Great start so far.

Mill scale is the black layer on the steel after it has been rolled at the mill.

Another issue that I have had with MIG welding is that I run an extension cord that is too light, my welds look like junk. I always try to plug directly into an outlet or use a 12 gage extension cord

Hope that this helps.

 

I'm actually running a 25foot 12gauge cord. I should probably plug straight into the wall though.

Thanks to everyone for all the tips you've given me. If I had a plasma cutter I'd probably finish this bumper up, sell it on the cheap and then build another one. I've learned a bunch of things and found some other stuff I'd wanna do differently on my next bumper build(yes I know I'm getting way ahead of myself.

 

NOPE it how well you can grind it down and make it look pretty.

 

LOOKIN GOOD!!!!

 

MORE POWER!! **& plug in to the wall where the outlet is less than 2feet off the panel

I have to say I agree.. but 1" is a bit much.. have enough cleanER steel around to melt/pull/drag molten steel to make your bead..

X2.. no extension cord..

too true.. the nice thing about metal is you can always add more! HAHA

From me 2 U:
1) put a grind where your grounding clip goes and tac-weld it in place ESPECIALLY when using indirect power.. daisy chained outlets.. ext. cords..
2) Confirm that your power is turned up enough for good penetration and line speed is fast enough that you move along before building/stacking the weld
3) get an auto dim welders mask.. $45 to improving your skill 10fold..
4) and (unfortunately I know this first hand).. wear LONG pants.. I welded with my 240v stick welder for nearly 6 hours straight.. (welding a dump truck frame).. and the "SUN" BURN!!! OMMFG!!!!!!! In short.. cover your skin unless want blisters

PS~ ZACH.. good to see you on the computer again dude.. my wife is due in 3 days with our first kid!! No worries, the XJ will hold a car seat! HAH

L8ter

 

It's the iron oxides on the surface of rolled steel.

 

is that gray coating on the steel. It is formed by the cooling of the steel and is full of nasty impurities.

 

Are these plates from a kit, or did you design & cut them out yourself?
They look like they'd be strong after they get welded up.

 

yeah, I did a bit more welding on it today and goodness it makes such a difference when you remove all that crap. Did that and also beveled the joint and laid my prettiest bead yet.

I designed and cut them myself. Used cardboard and some creative/overkill thinking to come up with a design I'd be happy with(aka more stout than it really needs to be) the frame plates and the winch plate are both 1/4" and welded together on 4 6" welds per plate. in other words the winch plate is attached to the frame plates by 24" of welds.

To get technical about it: typical MIG wire has a 70,000lb tensile strength per square inch. so a 1/4" bead times 24" of weld = 420,000lbs of tensile capacity holding winch plate and frame plates together. Somehow I think the steel would deform wayyyy before then. Overkill for a front bumper and a 10,000lb winch? Definitely.

Peace of mind? you betcha

Tomorrow I'll be grinding down some welds and I have to grind out two because I forgot to factor in the D-ring tabs I'll be buying so I need to get the area for those prepped. more pics will come tomorrow afternoon.

(anyone is more than welcome to chime in and correct/comment on my calculations, based on the info I have they should be right)

 

There are a few assumptions in your calculations. The biggest one is that the weld will not be loaded evenly. As you load the bumper (heavily), it will start to flex. This will put one end of the weld under a higher stress. If the locallized stress exceeds the limit of the weld material or the steel plate, they will start to crack. The cracks will continue to grow if the load remains high enough.

For example: Take a sheet of notebook paper and grip it in your hands on opposite edges and pull evenly. If a strip breaks off, turn the paper 90 degrees and repeat. Now grab the same piece on one edge to tear it and see how much easier it rips. Same concept.

Stress risers are also an issue. Make sure that all intersections end in a nice radius.

Overall, your bumper should hold up to any reasonable load you put on it. Keep the welds clean and strong and send us the pictures when you are done.

 

Should have drilled holes through the plate for rosette welds to the unibody... Much stronger!

 

no way in hell am I welding a bumper on. I figure 7 1/2" Grade 8 bolts PER SIDE will be way more than sufficient. Y'know overkill. Its how I roll.

 

Is the scale that occurs when the sheets of steel cool at the mill they were made at.

 

x2, why weld a bumper on, with that many bolts the unibody would rip in half before the bumper let go.

 

where do you buy steel?