Help me design and build an outdoor table.

[Big_eddy]

We put up an outdoor shelter last year, and it needs a proper table. Right now we have an old glass top patio table and my wife HATES it. She has asked me to build something appropriate. (It was one of the conditions of buying my sawmill)

I envision an 8' long, thick slab table. My current thinking is to make steel legs by forming a U from 3/16 x 4" flat bar, but I am also considering vertical slabs for legs instead.

The table is for outdoor use, so needs a suitable finish. It won't be fine furniture. Rustic is the goal.

I have an HM130Max, and access to just about every species of hardwood in various diameters but I don't think I want to try for a single slab top. Maybe two pieces book matched down the center . I don't think I want live edge, but I do have some EAB killed ash with very cool patterns under the bark.

Right now, the prime candidate for a starting log is an elm that dropped half the trunk in the ice storm a few weeks ago and tried to flatten my sawmill. The lowest section is still hanging off the main trunk and needs to come down anyway. The rest of the tree might come down too.

Assume I know nothing - you won't be far off the mark.

Whatever happens, I'll take you along for the ride.

[Old Greenhorn]

Well you are 'early in' here as far as design goes so some very open questions. First I want to make sure you mean 'table' and not a 'picnic table' (with benches)?
 Assuming a table, I don't think the species selection means a heck of a lot. You want the wood to be, at the least, very well air dried. Putting a finish on it before it's dry is folly. I'd suggest some nice hefty slabs because they look kind of rich (to me) and few folks have them.
 If you are doing picnic table style, I'd suggest the Ritelegs which make it very easy to assemble and look pretty slick. I did one with those and 2 1/2" white oak that brought a couple of grand. It did weigh between 3 and 400 pounds though and was 12' long.
 If you just want a straight table, there are a variety of legs you could up with, such as you alluded to but another option is to just use two big rounds, about 16-18" diameter to set it on. Leave the bark on. If they don't get rain or snow on them they should hold up a long time. Eventually you will have to take the bark off as a spring shore though. Cutting them and matching the heights is a little tricky, but with a laser level it becomes a bit easier with a good sharp chainsaw and a competent operator.
 All these are just spitball ideas to help you think it through. The only firm advice I have is to not use green wood and put a finish on it beyond BLO or something. For air dried slabs I found oil based poly in several coats looks very nice and is easy to wipe down and keep clean for food service.
 Again, all just ideas and thoughts. Others with better ideas will no doubt chime in over the coming days.

[Big_eddy]

Definitely a table and not a picnic table.  No benches, either attached or separate. 

We have oil based poly on the dining room table our son made, and it's held up well indoors. Not sure about outdoors though, albeit under a roof. 

Probably be possible to cut a pair of  blocks to the same length on the sawmill if I thought about it hard enough.  Come to think about it, one block split in half to make two ends would be pretty cool too.

[Magicman]

Elm is prone to be "twisty".

[Big_eddy]

Step 1 is selecting a log, and step 2 will be initial milling. So assuming I want a thick top, 2-3" or even more, how would you recommend I cut and sticker whatever log I end up selecting, expecting it will be 24-30" in diameter?

Slice it in 3" live edge  slabs ?
Slice it in 4" slabs and resaw thinner after drying ?

Create the widest square cant possible, and then slice it in 2, 3, or 4" thick boards?

I have some long pallets to stack on, and will cut stickers from the same log.