Food Living Outside Play Technology Workshop Three-Legged Knock-Down Sawhorse by ProfMuggs on December 7, 2010 Table of Contents Three-Legged Knock-Down Sawhorse . 1 Intro: Three-Legged Knock-Down Sawhorse . 2 Step 1: Design . 3 File Downloads . 5 Step 2: Lumber & Tools . 5 Step 3: A-Frame Leg . 7 Step 4: Mono Leg . 10 Step 5: Spine . 13 Step 6: Finished Product . 14 Step 7: Update: Handle and Clamp Holds . 17 Step 8: Updated Finished Product . 20 Related Instructables . 21 Advertisements . 22 Comments . 22 http://www.instructables.com/id/Three-Legged-Knock-Down-Sawhorse/ Intro: Three-Legged Knock-Down Sawhorse The more projects I make, the more I realize that my rickety old sawhorses are inadequate. I think that I am limited by the strength and sturdiness of these sawhorses and I feel like I am always compensating for them. Because these sawhorses are so unstable, I set out to make the most ideal and functional replacements I could. Ideally, my new sawhorses would be extremely sturdy and collapsible. That way I could take it anywhere and easily put them out of the way in my small workshop. I have a reprint of a woodworking book from the 70's that showed a couple different designs for sawhorses. The one that interested me most was a 3 legged design that touted its sturdiness on uneven ground. My backyard is very uneven and I often have trouble setting up tables or my sawhorses. I reposition them again and again until they stop wobbling. Unfortunately, the book only had a rough drawing of a 3-legged sawhorse. I looked around the internet but I didn't find any plans for a 3 legged sawhorse, so I had to design my own. I decided I wanted to make my design include knock-down legs, so they could be taken off for storage or transport. I used the following links as guides for the standard parts and adapted a traditional knock-down design to suit my needs. Knock down Sawhorses The Richard Standard Knock-Down Sawhorse Other designs 39 Free Sawhorse Plans Update: 3 Legged Sawbench Design http://www.instructables.com/id/Three-Legged-Knock-Down-Sawhorse/ Image Notes 1. These brackets no longer hold the legs straight in any direction. 2. Sometimes the 2' width of these sawhorses has been a problem for me. Step 1: Design Most sawhorses have the legs set out at 15º for stability. I decided to make the A-Frame legs splayed out 15º, and make that frame and the mono-leg splayed out 15º from each other. The idea was to make this as stable as it could be while still being a 3 legged sawhorse. To get the length of the legs, you can use these equations or you can just use this calculator . I knew I wanted to make the sawhorse 30" tall, and I knew all 3 angles of 1 the triangles (90º + 15º + 75º = 180º). For the single leg, I ran it through the calculator once and got a leg length of 31.05829"(31 /16 "). For the 2 legged end, I used that 3 result and solved for the hypotenuse again which gave me 32.15391" (32 /16 ). This number gives me the length of the compound mitered legs. For a detailed blueprint, open the attached PDF. Image Notes 1. Once I was done, I drew up some blueprints with more detail than the Instructable. If you want to see the full size original, download the PDF below. Image Notes 1. 2" x 8" board. I decided not to taper the leg this way on the final design. 2. 2" x 6 " board 3. 2" x 4" board 4. 2" x 4" board 5. 2" x 4" board 6. 2" x 4" board 7. This is the final design I went with. It is simplified from my previous designs, but still has some tricky angles to cut. 8. 2" x 6" board http://www.instructables.com/id/Three-Legged-Knock-Down-Sawhorse/ Image Notes 1. I was kinda making this up as I went along. I didn't know where I was going to put the braces for the A-Frame until I saw how much 2 x 4 stock I had left. Image Notes 1. Shorter notch. 2. Taller notch. 3. This idea was to add a stowable bench dog on the ends of the spine. This way if I was using the horses on a hill like my backyard, I wouldn't have to worry about the work sliding off the side. One way the block would line up flush with the top of the spine, the other side would sit a half inch proud of the other board. Image Notes 1. Originally the idea was to make it stackable as well. The notch would catch on the spine, the outer ledge on the single leg would catch on the inner ledge of http://www.instructables.com/id/Three-Legged-Knock-Down-Sawhorse/ the double legs. 2. Stackable would have been nice, but more work than its worth since it comes apart easily. 3. I decided on 36" wide after I had been kicking around ideas for much wider horses. My last set was only 2' wide, so I figured I could use the extra space. I came to my senses when I realized there wasn't room for anything this large in my workshop. 4. This notch would have matched up with the top of the lower sawhorse if they were stacked. Image Notes 1. I found this example in a book, but there were no measurements. Also, this is a saw bench, not a saw horse, so I decided to make my own. File Downloads 3 Legged Sawhorse blueprint.pdf (405 KB) [NOTE: When saving, if you see .tmp as the file ext, rename it to '3 Legged Sawhorse blueprint.pdf'] Step 2: Lumber & Tools Lumber One problem I had with my last sawhorses was the wood getting bleached and brittle. When I made them, I didn't expect to use them outdoors as much as I did. This time around I am using pressure treated lumber so they will stand up to the weather if necessary. The other main problem was the galvanized brackets that I used to put them together. They get bent over time and don't hold the wood tight. By using a knock-down design, I will eliminate these brackets. I made everything from 2 inch pressure treated stock. Specifically, I used 2 x 6's for the spine, 2 x 4's for the 2 legged side, and 2 x 8's for the single leg side. I had a bunch of 2 x 6 lumber left over from an earlier project, so I only had to buy one 2 x 8. I ripped everything else down from the 2 x 6's. For the last pieces, the leg brackets, I just ripped down all the scrap pieces left over from the other steps to 2" x 2". When you are measuring and designing something like this, it helps to be familiar with the actual thicknesses and widths of standard lumber sizes. Take a look at this page for more information. Tools Because of all the angles involved in this design, I absolutely needed my Craftsman compound miter saw. I got this saw as a hand-me-down from my cousin, so I am not sure how old it is, but it still works great. The legs of the A-Frame leg in particular couldn't have been cut without a compound miter saw. Because I was reusing 2 x 6 lumber and making 2 x 4's out of it, I needed my Craftsman 10 in. table saw. I've ripped down lumber with my circular saw, and it is a big hassle to do any more than 1 or 2 boards. With the table saw, once the fence is set, I can repeat the same cut again and again with minimal effort. This was especially important to make the 2 x 2 leg brackets out of the scrap wood. My older model compound miter saw doesn't have the slider feature that the newer saws like this one have. This means I can't cut anything wider than about 6" and less if its a miter cut. For these cuts I had to resort to my circular saw. You will also need a good drill, a sharp set of drill bits and a few medium sized quick release bar clamps. A good hand saw and jigsaw or coping saw will also be handy. To measure, you will probably need a steel framing square, measuring tape and a woodworking protractor. http://www.instructables.com/id/Three-Legged-Knock-Down-Sawhorse/ Image Notes 1. When I got this saw from my cousin, it was missing the dust bag. I use this one from my palm sander that fits, but fills up quickly. Image Notes 1. Since I am making this out of pressure treated lumber, I chose to use exterior screws. I have also heard that the chemicals used to preserve pressure treated wood can break down other types of fasteners. http://www.instructables.com/id/Three-Legged-Knock-Down-Sawhorse/ Step 3: A-Frame Leg 3 To start the A-Frame leg, I set the blade on my compound miter saw to 15º miter and 15º bevel. I then cut four 32 /16 " lengths of 2 x 4 stock. I made the first cut to 3 establish the angle at one end, then measured the 32 /16 inches and made the cut with the blade set at the same angle.