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How to Build-a Steel-Frame Weight Bench

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Introduction

I ran a small manufacturing plant for electronic components and had a wonderful network of vendors that offered all types of machining, welding and finishing processes. One great guy and fine toolmaker was (“Terrible”) Tim McCullum. Timmy had a CNC [computer numerical control] shop with welding capabilities located right around the corner from my company.

One morning I went to Tim's shop to drop off a box of parts for a telecom job along with two large Red Apple coffees, Tim's vital bodily fluid at 4:30 am. At this time, I noticed a small scrap pile of square steel tubing and flat stock thrown out in the side lot. Naturally, the lifter in me took over, and I stood staring at the rotting heap like a Spring breaker looks at a girl in a thong!

“Tim! That pile?”

“Whatayawant with that s#!% big bird?,” Tim barked.

“Could you whip me up a couple of flat exercise bench frames out of your scrap pile?”

“Make me a print Sticks and I'll rattle em' off before the week is out,” Tim squawked back.

The material was perfect for benches 2"x2"x18" (11 gauge wall) square steel stock and 1 14"x2 12" steel strip all in scrap three and four-foot lengths. Small fabrication shops make frames, racks, ball hitches from this stock material. And, if you can find a shop like Tim's, it will be like striking gold.

Bench Frame Construction Plan

Figure 1 below illustrates the print that I gave to Tim. When I picked up the frames a few days later at his shop, I found that they were perfect. They did not rock right side up or upside down. The bottom line is that Tim charged me $25.00 a piece because he considered them “out of junk.” Perhaps, though, it may have been the 500 bucks I spent on coffee to juice him up over the year.

Frame specification drawing for the steel frame weight bench
Figure 1: Drawing plan for building a steel-frame weight bench. Drawing by and courtesy of Chris ‘Sticks’ Bostick.

For the good fab man, the plan presented in Figure 1 is pretty cut and dry. It specifies complete seam welding and chamfering, grinding a slight 45-degree angle on the joining surfaces to provide for a better weld fill. Anyhow, just print out a copy of my frame plan and bring it to your local machine shop with a few dollars on hand. They'll do the hard part of the job for you, and your part of the bench-building project to follow should be a cinch.

Bench Pad Materials

With your new steel frame ready and in your hands, its time to top it off with a simple, clean and spiffy pad. All needed materials are readily available at local big boxes galore. Specifically, you will need to buy a piece of plywood, a piece of padded foam, a can of high quality fabric glue (spray) and vinyl covering.

Purchase requirements for the plywood and foam pad are described below. Regarding the spray adhesive, I consider 3M products AN77 [3M Super 77 in 2021] among the best. Traditionally, guys tack down foam and fabric with staplers and brads. However, in this age of modern chemicals using fabric glue is much easier and better for this application. A can of glue should cost around $11, and it will be good for ~50 pads.

For the vinyl cover, a 60"x24" piece or larger will allow for proper cutting per instructions below.

Make the Bench Pad Assembly

Let's now move on to putting together the pad assembly for your new bench. All of the instructions in this section refer to Figure 2, shown below.

Illustration of pad assembly for the steel frame weight bench.
Figure 2: Steps for making the pad assembly. Drawing by and courtesy of Chris ‘Sticks’ Bostick.
  • Drawing A: (1) 24"x48"x3/4" sheet of plywood. $15.00. Rip a 10"x48" piece nice and square. Then, plane ripped sides smooth (deburr).
  • Drawing A2: (1) 10"x48"x1" piece of quality high-memory cushion foam, white. JoAnne's Fabrics or a local upholstery store will stamp you out one for about $5.00.
  • Drawings B, C & D: Place parts A1 & A2 next to each other and spray a smooth and even coat of glue on each surface. Wait 30 seconds for the glue to tack, then carefully flip the foam side over and join the glued sides face to face. Be sure to get the alignment exactly right at the get go. Once the sprayed surfaces contact each other they will join instantly. For this reason, I recommend getting someone to help you with this task. Between the two of you, all four corners can be handled in unison for proper placement.

Add the Vinyl Cover

Okay, we're now ready to cover the assembly pad. All of the instructions in this section refer to Figure 3 (E), shown below.

Drawing that depicts the steps for adding a vinyl cover to the weight bench pad assembly
Figure 3: Installation of bench top cover to weight bench pad Assembly. Drawing by and courtesy of Chris ‘Sticks’ Bostick.
  • Drawing E:
    1. Trim the width of the vinyl covering down to 22" the entire length.
    2. Trim the length of the vinyl to 58".
    3. Measure and mark the underside of the covering with a Sharpie to the pattern depicted. This centers the pad.
    4. At each of four corners of the fabric, cut out a section to match the fabric pattern depicted. These should be 5" length and 6" width cuts.
    5. Take your glue can and spray the foam side of the bench top, lengthwise and across the entire surface. Immediately after this spray the underside of the fabric. Let the glue tack for 30 seconds.
    6. Carefully place the foam-side of the bench top on the underside of the fabric, lining up the corners of the top perfectly with the crop marks that were traced during Step 3 above. As before, getting a partner to help with this task is recommended.
    7. Starting with the ends of the top assembly, glue spray the folding edges on the underside of the fabric. Then, spray the edges of the bench top (wood and foam) and three inches up on the wood side opposite of the foam. Wait for 30 seconds and then wrap the sprayed fabric ends onto the adjoining sprayed surfaces. Follow with the same procedure for both sides.

Attach the Pad Assembly to the Frame

Great, the pad assembly is complete. All you need to do now is secure it to the bench frame.

  • Figure 4:
    1. Grab your steel bench frame and flip it upside down and center it on the wooden side of the pad.
    2. Mark hole centers with a Sharpie. Then drill 1/2" deep pilot holes at each mark with a #36 bit.
    3. Using a hand ratchet equipped with a 3/8"-inch socket, secure the frame to the pad with six 1"x3/8" hex lag screws and six 1/4-20 flat washers. Do not use an electric drill for this task because doing so could cause hole stripping.
Illustration showing how a top is fastened to a referenced steel-frame weight bench
Figure 4: Fastening a top to your steel weight bench. Drawing by and courtesy of Chris ‘Sticks’ Bostick.

Congratulations

Voila! You now have all the flat bench you'll ever need. The “Terrible Timster” would be proud. And, you should be, too! There is nothing quite as satisfying as building your own strength equipment.

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