crossmember patch in.
Notice how nice the welds...
Notice how nice the welds look, and all of this was done outdoors while the Santa Ana winds were blowing like crazy. The next step is to finish the welds off with a body grinder and then the repaired area will look as good as new.