How do you guys know if your weldments are flat, square, and to size? Are you using a tape measure to check for dimensions? Your warped welding table to check flatness? A framing square to check squareness? Here’s a short clip of a weldment made on the fireball fixture table than checked on my plate steel table. The plate steel table is 1/8 low in the center.
Tape and very badly layed concrete floor 
have been hounding them to invest in fixture tables but to no avail, they’ll regret that when I invest in one for my own business at home
I use a granite surface plate - it’s only a small one, 18 X 24 but I haven’t made anything bigger that needed to be significantly flat. If my weld table was flat I wouldn’t need to put things on this and then straighten them. I shim things on my table during set up which helps, but rarely does the job well enough for anything that’s important. Not many things I weld have to be very flat, but even ornamental bits and pieces look terrible if they are not square when they are supposed to be. It kind of sticks out like a sore thumb.
For squareness I use machinists squares, height gauge and dial indicator, a large set of vernier calipers I acquired for cheap.
I’m kind of surprised that more fabricators don’t avail themselves of the machinery auctions and pick up some used metrology gear. It can be had for next to nothing. Of course some of these auctions the price goes up like it’s all unobtanium. Bit of a crap shoot.
How would everyone check the frame in the video for flatness if you don’t have surface plate or flat welding table?
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Previously used woodworking squares to check square on small items and a precision concrete garage floor to check flatness.
Now I just got a pair of small fab tables to hold me over till I can get a large one for flatness and use fireball squares to check square. Large items check square is all through tape measures.
How would everyone check the frame in the video for flatness if you don’t have surface plate or flat welding table?
I don’t see how you can check a surface for flatness accurately without another known flat surface to start from. You can get an idea by using straight edges, but you can’t properly measure the entire surface that way.
I agree, yet most fab shops don’t have a flat table. And they are supposed to be making things flat. Doesn’t that seem weird?
It seems way out of whack. If I were starting a fab shop as a business I know I’d want an actual flat table as a key first tool - or one to add at the earliest opportunity, if the shop is going to do anything to any real level of quality.
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Yes fixture table is the foundation to every project. To me it’s like trying to start a machine shop without a milling machine.
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That’s a good analogy. The biggest thing I have built is this aluminum rack for the domestic authorities cactus and succulent collection. I’m rather pleased with it, but it was really difficult to build - firstly because I was literally brand new to welding generally, especially aluminum, and then the significant bulge in my weld table was a nightmare. Trying to keep everything square took a lot of time. I really think I could have halved the welding time on this if the table was flat. The amount of time I spent shimming corners was a bit insane.
My TIG machine is a Lincoln TIG 185. It’s an older (2005 vintage), transformer style machine, but it’s solid and has low hours (got it for 500 bucks with a foot pedal, decent torch and loads of stuff - pretty sure that was a decent deal). If I were starting a fab shop I’d still say the higher priority would be to replace the table before the TIG machine.
I guess we really like flat tables. 
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Something to think about, how will the customer possibly check squareness, flatness, etc. Most of the time their methods are even worse! For square, the ol tape diagonally have always worked for me. Flat ness is the challenge, the only method i know someone could do with a concrete floor is the string method. Ive once had a costumer state the frame i made wasnt flat. (It was because the concrete in his had a very gradual dip. )
Shouldn’t fabricators have a standard. Like a fixture table to check their work for flatness, and size. I think that’s a pretty important tool for QC
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Can’t imagine a machinist without boxes of various standards …
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I know more home shops with smaller fixture tables. But every professional welding shop ive visted (southern Missouri) all have the classic plate steel tables. Yet they have high end welding machines, fork lifts, cnc plasma tables even! I think its an issue where something works good enough. People dont see how much time they could save. Not to mention quality.
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The first shop I welded in had a steel plate table. We welded small jigs and fixtures to it. Wouldn’t want to treat a fixture table like that.
To give credit where it’s due though, it was two layers of around 3/8 plate with numerous 3/8 spacers welded to the underside of the top plate before the bottom, with a couple of large access holes was welded to every spacer that could be reached. I think the top had been Blanchard Ground flat at some point but I don’t know how flat it stayed. Had it been removable from its legs we could have sent it out for a re-grind though.
I know this is an old thread but afa blanchard grinding, in my area 60" in length is the biggest they can go in one setup. If they move the part, they can go bigger but …they’re moving the part.
Yep. And at 60" length their width is probably limited. Can’t match the precision x size you get with a purchased fixture table. But a cheap flat can be had if you stay below local machine shop Blanchard grinder sizes.