I did a little more drawing last night (need to scan some of it for visuals) and It looks like if I put the plainer in the middle of the shed, I'd have enough headroom to put a main shaft directly above the plainer. If I did that, the plainer, lathe and shafting can all run parallel with the shed. The plainer is also the only machine that the work might require some kind of rigging on and off the table, so more headroom helps with that too. The other machines are fairly square in the space they occupy with work and tooling being hand-held, so they can be set-up in whatever orientation is needed. I'll be on the lookout for a right angle gearbox or some kind of exposed coupling to use If twisting the plainer belt is going to cause too many problems.
Floor plan right now is approx. 15 feet wide and 20 feet long with 8 foot at the eaves and 12 feet at the ridge. I know it's really small but aside from turning the planers incoming power, it gives plenty of room for the current machine line-up. I'm trying to keep it modular in construction since I'll be putting it up by hand in sections. Inside, it would have wood posts to reinforce the structure and divide everything into 5x5 squares, however the foundation(s) would still be specific to each machine. This does mean that there will be a wood post on either side of the planers mid section, but it doesn't look like they'll inhibit set-up or operation. The last 2' of the plainer base will project out the back of the building into a 6' long "doghouse" to save some room. To reduce noise and carbon monoxide risk, The engine will similarly project out the side of the shed with the controls and PTO pulley just inside the wall. If I ever decided to upgrade to some other form of power The pad and walls of the "engine room" (more like engine cabinet really), could be expanded without messing with the rest of the shed's layout.
Did some surveying last night with the dumpy scope and found that the spot I plan to build on will need to come up 2' to 4' to have the floor level with our main building. If I go with the pier and beam floor, that would be a lot less dirt to move, but more form-work for the concrete machine foundations. At this point, I want to put the Whitcomb plainer, Brown & Sharpe #12 mill, and engine on concrete foundations. The other machines are light enough to bolt to a reinforced section of floor, and the lathe has it's weight spread over a bigger area.
I'm not excited at the cost of lumber right now, but on the bright side the pier and beam floor is something I can re-level later as needed. Concrete is cheaper, but to get something under the whole shed that won't move would take quite a few sacks of quik-crete.... and even then there's no guarantee that it won't move. I'm more fond of the idea that nothing is truly maintenance free, it's just a matter of how easy it is to maintain. Calculating the pier and beam foundation, I'm estimating an average of 200 lbs. per square foot (note that the heavier machines are on separate foundations), so if the whole 15x20 shed was up, it would have 20 piers spaced every 5', so each pier would have a load of 3000lbs. and a total capacity of 60,000 lbs (includes machines, walls , roof, etc.). Part of that floor would also be aided by the concrete machine foundations since they'll have the floor setting on a ledge around their perimeter. To lighten the load, I'll likely add more piers between the main ones.
These summer months have been a killer this year (something to think about later when the shed and machines are operational), but I'm going to start with the planers foundation and build out from there. Cooler autumn weather should help the process along.