Introduction: DIY Concrete Dumbbells

Picture of DIY Concrete Dumbbells

I made this 10 kg (23 lbs) dumbbell out of really cheap and recycled materials. It does the job really well, except it's very large compared to a regular dumbbell.

I hope you'll find it useful, enjoy.

Step 1: Tools & Materials

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For a single dumbbell you are going to need

Materials

  • Two 3 liter containers. I used 6 liter water bottles that I cut to size.
  • 50cm (16") long metal pipe 3/4" in diameter
  • Two 10cm (4") bolts 10mm in diameter and 4 accompanying nuts
  • 25 kg (50 lb) bag of cement
  • Pipe insulation or a pool noodle

Tools

  • Drill
  • X-acto knife or a box cutter

Step 2: Measuring

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To learn how tall 3 liters would up to be I poured 3 liters of water in the bottle and marked the water level with a sharpie.

Step 3: Mixing Concrete

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I started pouring 500 ml of water into the container and gradually added 2.5 liters of cement. This ratio might vary for you so start with a little bit first and go by feel.

Step 4: Assembling the Pipes

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You need it to act as an anchor so that the pipe won't slip out and smash your skull while you're doing triceps extensions.

Step 5: Fixing the Rod

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To secure the rod in the center I cut out the hole in the cap of the bottle and slid the top portion of the bottle onto the rod. Then I secured it with a sticky tape. I let it get hard enough so that it would support the rod in the center, after which I took the top section off and let it cure overnight.

Step 6: Vent Holes

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I had cut out the vent holes in the top portion of the bottle beforehand.

Step 7: The Other Half

Picture of The Other Half

For the other half I did the same process. Except this time i had to slid the top part of the bottle onto a rod before I would insert it into the other half of the dumbbell. I propped it up in the corner so that the halves would stay parallel to each other.

Step 8: Handle

Picture of Handle

For the handle I wrapped the rod with a pipe insulation and secured it with a strip of electrical tape on either ends.

Step 9: What Would I Do Differently

  • I would definitely make the handle 8-10 cm shorter. I didn't consider the indent on the bottom of the container which made the whole thing even longer. Now it's a bit awkward to do alternating bicep curls with it but for the other exercises that I do it's totally fine.
  • The walls of the bottles are thin and flimsy and the mixture warped it. Which is not a big deal, it doesn't really interfere with the balance of the whole thing but it's kind of annoying. To avoid warping taping the whole mold with duct tape might be a way out.

Comments

Timothee Gillier (author)2017-04-26

Interesting project!

Thanks!

BirgitJansen (author)2017-04-26

How did you get to the exact overall weight? Was it just luck or did you somehow calculate it? Or is it OCD to wonder about that? :-)

Cinnamonik (author)BirgitJansen2017-04-26

I had some experience with it before so I knew aproximately how much volume I needed. I weighed them on floor scales after they were finished to double-check.

BirgitJansen (author)Cinnamonik2017-04-26

Cool. I have been looking into purchasing some, but man, they are expensive. So I have been thinking about a DIY project, but always stumbled over that little detail. I guess I'll just have to go for it and who cares if I'm off by a bit, right? Thanks for the instructable, it will definitely help!!

Cinnamonik (author)BirgitJansen2017-04-26

Yeap, they're really expensive. These cost me literally 10 times cheaper than legit ones.

AndreasO1 (author)2017-04-25

excellent for Fielder Curls :)

About This Instructable

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Bio: I make useful low budget projects. I focus on home improvement, DIY gear and recycling topics.
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