Introduction: D.I.Y Ultra Quiet Shop Compressor From a Refrigerator Motor (compressor)
I needed to build a very quiet, higher capacity compressor for my Industrial Design Studio shop, since the one I have is quite loud and does not have the capacity that I was comfortable with for my urethane casting work.
In this Instructable I show you how to build a light duty compressor from parts you can buy on Ebay and or your local hardware store, Home Depot, Lowes, Menards, or a scrap yard, using a refrigerator (fridge) motor compressor. This is not for using heavy power tools or spray painting a car. It's for blowing off parts, maybe airbrushing if you add an air/oil dryer to it or just need some air in your shop for various projects. Add your own optional Motörhead badges too. See the Video below for full details. It's a great companion to this Instructable tutorial.
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Step 1: Get a Compressor Air Tank and Fridge Motor
I sourced a 6 gallon unwanted Bostich air tank on eBay for $35 including shipping from a fellow in Indiana. I then needed a refrigerator compressor..... I got lucky and have a buddy I play hockey with that is in the small appliance repair business. Joe was able to get me a new replacement unit that was not needed on a recent job. He was also able to get me some of the copper tubing I needed for the project to connect the compressor to the tank.
Step 2: Making the Adapter to Mate the Compressor to the Tank
The first thing I built an adapter plate to mate the tank to the compressor motor. I made this from form sheet metal from an old "Big Iron" IBM server cover. I made a cardboard template of the hole pattern to follow and then transferred it to the sheet metal and folded the edges for extra strength. Then I applied a bit of primer and paint to finish the exposed metal. See the video for the details.
Step 3: Drain and Replace the Existing Oil
Next I drained and replaced the original oil in the compressor with 10W40 weight motor oil for added protection. Most fridge compressors have a separate filler tube for this purpose, since mine was a replacement unit it has a rubber stopper, yours may be crimped or soldered shut, if its from an old fridge.
Step 4: Mount the Bracket and the Compressor
First I mounted the bracket to the tank, then the compressor motor on the sheet metal bracket I made and connected the compressor to the bracket with some 1/4-20 Allen head bolts washers and lock nuts.
Step 5: Connect the Compressor to the Tank With Some Copper Tubing and Add a Saftey Relief Valve
Next I connected the compressor side to the tank with some 1/4" copper tubing and a one way check valve to keep the air from flowing out of the tank back through the compressor inlet. I soldered the copper tubing to the compressor. I would suggest using some compression fitting to the tank and the compressor so you can fix things easier should you ever need to do so.
I used a brake line tubing bender that I rented from my local auto parts store to bend the copper tubing. You can fill the tube with sand or ice to bend it as well. See the Video for more details.
Next I added the 125 psi safety relief valve to the bottom of the tank. It's 1/4" threaded part and they are readily available on ebay or the store. Be safe you don't want this thing to explode.
Step 6: Build the Business Side of the Compressor, the Air Outlet!
On the business side of the compressor I used some parts I had laying around including a pressure shut off valve that I had from when I attended college at Pratt in the late 80's from my dorm airbrush set up! It still all works great and is able to turn the motor on an off with no issues. I also used a main pressure gauge and added a pressure regulator so I could adjust how much air comes out of the tank. Additionally I added a quick disconnect to I an easily connect an air hose to the tank.
Step 7: Electrical Wiring
I connected the compressor motor to the on/off pressure Furnas switch. There is a run and a start and a ground to connect to the pressure switch. There is usually a wiring diagram included with your on off pressure switch, follow those instructions when wiring, they may differ from what I did.
Then for the AC outlet power I added a computer electric socket connector to the set up so I can remove the power cord if I need to as well. I epoxied the connector to the underside of the tank bracket so it was out of the way. See the video for more detail.
Step 8: Making It Ultra Quiet: Adding an Intake Manifold
The key to making the whole thing ultra quiet is building a intake manifold that absorbs the sound of the compressor. For this I used a spent metal aerosol travel shaving cream can. It already had openings at both ends and was perfect for my needs. I packed it with some brass wool to help absorb the sound of the compressor and added some pink packing foam for a filter. The combination of the metal can and the brass wool significantly mutes the sound and makes the whole set up extremely quite.
Step 9: Customize It With Some Motörhead Logos
Last but not least I added some Motörhead badges I cast to give it some character. R.I.P Lemmy Kilmister
This was a super fun build and an essential piece of shop equipment to have when making Industrial Design models and prototypes. Visit my web site www.botzen.com for more information about Botzen Design I and how I can help design your next consumer product.
A bit about me. I am an Industrial Designer living in Southfield MI USA. I have a home-based Industrial design studio "Botzen Design" and have been designing consumer products for 25+ years ranging from sunglasses for Bauch & Lomb, Traps eyewear, entry level luxury vehicles for Ford, wireless charging PowerMat for Homedics, to magnetic toys for Guidecraft. I specializes in tabletop and handheld products, ranging from routers to cosmetic products to Bluetooth devices and everything in between, I also teach Industrial Design at Wayne State University and CCS (College for Creative Studies)
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