| This board frame is constructed of 1X1 angle steel, bridged together with 1/2 inch steel square tubing and is mig welded together. Overall it measures 72 inch by 17 1/4 inches, (Illustrated 1).
It was assembled at work on a couple of saw horses. It was squared using a carpenter's square. Twist was checked using a couple of straight tubes with one laid on each end. The frame was shimmed as needed to achieve perfect parallel surfaces front to rear while sighting the parallel straight tubes, similar to (ill. 6) .
My bench top at home is far from flat and level. The frame bottom was drilled and tapped for eight 1/4X20 flat headed screws which were used as adjustable legs, (ill. 5). Each also has a lock nut. The frame was then located on the bench top with four restraints, one located at each corner of the steel frame, (ill 4), and glued to the bench. The restraints were 1/8 lite ply drilled in the center the size of each leg screw head. The frame was then leveled and adjusted for twist in the same manner as when welded at the shop.
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1. Steel Frame Sitting on Work Bench
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The 1/2 inch square cross tubes were cleaned with alcohol and covered with electrical tape. Four Double sided tape strips approximately one inch long were placed on each cross tubes and end frame surface to secure glass placement. A piece of 1/4 inch thick glass, (ill. 2), was then placed into the frame sitting on the cross tubes. Five pieces of double sided tape was then placed on top of the glass running length wise and evenly spaced.
I spent some time at the local lumber yard trying to decide on which synthetic material to choose for the board surface. I chose rubber roof underlayment material, (ill. 3). It comes in 4X8 sheets and is 1/2 inch thick. It takes pins very well and should remain stable in shape, given its inherent purpose. It's also very inexpensive, about $9.00 per sheet.
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2. 1/4 inch Glass Sub surface Support Installed
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3. Rubber Roof Sub Surface Material
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4. Restraint Close Up Glued To Bench Top
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5. 1/4X20 Flat Headed Screws Used as Adjustable Legs
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6. Check Finished Building Board For Twist
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