[outdoort]

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.

 

[shovelon]

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.

 

[shovelon]

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.

 

[Gamble]

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 things

 

[MinnesotaDave]

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.

I like this idea - seems it would be pretty fast

I think the router base would need a partial spacer to get it above the weld that has not been cut yet.

 

[Sharon Needles]

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.

 

[Iain P]

I don't always grind down aluminum but when I do I use flap disks.

 

[Machine_Punk]

Or set up a wood router with a carbide round-over bit...would be uniform and QUICK.

Kev

 

[Karl Robbers]

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.

 

[outdoort]

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.

 

[Sedanman]

I would be seriously concerned about cracking. You might want to torture test a fully ground bag against an "as welded" one.

 

[Sharon Needles]

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.

A router is probably the easiest and safest method. As long as you keep the router flat the guide bearing will keep it from digging too far.

 

[Harry72]

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).

 

[naterpatater77]

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 edge

Sent from my SM-N920V using Tapatalk

 

[Machine_Punk]

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 edge

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You can get carbide wood router bits with just about any fractional radius you can imagine, from an tiny 1/16" to over an inch. If you are going the router route (no pun intended), 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. If you are going to finish off the edge anyway, you want to spend the least amount of time welding as possible.

Kev

 

[outdoort]

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.

 

[bassboy1]

I think the router base would need a partial spacer to get it above the weld that has not been cut yet.

This is correct. My router table is set up with a spacer of phenolic so that the weld isn't riding on the table. And yes, a router table will be heads and tails above a handheld router for this application.

I use a regular woodworking roundover bit with a bearing, but also set a fence up, about 1/16" back from the plane of cut. This allows me to hold the part solidly against the fence at the beginning of the cut (to keep it from kicking at the corner) but then the bearing pushes the part away from the fence, and guides the part.

I match my bit radius to the outside bend radius of the brake formed parts. This is fine on parts bent to a tight inside radius, or with a knife edge punch - it is critical for the weld to keyhole, and leave a fully fused back bead, to carry the material thickness fully around the seam after cutting the corner off. If it isn't critical that your brake formed corners match your welded corners, you can certainly scale back to a smaller radius.

You can get carbide wood router bits with just about any fractional radius you can imagine, from an tiny 1/16" to over an inch. If you are going the router route (no pun intended), 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. If you are going to finish off the edge anyway, you want to spend the least amount of time welding as possible.

Be careful with this, you'll end up getting fusion primarily on the portion you are cutting off.


Short of a router, your 4.5" grinder is the ticket. Start with a 50-60 grit (FLAT sanding disk - flap disks are useless for fairing outside corners, they are designed to flex and contour - you want something with a rigid backing and flat plane of cut to cleanly blend those corners), move to 120, then hit it with a scotchbrite. Wax is a necessity on the sanding disks (not on the scotchbrite). I use the Lenox Lube Tube.
Tedious, dusty, miserable work that will leave you with hand fatigue if making these in large quantities.

The router table has become a lifesaver for me. I have parts that used to take roughly 4 minutes each with a 50 grit, and 5 minutes each for the second sanding (brown scotchbrite). I now am at a bit under 2 minutes each at the router, at 1 minute each with the 50 grit, and 2 minutes each with the scotchbrite. My hand used to feel like rubber after an hour - I'm now able to make many more parts before fatigue sets in

 

[Steffan]

Could you post a picture of you router table set up?

 

[Randall_H]

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 products

just my 2¢

 

[miller300a]

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