Welding Table on a Budget - Sorta

[Bob La Londe]

I have a couple projects to do, and I am just getting tired of welding on the floor. So, the latest project was to setup a welding table. I had some 1/8" wall 2" square tube left over from another project and I made a plan... well sort of. Then I gave my son a list of pieces and lengths to hack out on the bandsaw. Then I had him tack up the entire assembly for the legs, cross pieces, and braces. We took turns welding it out. I've already used the frame for a couple small projects, but I wanted a top.

My local metal vendor gave me some prices on plate. I think they give me ok prices, but it was a lot for a table top. I priced 1/4, 3/8, and 1/2. 4x8 piece. Yes the structure will support it. It was 9 legs and they all rest on the floor. I would have really liked 1/2, but I'm realistic. I knew it would probably be more than I wanted to spend.

I search the usual places. Craigslist, Facebook for sale groups and Market Place, and finally EBAY. I found a guy about 300 miles away with 4'x8'x1/4" A36 plate for $110 less than my local vendor. Now that's hardly worth it in reality. I would cost more than that in just diesel fuel to go get it and a day on the road. I contacted the guy anyway, and he said he'd sell one piece at asking price, and every additional piece at another $35 less. I did the math, and ten sheets would max out my little utility trailer so I agreed to buy ten sheets and headed off across the state. I figured at that price I'd have steel plate for many projects. In fact I have already thought of uses for almost all of it, and wish I could have hauled more.

Anyway, getting back to the project. I'd like a grid of holes on the table top, but I am struggling with how to lay that out and drill them accurately. I've got a couple small and mid size CNC mills, and my best guess is to make a template / drill guide and use pins to shift the template across the sheet along a straight edge. I'm not to worried about a few thousandths from hole to hole. That would be silly. I'd more like to keep it fairly close "on average" across the entire sheet. I'd like to avoid cumulative drift of the holes. Any suggestions on how to tackle that.

I know I could use squares and just keep the table top pristine clamping everything up to the squares, but It would be so much faster to be able to use a grid on the table to insert stops and square up pieces.

[kvom]

Magnetic drill for the holes.  You might be able to rent one?  Find a shop with a CNC plasma table.

[Bob La Londe]

Magnetic drill for the holes.  You might be able to rent one?  Find a shop with a CNC plasma table.

That's not a bad idea, but plasma does leave "some" slag.  Its far better than torch cut, but it does have lines from the air blast.  I'd like modestly close tolerance holes.  The idea is you can drop bolts or a pins in the holes, and place parts up against them to quickly square up pieces before tack welding. 

[EddyCurrent]

I thought they used these for squaring up ?

https://www.grainger.com/category/magnetic-welding-squares/welding-supplies/welding/ecatalog/N-nat

[Garyhlucas]

I think your template is workable. We used to do fiberglass electrical back panels using an accurately drilled 16 gauge sheet metal template with clinch style drill bushings. You could circle interpolate the large holes on your small machines to accurately drill the holes without the bushings wearing out quickly.

[Bob La Londe]

I thought they used these for squaring up ?

https://www.grainger.com/category/magnetic-welding-squares/welding-supplies/welding/ecatalog/N-nat

Those work pretty well, as do simple right angle squares and clamps.  I have some.  I'll probably use them today to weld up the mounts and levers for the retractable casters.  

I have 5 or 6 magnetic right angle squares now.  I'll probably use them today, but a jig table is so much faster.  

Cheap magnets do have some issues.  

They have almost no "clamping" force.  This means if you want to constrain a weld out (there is more to it than that) they will not hold the pieces.  You can use them to do a tack up, but they are useless to constrain a piece for a weld out.  Of course welding choices (where and in what order you apply heat) and a hammer are a bigger factor as to how your metal distorts, but the magnets are useless to constrain the parts for more than a quick tack up

They also loose their magnetism with heat.  Not that the metal becomes non-magnetic, but that the magnet itself looses it magnetism permanently.  It does that at a much lower temperature than you would think too.  Only around 300F degrees.  Some at much less.  Some special made Neodymium mags tolerate a little more heat, but not a huge amount.  I use magnets in aluminum lead casting molds to hold inserted steel parts, so I am sensitive to this issue.  

A jig table is faster and consistency is very easy.  Especially if you are making more than one of the same part.  It can distort from heat, but only in such that steel grows about .001" per 1" per 100F.  You can square up two pieces very quickly and clamp them in place anywhere on the table just as quickly.  It doesn't lose its hold from low heat, and you can clamp and unclamp parts without loosing their fit up.  

I find myself welding more often and my knees less and less tolerant of working on the floor these days.  If I am building a welding table I'm going to do it so it saves me the most amount of time and work on future projects.  The nice thing about a grid of holes on the top is I don't have to do it "today."  Today I'll probably throw a piece of plate on top loose, and get the lifting levers done for the casters.

[Bob La Londe]

I'm probably going to use a variation of the idea aametalmaster suggested here https://forum.millerwelds.com/forum/welding-projects/591718-welding-table-on-a-budget-sorta on the Miller Welding forums.  Its sort of a variation of my original template idea, but his is easier. 

My variation on the idea is to make a t-square out of the 3/8 x 3 flat bar I have and drill a line of holes on one inch centers.  I'll probably make the long arm 48+ inches long.  This will make it a multiple use tool.  For any gven project so that I don't lose track of which holes I am supposed to be using to transfer I can just mark them all ahead of time with a steel marking pen. 

Of course it still requires that I drill or cut all those holes on the plate itself.  I guess a mag drill is in my future.  LOL.  A piloted annular cutter should do the trick.  While any hole might not be exactly on position depending on how well the pilot pickes up the punch mark, the grid should not vary on square particularly much over the entire range of the table. 

I will have to choose one edge of the plate as my refference.  It is mill rolled plate so I am sure its not perfect. 

[Bob La Londe]

https://youtu.be/bZq9G8mKKdw