CoreControl DIY





Introduction: CoreControl DIY

Designed by two Stanford professors, the Avacore Core Control is a heat extractor for the human body which will provide an athlete the ability to recover more quickly than natural methods such as sweating. An interesting product, but with a price tag of $3000, I doubt the the public will get their hands on this anytime soon. This instructable will show you how to build your own CoreControl for about $150.

Before you get started, please familiarize yourself on how the CoreControl works. You can check the published study that goes in depth with the CoreControl. I was able to replicate the functions for my DIY CoreControl using the design specs from this study.

FAQ about the Corecontrol.
More Published studies (bottom of page)
Check out instructable user emckee1's blog on his DIY CoreControl with improvements!

When our body overheats, it goes through a thermoregulation process to expel excess core body heat.  The palm of our hands is one of the body's "radiators" to expel heat. Why the palm of the hands? The palms have numerous capillaries which cover a large surface area, allowing the removal of excess heat from the body. The vacuum is supposed to draw the blood to your hands to increase the heat transfer rate. The faster you remove the excess body heat, the faster you will recover from exercise.  

You may have heard about rubbing ice cubes on your wrist to reduce recovery time.  However, this method is inefficient because low temperatures cause the blood vessels to constrict, thereby reducing the blood flow.  The CoreControl applies a similar concept, however, is more effective because it uses a vacuum to draw the blood quickly to the palms, and the controlled temperature prevents constriction of blood vessels.

I built my first homemade CoreControl a year ago.  Due to numerous requests, I decided to build a second one in order to write a detailed step-by-step guide. Let's have some fun!

Step 1: Materials

Materials Needed
  • 4" Diameter PVC Pipe
  • 4" to 3" PVC Reducer 
  • 4" Rubber End Cap
  • 3" Metal Fastener
  • 20' Vinyl tube 5/16" x 3/16" 
  • Long Cuff Neoprene Gloves 
  • Four 3/16" Barb x 1/4" MIP 
  • Two 1/2" FIP x 1/4" FIP Pipe Reducing Coupling
  • 1/2" x 5" Brass Pipe Nipple 
  • Via Aqua Model: VA-302 (Can be found at a pet store, could use any other water pump)
  • OEM Brake Bleed Kit Pump (Can be found at Autozone)
  • Digital Thermometer 
Everything can be found at Home Depot or your local hardware store except for the last 3 items.

Step 2: Tools Needed

  • Electric Drill
  • 13/16" Spade Bit
  • 1/2" Drill Bit
  • PVC Saw
  • Teflon Thread Seal Tape
  • Pliers
  • Measuring Tape
  • Marker
  • WaterWeld Epoxy Putty
  • Sea-All contact adhesive and sealant
  • Silicone caulk (optional)
  • PVC cement
  • PVC primer
  • Scissors
  • Flathead screwdriver
  • File Sander

Step 3: Vacuum Chamber - Cutting the PVC

  1. Mark an 8"  section on the 4" PVC pipe.
  2. Cut the PVC pipe using the saw.
  3. Deburr the edges with your hands or with the file sander. 

Step 4: Vacuum Chamber - Drilling the Holes for the Heat Transfer Rod (Brass Rod)

Heat Transfer Rod
  1. Mark 4" from the edge with an X. This is where you drill a 13/16" hole to fit the brass rod. It is better to mark the center hole for both sides because if you just drill straight through, you will run the risk of having a slanted brass rod.
  2. Carefully drill both sides. 
  3. Deburr the holes.

Step 5: Vacuum Chamber - Vacuum Hole

  1. Turn your PVC around and mark 2" from the edge. This is where you will insert the 3/16" barb which will connect the vacuum pump.
  2. Deburr the edges with the sanding file.
  3. Once you have deburred the edges, tap the hole with 3/16" barb. Do not overtighten or else you run the risk of stripping the newly created threads. Once it's stripped, you are going to have to start over because this needs to be tightly sealed. Turn all the way to the pipe and remove it. You could leave it on but it will get in the way.

Step 6: Heat Transfer Rod - Sealing It Air Tight


You don't want to mess this step up or it will get real messy. When I built the first one, I was having trouble creating a perfect seal and this area was the main problem. I have tried many methods to plug up the holes and this was the best solution I came up with. I just tested it and it works perfectly. If you have a better method of sealing, by all means go right ahead. 
  1. Push the brass rod all the way through until you reach the inner wall of the next hole as shown in picture 2
  2. Get you Seal-All ready and place it on the Brass threads and the hole on the other side shown in pictures 6 and 7.
  3. Once that is done, grab the brass rod in the middle and turn it as if you are screwing it in shown in picture 8. This will spread the Seal-All adhesive all around the the holes which will hopefully fill in most of the gaps between the threads 
  4. Screw until you cannot seal the threads inside the pipe shown pictures 9,10 and 11.
  5. Take the two 1/2" Pipe Reducing Coupling and screw them to both ends real tight. Use a wrench if you need to. Again, make sure the threads aren't visible in the inside.
  6. Smear Seal-All all around the couplings
  7. For best results, let it dry for 24 hours. It should be hard and rubbery after a day and It will become rock solid when completely dry.

Step 7: Heat Transfer Rod - Double the Sealing

Once the Seal-All has set, it's time to cover it with the WaterWeld Epoxy Putty. This epoxy is tough and I prefer using this than the 2 part epoxy glue mix. It is much easier to work with and is less messy.
  1. Cut about 1/2" off the epoxy, mix it
  2. Lay the putty around the brass couplings.
  3. Press the epoxy all around with your thumb, making sure it gets into every nook and cranny it can get into.
  4. Let it dry for about an hour.

Step 8: Insert the Barb Hose

Take the three 3/16" Barb x 1/4" MIP and wrap them all with Teflon tape. 2 to the brass rod couplings and 1 to the vacuum hole.

Be careful not to overtighten.

Step 9: Hand Insert - PVC Reducer

  1. Take the 4" to 3" reducer and apply the purple primer. This will soften up the pvc which will form a chemical bond when joining both pvc together. 
  2. Wait a couple seconds then apply the PVC cement on both reducer and pipe.
  3. Push the reducer to the pipe
  4. Now take your Seal-All or silicone caulk and run around the edge of the pipe and reducer. 

Step 10: The Rubber Sleeve and End Cap

I found these neoprene gloves at the garden section in Home Depot. Get the smallest size you can find because we want to have a tight fit around the forearm. I once tried to test this device on my friend but realized his forearm was too small and couldn't get a tight seal. You could use any type of rubber gloves but make sure it has a long forearm and small diameter.
  1. Cut the gloves right below the fingers, we won't need this so toss it
  2. We are going to label both ends the "cut" and "uncut" side. We want to insert the "uncut" side to the PVC reducer shown in the pictures below. You can notice the "uncut" side is wider than the "cut" side.
  3. Place the rubber sleeve and get it centered. 
  4. Take the 3" metal fastener and tighten.
  5. Take the 4" rubber cap and place it on the other end. 

Step 11: The Vacuum Test Setup

We're just about done and now you have to test if it can hold a subatomic pressure aka vacuum.
  1. Cut a small piece of the Vinyl tube 5/16" x 3/16" and insert it to the brake bleed pump and to the vacuum barb
  2. Stick you hand in and have the rubber sleeve all around your forearm and grab the brass rod.
  3. Give it a few pumps and see if the vacuum holds. You may notice the the rubber seal will start to concave into the pvc but don't worry this will create an even more tight seal around your forearm.
  4. Here's a couple scenarios that might happen:
  • If the gauge stays, you have sealed vessal.
  • If the gauge drops quickly or doesn't move at all, you need to plug up either around the brass rod or at the vacuum barb.
  • If the gauge drops slowly, you could plug up and put more teflon tape on the vacuum barb but you can always compensate by pumping more
Once you are done, you can take it off. What I like about this brake bleed pump is that it has a gauge and pressure release valve.

You could go all the way to 25 in.HG to see if it really works but don't do it for so long because your hand will get red and feel funny.

Step 12: The CoreControl Setup - Water Reservoir

Depending on what water pump you get, you may have to install a 3/16" Barb into it. If you got the same model I have, this fits perfectly and you just need thread the Barb into the water pump

Find yourself a small bucket to act as the water reservoir. You are going to have to jimmy rig one by drilling some holes to fit the vinyl tubes in. I used a chinese takeout container. 

Step 13: How to Use: the Required Design Specs

Congratulations! You just finished constructing your own CoreControl. Before you use the device, there are two design specs that you must know in order for this to work.
I recently came across a more recent published studies on the RTX CoreControl Glove and I will list them below. The big change is the water temperature from 18 degree Celsius to 10 degree Celsius. This water temperature was chosen based on previous hand immersion studies showing this is the optimal temperature that limits vasoconstriction in the hands. I have only tried the 2005 specifications but I would try the new water temperature.

Design Specifications
Published paper from 2005. 
  1. Water temperature: 18 to 22 degree Celsius or 64 to 71 degree Fahrenheit
  2. The subatomic pressure (vacuum): 35 to 45 mm HG or 1.4 to 1.8 in.HG (edit - courtesy of user "milwaukee" for the correct conversion)
Published paper from 2009.
Published paper from 2010.
  1. Optimal water temperature: 10 degree Celsius or 50 degree Fahrenheit
  2. Subatomic pressure (vacuum): 45 mm HG or 3 in.HG
Getting the right subatomic pressure
The gauge on the brake bleed pump is actually in in.HG. so after you convert, it's around 2 to 3 in.HG. This is what you should aim for. When the gauge drops, you can compensate by pumping more to keep it around that area.

Getting the right temperature
It took a lot of fiddling around to get this right but don't start off with a handful of ice and water. It's too cold. Start off with a reservoir of cold tap water which is just a tad colder than it's required spec but once it warms up, ONE ice cube will bring it down to the right temperature. For example, cold tap water is around 16 degrees celsius, when you use the device and goes past 22 degrees, put ONE ice cube and it will bring down to around 18 degrees or 10 degrees. Only put one ice cube at a time if it needs to go lower.

What happens when there's too much vacuum pressure?
Your hand will get red and feel funny but nothing life threatening

What happens if the water is too cold?
Base on the published paper, too cold of a temperature cause vasoconstriction across your hands. 

Step 14: How to Use: the Setup

This is it, all you have to do is cut up some Vinyl tube 5/16" x 3/16" and hook it up. 

When you hook up the water pump, make sure the water going in is going through the bottom because you don't want any air in the brass rod. Check the notes in the pictures to get the idea.
  1. Measure the water temperature using a thermometer and get it down to 18-22 degree Celsius/ 64-71 degree Fahrenheit
  2. Insert hand, make sure it's tight
  3. Pump the vacuum until 1 to 2 in.HG
  4. Use for 2 minutes
And that's it! 

What am I suppose to feel?
The feeling of being "refreshed" similar when you sit down, drink water and rest for 30 minutes. When I first tested this, I did 5 sets of 20 pushups. After each set, I would use the CoreControl for no more than 2 minutes and on to the next set. In the past, by the time I reach the 4th and 5th set, I start to struggle and slow down. Using the CoreControl, I noticed each set felt like the the 1st and I felt a bit surprised about it since I was expecting to feel the pain.

Now, this could be placebo effect on me and I have nothing to quantify it. I have thought of having a BPM heart rate monitor attached to me to see the time it takes to slow down my heart rate back to normal. In the end, the published paper have shown in their studies positive results so you could take their word for it.  

Room for Improvement
There are definitely ways to make this better.
  • Larger vacuum chamber
  • Increase heat transfer by using a copper pipe, larger pipe or metal dish shape.
  • Box rig for portability
  • Some sort of twist lock for the arm seal
This guide was meant to show you the cheapest route but with a little extra money and ingenuity, you could come up with an idea to improve this. 

Special Thanks
Just want to give a big thank you to fellow redditor/instructable staff 
dworley and redditor coconutketoer for supporting me. This guide would never have been completed if it wasn't for these two.

In case you missed it in the first page, check out this 2nd gen diy CoreControl build in this blog!



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    Hi people! I made a prototype and I also put up a video on youtube featuring the device, it's a bit differnt to this one but the concept is still the same! I know that my energy is higher using this comparing to not, Iv meassured my performance for different excercises!

    Is there some reason why you just can't plunge your hand into ice water?

    If the point is to just chill the palm, where the transition is between arteries and veins, why not a neoprene diving glove with the palm area cut out?

    Better, save damaging your glove and just shove an ice cube or two in.

    Seriously, what am I missing?

    They say that excess cold causes your blood vessels to constrict, reducing blood flow.

    I like to keep a bucket of water, a small towel, and a straw hat for working in the heat. You can wet the towel and the hat, wear them around your neck and on your head and they absorb a lot of heat. Each half hour or so I'll rewet the towel and towel off a bit.

    After reading about this, I'm curious to try it out while excersising.

    HI :) Is there any way I could cover the supplies and your labor and you could make one for me? I figure it will still be cheaper than the original and much faster for you to make since you've already done it once than for me to try and figure it out? Thanks.

    Have you thought about using a peltier cooled heat pump instead of ice water?

    by 'heat pump' i mean braided copper cable or something pulling heat from your hand to the peltier, so it won't be as cold as directly grabbing an icy peltier. there are glues [i think loctite?] that will bond metal to metal with thermal conductivity without electrical conductivity (found out the hard way some LEDs with metal backing had that backing wired to ground, and thus the heatsink we were trying to attach them to).

    Also, it might be possible to retrofit an aquarium air pump as a diaphragm vacuum pump, just gotta figure out a way to attach tubing to the air inlet instead of the outlet. :)

    Oh duh, just read the emckee1 page. way better idea than a scavenged aquarium pump

    Nice instructions. I wonder if the whole reservoir could be replaced by one of those external aquarium filters. Just fill it with water and ice

    It looks like a new model of the CoreControl is on the market. Only for $895!!
    I did some research online, and found this website:

    They have tons of scientific studies, and videos there. It looks like the NBA Golden State Warriors & the NFL 49ers have been using this new model.

    So for all you who doubt, you can stop now :)

    This is very impressive. If I pay you could you build and send your prototype to me? I own the commerical version and would love to compare them.