4 x 4 labs rear bumper? I must be bi-polar... RR?-LC?
- Thread starter RalphB
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A one-day project? I could swing that. The HOA special forces only snoop at night. The offer is open ended.[/QUOTE]
The final welding is what takes the longest on these kits, the 62 bumper went together really well except the shackle mounts that go through the main shell were too large for the holes so I had to open them up. I also didn't fill in and grind down all the areas where the welds were concave in comparison to the main pieces. The getto booty on my 62 smashes rocks all the time no matter what line I pick so I figured the rocks would do the grinding for me. Fitting and Tacking (including pivots for swingouts) should take half a day, welding the whole thing is another half a day, including grinding if you start with the most aggressive pads (25 grit) then move on to 80 or less for finishing. Oh and can't forget the 7" grinder to speed things up a bit, but don't let it get away from you...:whoops:
I also favor the spindles that 4 Wheeler supply makes FWIW, they are much stronger than anything that is supplied by any after market companies and from what i've seen you don't want a spare tire carrier to break and your spare pass you on the freeway.
The final welding is what takes the longest on these kits, the 62 bumper went together really well except the shackle mounts that go through the main shell were too large for the holes so I had to open them up. I also didn't fill in and grind down all the areas where the welds were concave in comparison to the main pieces. The getto booty on my 62 smashes rocks all the time no matter what line I pick so I figured the rocks would do the grinding for me. Fitting and Tacking (including pivots for swingouts) should take half a day, welding the whole thing is another half a day, including grinding if you start with the most aggressive pads (25 grit) then move on to 80 or less for finishing. Oh and can't forget the 7" grinder to speed things up a bit, but don't let it get away from you...:whoops:
I also favor the spindles that 4 Wheeler supply makes FWIW, they are much stronger than anything that is supplied by any after market companies and from what i've seen you don't want a spare tire carrier to break and your spare pass you on the freeway.
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I have to get me some of those.
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Metal removal is all about having the right rock and driving it with enough HP.
Personally, I like the flap wheel sander disk in 60 grit. It lasts a surprisingly long time, it mows metal faster than you'd expect, the heat-up on the part isn't out of control, and it leaves a very nice finish for welding or just leaving alone.
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They should make a nice finish, they are finishing disks, great for light blending, etc. For any real metal removal they are slow/glacial. For a job that calls for significant metal removal I use; a 4 grit stone, followed by 24 grit resin fiber disk, then 40 grit flap, finishing with a 80 grit disk on a palm sander. Grinding isn't my favorite, so prefer to get it over with as quickly as possible.
A 4 grit stone on a 4hp Top Cat grinder, the .3hp grinder is for scale.
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Full disclosure; I can't run that TC grinder at by shop, I repair them. They require ~60-80 cfm, my pump only puts out ~25 cfm, so in a minute or so the 80gal tank is empty and the tool is worthless.
That rock is too big/heavy to run on any "small/normal" grinder. My customer uses them down to ~1" thick and discards them, I collect the discards. At that size they are great for a normal grinder, remove a bunch of metal in a hurry. This has good and bad; if you are hitting where you want metal removed, it is good, if you touch where you don't want metal removed, it makes a big hole on a hurry, bad. They take control, with about zero forgivingness.
I see abrasives in two basic categories; hard, little/no flex (stones, resin-fiber on hard backing plates, etc) and soft, somewhat flexible (flap wheels, resin-fiber on flexible backing plates, D/A pads, etc). They have differing uses.
Say you want to make two welded parts look like one, a relevant case would be where the hitch comes through the flat face of the bumper. The hitch is somewhat proud of the surface, the weld is done somewhat excessive so there is excess to grind off. Given enough time it could be done with a flap wheel, but the result would be a wave in the surface. The weld metal is harder, some metal is higher, the abrasive is flexible, so is going to get into/remove base metal, the result is never going to be flat.
I start with the most aggressive hard stone available, use it to quickly mow the high stuff off to just proud of the base without hitting base. This make it look like
big scratch canyons. Switch to aggressive (~24-36G) resin-fiber on a hard backing pad, bring it down to just a hair high and start smoothing.
If you watch experienced grinders, at about this time they start dancing around the work, this is for a few good reasons: If abrasive is run the same direction over the surface it will make a series of ridges. When all of the scratches are in the same direction, it is hard to see what you are doing, when the angle is changed, it is much easier to see. Most importantly abrasives act differently depending on the angle that they hit scratches/edges, by changing angle the resulting effect is different.
Now also enter another very handy tool, especially for old, blind guys, spray paint. Color, brand is irrelevant, it is all going to be ground off, cheap and fast drying is what is important. The metals, welds, are slightly different colors, scratch patterns at angles look different, all of this tends to look like texture to the eye. Apply a light coat of paint and that disappears, can more easily see what you are working with.
At this point it should be flat with the surface, any pits, holes can be fixed with a quick spot weld. Now switch to a softer wheel, like a flap wheel and blend the ground area into the base, smooth scratches, etc. I finish with another shot of paint and run a D/A sander over it with ~80G paper. This results in a smooth random scratch pattern that quickly highlights any areas the need attention.
This can be done with one grinder and a sander, some are all proud of their boutique named grinder. I like powerful grinders, prefer to have several, loaded with differing rock, so can grab what is needed without changing rocks/pads. The other night, Phil and I were having a "who can spray the most sparks on the other" contest, so had a bunch of grinders out, some electric, air, different brands, etc.
IMHO it is all about the rock, cheap abrasives will result in frustration, take forever, poor result, good industrial abrasives make quick work and a good result. 
That rock is too big/heavy to run on any "small/normal" grinder. My customer uses them down to ~1" thick and discards them, I collect the discards. At that size they are great for a normal grinder, remove a bunch of metal in a hurry. This has good and bad; if you are hitting where you want metal removed, it is good, if you touch where you don't want metal removed, it makes a big hole on a hurry, bad. They take control, with about zero forgivingness.
I see abrasives in two basic categories; hard, little/no flex (stones, resin-fiber on hard backing plates, etc) and soft, somewhat flexible (flap wheels, resin-fiber on flexible backing plates, D/A pads, etc). They have differing uses.
Say you want to make two welded parts look like one, a relevant case would be where the hitch comes through the flat face of the bumper. The hitch is somewhat proud of the surface, the weld is done somewhat excessive so there is excess to grind off. Given enough time it could be done with a flap wheel, but the result would be a wave in the surface. The weld metal is harder, some metal is higher, the abrasive is flexible, so is going to get into/remove base metal, the result is never going to be flat.
I start with the most aggressive hard stone available, use it to quickly mow the high stuff off to just proud of the base without hitting base. This make it look like
big scratch canyons. Switch to aggressive (~24-36G) resin-fiber on a hard backing pad, bring it down to just a hair high and start smoothing.If you watch experienced grinders, at about this time they start dancing around the work, this is for a few good reasons: If abrasive is run the same direction over the surface it will make a series of ridges. When all of the scratches are in the same direction, it is hard to see what you are doing, when the angle is changed, it is much easier to see. Most importantly abrasives act differently depending on the angle that they hit scratches/edges, by changing angle the resulting effect is different.
Now also enter another very handy tool, especially for old, blind guys, spray paint. Color, brand is irrelevant, it is all going to be ground off, cheap and fast drying is what is important. The metals, welds, are slightly different colors, scratch patterns at angles look different, all of this tends to look like texture to the eye. Apply a light coat of paint and that disappears, can more easily see what you are working with.
At this point it should be flat with the surface, any pits, holes can be fixed with a quick spot weld. Now switch to a softer wheel, like a flap wheel and blend the ground area into the base, smooth scratches, etc. I finish with another shot of paint and run a D/A sander over it with ~80G paper. This results in a smooth random scratch pattern that quickly highlights any areas the need attention.
This can be done with one grinder and a sander, some are all proud of their boutique named grinder. I like powerful grinders, prefer to have several, loaded with differing rock, so can grab what is needed without changing rocks/pads. The other night, Phil and I were having a "who can spray the most sparks on the other" contest, so had a bunch of grinders out, some electric, air, different brands, etc.
IMHO it is all about the rock, cheap abrasives will result in frustration, take forever, poor result, good industrial abrasives make quick work and a good result.
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Ran the Norton AVOS Speed-Loc system for the first time the other night. It gets the "kick-azz" stamp of approval! Good, smooth metal removal, disks are easy to change, but not needed often, they lasted a looonnng time, the see through feature is 
.
Good, smooth metal removal, disks are easy to change, but not needed often, they lasted a looonnng time, the see through feature is .
Ran the Norton AVOS Speed-Loc system for the first time the other night. It gets the "kick-azz" stamp of approval!
kick azz is an understatement...
With the list of grinders above this is the kind of results you can get in a few hours otherwise plan on a couple days. Prior I had a 1/4" plate overlaping
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You are a photochop god! It almost looks good in that pic.
As long as this thread is morphing into grinding skool, for me...
Where is that awesome disk with the holes sold? I'd love to try that one.
Also, what would make you choose an air grinder over an electric angle grinder or vice versa?
Where is that awesome disk with the holes sold? I'd love to try that one.
Also, what would make you choose an air grinder over an electric angle grinder or vice versa?
he does air tools for a living
Well, that might account for a bias, but then again he just posted a pic of a DeWalt electric grinder in the previous post with a particular disk he liked.
I've got biases too. I'm a surgeon. However, that doesn't mean I used 4-0 Vicryl to stitch my roll cage together.
... I should have, though. That would have been cool.
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I'm in the biz, so get samples.
In my experience, your abrasive $$$ is best spent at industrial outlets, MSC, ENCO, etc. The stuff sold at home centers is marginal quality and overpriced, for the same $$$, can get much better at industrial suppliers.The Norton disks:
MSC Item Detail
http://www1.mscdirect.com/CGI/NNSRCM3?PARTPG=NNSRIT
As Claudia mentioned, I repair tools, so tend to acquire tools.
Air tools are my first choice. They are smaller, lighter, more durable, etc. But grinders require a lot of air, that most home shops don't have. Ultimate durability isn't an issue to the hobbyist, they will never run the tool enough to wear it out.
Electric grinders are more bulky per HP, but everybody has an electric outlet, so easy to feed. They are more delicate, but this isn't an issue for a home shop. For the best cost/benefit ratio, I prefer the metal gear box Dewalt grinders. They are durable, easy to service, parts are easily available and one of the last electric tool companies that is still US based.
I've got biases too. I'm a surgeon. However, that doesn't mean I used 4-0 Vicryl to stitch my roll cage together.
you should see us scientists approach wrenching then . . .
