Intro: The 12 Cent Kettlebell for Your 4 Hour Body Workout
Looking online for DIY Kettlebells brings up the standard pipe fittings 'T' bar handle and it is a great solution but definitely not a solution I can take traveling with me.
Here are two solutions I have come up with that have cost me a total of 12 cents!
Below is the video podcast we have made but the written instructions are on the next few pages
Here is the link to the MechanicalMashup website
Step 1: First the Supplies Needed
The supplies needed are:
1' of 3/4 sched 40 PVC pluming pipe
2' of rope or tubular webbing with at least 700lb breaking strength
1 Linchpin (preferably 3/8 hairpin version)
Work out plate weights
Drill with 3/8 inch bit (only needed for one of the two builds
PVC cutter or saw
utility knife (or a deburing tool)
Step 2: Prep the Materials
First take your PVC and cut a 5" section and a 6" section. The 5" section is for the handle, the 6" is for the weight mounts. DEBUR the inside edge of the PVC THIS IS CRITICAL you do not want a sharp edge on the rope or webbing.
Drill a 3/8 inch hole 1/2 inch from the bottom of the 6" tube
Step 3: Math Section
I know someone is going to give me the "Is it strong enough" or something to the effect that no way could this work and that it is dangerous (and make it seem that this is a threat to humanity itself if used ;) ) in the next section.
So here is the math
To calculate centrifugal force we use this equation:
RPM2 x Radius (in cm) x 0.00001118
- First a kettlebell swing takes about 1 second to complete one half a full swing or 1/4 revolution This equates to 15 RPM
- I measured from the floor to my shoulder for the length of the radius of the swing and got 95 cm
152 x 95 x 0.00001118
and get about 0.2g
So in the worst case scenario in the bottom of the swing we get 1g due to gravity and have to add 0.2g due to the swing so multiply the weight you are using by 1.2 to find out the max force exerted on the rope or webbing.
Most people will not be able to handle a 50lb kettle bell so lets use that as a max weight. 50x1.2 = 60lbs max force
Now knots compromise the strength of a rope but worst case is they half the breaking strength. Lets assume you get some cheap braided rope that is rated at 750 lbs. If you half that you get 375lbs max force. No where near the 60 lbs you can use in a kettlebell. In fact that gives you a safety factor of 6.25!!!!! If you use 1" tubular webbing like in the second build it is rated at thousands of lbs.
Suffice to say this is plenty strong enough!
Step 4: Put It All Together
Step 5: Put It All Together Kettlebell #1
For Kettlebell #1
This is for the home steel weights you may have lying around...
- Take the 5" PVC handle and run the rope through it
- Tie the first half of the double fisherman in the rope
- Push the loop through the second PVC pipe
- Get the length of the rope needed by having the loop just peak out of the end
- Tie the other half of the double fisherman and cut off the extra rope
- Place the weights on the 6" piece of PVC with the hole you drilled at the bottom
- run the rope loop through the PVC
- Place the linchpin through the hole in the PVC and capture the loop of rope
- Tighten the rope with a tug to the handle
Step 6: Kettlebell #2
This one is for use with the gym weights that have bigger holes in them
- Take the 1" tubular webbing and tie a overhand knot in one end (note this is only 1/2 of the weave back knot)
- Put the tail of the rope through the center of the weights you want to use and through the handle
- Take the tail end and weave it back through the overhand knot you made in step one with as little webbing (shortest length) as possible
- Cut extra webbing off
Step 7: The End!
There you go two kettlebell builds for 12 cents (because I had all the materials at home minus the 12 cent linchpin, I suspect if you are here on instructables you will be in a similar situation)
If you want to see the build video go to MechanicalMashup and have a watch or watch the video in step 1. ..