How-to-dress-metal

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How-To-Grind-Metal

Ok, there seems to be alot of confusion on how to grind metal, I am gonna try my best at helping everyone out some, I still have more to add, but this will be a start.

FIRST: THE TOOLS NEEDED.

:Sanders,

6" Dynabrade for my finish work, this does finer swirl marks in the metal, creating a more uniform appearance.
6" Dual Action sander, AKA,"THE KNUCKLE BUSTER" if you know the meaning of this, you have used one. used for medium sanding
8" Mac sander/grinder, used for initial knockdown and leveling.

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:Grinders, there are several, this is what I use

Bosch 4.5" electic grinder with either a flap disc or grinding stone, or cut off wheel. This is my favorite.

El Cheapo air grinder for all of my Carbide bits, these are used for corners and any place I can not grind with a stone

Air tool for my cut-off discs and 3" grinding stones

Mac 90 degree grinder for my ROLOC discs, ranging from 36 to 80 grit, also comes with abrasive pads and surface pads.

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:Safety Equipment, A MUST HAVE!!!!!!

proper gloves, I use tig welding gloves
face shield
ear muffs
3M particle mask
Safety googles

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SPOT WELDS.

So you have a spot weld you want to grind down, what now, do I just hit it with a hard stone till it is beyond flat and heated the metal along the way, NOPE. stop right there, you never want to heat the metal when grinding, especially when it starts turning blue, bad, very bad, you just warped your metal and now have more work to deal with.

First thing to do is grab a 3" hard grinding stone, or one on the elctric grindre and slowly, I mean slowly, grid down that weld, get it close to the surface od the original metal, without touching the original metal. It takes practice, I know.

Once you have it close to the bottom, switch over to your ROLOC disc and start smoothing it out, never put too much pressure on the metal itself, just let the grinder do the work for you, nice and easy does it. This will take some getting use to but once it is mastered, you have won half the battle.

Now you have some marks either in 36, 50, or 80 grit leftover from the grinder, what now, leave it, nope, depending on how bad you have cleaned up that weld, you can now use your sanders and smooth them out, I always use 80 grit on my pads to do this. Sand it for a bit and you are done, 8 out of 10 tens, no mudwork is needed. You have jsut mastered the spot weld grinding.

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More

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STITCH WELDS.

This is where it gets tricky. Lets say you have a weld 10" long, well that is a major heat source waiting to warp. Time must be taken to do this.Patience will prevail.

Well which tool should i start with? For a weld this large I either start with my 3" air grinder or my Bosch 4.5" hard stone grinder. Depends on what you have and how you feel, Now remember to go slow and let the stone do the work for you, nice and easy, remember not to rush into things, or it just gets messy. Grind a small section at a time or go back and forth over it slowly. Never sit in one spot too long or you just heated the metal and causes more work for you.

Since you have now ground down the majority with the stone, I swithch over to my Bosch grinder with a flap disc in 36 grit normally, this allows me to remove material quickly without pressure and does a nice smooth job. I never go to hard with this one either. Start at one end and go back and forth over the metal, these flap discs do an amazing job on leveling the weld and vreating a nice uniform surface, if you still feel wearily about getting too close with an electric grinder, then just finish it up with you ROLOC disc and smooth it out.

Now that I have gone this far, I will normally take my 8" MAC sander and smooth over the whole surface with 120 grit. After this is done, I use my D/A sanders and finish the job, nicely ground down and sanded, nothin lookds better than this.

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Some more

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OTHER TID BITS.

Wire wheels on the electric grinder work great for that cleanup of alot of stuff, such as , seam sealer, old greae and grime, gutters.....

I also have a Hard grinding disc for my MAC 8" air grinder and this works gret for many many welds that need smoothing, pinch weld seams, stitch welds, frames......

The carbide bits are a god send in my workd, you can use them for just about anything, from cleaning up a wled in a hard to reach area to smoothing out that corner that nothing else can get to, to creatinf a nice radius in a transition area.

Keep all of you old 3" air grinder hard discs around, you never know when that one that is almost worn out to nothing will be used next, but it could be the right diameter for a job that you are tring to get a smooth grind in or transition.

Even worn out ROLOCS come in handy, when they wear out, they tend to bend,well this is perfect for when you are trying to blend in a radius or doing a corner, they hardly bit and more pressure can be put on them.

Flap discs for the electric grind have their purposes also, new ones are great for tight 90's, and much more, but sometimes that old used one works better for edges, jsut trim it down some on the edge and you have a brand new, but smaller flap disc!

I hope this helps some ppl out in the hobby world, there is so much more yet to learn, but this is a start.

Later and happy grinding James