Welding Tips and Tricks

Hello all,

I was recently able to pick up a 1" thick slab of 3'x5' aluminum that I'd like to make into a welding table. I'm looking for ideas for a frame for the top to sit on. My aluminum welding skills aren't good enough to make a frame to hold that slab, and even if they were I don't have a machine big enough to weld that thick of a top to a frame.

I'd like to use (mild) steel for the base and maybe drill and tap the aluminum slab to connect the two, but I'm worried about galvanic action corroding one or both. I've considered things such as putting a rubber grommet between the two metals or that anti-oxide paste that you use with aluminum wiring, but I dunno...

Ideas/thoughts?

Thanks,

j

If you put a rubber grommet between the two, then the top is isolated from the base for conductivity. Maybe you plan to attach your ground directly to the top of the work piece, but it is often nicer to simply have a ground post on the base and the entire surface is then ready to support welding.

I wouldn't be too worried about the corrosion between the two. You could always use some dielectric grease slathered between the base posts and the tops. Reapply as necessary.

I, too, would not be worried at all about corrosion. And you really shouldn't even see any corrosion form unless you have the table in a particularly moist environment, and even then, a tiny bit of surface corrosion at those mating surfaces isn't gonna hurt a thing at all.

And FWIW, I would also elect to bolt the top to a base even though I have the equipment to do those heavy welds easily. Cleaner and easier that way if you ever want to move that nice slab onto something else or use it for some other purpose. Just a few drills and taps in AL. Too easy.

Thank you both for the replies. Great information and thoughts all around. Sounds like I'm overthinking this one and can mitigate any issues easily.

An add-on question... If you were to build a frame for a top this size/thickness, would you just have the legs touch at four points or would you "box out" the top of the frame (meaning that the aluminum would be supported by a big rectangle vs just touching where the legs bolt on)?

I’d post it up every foot in length across the 5’ dimension, and once through the middle of the 3’. It will be tedious to make sure you keep it flat, but this will prevent it from sagging. You don’t need thick tubing to do this. 1/8” wall 2x2 with plates on top will be fine. You can make a frame then install short “posts” above to thread into from the top.

Aluminum makes a nice welding surface, but it will scratch and gouge very easily so use care slamming pieces around or dragging heavy steel across it.

Use stainless for the top frame if possible & for sure stainless bolts for the top. Antiseize the bolts & you should be able to control the corrosion.

cj737 wrote: ↑Sun Jul 11, 2021 6:21 am Aluminum makes a nice welding surface, but it will scratch and gouge very easily so use care slamming pieces around or dragging heavy steel across it.

My thoughts exactly. Only major downside of AL is the gouging and scratching. It can also occasionally be more convenient to have the steel surface for easily tacking parts onto it for temporary holds/jigs, and then easy removal and re-dressing of the surface. But everything else about an AL surface is usually far superior to steel surfaces, IMO.

I've found that AL surfaces will survive for a long time when used in a personal shop because the owner of said surface will likely be the only one using it and therefore taking care of it when it comes to the material handling and gouging. But when used in a shop where others are also using it....Bubba will certainly have his way with it in short order