How to make a concrete seat

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Step 1.5   Aligning and bolting the leg forms to the seat form

The purpose of this step is to allow for easy alignment of the leg forms over the seat form during the casting process.
The casting process involves half-filling up the seat form with concrete, placing in the reinforcing, filling the seat form with concrete, and fixing the leg forms in place ready for more concrete.
It is the latter stage that is made easier and quicker with the addition of the angle brackets.

Do this step in the following order:

Measure 4⅜” (110mm) along pieces (c) from the inside corners of the seat form and mark across pieces (c). See fig.1.

Place the leg forms against the mark. Ensure that the leg forms are equal distance from the sides. Mark the drill holes on pieces (c) through the holes in the angle brackets. (See fig.2.) Then remove the leg forms.

Drill down into pieces (c) to a depth of ½” (12mm) with a 1⅛” (28mm) diameter drill bit, and then continue the rest of the way through with a ½” (12mm) drill bit. (See fig.3.) There will be four holes in all.

Insert a ⅜” (10mm) coach/carriage bolt into each hole from underneath and secure each bolt with a washer and nut. The nuts will finish below the surface of the wood. See fig.3.

*Note:   The angle brackets are to hold the leg form to the seat form. They make for easy alignment when it comes to assembling the form for casting. The bracket size given above is not absolute. Anything similar will do as long as it does the trick. You may have to make your own by cutting, bending, and drilling a piece of sheet metal. On the other hand, you can do away with them altogether and use clamps to hold the leg forms to the seat form. The latter method however, will require a bit of extra measuring and aligning when it comes to assembling the forms for casting.