DIY Adjustable Wooden Weightlifting Bench

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Introduction: DIY Adjustable Wooden Weightlifting Bench

    If quarantine has got you looking for new ways to exercise--look no further! This bench is designed with weightlifting in mind and is adjustable for different exercises.

    You can angle it for flat bench press, inclined press, and 90 degree military press--and everything in between. Being a bench, it also allows for a variety of other exercises such as preacher curl, hip thrusters, or dumbbell back row.

    Minus a few special items, this can be built with basic woodworking tools at your home. You can also upholster the seat and back with faux leather fabric to make it more comfortable, but this is optional.

    This design was adapted from a bench made by afajarito but this model is designed for heavier weightlifting. It is also portable and can be easily disassembled by hand for transport.

    The approximate total cost of this bench is $66.27 but will vary depending on current prices.

    Note: This bench has not been stress tested; so be careful when exercising and never lift more than you can handle.

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    Supplies:

    **here's how you interpret qty, in, ft, etc. if you aren't familiar with lumber lingo

    ex.1- 4x4x10 ft = 4in x 4in lumber that is 10ft long (quantity = 1)

    Wood:

    • 1- 4x4x10 ft
    • 2- 2x4x8 ft
    • Plywood 1ft x 4ft (3/4'' thick) *(usually comes in a 2'x4' section)

    Hardware:

    • 22- 3'' wood/deck screws
    • Zinc Hex Bolts:
      • 2- 4'' long (1/2'' dia)
      • 1- 10'' or 11" long (1/2'' dia)
      • 3- 8'' long (1/2'' dia)
    • 4- 4.5'' long zinc lag bolts (3/8'' dia)
    • 12- 1/2'' flat zinc washers
    • 6- 1/2'' zinc hex nuts
    • 4- 3/8'' flat zinc washers

      Tools Needed:

      • hand drill
      • 1/2'' to 5/8'' drill bit
      • 1.5'' countersink drill bit
      • hand saw (or circular saw)
      • jig saw (or any reciprocating saw)
      • table saw, router, or wood chisel (for cutting dado joint)

      Optional (for upholstering the bench):

      • heavy duty stapler, or stapler gun
      • 1 sq. yard of faux leather (Walmart is a good option)
      • foam yoga or exercise mat (1/2'' thick or more)

      Step 1: Cutting the Wood

      Once you have the correct lumber then use this cut list:

      4x4x10: cut into pieces measuring 13", 13", 18", 18" and 49" in length

      2x4x8: cut into pieces 36", 36", 15" and 9" long

      2x4x8: cut into 34", 34", 15" and 9" long pieces

      plywood: cut into rectangle sections 34"x12" and 14"x10"

      Most parts will need additional cutting or drilling for holes. Refer to the files attached for exact part dimensions. The following steps will describe and outline the order I recommend for cutting and building the bench. All dimensions are inches (in.)

      Step 2: Building the Base (part 1)

      The main task here is to cut what are called "dado joints" into your 4x4 lumber to form the base of the bench. Depending on what tools you have, you can use a table saw with a stacked dado cutter blade, a router with a straight-cutting bit, or a hand saw and a wood chisel. Check out more info on Dado Joints or weight bench for more help.

      Start by cutting a dado joint halfway along both 18" 4x4 pieces. I cut mine 1.25" deep and 3.5" wide. You want it just wide enough to fit another 4x4 on its end snugly and make what looks like a T-shape with the two pieces.

      Put the end of the 13" 4x4 into the dado joint on the 18" piece and flip it upside down. Countersink a hole directly in the center of the 13" piece, about 1.25" wide by 3/8" deep. Next, pre-drill a hole in the center of the countersink that goes through both wood pieces. Then drive a lag bolt (with a washer!) down the hole to connect the two pieces together. You can start with a few taps of a hammer then tighten with a rachet set.

      You know it's right when the lag bolt with the washer is countersunk deep enough to be flush with the surface of the 13" long piece. These will make the legs of the bench.

      Step 3: Building the Base (part 2)

      Perform 2 more dado joints in the same manner on the 49" long 4x4 piece. The joints will start 2.5" from one end (back of the bench), and 7" from the other end (front of the bench). Again, about 1.25" deep and 3.5" wide.

      Flip the 49" piece over and countersink holes directly above the dado cut. Again, they will be about 1.25" wide by 3/8" deep. Insert the ends of the 13" long pieces into the dado joints, attaching the legs to the body of the bench. Then pre-drill holes through the countersink on the 49" piece deep enough to penetrate the end of the 13" piece. Follow with a washer and lag bolt to fasten the dado joint. Screw the lag bolt until it is flush with the 49" long piece.

      You have now completed the base of the bench!

      Step 4: Cutting the Curved Pieces

      Here's another interesting part of this build. Since the bench has adjustable angles, the pieces need to slide past each other smoothly. Using a jig saw (or a really tough job with a hand saw) you will cut a curve at the end of the 2x4's to make a semicircle.

      Grab each 2x4 piece that is 36", 34", 15" long. Trace out a 3.5" circle drawn on one end of each piece and mark a dot in the center. In other words, it has a 1.75" radius and is at one end of each piece. Using a jig saw, round out the end of the 2x4 by cutting along the line to make a semicircle. Now drill a hole 1/2" wide in the center of those holes.

      Do this on ONE end of each of the 2x4 pieces mentioned above. Also it's a good idea to widen the 1/2" hole out enough for a 1/2" hex bolt to fit through and twist by hand.

      Step 5: The Backrest

      Take the 36" long piece and countersink a hole 21.75" from the rounded end of the board. The hole should be 1.5" wide by 0.5" deep. Then drill a hole slightly larger than 1/2" in the center of the countersink. Do this for both pieces.

      Put the 36" pieces side-by-side with the countersink holes facing toward each other. Lay them on top of the 34"x12" plywood, with the curved ends hanging over the edge by exactly 3.75". Space the pieces equally apart, wide enough for your 4x4 base to fit in between and clamp them into place.

      Flip the assembly over and drill screws going in the direction from the plywood down to the 36" piece directly below. Securely attach both 36" pieces to the plywood in this manner, ensuring your 4x4 base can fit in between.

      Make sure the 4x4 can easily be removed when sandwiched between the 2x4's, but too much space will make the bench wobble just a bit.

      **As you will see in the pictures, I have already upholstered the bench with black faux leather, but you can imagine it's just the plywood back rest instead.

      Step 6: The Seat Post (part 1)

      Take both 15" 2x4 pieces and attach them to the 14"x10" plywood bottom in a similar way to the previous step. Leave the curved ends of the 2x4 hanging 2.5" off the longer end of the plywood. Center everything and leave a gap between the two boards just wide enough for your 4x4 base to fit between. Screw the three pieces together with wood screws going from the plywood down towards the 2x4.

      Ensure the 4x4 can easily be removed when sandwiched between the 2x4's, but too much space will make the bench wobble.

      Step 7: The Seat Post (part 2)

      Now, you'll make the seat post that allows you to raise the seat at an angle for incline bench press. Take the 9" long 2x4 pieces and cut a 65 degree angle on one end of each (see picture). Then drill a 1/2" hole about 3.5" down vertically from the tip of the angled end and centered in the middle of the 2x4. Repeat this for the other 9" piece.

      Next, attach the seat post to the seat. Align the tip of the angled 9" piece with the square end of the 15" long 2x4 seat. I used a pocket hole jig for drilling holes at an angle, which is great for disguising nails in a woodwork job. But you can just drill your own screws in at an angle if you don't have that. Make sure to pre-drill your holes before you sink your screws!

      Step 8: The Back Supports

      These 34" long 2x4 pieces are what allows the bench to adjust for different angles while benching. I made a 45 and 90 degree angle (plus flat 0 degrees) but you can customize it for any angle 0-90 degrees that you like!

      For a 45 degree, countersink a hole that is 15" from the square end of the 34" piece. The countersink would be about 1.5" wide by 0.5" deep. Then drill a hole slightly larger than 1/2" into the center of the countersink.

      For a 90 degree, do the same thing but make the hole and countersink 9.5" from the square end of the 34" piece.

      Step 9: Assembly (part 1)

      Now that all the pieces are made, it's time to assemble to bench. Insert the 4" hex bolt through the countersunk hole drilled into the 36" piece with the bolt facing outward. Attach the rounded end of the 34" piece to the bolt, with a washer on both ends and fasten tight with a hex nut. Do this for both 34" pieces (see picture).

      **For many of the 1/2" drilled holes, you may have to widen them to allow the bolts to fit. You want it to be snug but able to remove by hand.

      You want to mount the seat and backrest as close as possible to each other, and the rounded edges help with that. For the seat, I drilled a 1/2" hole about 13-5/16" back from the front of the base, and another one 17-3/16" from the front to mount the backrest. The front of the base is the part of the 4x4 that extends the furthest past the dado joint. Now attach the seat and backrest using the hex bolts.

      Step 10: Assembly (part 2)

      With the seat and backrest mounted, it's time to drill the holes to allow for adjusting the angle of the bench.

      For the 45 degree angle, drill a hole slightly larger than 1/2" and locate it 40-7/8" from the front of the base.

      For the 90 degree angle, drill a similar hole located 27.5" from the front of the base. Use the 10" or 11" bolt

      For the seat angle, raise the seat until that hole we drilled into the seat post is centered in the middle of the 4x4 base and pre-drill through your hole into the 4x4 to mark where the 1/2" hole will go. Finish by widening out all your 1/2" holes just enough that you can take all the bolts out by hand.

      And you're all done! This is a fully functioning, adjustable, and portable weightlifting bench. Remember, this bench has not been stress tested, so always be careful when weightlifting and practice safe lifting.

      Also, please refer to the following optional steps to improve the ergonomics...

      Step 11: (Optional Step 1) Upholstering

      The bench works alright, but it isn't very comfortable to lie on a piece of wooden plywood while cranking out reps. To upholster your bench, all you need is a foam yoga or exercise mat (hopefully about 1/2" thick), 1 yard of faux leather or vinyl (Walmart is a great option), and a heavy duty stapler.

      I followed this Youtube video from Buff Dudes for how to upholster my bench. They are also a great channel for DIY weightlifting equipment.

      Basically, you cut the foam mat about 1/2" or more larger on each side than the outline of the plywood. Round off the corners of the plywood with a hand saw and some sandpaper. Then flip the bench upside down and stretch the fabric over both the foam and plywood then staple it on the underside, making sure the fabric is taut. That's it!

      Due to the bench design, I could not put the seat and backrest closer together while laying in the flat position. To help with comfort, I also added a small leftover section of foam padding to cover the wood. This is only temporary when doing flat bench press and can help provide padding for your tailbone.

      Step 12: (Optional Step 2) a Bit More Stability

      I did notice that on the back side of the bench where you insert the 10" or 11" hex bolt to adjust the angle, it can seem a bit wobbly because the bolt doesn't make full contact with the wood everywhere. It resulted in a bit of a wobble, but nothing big enough that it wasn't safe.

      My best idea for ensuring more stability in that area is to attach a small section of 2x4 wood to each 34" long piece so the bolt won't be exposed and make full contact with the wood.

      Comment on your thoughts and if you think that's an important fix! Thanks for reading and good luck with your weightlifting!

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        13 Comments

        0
        perrybear
        perrybear

        Question 5 weeks ago

        Great instructable! How much weight do you use with this bench?

        0
        jaksci98
        jaksci98

        Answer 4 weeks ago

        The most rigorous testing for this bench would be in the 45 degree incline. This held all the weight I have on hand. My friend (who weighs 200 lbs) benched 230 lbs. That's a total of 430 lbs. Not to say it won't hold more, that's just all the weight we had.

        0
        perrybear
        perrybear

        Reply 4 weeks ago

        Thank you for your response!

        1
        nilsrmenz
        nilsrmenz

        5 weeks ago

        Impressive! Well done!

        0
        jaksci98
        jaksci98

        Reply 4 weeks ago

        Thanks mate!

        0
        jfitzpa22
        jfitzpa22

        Tip 5 weeks ago on Step 12

        Very nice build! I would recommend using mortise and tenon joints wherever possible and reinforcing them with Simpson strong ties.

        1
        jaksci98
        jaksci98

        Reply 4 weeks ago

        Great idea! Those would definitely add an additional stability to the bench. Mortise and tenon joints might be more advanced for some, but the Simpson strong ties definitely work for all experience levels.

        0
        mtbike2
        mtbike2

        Question 5 weeks ago

        What made you choose treated lumber over lumber that was not treated?

        0
        jaksci98
        jaksci98

        Answer 4 weeks ago

        I used non-pressure treated lumber because it was slightly cheaper. However, if you need to put your gym setup outside then it would withstand the elements if it is pressure treated. Just personal choice and if you plan to use it outside or not.

        2
        bgreen3
        bgreen3

        5 weeks ago

        If I can make a suggestion for anyone building this... the "90 degree" military press position is figurative and really just means sitting fully upright. To achieve this with proper support, the backrest should still have some amount of decline. 5 to 12 degrees from vertical (or 78 to 85 degrees from horizontal) are a good range of angles for this. Some machines use 85 degrees (Like the Rogue Adjustable Bench 2.0). Some use 78 degrees (Like the Rogue AB-3). Making a seat with a true 90degree back angle, as shown, will actually have the user leaning slightly forward if their hips are placed against the rest, and this forward leaning position does not provide good spine support.

        1
        jaksci98
        jaksci98

        Reply 4 weeks ago

        You are completely right! Thanks for mentioning that, I will try to make that change in the instructions

        1
        jessyratfink
        jessyratfink

        5 weeks ago

        Well explained and built! Thanks for sharing :D

        0
        jaksci98
        jaksci98

        Reply 5 weeks ago

        Thank you for reviewing!