I tried to drill the holes on the cheap, using an underpowered 3/8" drill that supposedly had an impact setting. I managed, with much difficulty to get about half of the holes made with it. I'm certain that the rocks in the concrete mix prevented the other ones from becoming full fledged holes. A trip to Menard's and some $$ later, I was the proud owner of a shiny new 1/2" Bosch impact drill. Its ability to finish those holes was a piece of cake. I wish I had bought it before I ever suffered through that first hole with the "baby drill". I also bought an adapter for it that lets me chuck up conventional drill bits so I can use it in the non-impact mode for regular drilling. This was an extra expenditure that was not necessary but so worth the expense.
After looking at locally available hardware, I opted to use Red Head 1/2"x7" zinc-plated steel solid concrete wedge anchors to keep those frame rails from moving around. This required a 4 1/2" deep hole in the concrete footer. They too aren't cheap but they will last and meet the specs for anchoring the shelter per VersaTube's requirements.
Here is one end of a frame rail. You can see the masking tape I previously mentioned. I'll mention here that I found it very helpful to have an extra pair of hands to help hold the rail in position while drilling. The holes for the anchor bolts were already in the rails so I used them as a built in template for drilling the holes in the pad. Since we are talking about an impact drill, the rail had a tendency to want to move a bit while the hole was started. Once the bit was into the pad a bit, nothing moved. Since the rail was comprised of multiple slip joints, there was a small bit of flex. It's important to keep that rail straight so your rafters are true and plum when being attached to the rails.
Here you can see two sections of frame rail, slipped into each other, being securely held together with a couple of self tapping metal screws. The cordless driver I mentioned earlier, equipped with a hex socket, made short work of these screws.
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