Air Compressor Cart

image-2016-10-29-2244The company I work for give me a choice of gifts for my 20-year anniversary, and a DeWalt compressor was one of the options – so I got a new toy. I’ve run it for a total of about an hour, and so far it seems great.

I’m going to take it down to the beach house and keep it there, since I have a 25 gallon one in my shop at home. With all the remodeling I’m doing, I’ll put it to good use in the next couple of years. I currently have a Harbor Freight pancake compressor there that I assume will give up the ghost one day. image-2016-10-30-2259I’ve actually been impressed with it’s performance. At the $100 price point (with a 20% coupon), I think it’s a good buy.

The DeWalt is an oil cooled model, so it’s not as loud as the HF one, which is rated at 90 dB. I figured if I could make it just a little quieter, I wouldn’t need to wear hearing protection when I’m near it.

I started off by building a box for it out of OSB. I designed it to have just enough clearance for the tank and plenty of room around the motor.

I cut and reinforced the bottom, then put sides on. My main method of construction with OSB is to glue, then mainly put everything together with 1/4″ crown staples. I typically add a few screws to keep things from loosening up, especially if I moving the piece around a lot.

Once togetherimage-2016-10-29-2249, I drilled a number of large holes in the bottom. The compressor motor has a built-in fan, and needs the air flow to stay cool. There are a number of designs I could have done for this, including a more complex baffle system to really reduce the sound, but I decided to keep it simple.

To help absorb some of the sound vibration, I added carpet pad around the motor. I mounted it on battens to make it less rigid. I had a little bit left over, so I put some strips in the bottom. The sticks in the bottom hold the feet in place so the motor stays away from the carpet.

I added a pair of upright 1×3’s for the handle, plus wheels and blocks for feet. The bottom is almost 5 inches off the the ground, which should allow for good air flow up into the box.

I also trimmed it out so a tray could just drop in on top of the box. It’s about 1/16″ smaller than the trim, so it fits snugly. I think this is key to blocking the sound from coming out of the top. I tried weather stripping the inside edge, but it didn’t stick well – and it didn’t make any difference in terms of sound reduction.

image-2016-10-29-2252

The side handle holes on the tray are a must – I think I’d end up dropping it without them. I added a couple of plastic organizers to  hold nails and fittings. The smaller guns just fit on either side of them. I didn’t plan it this way, I just got lucky.

The air hose and power cord pass through the box right under where the tray sits. It’s a simple solution. When I looked online for ideas, most people used air fittings and an electric receptacle mounted on the box. This seemed too complex and costly, with little added value.

I made a keeper for the cord and hose, similar to what I have on my pressure washer. I also put a couple of dowels in the handle for hanging the larger guns. I don’t know how much I’ll use them, but they were easy to add.

image-2016-10-29-2255

From a functionality standpoint, I like the cart. I’ll have everything together, and it will stop me from making trips back and forth for the small stuff. The larger wheels will make pulling it around on the gravel driveway easy.


Sound Reductionimage-2016-10-29-2243

The listed rating for the compressor is 83 dB. When I measured at 3′ directly above the unit, it was 92 dB. After I put it in the cart with the tray in place, it was a consistent 82 dB – so half as loud.

All the sound that’s not absorbed comes out the bottom vent holes and hits the ground. In my shop with the wood floor, I assume this is the max condition. If it were outside in the grass or on gravel it would be less, because the energy absorption would be greater. image-2016-10-29-2257

Based on 82 dB at 3 feet:

  • 72 dB at 10 feet
  • 66 dB at 20 feet
  • 58 dB at 50 feet
  • 52 dB at 100 feet

The charts I found stated that you can have 82 dB sustained for as long as you need without any hearing damage. It might still be irritating, but it’s not harmful.

Here are typical sounds by dB level:

image-2016-10-29-2259

So with the cart being on average 10 feet away when I work, it would be the same as the dishwasher. OHSA requires it at 85. I tend to use it if it’s over about 80.

If I’m working outside the neighbors will still hear it, but will sound like the other sounds around the area.


image-2016-10-30-2261Time and Money

This is a nice project to do in a day or over a weekend. I think I put 6 hours into it in total.

Costs – about $25

  • 1/2 sheet OSB – $5
  • Scrap lumber and carpet – free
  • Wheels – $15 for 2 at Harbor Freight
  • Organizers – $6 at Harbor Freight

I currently have a 25 ft air hose. I think I’ll replace it with a lightweight 50 ft one, since that what I’ll typically need.

 

 

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