1. 3 sticks #3 is adequate but 3 #4 is probably just as cheap and is better/easier/stouter. 3 pcs is because it's less than 4 but still 3D in cross section. Space them 2"-3" from the outside of the concrete.
2. I would frame the three legs at top. This isn't hard, three small hunks of wood like pcs of lathe or 1X2 wood stake @ about 6" long will suffice. Drill the holes, position the sonotubes and then fasten the stakes around the top underside. This will stabilize the tube.
Remember that the tabletop (I'm assuming you're pouring the top w/legs???) weighs 460-600lb depending on dimensions...... it can't just set on the sonotubes! The support/bracing adequate for 600lb will stabilize the tabletop and the wee estake's will hold the top of the tubage. If the tubes are cut short (recommended) then you can hang them from the tabletop and let them dandle into the holes. This in turn brings us to point 3.
3. NO chance, zero, nada. if it's actual concrete you're pouring. You could have 12" diameter holes and 8" tubes....... I say DIG deep and dangle the sonotube into the hole at least 6". Now you can pour mud to your heart's desire and if it DOES start to ooze just shovel some dirt on the ooze and it'll stop. DRY dirt, like sand even. You're just causing the concrete to crust over, it'll suck the moisture.
TAMP, stick, chunk or in other words WORK the concrete down the tubes. Dump it in and then jam in and tamp the peewaddy out of it all. You need a 4 foot hunk of something like a broomstick, we'd use a 4ft woodstake. You also can then feel for and work around the bar. BTW the bar MUST extend up and into the tabletop w/90's and you must lay a mat of bar in the tabletop itself on max 18" centers and suspended in the middle of the tabletop thickness. When you pour out the top tamp it well all the way around the edges and tap the sides of the form rat-a-tat-tat with a hammer to drive the fat or cream to the edges getting rid of rock pockets. Form edges will most likely be 2X4's standing on edge? for a 450lb top. 2X6's will give you a 600-700lb top.
4. No need for release agent in sonotubes. Sonotubes are waxed and peel off in a circular fashion. Just start the peel up under the table where it's hidden and peel 'er down like wet jeans off a ....... but I digress. Strip them next day.
Call me @ 360 904 6941 if you've got any sort of question that can't be answered here. Call me during the pour if you have a panic. I sling mud for a living, poured 450 tons of it today.
Good cheap release agent for the formwork is 5gal diesel/1qt Dexron tranny fluid.
When you trowel the top take twice't as long as you think you need. You need a magnesium float first, then immediately edge to break the corners using a 1/4"-1/2" radius edger. Now trowel it again making sure it has a slight crown. Wait 20min and wipe it smooth with a steel trowel. This is thin spring steel, sharp edges, will cut you. Now, over the next hour hit it with the steel trowel every 20min or so as it dries. bear down, hard, with the trowel very slightly tilted. Keep letting the top dry and re-steeling until it "burns off" to a glassy smooth finish. When troweling with the steel trowel you will keep increasing the angle such that you're laying down a smooth "fuzz." If you get too steep you'll pop rocks or cause chatter. By the time the mud is hard enough to "burn" you'll be bearing down with one hand on the handle, two fingers on the tip or hand on the lower "steel" blade and BEARING DOWN with the blade tilted almost to 45*
Some tips:
-spend extra time on the forming, make it twice't as stout as you think you need.
-If you've got limitless time and it's not raining caulk all the downside corner edges with $1.99 painters caulk. It's the stuff that goes on milky white and dries clear, peels off like silicone rubber. Tool it into the corners with your finger, make it nice and match the radius of your edger. Stuff takes a day ore two to dry clear. You'll thank me the first time you stand up under the table and don't gash your leg. If you don't have time for the painters caulk you can carefully cove the edges using duct tape but this will show ugly when you strip the forms unless you carefully strip and "face" same day. This is wickedtricky.
-If you spend days on the forming make sure that you use plenty form release applied just before you pour, strip following day.
-buy some 8D and 16D duplex nails for forming always thinking about how you're going to disassemble the form after the concrete is hardened. Leave "stripping gaps" for relief.
-remember that the forms must come OFF. This is harder to plan than would first seem obvious. For instance, how ya' gonna get the bottom plate off around the legs?
that's all I can think of offhand.
al
