Grinding Aluminum

[rockable]

I learned two important lessons today while practicing my TIG welding of aluminum. Everyone needs to recognize the symptoms of a contaminated electrode. As I was welding along in a nice shiny puddle, apparently I touched the filler rod to the electrode and everything went to crap. I'm a little slow on the uptake sometime but I finally figured out that I had contaminated my electrode. After two or three attempts, trying it on a piece of scrap, I finally got a good electrode again. Lesson 1 - When the puddle is no longer shiny and the filler material no longer flows into the puddle, you have contaminated your weld! Stop now!

Lesson number 2 was don't try to weld over the contaminated weld. Further, you should stop immediately upon recognizing that your weld is contaminated. You will only make it worse if you continue. The contaminants will not float off or burn off!

Here is my question. How is the best way to remove the contaminated weld from the workpiece after you've fouled it? I tried a sanding disc but it gets clogged and I know what will happen with my Dremel burrs if I try them. Also, how do you grind down the welds and finish the area when you don't want the weld bead showing, like when you butt weld two panels?

Thanks,
Rock

[no999gr]

Rotary file. You will add more contamination by grinding or sanding.

[Overkill]

I use WD40 from preventing it getting clogged up. You have to watch your speed as well.

[nosire]

we used to use bees wax on a burr also you need a sharp burr

bob erison
cleveland ohio

[rockable]

Ok. Use a rotary file treated with something slick to keep the aluminum from sticking for cleaning ups fouled up welds. What about smoothing a weld on butt welded panels? Sander with something slick?

[Cal D]

Check out you local weld supply shop. They should stock 4 inch grinding wheels specifically for aluminum and stainless steel. They do not load up and do not contaminate the parent material. Kind of expensive - $10 each.

[welderboy]

I use this, it's my "Taz" saw. The aluminum boat industry here in Southern Oregon uses this tool, but you won't see it till it's needed as OSHA doesn't like them. I use it to bevel thick aluminum, and to grind out a bad weld or even do a nice clean plunge cut. When you use a grinder with a wheel or flap disk to cut or bevel or even grind out a bad weld.....you have a very contaminated area loaded with contaminates and oxides. The air motor is low torque so when it binds it doesn't decapitate you...it stops pretty easy.

[Pete's Metalshaping]

we used to use bees wax on a burr also you need a sharp burr

bob erison
cleveland ohio

You can also use bees wax with a grinding disc. Either way would work.

[welderboy]

The saw I have show and a burr for aluminum are the tools that remove the bad metal...it actually cuts it away. A grinder gets the metal hot and smears the metal you are removing into the surfaces around that area. thats not to say you can't "wash over" contaminated surfaces. The integrity of that area will be compromized by grinding the metal though. my .02

[frank luten]

I use a diegrinder with a carbide cutter for aluminum. Getting WD40 or whatever into the weld area seems counterproductive to me.
Frank

[TheRodDoc]

"Alumicut" by Tap Magic is one of the best for any aluminum grinding, sawing, drilling, taping, milling or cutting with carbide rotery cutters.

Eliminates all pluging of cutters and sanding disks.

Won't contaminate weld areas or bother for painting later. A very little goes a long way.

[Jim Stabe]

I use this, it's my "Taz" saw. The aluminum boat industry here in Southern Oregon uses this tool, but you won't see it till it's needed as OSHA doesn't like them. I use it to bevel thick aluminum, and to grind out a bad weld or even do a nice clean plunge cut. When you use a grinder with a wheel or flap disk to cut or bevel or even grind out a bad weld.....you have a very contaminated area loaded with contaminates and oxides. The air motor is low torque so when it binds it doesn't decapitate you...it stops pretty easy.

What is the cutter made from or can you buy them ready made? What diameter is it? I want one of those .

[beatamax]

I use this, it's my "Taz" saw. The aluminum boat industry here in Southern Oregon uses this tool, but you won't see it till it's needed as OSHA doesn't like them. I use it to bevel thick aluminum, and to grind out a bad weld or even do a nice clean plunge cut. When you use a grinder with a wheel or flap disk to cut or bevel or even grind out a bad weld.....you have a very contaminated area loaded with contaminates and oxides. The air motor is low torque so when it binds it doesn't decapitate you...it stops pretty easy.

Feck that looks lethal I guess OSHA is health and safety, if it is I can understand why they dont like them.

I use french chalk on sanding pads and files to stop them clogging.

[rockable]

I use this, it's my "Taz" saw. The aluminum boat industry here in Southern Oregon uses this tool, but you won't see it till it's needed as OSHA doesn't like them. I use it to bevel thick aluminum, and to grind out a bad weld or even do a nice clean plunge cut. When you use a grinder with a wheel or flap disk to cut or bevel or even grind out a bad weld.....you have a very contaminated area loaded with contaminates and oxides. The air motor is low torque so when it binds it doesn't decapitate you...it stops pretty easy.

Ooh! That thing is bad to the bone! Don't screw up and let it hit your body anywhere or you'll be minus a limb!

Thanks for all the suggestions.

[LARRY KAEMPFER]

welding shops and body supply shops sell rotary files just for aluminum just like they sell hand files for aluminum , they don,t load up like the fine teeth do, i just don,t like anything on my aluminum welds but more aluminum, it,s up to you ???

[welderboy]

Larry, I agree with aluminum, cleanliness is paramount! I even clean it with acetone before welding. The guy wondering where to get this saw, we have a local saw shapener who orders the 4" 24 tooth 0 degree rake blanks and then puts the teeth on them. As far as original thread this started talking about tungstens. If you touch you should start with a clean tungsten. I would also suggest using the smallest diameter you can for the amperage needed and there will be a more focused arc. So don't use 1/8" for welding .050 body panels together. Aluminum also shrinks a ton, so if you are filling a gap between parts...beware as it will shrink and pull, maybe your parts apart!

[Kevin Morin]

these flap sanders don't contaminate as they're pretty soft and when then cut off a piece of aluminum the metal and the grit get thrown clean off the sanding disc face.

http://www.lehighvalleyabrasives.com/servlet/the-198/Flap-Disc-4.5%22-Special/Detail

I like carbide burrs too, and the Mini-Arbortech works well as a miniature version of steelyfe's 'Taz' saw.

http://www.arbortech.com.au/view/woodworking-information/mini-grinder_20070202100615 the carbide blade is 2nd down on the accessories list. We usually lap them with a plastic diamond hone a couple times a day to keep them sharp, they're intended for wood and are not a high grade of carbide but they do reach in tight and are handy for back chipping welds.

http://www.abrasiveresource.com/category_10329__Zirconia_Resin_Fiber_Grinding_Disc s.html
these discs or sanding belts work great for removing lots of metal, and if they are sprayed with Pam or a generic frying pan spray they will release the build up and can be cleaned with regular rubber belt dresser bars.

the pan spray vaporizes at lower temps than petroleum or animal oil products so even if the normal acetone wipe down doesn't get it all the weld is sound but will have a wider, darker, colorized margin if the vegetable oil is not all removed.

Also a regular wood working router with a spiral Onsrud cutter will work like an end mill if the base is raised on a couple small blocks of plastic or plywood. A 3hp plunge router with a 1/2 shaft bit and three spiral flutes will cut a weld seam's bead profile completely flush to the surface of a sheet with very controlled cosmetic results. Using a straight edge to guide the cut and a well adjusted router bit setting can result in very fine surface finish.

This method will also work for weld prep to add a V to a square corner butt joint. If you were working in 0.125" sheet or heavier where a butt joint might be V'd; the router can bevel both sheets at one time using a V bit. Whitesides bits at routerbits.com seem to hold up well. We lubricate the bit off the work, then cut some joint, then remove the router to relube to avoid any form of lube in the V groove.

This same method will work as sheet edge preparation before the two edges of a butt weld are tack up. This case is common when you want to bevel a given sheet or hull plate edge in welded aluminum boats for example, and there the sheet edge it most often prepared after the outline cut is made and prior to mounting to the hull. So, the edge is lubricated as it is cut and then cleaned prior to tack up.

Lubricating tablesaws, band saws, sanding pads, sanding belts, carbide burrs and all other aluminum sanding, grinding and cutting operations is standard in our shop.

cheers,
Kevin Morin