To summarize I used 5/8” galvanized since I found some with longer threaded shank (2”+) at local hardware.
I had originally purchased some 1/2” diameter with 12” length (standard recommendation) and threaded portion was only around 1.5”. At the time I was thinking of following Bisque recommendation and placing pier directly on pier pad (vs up about 1” on adjustable nuts). I’d planned on adding layer of self-leveling after ‘rough’ pour cured to handle minor irregularities so pier would have been bolted up with adding thickness of just a leveling washer (if needed) to be ‘level within tolerances’. I would have painted concrete with sealer prior to placing pier to help isolate surfaces a bit for prevention of corrosion.
When I changed to ‘adjustable nut’ scenario and I knew that 1/2” sets’ threaded shank was not long enough then I went back to the ‘goof center’ (local hardware store) and came back with different bolts (5/8”) since couldn’t find 1/2” galvanized with adequate length of threaded shank.
With larger 5/8”diameter it’s important that the template has bolts set well aligned since less tolerance to fit in slotted holes than 1/2”. For designing my template I flipped pier vertically so base was up and took a 20x20 1/2” thick piece of plywood and traced four slotted holes and the perimeter of the base onto template. I drilled in middle of each elongated slots (so bolts at mid-span for East-West adjustment when doing polar) and put j-bolt on template (nut/washer used on top and bottom). I then tested alignment by placing template on pier (bottom of pier was still flipped vertically) and slid down onto slots (1” of shank was exposed). It fit onto the four slots with a bit of angle to push fourth side down. Once in slots I tested by rotating of template to left and right to ensure that it was square enough on slots. It worked as expected so I was confident that I’d be able to sit pier on bolts once moored in concrete.
Before actually sitting template in concrete I coated the underside of wood with vegetable oil (let soak in) which helps a bit when lifting/releasing template on concrete. I unscrewed the top visible nuts and removed washers. Then pulled off template. I had left the template positioned a bit above the surface of concrete so I was able to remove the bottom side washer and nut after was removed. I then cleaned bolt threads a bit and put the square 2” slotted plate on bolt against concrete and added arrangement of washers/nuts that you see in earlier photo.
photo below with template in concrete on day of pour
Edited by Travellingbears, 10 September 2020 - 08:08 AM.