Best abrasives for grinding down booger welds?

[artech]

Hope some of the more skilled fabricators can help out! I finally am healthy enough to do some more work on my rig! I got in on the 4x4 Labs Bumper Group Buy and looking forward to building my own rear bumper, but my welding skills are mediocre at best. I do get good penetration and adhesion, and my stuff don't break, but my welds just look like crap. So I want to make the bumper look nice, and am looking at grinding everything down and smoothing it out. So what brands of flap wheels and discs give the best bang for the buck?

Equipment: Welder- Lincoln 220V Buzz Box. Grinder- Dewalt 4-1/2" angle grinder. Operator- Paramedic who took shop class in high school 35 years ago, and makes ugly strong stuff that works. Budget- tight, but flexible. Probably going to use 6013 rod for most of the joints because I have had good luck making decent looking welds with it in the past, with maybe higher strength rod in key areas. Plasma Cutter- cheap Chinese Ebay thing that actually works surprisingly well as long as the material isn't too thick. Also got a gas torch, chop saw, and sawzall for hacking through tough stuff.

Strategy: Planning to reinforce wings with braces like pandathrust's and jcardona's builds(thanks for the pics, great idea!) and somehow want to run my winch line through the bumper from a rear mounted winch in the spare tire area. Need a trailer hitch too, which complicates things a bit but should be doable. Don't think there will be room enough to cut in LED lights without weakening things too much. I'd also like to run the exhaust out through the bumper but that may not be legal in this State, gotta check if flex pipe is usable here for on-road vehicles. Not looking for perfection as the final finish will be rattle can for easy touchup after rock stripes, but I'd like it to look decent and not like a hack job.

So some extra fab involved anyway, which means more welds to grind down. Obviously the best answer is to learn to weld better, and projects like this one are helping with that, but in the meantime I know I got some grinding to do. So what should I buy for flap wheels/discs?

Thanks!

 

[Lumpskie]

Sounds like you are a better fabricator than me. I like those sandpaper flap disks as well. I haven't really noticed a difference in brand, though.

 

[gummycarbs]

Best bang for the buck flap disc is the Harbor Freight Zirconia.

Buy an extra grinder while you're there so you can have 36 grit on one and 80 or 120 grit on the other.

 

[Pin_Head]

Please reconsider welding on anything like a bumper that could kill someone if it breaks off. It is not something that you would want to guess about.

 

[Corbet]

I've never noticed much difference between flap wheels so I just buy them where ever when I need other stuff.

What I do avoid now are the really think ones as i generally toss them long before they are completely shot. I round off the end log before the whole body is done.

4x4 labs kit is an easy build Have fun with it.

 

[HAAANK]

I've had the best results and wear from Milwaukee flap discs from the Home Depot. They sell ~6 packs by the contractor counter.

 

[Rwhat]

You try using 7018 rod?

 

[inkpot]

I have built tons of stuff over the years with my cheap Chinese 110v mig. Some of it on the USA Today printing presses, some of it on my Piggy. Bumpers, suspension, roof racks, anti-wrap bars, etc. NONE of these items ever failed after decades of use.
My welds are not pretty, but they do have good penetration and no bubbles. My welds are occasionally more proud than needed, so in cosmetic applications I often smooth them down, usually starting with a coarse wheel and progressing thru several steps of finer and finer flap wheels to blend it in smooth. Really just need to take your time and get a feel for it. I don't weld often, but when I do, I warm up on some scrap, similar to the thickness of the project at hand.

 

[artech]

Please reconsider welding on anything like a bumper that could kill someone if it breaks off. It is not something that you would want to guess about.

I appreciate the concern, but I welded up a set of pushplates and headgear snowplow mount for my Sequoia that is still going strong after 5 years of hard Maine winters. Some of the Meyer factory welds on the plow have broken, but none of mine have, and none of my repair welds on the plow have either. I'm not saying I'm a great welder because I'm not- there are tons of guys out there welding that are way better than I'll ever be. But once I stick it it does stay together, it just looks like .

I have tried 7018 rod but have not been able to lay down a reasonable bead with it yet. I think it needs very different settings than the 6013 and I haven't figured out the 'sweet spot' for it yet. However, I shall endeavor to persevere...

 

[gummycarbs]

I thought I was a terrible welder for a long time. Then I switched to 7018 and, like the ugly duckling, discovered that I was, in fact, a mediocre welder!

I also started using thinner electrodes with higher amperage. My 220V setup couldn't push enough amps through my old transformer-based Lincoln 'tombstone' to effectively weld with the thicker electrodes.

 

[BILT4ME]

I appreciate the concern, but I welded up a set of pushplates and headgear snowplow mount for my Sequoia that is still going strong after 5 years of hard Maine winters. Some of the Meyer factory welds on the plow have broken, but none of mine have, and none of my repair welds on the plow have either. I'm not saying I'm a great welder because I'm not- there are tons of guys out there welding that are way better than I'll ever be. But once I stick it it does stay together, it just looks like .

I have tried 7018 rod but have not been able to lay down a reasonable bead with it yet. I think it needs very different settings than the 6013 and I haven't figured out the 'sweet spot' for it yet. However, I shall endeavor to persevere...

I would use the 7018 rod as well, as it SHOULD give a smoother weld and lay down, HOWEVER, it is a HORIZONTAL position weld, so it does NOT like to weld at an angle or on the side or overhead. Flat, horizontal only and it will give a very nice looking weld and will be easy to do.

The 6013 is a nice "repair rod" to burn through rusty, ill-prepared steel that will end with a rough-looking weld and will require much more grinding. I grew up with this rod and if I knew more then, I would have taken the time to prepare better and had overall better looking (and better quality) welds and a LOT less grinding when done.

Depending on how large of boogers you have, I would progress from 80 grit on the REALLY big boogers, but DON'T touch it to the main surface because it will cut lines quickly that won't fill in with paint. Step up to 120 grit and even 220 grit for a finishing/smoothing process. Use the flap type discs, as they give a much smoother surface than the traditional abrasive grinding wheel. Brand is not that specific. I work with 5 local to 19 fab shops across the USA and every shop I'm in, I look at those things. Each shop has their brand preference, but it may be because the local salesman is better at peddling is wares, or the purchasing agent found a deal online.

I don't know how the 4x4 Labs bumper is laid out for a fabrication fit, but usually, if it is designed for a 1/2 material thickness gap between pieces should give you a nice, smooth weld when done. If you are welding inside and outside, then do the OUTSIDE weld first, as that will allow the heat to be more even between the pieces. Then do the inside weld, then do your final stages of clean-up. Make sure to grind ALL of your edges FIRST, BEFORE welding to remove any cutting oxidation (Plasma cut parts have a layer of oxidation on the edge that affects welding, laser or water-jet cut parts do NOT) A light grind on ANY part will give you a clean edge to start, regardless of how the part was cut.

How do you plan to coat the bumper when done? Cleaning, (sandblast, power tool clean, solvent wipe) then painting by spray bomb (Krylon or Rustoleum) or actual spray gun (HVLP, Airless) or Powder Coat MAY affect your decision on what weld process or grinding process to use.

I know I have given WAY more here than may seem important to you, and I get that. I want to post for others as well that may be EXPECTING the highly glossy, perfectly smooth finish when done, only to find out that if they would have started differently, it could have helped.

Good Luck!

Happy Welding!

 

[Rwhat]

If you can find a miller or Lincoln Mig on CL you will cut your time down a lot on grinding and cleaning up. I can lay a nice penetrating bead down and no clean up. Factor in the cost of grinding discs, etc and the time spent on it.

I spent a lot of time grinding and prefer not to do it.

 

[artech]

Looking back I think I have mixed up the 6011 and 6013 rod, if the -13 is for rusty metal then I have been using mostly the -11. That stuff makes nice welds. The electrodes for rusty metal I have had no luck with, instead I grind stuff until it is clean and use the other electrodes, even if it takes filler pieces.

"I know I have given WAY more here than may seem important to you," Not really! I'm always down to learn new things, and I didn't know half of the things you mention in your post, mainly about the oxides on cut pieces, so thank you! That helps!

I would love to pick up a MIG, but I have 4 welders right now and rally can't see getting another one since I am just fixing stuff around the house. Gas torch, tiny Harbor Freight TIG unit(great for small stuff), cheapo wire feed welder using flux core (not great, but it works), and my buzz box, which gets the most use. I should probably sell all this stuff and buy one good MIG unit, but I have a lot of history with these rigs and I'm comfortable with them. The tiny TIG is a real joy to use on tiny parts, and the buzz box cranks as good as ever on big stuff. I have gas welded before but usually use that torch for cutting instead. The wire feed rig seemed like a good idea at the time and it does weld, but the spatter goes everywhere and the wire speed is not really that constant. But it was cheap and it does work.

 

[BILT4ME]

Looking back I think I have mixed up the 6011 and 6013 rod, if the -13 is for rusty metal then I have been using mostly the -11. That stuff makes nice welds. The electrodes for rusty metal I have had no luck with, instead I grind stuff until it is clean and use the other electrodes, even if it takes filler pieces.

"I know I have given WAY more here than may seem important to you," Not really! I'm always down to learn new things, and I didn't know half of the things you mention in your post, mainly about the oxides on cut pieces, so thank you! That helps!

I would love to pick up a MIG, but I have 4 welders right now and rally can't see getting another one since I am just fixing stuff around the house. Gas torch, tiny Harbor Freight TIG unit(great for small stuff), cheapo wire feed welder using flux core (not great, but it works), and my buzz box, which gets the most use. I should probably sell all this stuff and buy one good MIG unit, but I have a lot of history with these rigs and I'm comfortable with them. The tiny TIG is a real joy to use on tiny parts, and the buzz box cranks as good as ever on big stuff. I have gas welded before but usually use that torch for cutting instead. The wire feed rig seemed like a good idea at the time and it does weld, but the spatter goes everywhere and the wire speed is not really that constant. But it was cheap and it does work.

Actually, I had it backwards. It's the 6011 that is the "Rust Rod". The 6013 is better for thinner metals and gives a better weld, but doesn't give good penetration. It's been so long since I've actually burned a rod, that I forgot it...... But the other stuff is right......in my mind......

 

[maxamillion2345]

Is your polarity set right?

I buy hd 40 grit discs off amazon, definitely the thick ones. For bumper seams, I go flat with each plate until I have sharp edges where the welds were. Then I'll slowly radius those edges until you get a nice smooth rolled edge. You can weld over the porosity from there and then sand it down again.

 

[LINUS]

I am a welder by trade, we have a dusty old Lincoln buzzbox we laugh at, but it does work to its' credit.

The biggest thing I see guys do dressing out ugly welds is they grind off all their weld - seriously, it's really common.

The fix for that is to bevel back some of the metal where your seam to be welded is, then you'll still have weld despite surface grind to 'pretty it up'.

Honestly, you can buy old transformer based MIGs for cheap. I sold my Miller Challenger 172 (was the 2nd level 220v machine back in ~2000) - it was well kept, only was worth $500.
And the new inverter ones will near pay for themself if you push your amps constantly - my Dad bought the Miller 211 and it's a heck of a machine for hobby work. I run the Miller 350 MIG, but I push-pull AL wire & AL takes amps to penetrate versus steel of same guage.

As for discs I get a decent discount at the LWS so I just grab handfulls of Pferrd (sp?) flapwheels - I grab the 40 grit & just wear them down - a worn 40 from a heavy job will act like a 120 for prettying up booger welds, if you grind enough to handle one well enough to not just destroy the edge but evenly grind across the disc. I have a rack of 1/2 used flaps in various stages of wear, so they act like the full range of grit & you get more milage.

I'd really try & justify a entry MIG of either transformer/inverter style - esp if you get the inverter you'll use less consumables & power to justify cost.

As long as you always remember to turn/close the valve on your gas bottle.
(I have a buddy who habitually forgets, and even BS8 bottles get pricey)

 

[1973Guppie]

I 2nd what Linus said, I would be concerned about grinding off my weld too much and making it a weak joint. With a decent mig there really should be little weld clean up, some here and there but for the most part you can lay a strong weld easily. I actually prefer the look of a weld vs. a smooth joint, but that's me.

 

[shocktower]

I am a welder by trade, we have a dusty old Lincoln buzzbox we laugh at, but it does work to its' credit.

The biggest thing I see guys do dressing out ugly welds is they grind off all their weld - seriously, it's really common.

The fix for that is to bevel back some of the metal where your seam to be welded is, then you'll still have weld despite surface grind to 'pretty it up'.

Honestly, you can buy old transformer based MIGs for cheap. I sold my Miller Challenger 172 (was the 2nd level 220v machine back in ~2000) - it was well kept, only was worth $500.
And the new inverter ones will near pay for themself if you push your amps constantly - my Dad bought the Miller 211 and it's a heck of a machine for hobby work. I run the Miller 350 MIG, but I push-pull AL wire & AL takes amps to penetrate versus steel of same guage.

As for discs I get a decent discount at the LWS so I just grab handfulls of Pferrd (sp?) flapwheels - I grab the 40 grit & just wear them down - a worn 40 from a heavy job will act like a 120 for prettying up booger welds, if you grind enough to handle one well enough to not just destroy the edge but evenly grind across the disc. I have a rack of 1/2 used flaps in various stages of wear, so they act like the full range of grit & you get more milage.

I'd really try & justify a entry MIG of either transformer/inverter style - esp if you get the inverter you'll use less consumables & power to justify cost.

As long as you always remember to turn/close the valve on your gas bottle.
(I have a buddy who habitually forgets, and even BS8 bottles get pricey)

So when I get around, to prepping my 4x4 labs, and I come visiting with after hours beverages( I don't drink adult beverages), you can help me weld my bumper, I can tack it together but want it purty

 

[Pin_Head]

If you don't know the difference between 7018, 6013 and 6011 rods, you have no business welding on trailer hitches and spare tire carriers in my opinion. You can tell a weld is bad by looking at it, but you can't tell if it is good enough for critical applications. You can only tell by testing them and that is one of the things that they teach you in welding class, besides things you should not be welding on if you are not certified.

 

[artech]

Was planning on beveling all the joints, then tacking from the front, pulling it off the truck, and welding from both front and back sides in order to get deep enough to make it strong. Probably will lay 3 or 4 beads on the back of each joint to really hook it all together. Then grind the front smooth and fill whatever needs filling. Uses a lot of rod, but in my limited experience stuff really stays together after being done that way. And since time is pretty much the most abundant asset I have...

MIG would be great but it is just not in the budget, I can barely afford the bumper! Gonna hafta be done with plain old arc, that's all I got that'll work on steel this thick and it does do the job. Just looking for advice from folks on their favorite abrasives to clean up my mess afterwards.

For the final finish I plan on sandblasting it and priming it with an etching primer, then rattle-canning whatever color I decide on. Might try a cold galvanize base then paint over that, since rust is always an issue up heah. Going with spray paint to make repairs easy, as this truck gets dragged over stuff quite a bit. But the road salt means bare metal gets rusted fast, so quick finish fixes are desirable and it'd be nice if it all kinda matched. Plus it fits the budget, so there it is!

And as a side note, Paramedics make squat for money. Seriously. I made more driving a forklift than I make providing advanced life support in the ambulance, and while that sucks, it is what it is. I love what I do but it is damn hard to make a living at it. So I do budget builds. Don' be hatin'!