Thursday, February 1, 2007

Strongback and float form frames

Building outside meant I had to figure out how to level and anchor my strongback. I didn't want to pour a temporary slab (a decison I hopefully don't come to regret) and Ian didn't have any suggestions for building on dirt. In the end, I stole an idea from when I built my shed: I'd build the strongback on top of 4"x4" posts running sideways, mounted on top of concrete pier blocks, themselves sitting on top of a packed-down sand base. A picture would probably help here, I guess:

Each of the concrete blocks is dug into the ground a ways, to ensure a comfortable building height. I was careful when digging each hole to not disturb the bottom dirt too much, and filled each hole bottom with a packed-down sand\gravel mix. The saddles on the pier blocks are the adjustable kind, and this allowed me to get all of the beams pretty close to level using a high-quality bubble-level. (A laser level would have been more accurate, but I'm pretty sure I'm close enough.)

Once levelled, I packed more sand\gravel mix around each pier block, re-checked for level, then removed the beams & saddles and layed down my blue poly tarp for a moisture barrier. I cut a small hole in the tarp over each hole in the pier blocks, and inserted the saddle-posts through the tarp into the blocks. Then I put the beams back on, re-checked for level, and secured them with screws to the saddles.

I now had a pretty stable base on which to mount the main strongback frame, built out of 1"x6" boards as described in the plans. This is what it looked like:

After putting in more screws, rechecking level, mounting the station cross-beams, and adding my center-string, I had this:

One of my neighbors has a custom woodworking business that he runs out of his home, and as it turns out he has a CNC machine in his shop. Isn't that great? Long story short, I obtained the DXF files from Ian and my neighbor used his CNC to cut the float form frames for me. I was very pleased with the results:

Next I anchored each form-frame front-to-back, so that they were vertical:

Next up was ripping a pile of battens...

...and mounting them on the form frames:


Anonymous said...

I love your strongback mounting - Brilliant! Where did you find the concrete pier blocks?

Jay said...

My local Home Depot...they are really nothing special, just regular pier blocks. The adjustable saddles are what make them easy to use.