Portable Rifle Sight-In Bench
Posted Oct 25th 2012 | By:
There are many hunters who have places near their own home where there is room to fire a rifle. All you need is about 100 yards of open space and a good backstop ( YOU are responsible for following ALL laws in your area.). However, building a permanent rifle range is not something that most people want to do. So having a portable bench like the one in this article allows a person to temporarily use an area to sight-in a rifle without restricting what you can use that area for tomorrow. If you have the proper tools, then this project will probably only take a few hours of actual work time, however, there is a gluing step which needs at least 24 hours to cure properly. I would strongly recommend that you do not put any stress on the bench until all braces are in place and the glue has dried thoroughly. Note also that this article is provided without any warranty for accuracy of the measurements or safety of the described bench. Those who decide to attempt construction of this project DO SO AT THEIR OWN RISK.
The design of this bench is relatively simple and you can modify it for your personal needs if necessary. For purposes of this article, we will select a seat height of 18" and bench top height of 30'. The size and dimensions we will use are intended for a typical-sized man; say about 6' tall and about 200 lbs. To customize the bench, you should adjust the measurements or materials to fit your needs. There is a video showing some (NOT all) of the cutting and assembly steps available on the LaRoVideo YouTube channel or by visiting my website (www.larovideo.com). If you would like to have a mechanical drawing of the bench, please visit the 'Sample Video' page of the website.
As you can see, the bench is primarily made out of wood. You can buy the necessary materials or, if you happen to have some scrap lumber lying around, you may use that to build this bench. Just make certain that it is in good condition without any apparent rotting or other damage. You may want to add some materials like paint, or padding on the seat, etc. to improve the overall look but the list of required materials is:
- One STRAIGHT pine 2x6 board (need ~11' for required pieces)
- One sheet of 3/4" plywood approximately 2' square
- Two 1/4x20 bolts at least 3" long
- Four " flat washers Two 1/4x20 (wing) nuts
- One box of 2" wood screws (rust resistant, for outdoor use)
- Some wood glue
- Some form of adjustable surface (possibly a pillow?)
Required materials and hardware
The following is a SUGGESTED list of tools and equipment. Your situation may affect the choice of tools.
- A miter saw (capable of 60 degree cuts)
- A power drill A 90/45 degree angle standard
- A straight edge
- A metal bit sized to be a 'pilot' bit for the wood screws
- A " metal drill bit (can also be used for the countersink bit for the wood screws)
- A 5/8" wood drill bit
- A screwdriver to fit the wood screws and/or the 1/4x20 bolts
- Assorted clamps to hold pieces in place for gluing and drilling
Cutting the parts:
RETAIN ALL SCRAPS until the project is completed. Some of them will be used for extra braces, etc.
The actual width of a so-called 2x6 is approximately 5.5 inches. The first cut will convert the end of the 2x6 from a 90 to a 45 degree angle. Set up your miter saw to make 45 degree cuts across the width of the 2x6. Use the 45 degree standard to confirm that the saw blade will make the proper cut. Cut the end off of the 2x6. SAVE the triangle piece!
Small triangle pieces will be trimmed from ONE end of the long brace. You MAY want to trim BOTH ends of the 60 degree brace by about 1".
The length of the first brace is determined by the height of the bench top as required to meet your needs. Our example has the bench top at 30 inches. The brace will be set at a 45 degree angle from the floor/ground so we must multiply 30 inches by the square-root of 2 (we can use 1.414 as an approximation) to find out how long this first piece must be to reach 30 inches vertically. That number is 42.42 inches. There will be a 'foot' piece on the bottom made from 2x6 material and the table top is made of " plywood. So we subtract the actual thickness of the 2x6 (1.5 inches) and the thickness of the plywood (3/4") to get 40.17 inches. Measure along the side of the 2x6 and mark at 40 3/16". Cut the board to form a parallelogram. Measure along the angled BOTTOM edge of this 'long brace' 5.5" and mark. [The mark should be 2.277" from the sharp pointed end.] Draw a line across the pointed end and cut it off. The scrap piece should be a small 'right' triangle piece with sides of 2.277". Set this piece (long brace) aside.
Use the miter saw set for 45 degree cuts to trim the ends.
The second brace length is determined by the seat height but this brace will be set at a 60 degree angle. There will be a seat on one end and a foot piece on the other. The thicknesses of these two pieces subtracts 3" from the desired 18" height. We multiply 15" by the inverse cosine of 60 degrees to get 30" for the length of this brace. Set your miter saw to cut 60 degrees and trim the angled end of the 2x6. Try to minimize the size of the scrap piece. Then measure 30" along the side of the board and cut another 60 degree angle to form a second parallelogram. You may want to trim a small amount (appx. 1") from each end to eliminate the sharp points. Set this piece [60 degree brace] aside. Adjust the miter saw back to 45 degrees and trim the angled end of the board. Again, try to minimize the scrap piece. Then adjust the miter saw for 90 degree cuts and trim off the angled end. SAVE that piece.
The dimensions of the next three pieces are not critical and you may adjust them to suit your needs. For example, if you wish to have longer 'feet' to increase stability, you might choose to cut down on the 'width' of the seat board. If you wish to have a wider seat, you will have to reduce the length of the 'foot' pieces. For purposes of this demonstration bench, I chose a seat of 18 inches, and a long 'foot' of 18" which left approximately 10" for the shorter 'foot' with a scrap piece (at least 5.5" long) which was used to make two additional 90 degree brace triangles.
Adjust the miter saw for 90 degree cuts and cut the seat and the two 'foot' pieces to the dimensions you have selected. Adjust the miter saw for 45 degree cuts and cut the remaining scrap piece to create two more 90 degree triangle pieces. When the footers and seat are cut, measure and find the exact center of each piece and draw a line at 90 degrees across. Then measure " to one side and draw another line to be used as the center line for the pilot holes for the wood screws. Drill the pilot holes. Next turn the boards over (to the side without the center line) and counter sink the holes to a depth of "using the" bit.
You should have FOUR of the large 'right' triangle shaped pieces. Adjust the miter saw for 90 degree cuts. Place the LONG side of the large 'right' triangle pieces against the miter saw guide and cut each triangle in half. You should now have eight 'medium' sized 90 degree triangles.
The first step in the assembly process is to attach the seat and long footer to the 60 degree brace using wood screws. Align the center line on the footer and seat with the INSIDE edge of the brace. Next, attach the short footer piece to the bottom of the long brace in a similar manner.
Coat the sides of the 90 degree triangles generously with wood glue. Place one triangle in each of the corners formed by the footers and seat with the braces. Use clamps or other means to ensure a good joint and allow to 'cure' for at least 24 hours.
Loosen clamps and adjust braces, then re-tighten clamps until all measurements are correct. THEN drill.
Alignment of the braces is more easily done with two people, but it CAN be done by yourself. Position the braces as near to correctly as you can. Use clamps to hold them together. Set the bench on a flat surface. Ensure that both footers contact the surface properly. Measure the seat height and bench top height. Also check that the back edge of the seat and the short footer align. If any of the measurements are incorrect, loosen the clamps and adjust the position of the braces, then re-tighten and re-check all measurements. When the braces are in their proper position, find suitable locations and drill two " holes through BOTH braces. Then use the 5/8" wood bit to drill into the outside of the braces approximately 1/8" on both sides to make room for the washers and nuts. Insert the 3" 1/4x20 bolts with washers and nuts and tighten.
OPTIONAL: You may choose to add glue between the braces for additional strength and stability. If you choose this path, then you will NOT be able to separate the braces for easier transport. Decide which is more important to you and act accordingly. (Note: I chose easier transport and DID NOT glue the two braces together.)
Next glue the last two medium sized triangles to the side of the TOP of the long brace to form a flat surface for mounting the bench top. If you wish you can use some of the scrap material to extend the flat surface formed by these pieces. See photo #7. Allow at least 24 hours to dry.
Find the center of the table top and draw a square line. Place the inside edge of the long brace on this line. Locate and drill (at least) two holes through the top of the table to the approximate center line of the long brace. Countersinking is not necessary in this step. Attach the table top to the top of the long brace with wood screws.
OPTIONAL: You may wish to paint or stain your bench to protect it from water or improve the overall appearance.
OPTIONAL: Adding some padding to the seat piece will improve the comfort of those using the bench.
That's it. Your bench should be ready for use. If you find value in this article, please visit our website and our YouTube channel. Click 'like' on the videos that you like. Make comments if you wish. We appreciate any feedback.
You MAY wish to use some of the scrap material to extend the flat surface supporting the bench top as shown above.
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