How to level/square things...

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if you don't have something to work on thats exact? I am about to build a big "table" for the frame I plan to build and this has to be perfectly flat and square. I plan on using 2x2 3/16 wall. How can I be sure its perfectly flat, and not cocked to one side? I will be using bolts out the bottom of the legs for adjustment, but I mean the actual table top, does that make sense?
Reply:It makes sense.  Can you work off the "acutal" table top that you are planning to mate the base to?
Reply:without a welding table to weld it on, it will be hard to get perfectly flat. I recently welded a welding table together, so I had to prop it up on saw horses and get a base established etc.....but you can get it close. You would be surprised what your eyes can do! - if you have a good eye. Even if you had a perfectly flat welding table, your frame is probably going to have minimal distortion in it anyway. To get a top close to perfect, you will probably have to shim the plate.
Reply:A decent machinist level is a must, as a start. Level isn't always the goal, but level is easy to measure, so that is the most common way of insuring that large frames and tools are set up flat/straight (Example: you level a lathe to insure that the bed is straight. It will work fine out of level, as demonstrated for many, many years at sea by the navy, but leveling is easy)Shims, wedges,  and jackscrews are the tools for getting and holding the position. Plan so that you can make the adjustments as needed.In a welded structure, planning the weld sequence is important, as distortion will be a bigger issue than initial fit. Restraint helps a lot, but there can still be distortion from residual stresses. This brings up the last tool set: torch, hammer, and jacks. Remember that when welding the corners, each weld (partial or complete) will act as a hinge, allowing rotation as the next weld cools. Copious tacks help a lot, and allow for adjustment  with the torch, hammers, and jacks before finishing the welds,
Reply:There is a simple ratio that can determine when two framing members are at a right angle. Picture in your mind a framing square. Start from the corner and measure outward on the longer leg to 4 inches, mark that point. Now start from the same corner and measure out along the shorter leg to 3 inches, mark that point also. Now, for a true right angle, the distance between the two points (the diagonal) will always be exactly 5 inches. 3-4-5 easy to remeber. And this is a ratio, that means it works the same if you measure 3 feet, 4 feet and 5 feet. Or yards, or centimeters, anything. Check all the corners for square and tack everything first.City of L.A. Structural; Manual & Semi-Automatic;"Surely there is a mine for silver, and a place where gold is refined. Iron is taken from the earth, and copper is smelted from ore."Job 28:1,2Lincoln, Miller, Victor & ISV BibleDanny
Reply:Thanks a lot for the squaring technique, I will just measure measure measure before I start to fully weld.
Reply:after you get it square ,how you weld it up will make the defferance betweenit still beeing square and not wen your done .here is a post on how i weld up square tube http://www.weldingweb.com/vbb/showthread.php?t=15812ChuckASME Pressure Vessel welder
Reply:I think granth was talking about how to make sure that the table was level, as in completeley horizontal from corner to corner?? Not so much as being square. Am I right???
Reply:I used a laser transit/level when I set up my chassis jig.
Reply:Oh hell. Build it crooked, blame it on someone else!!!And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:Originally Posted by TSORI used a laser transit/level when I set up my chassis jig.
Reply:Originally Posted by TSORI used a laser transit/level when I set up my chassis jig.
Reply:You could go to a machine shop get a piece of 1-2 inch thick sheet milled flat , then use your feet to level the top.  Don't know that 3/16x2x2 will withstand the load of 2 inch thick.  I think a level would work fine, then.
Reply:Originally Posted by tapwelderYou could go to a machine shop get a piece of 1-2 inch thick sheet milled flat , then use your feet to level the top.  Don't know that 3/16x2x2 will withstand the load of 2 inch thick.  I think a level would work fine, then.
Reply:Originally Posted by tapwelderYou could go to a machine shop get a piece of 1-2 inch thick sheet milled flat , then use your feet to level the top.  Don't know that 3/16x2x2 will withstand the load of 2 inch thick.  I think a level would work fine, then.
Reply:I was thinking more like 18 of your 12 oz. buddies to sit and think it over for a good while before starting.
Reply:I don't know about anything more than the corners getting 1/4 inch sheet so the suspension truly lays out when I finish as I am trying to get a frame going for my 72, and I want it on the ground with air ride. That quarter inch would be a little insurance anyways.I think clamping like shown above, and some careful measuring I may be able to get it done.
Reply:What about a water lever.http://www.factsfacts.com/MyHomeRepair/WaterLevel.htm
Reply:that link didnt work for me?
Reply:Probably the cheapest technique you could use to make sure the frame is level/square. Would be to simply attach two string lines diagonally corner to corner. If the table has any twist to it the will not touch in the center where they over lap.Patriot Performance AutoLincoln Power Mig 255CLincoln AC-225 StickVictor Journeyman O/AQuincy QT-5 Compressor
Reply:...this is what I have thought about doing if ever presented with the problem. Build a frame works out of square tube with a relatively flat surface to the top.  Use plenty of tube and diagonals so that the structure is plenty stout.  You wouldn't have to worry too much about the top being perfectly flat.  That will be taken care of later. Cut a bunch of blocks from something like 1/2" x 1" x 1-1/2" long and drill and tap a hole in the middle of it.  Lay out a grid of holes on the plate that you will be using for the top that are centered over the tubes that comprise the top surface of the under structure.  Drill and countersink these holes to match the holes taped in the blocks.  Then on either side of the countersunk hole, drill and tap a couple of other holes for socket head set screws to be threaded into.Bolt the blocks to the table top and center everything up on the framework and weld the blocks to the framework.  Then you can adjust the top until it is level by the combination of raising the top plate with the set screws or lowering the surface with the flat head screws.  You'll probably want to rent or borrow a mag drill to do all of the drilling and tapping on the top plate.  How many of these blocks you would need would probably depend on the size of the table and condition of the top plate as far as flatness goes.  Remember that the under structure needs to be extremely rigid for this to work, but if it is, you should be able to dial the top in to be very close to perfect.
Reply:I like your idea, although it could be done in a much simpler fashion I believe. Correct me if I am wrong of course.You could build your table as perfect as you can as you are actually assembling it. Once thats done, your legs can be capped on the lower portion touching the floor with some 1/4-1/2 plate with a relatively large bolt (read: with a good deep thread) either drilled/tapped into the plate, or a nut welded to the inner side of the "cap" and the bolt can be threaded into that nut. This way each corner has an adjustment possibility. If you can't get it level messing with just the corners, your not going to be level anywhere. You block idea is a good one, my only concern would be like I said, you really only tune levelness at corners, or full sides, which can be done by two corners. Outside of that, the rest are support. Am I thinking right?
Reply:Originally Posted by GrantHI like your idea, although it could be done in a much simpler fashion I believe. Correct me if I am wrong of course.
Reply:because that would be TOO simple haha! good idea though.