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Side-grinding aluminum

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  • Side-grinding aluminum

    I used the Search, but what I saw was info on finishing aluminum welds, with the recommended abraisives (to use in a side-grinder (right-angle-grinder) being flap-wheels and what I'd call sanding disks. I have to try to repair a bunch of cracks under the back end of an aluminum dumptruck box, some of them being difficult to get at (a project which has been put off and put off, as the cracks grow and grow).. I have electric die-grinders with some carbide rotary files (burrs), but I'm guessing some of the cracked welds might be faster to grind out, where I am able to get at them with small or large side grinders. The local welding supply sold me a 7" wheel for aluminum (Pferd, I think), but a 9" disk would reach more places, maybe. Probably this is because I am OLD, but I have a very hard time finding anything on a majority of commercial websites, which seem to be devised by software geeks and data-entry folk who know little about their customers, or welding. Have you found any good 9" side-grinding disks (not sanding disks and not the very thin cut-off wheels)?

    Other tips are welcome. Aluminum seems to me to be a lousy material for dumptruck boxes. I have a spoolgun, an MM175, and a rented bottle of Ar/He (which I figured might give that little welder more of a chance). But how I'm going to get some of those nearly inaccessible cracked welds anything like clean enough to weld worries me. For this job, I really wish I had some new inverter equipment that I could dial in for extra "cleaning" action on the first pass, after which I could grind out that bead and then try to make the weld. Frankly, I'm not expecting much. This job has been put off again and again (it's the customer's main rig), but I'm told I'll get a shot at it this weekend. Customer ought to buy a new STEEL box, but his customers owe him a ton of money and are slow to pay, a usual situation.

    Oh, I was looking at Home Depot's "Diablo" 7 1/2" circular saw blade, with 56 carbide teeth and stating that it is designed specifically for cutting non-ferrous metals. The idea was to put this in my side-grinder (I can make the guard cover part of the blade) and use it WITH GREAT CARE to gnaw out some of the welds faster than other methods allow. What are your experiences, if you've tried this (I only know one guy who has, and he likes it for exactly the job I have to do, but doesn't tell his boss).
    Last edited by old jupiter; 06-05-2015, 01:21 PM.

  • #2
    I use a wood blade on my air die grinder for aluminum.
    (this one is from a "jam saw" or "toe kick" saw - smallest I could find)

    I drill it out to fit a reducer bushing that I have and chuck it up.
    (yes, it's dangerous - so are chain saws...lol)

    I would fit a skill saw blade up and not look back (with a guard).
    But, I've been told there are already aluminum saw blades made for the big angle grinders - aluminum boat builders use them from what I heard.

    Click image for larger version

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    Click image for larger version

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    Note: you may need a bushing, and an extra washer to clamp it down. That's what I had to do since the blade body was so thin.
    Last edited by MinnesotaDave; 06-05-2015, 01:41 PM.
    "Beware of false knowledge; it is more dangerous than ignorance." ~George Bernard Shaw~

    Airco 300 Heliwelder
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    Dirty ugly tools - perfect

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    • #3
      LOL i think we all have our crazy moments, it 's way more dangerous than a chainsaw. (i wonder if a carbide chain would work??? )

      I can kick back, it has no guard, chips projection is insane.... and, yes i did it too, will never do again. Use a die grinder with end mill , it's slower but healthier.

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      • #4
        Yea that is crazy. I've had my little grinder get ripped out of my hand with a cup brush. Then your left with one dangerous jumping jack till you can pull the cord out of the wall. Couldn't imagine that with a carbide wood blade in there, I'll keep my digits and take a little longer.

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        • #5
          was on a job and I grabbed my big dewalt grinder out of the truck tool box layed it down plugged it in an wam that big beast took off. trigger must have go pressed in and the hold botton too while getting bounced around in the box.

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          • #6
            Aside from the pucker factor, Dave, your photos show a setup that I don't think will reach into most of the restricted spaces where the broken welds are on this truck (and the job has got delayed AGAIN).

            Snowbird jokingly asks, well, what about a chainsaw? My similarly unserious response is the 4 1/2" circular blades that in fact have a length of chainsaw chain around their periphery; these are used for finish work by the fellows who do wood-carving with regular chainsaws.

            Where it will reach, I will use a gimmicky-looking tool that actually has proven useful on occasion, a "demolition saw" with counter-rotating carbide blades called a "Dual-Saw." I got one on a close-out from Lowes a couple of years ago (they didn't sell well)(and being Chinese made, the reliability was so-so). The idea of the counter-rotating blades is to minimize kick-back, and if you can avoid any binding, it works pretty well, and far better than single blade. Unfortunately the blades are only 5" or 5 1/2" in diameter, so reach is restricted. That's why I was asking about 9" abrasive disks for aluminum.
            Last edited by old jupiter; 06-07-2015, 07:35 PM.

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            • #7
              Jupiter,

              How about these: http://www.grainger.com/product/3M-D...Code=P2IDP2PCP ??

              or here is a link with only paramter I serardhed is 9" abrasive wheels. You can then choose thickness, arbor size, type, material, grit, etc. -- http://www.ebay.com/sch/i.html?_odkw...heels&_sacat=0

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              • #8
                Bramble, I couldn't get the second link to load. The first is for a disk designed for mild steel and stainless, not aluminum.

                FWIW, for grinding steel I happened to get lucky and find a deal on about a dozen of Norton's "NorZon Plus" 9"X1/4" grinding disks, which are normally rather spendy. I'd never tried them before; man, they cut good!!!

                (EDIT) Well, I tried again on the Pferd site and this time found 9" depressed-center wheels of various specs for aluminum. No mounted wheels, but that's okay. Thanks for the help so far, though if there are any more ideas on fixing aluminum dump-beds, I'm sure open to them. Maybe THIS weekend I'll finally get to have the truck and actually DO the job, not just talk about it!! Oh well, it'll probably pour rain, LOL.
                Last edited by old jupiter; 06-08-2015, 12:13 PM.

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                • #9
                  The Application information for the first link says: Ferrous Metal, Stainless, Aluminum

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                  • #10
                    Any good local welding supply should have 4 1/2", 5", 7", and 9" aluminium grinding wheels in stock. Just like I don't go to the grocery store or drug store for nuts, bolts, and nails; I also don't go to Home Depot or Lowes for welding supplies or metalworking consumables.
                    Obviously, I'm just a hack-artist, you shouldn't be listening to anything I say .....

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                    • #11
                      It does say that, Bramble, but on 3M's own site, that part number states "specially formulated for mild steel and stainless."

                      The local LWS, Central Welding Supply, Renton, WA, is the first place I looked, and they sold me the one 7" Pferd wheel, which was all they had.

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                      • #12
                        first of all. that saw blade thing is the dumbest thing ive ever seen! a serious painfull disaster waiting to happen.
                        second if you ever need to grind aluminum, you can use any wheel or cutter made for steel with the help of wd-40. spray the wheel or cutter and it will absolutely rip through aluminum and wont ever clog up.

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