4' x3' x 3/8" steel plate from supplier came with 1/4" bow

[60Hz_Brit]

Opus. Thanks. That's good to know. I'm in Southern California.

$188 delivered is good value. I paid $154.60 plus tax for this sheet. $166.58 total.

I live near the ocean so there are loads of welding places around. Some large, some small. I might go for a walk one day and put some feelers out.

[forhire]

Originally Posted by 60Hz_Brit

Yes. I like this solution as well.

Another option would be to run a tube down the middle. Put the plate on the table bow down. Clamp one outer edge down, then clamp the other outer edge down. You'll need a bunch of clamps. Now the plate should be flat. Tack weld the center which will relieve some of the stress. Tack down the outer edges. Done.

[60Hz_Brit]

Originally Posted by forhire

Another option would be to run a tube down the middle. Put the plate on the table bow down. Clamp one outer edge down, then clamp the other outer edge down. You'll need a bunch of clamps. Now the plate should be flat. Tack weld the center which will relieve some of the stress. Tack down the outer edges. Done.

This feels like it might go better for me.... in my welding ignorance!

[OPUS FERRO]

60Hz Brit - When building a table the surface is the tool feature,
and often the most ignored.

Metal fabrication isn't welding, it's metal joinery. Anything that aids
fit-up is a big plus; it all starts with your table's surface. Think of it,
not just as a work place, but as your biggest tool.

If you are building a steel fab table from all new materials in this day
and age, the surface should be nothing less than:

Cut, all 4 sides, by: Hi-Def plasma, laser, or water jet.

The life long reward is: a flat plane, square corners, straight and
parallel edges. These features make your table a tool.

You can only have these life-long benefits if you build them in from
the beginning.

Don't turn the fabrication of your dream table into a marathon, serial
repair nightmare. Put your sheared plate in 'inventory' for future
projects, and order a new proper-beginning. Opus

[60Hz_Brit]

I completely agree... and I'm kind of pissed at myself for falling for this one.

I wanted to take my time making a nice little bench for myself. Not wrestling a sheet flat.

I'm going to sleep on it and then maybe PM you tomorrow about your offer. Thanks.

[Eliotmay@yahoo.com]

Good plan, while youre at it consider going with at least 1/2 inch material

[Kelvin]

Holy cow. Dude. It's a quarter inch on 4 feet. BFD.

If it bothers you that damn much, get your stick welder and weld at high amperage a big "x" in the middle of the convex side, then take a garden hose with cold water and quench the opposite side. If you do it right, the shrinkage of the welding will "pull" the plate back into a plane.

Google "flame bending" for a better explanation.

Keep checking flatness with a straight edge and lather/rinse/repeat until it's flat.

Then grind off your beads to make the tabletop fair/smooth.

Then attach your tabletop to your table ... and watch it pretzel up into a taco again due to shrinkage!

[60Hz_Brit]

Originally Posted by Kelvin

BFD

What does BFD mean?

[Monica]

BFD - big Effin deal

So, I might be crude and ignorant thinking this, but after reading the options I'd run it over with the truck. Would that be useful in any way?

[A_DAB_will_do]

60Hz_Brit,

build your table frame, using advice posted previously. Place your 3/8" plate on the frame, so the edges are floating, and the plate is resting on the frame in the center. Set 2 Clamps in the center and tackweld near the clamps. Then set 2 clamps on either side of your center tack welds. 4 clamps is the minimum I'd use, but if you have more set them in pairs every 6" outward from the center. Tack near each clamp. Move clamps and tack as necessary. you should be able to pull the sheet flat. Use screw=type c clamps; not vise grips or woodworkers sliding jaw clamps. C clamps generally generate more clamping pressure, unless they're low quality crap.

Once you're tack welded down, you could declare victory. If you intend to use the top as a clamping surface to pull other objects flat, then you need to take one more step. Carefully roll or flip your table upsidedown. Make 4 fillet welds, 2 each long side, each about 1/3 along the length of the frame. 2" of fillet weld, a single pass, about 1/4" wide will strongly attach the top to the frame. You should see minimal distortion with just 4 welds.

Roll your table back upright, move to it's permanent home, and shim the 4 legs so it sits level and doesn't wobble.

Declare victory and have a beer if that suits you...

[A_DAB_will_do]

Originally Posted by Monica

BFD - big Effin deal

So, I might be crude and ignorant thinking this, but after reading the options I'd run it over with the truck. Would that be useful in any way?

if you happen to have a tank or a steam roller it might flatten out. But your average pickup truck won't even make that plate twitch.

[60Hz_Brit]

Originally Posted by Monica

BFD - big Effin deal

So, I might be crude and ignorant thinking this, but after reading the options I'd run it over with the truck. Would that be useful in any way?

I think this is a great idea. I'll take pictures Might start with the Jeep first

[farmshop]

To be successful you need to bridge it. Non controlled will probably make things worse

[60Hz_Brit]

Originally Posted by farmshop

To be successful you need to bridge it. Non controlled will probably make things worse

Agreed.

[60Hz_Brit]

A_DAB, I can *just about* move it by wedging myself between the sheet in the back of the truck and the top of may garage door frame (using all my strength). I tried just to see how much it would move.

I might wedge it and have the Mrs. drive over it to see what happens in the name of science.

Your advice is great... Thank you, but I'm also looking at getting another top cut properly on all 4 sides, possibly 1/2 inch as some one else here suggested.

So, I might just practice on this sheet. I just started out so I'm a bit green to say the least.

I was thinking though. I was going to go for 3 inch clearance all round for clamping. It's going to be on wheels to pull out for various projects.

Pretty much everything in my workshop is on wheels so I can re configure for what ever I'm doing.

Is 3 inches too much? 2 inches perhaps?

I see some people drill and tap all over their work top. This appeals to me. What does everyone think? Pro's & cons?

I was going to drill & tap for the vice bolts. No reason why I shouldn't, right?

Also I have been thinking about the wheels and maybe having bolts that I can wind down to level and take the wheels off the ground for when I'm working.

Thoughts?

[zapster]

Originally Posted by 60Hz_Brit

Yeah it was cut specially for me in another branch. Had to wait 3 days for it. No special deal.

That's where the bend came from.
It was flat after processing..
Loaded on the back of a flatbed steel delivery truck..
STRAPPED DOWN with a piece of wood under the MIDDLE of the plate so they could get under it to move it when needed..

We get steel bent like that constantly!
On some round stock orders that come 20 feet you should see the bend in the middle from the strapping down practices..and that's on stuff up to 5" in diameter!

Nothing new in the real world.

...zap!

[puddytat]

Hi all, if you put the 3/8" plate on the floor and put two pieces of wood under the ends, then stood on the middle, assuming you weighed 80Kg, you would bend the plate back the other way......doesn't take too much force over 4 feet to bend a piece of plate, even 3/8" thick, but it'll spring back when you get off it, but it can be "persuaded" to lie flat and stay flat with a bit of clamping to a strong frame etc.

So, make the table frame with a substantial sub frame round the edge, we used 100mm X 50mm 3mm wall square tubing, mitred corners and just welded the top to the frame with short welds and clamping it to keep it straight......never moved, and as flat as is "good enough".....you won't get it dead flat unless you have it machined and that is going from the sublime to the ridiculous for a welding table.

BTW, you can warp the table by having it sit on an uneven floor, so have screw adjusters on the bottom of the legs and you can "dial" it flat by screwing the adjusters out to suit the floor, or just use packers under the legs tacked in place.....the table should not be moved anyway or you will get uneven top features from the floor levels if the sub-frame is not all that rigid.

I would also add two cross spacers across the front and back to keep the sub frame as rigid as possible and this will keep the top relatively flat even if you move the table and it needs the legs adjusting to keep it from rocking.....if it rocks when moved it's rigid, if it doesn't it's flexing.

Incidently, if you haven't got a decent straight edge....one can be made.......you are working in the dark and can't judge the flatness or truth of ANY work you do.

If you can find out what a Camel back straight edge is and make one, then you'll have a method to guarantee 100% to anyone what flatness is all about, but you'll need to make three of them (and certify them) to make one true one.....you end up with two extras you can sell for profit.

Without a straight edge of known quality, anything "flat" is anyone's guess.

If you can move the table and it "adjusts" itself to the uneven floor (flexes) then you'll never have a level top without going to the trouble of packing the bottom of the legs each time you move it etc, and sometimes you want to move the table to the middle of the shop to suit the bigger jobs and allow you to move around it.
Ian.

[OPUS FERRO]

60Hz Brit - As suggested by E@y, 1/2" would be better - Opus