Whats the best way to grind aluminum welds flush for powdercoating?

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Hey guys, I build these luggage panniers for adventure style motorcycles and some of my customers have mentioned that they would prefer that the tig welds be ground flat and smooth. I normally don't like to grind my welds after I'm done, but now I'm starting to agree with them. My tig welds I feel are pretty good quality, but when they come out of powdercoat, it seems that the welds do become much more noticeable. So If I start grinding these welds, whats the best way to do this? I was thinking a hook and loop attachment for a 4 1/2 angle grinder and slapping some sand paper disks on it and grinding that way. ??? would there be a quicker and easier method?   These are made out of .080 5052 and I use 5356 filler.  Does anyone see doing this compromising strength significantly?     Thanks. Dynasty 200DX   (2014)Millermatic 211 (2015)Optrel 864   (2014)Smith Medium duty MBA 30510 (Xmas 2014)Tennsmith 16ga 4ft finger brake (2015)Trailblazer 325 EFI and excel Thermal dynamics Cutmaster 82Miller maxtron 450
Reply:Looks nice!You are on the right track with your grinder. However the sand paper tends to load up so I use lubricant. Some people use wax, I use AlumiCut oil. Wax I believe only cleans up with Naptha as I recall.  After feathering top and sides with the sander taking care to keep the grind flat and not going over the edge, I take a file and blend in the radiuses. Then I wipe down with acetone and further blend everything in with an orbital sander. You probably could have thickened the weld so you would have more to grind down. But overall I think you are ok strength wise.My stuff I make sure the powdercoater uses a degassing primer and then topcoat.Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.
Reply:You could preempt the sanding with hitting the corners with a carbide router bit and bottom bearing. I use the same Alumicut. Sometimes cutting from both egdes cleans it up complete. Then jitterbug with orbital sander.Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.
Reply:Try a flap wheel?Don't go too crazy, or else the aluminum will tend to crack.Also wrinkle powder tends to hide a lot of thingsTorchmate 2x2 CNC with Flashcut CNC controlsHypertherm Powermax45 Esab ET220i Razorweld 195 MigRazorweld 200ac/dc TigTormach 770, Tormach xstechRazorweld, Vipercut/Vipermig, SSC Foot Pedal Dealer
Reply:Originally Posted by shovelonYou could preempt the sanding with hitting the corners with a carbide router bit and bottom bearing. I use the same Alumicut. Sometimes cutting from both egdes cleans it up complete. Then jitterbug with orbital sander.
Reply:I find fiber discs to be a little nicer for weld grinding than anything hook and loop. We have a hook and loop pad for scotchbrite discs and if you don't get it on just right they turn into supersonic frisbees.
Reply:I don't always grind down aluminum but when I do I use flap disks.My "collection":Homemade Stick WelderVictor O/A TorchAC 225Ideal Arc 250HF 90 Amp Flux CoreHF Mig 170Solar 2020 Plasma CutterPower i-Mig 140EHarris O/A torchHF Dual Mig 131140STAlpha Tig 200x
Reply:Or set up a wood router with a carbide round-over bit...would be uniform and QUICK.KevKevin / Machine_Punk from The Aerodrome Studio - Lincoln PowerMIG 210 MP - Meco N Midget w/custom welding station - Vintage Victor 100Current Projects: The Aerodrome Studio
Reply:In a previous place of employment, we did something very similar.  We used 40 grit flap discs on a 5" grinder with plain old candle wax as lube - you don't need to go overboard with the wax, just enough to stop the disc loading.  We then finished off with a maroon Scotchbrite on a 5".Quick, simple and effective.
Reply:Thanks for all the responses so far. I was using a sanding disk that I had on my metabo die grinder just to see if the sanding disks would work, and It sure did. -even a little too well. Its thin material at .080 so I cant remove too much. Using a router or a flap disk kinda scares me, but I'll have to test at least the god ol flap disk.Dynasty 200DX   (2014)Millermatic 211 (2015)Optrel 864   (2014)Smith Medium duty MBA 30510 (Xmas 2014)Tennsmith 16ga 4ft finger brake (2015)Trailblazer 325 EFI and excel Thermal dynamics Cutmaster 82Miller maxtron 450
Reply:I would be seriously concerned about cracking. You might want to torture test a fully ground bag against an "as welded" one.Eventual master of the obvious, practitioner of "stream of consciousness fabrication".  P.S. I edit almost every post because because I'm posting from my phone and my fingers sometimes move faster than my brain.
Reply:Originally Posted by outdoortThanks for all the responses so far. I was using a sanding disk that I had on my metabo die grinder just to see if the sanding disks would work, and It sure did. -even a little too well. Its thin material at .080 so I cant remove too much. Using a router or a flap disk kinda scares me, but I'll have to test at least the god ol flap disk.
Reply:Id go as far too set up a router table... much faster but you'd need to take care of the chips scratching the rest of the box(decent draughting should fix that).
Reply:I was going to suggest a custom carbide router bit with the radius tailored to your application. I haven't really looked into wood router bits and I couldn't tell you if they have one off the shelf that would give a good round edgeSent from my SM-N920V using Tapatalk
Reply:Originally Posted by naterpatater77I was going to suggest a custom carbide router bit with the radius tailored to your application. I haven't really looked into wood router bits and I couldn't tell you if they have one off the shelf that would give a good round edgeSent from my SM-N920V using Tapatalk
Reply:I like the router idea, I'll have to consider it in the future. If I'm not mistaken I don't believe you can do a fusion weld on 5052 Al or many other types either without experiencing a crack right down your weld. Limiting my use of filler (5356) is def something I could work on so I'm not creating more work later.Dynasty 200DX   (2014)Millermatic 211 (2015)Optrel 864   (2014)Smith Medium duty MBA 30510 (Xmas 2014)Tennsmith 16ga 4ft finger brake (2015)Trailblazer 325 EFI and excel Thermal dynamics Cutmaster 82Miller maxtron 450
Reply:Originally Posted by MinnesotaDaveI think the router base would need a partial spacer to get it above the weld that has not been cut yet.
Reply:Could you post a picture of you router table set up?
Reply:In my opinion, grinding welds is never a great idea, being said, .080 aluminum is pretty thin to begin with, have you considered welding the back side for additional strength, maybe use an industrial grade two part epoxy/glue, Locktite and Lord Adhesives have some good productsjust my 2¢
Reply:I've ground down some of my welds before. The welds looked nice and appeared to have good penetration when welding....it just didn't seem to have enough meat left to make me happy about the strength and crack resistance post grind.I ended up tigging the outside and then migged the inside. Then I felt good about taking the metal off the outside.Chay
Reply:Originally Posted by Machine_Punk...you may want to think about a different welding method (perhaps leaving a bit of an overhang and doing a weld without filler material, then routing over that edge. Kev
Reply:Originally Posted by SteffanCould you post a picture of you router table set up?
Reply:Some of my parts are smaller, and require routing on the inside of the L.  As such, I often setup with just an infeed fence.  This screws to the table from the bottom, and has a strip of UHMW tape on it.  It is also set back about 1/16" from the cutter/bearing.  This allows me to hold the part firmly against the fence, to avoid the part kicking, but still lets the bearing set the depth.  When I get to the cutter/bearing, it simply pushes the part out slightly.  Once the cut is initiated, the fence is no longer needed - I am now leaning against the bearing.  This is very rudimentary, and I have plans to improve everything - it's lacking in the elegance department.  But, it works, and it makes money, so that is what matters.Who is John Galt?