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Centerfire Discussions / Re: Bench Designs
« on: May 19, 2010, 10:22:30 PM »
Dwayne C sent the following information for the benches they built for the range in Kenora.
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We got the idea from Benchrest Central forums when we read about HOF shooters who thought the Mickey Coleman design was the best they ever shot from. We modified the plan for 45 inches wide instead of 36 inches ( room for spotting scopes) and used 6 5/8ths O.D. well pipe casing for legs instead of square concrete blocks filled with concrete and rebared to the slab. Our benches must be portable at our home range. The form is made by ripping 2 X 6 into a true 1 1/2 X 4. The form is made from one sheet of ≤ inch G1S doubled for 1 ∏ inch thick 48 X 48. The front 2 x4 is removable to slide the top out of the form. Each top has 30 feet of 5/8ths rebar in it. Each top uses about 3.6 cu ft of concrete at 150 lbs per cu ft and is approximately 540 pounds without rebar or legs. We settled on a height of 32 inches (standard is 32 to 34 inches high). Leg braces are 2 X 4 X .125 wall rectangular tubing. The feet are 8 X 8 X π plate. There was somewhere between 6 and 8 bags of Kwickcrete redimix from Home Hardware went into each top. The form must be tapped on all sides with a hammer for 5 or 10 minutes to get the air bubbles out or the concrete honey combs on the sides and looks like hell.
We could have made the shape curved instead of angled but the strength of the form needed to make 12 benches, we doubted the form would last. Also angled was easier to make.
The inside of the form was painted with clean motor oil before as a release agent before each pour.
The prototype had the legs free standing and the top could be lifted by 5 old guys onto the legs and bolted in place through the bottom with 5/8ths bolts into 2 inch long threaded rod coupler nuts that were welded to the rebar and held the rebar up in the center of the concrete. The next 3 benches use railway tie plates welded to rebar and cast into the top. The legs are welded on after. The logistics of slinging a bench with a Hyab crane to put them right side up on spot have to be worked out. Total cost per bench was around $150 to $175.
If the bench doesn’t need to be portable, the 7 ∏ inch square concrete block legs are the easiest. Glue them together with landscaping adhesive and fill with concrete rebared to the slab and top.
These benches are solid; you can lean into them and do anything behind them while shooting. We put a 60 X spotting scope on one and it was the 16 foot wide X 80 foot long X 5 1/2 inch thick concrete firing line slab that the bench was sitting on that was flexing.
http://benchrest.com/articles/benches.pdf
Kenora Benches:
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We got the idea from Benchrest Central forums when we read about HOF shooters who thought the Mickey Coleman design was the best they ever shot from. We modified the plan for 45 inches wide instead of 36 inches ( room for spotting scopes) and used 6 5/8ths O.D. well pipe casing for legs instead of square concrete blocks filled with concrete and rebared to the slab. Our benches must be portable at our home range. The form is made by ripping 2 X 6 into a true 1 1/2 X 4. The form is made from one sheet of ≤ inch G1S doubled for 1 ∏ inch thick 48 X 48. The front 2 x4 is removable to slide the top out of the form. Each top has 30 feet of 5/8ths rebar in it. Each top uses about 3.6 cu ft of concrete at 150 lbs per cu ft and is approximately 540 pounds without rebar or legs. We settled on a height of 32 inches (standard is 32 to 34 inches high). Leg braces are 2 X 4 X .125 wall rectangular tubing. The feet are 8 X 8 X π plate. There was somewhere between 6 and 8 bags of Kwickcrete redimix from Home Hardware went into each top. The form must be tapped on all sides with a hammer for 5 or 10 minutes to get the air bubbles out or the concrete honey combs on the sides and looks like hell.
We could have made the shape curved instead of angled but the strength of the form needed to make 12 benches, we doubted the form would last. Also angled was easier to make.
The inside of the form was painted with clean motor oil before as a release agent before each pour.
The prototype had the legs free standing and the top could be lifted by 5 old guys onto the legs and bolted in place through the bottom with 5/8ths bolts into 2 inch long threaded rod coupler nuts that were welded to the rebar and held the rebar up in the center of the concrete. The next 3 benches use railway tie plates welded to rebar and cast into the top. The legs are welded on after. The logistics of slinging a bench with a Hyab crane to put them right side up on spot have to be worked out. Total cost per bench was around $150 to $175.
If the bench doesn’t need to be portable, the 7 ∏ inch square concrete block legs are the easiest. Glue them together with landscaping adhesive and fill with concrete rebared to the slab and top.
These benches are solid; you can lean into them and do anything behind them while shooting. We put a 60 X spotting scope on one and it was the 16 foot wide X 80 foot long X 5 1/2 inch thick concrete firing line slab that the bench was sitting on that was flexing.
http://benchrest.com/articles/benches.pdf
Kenora Benches:
Looks to be taking about 3-4 weeks once they have it in their hands.
