The Desperation "Repair it Regardless" Dilemma

[matthewsx]

The shop I ran from 2009 to 2014 was Briggs, Echo, Tanaka, and many others. I knew it was a lost cause when the Sthil rep gave the local dealership to the hardware store just after I built a new 2400 sq ft shop so I could make the entire back of my other 2400 sq ft building into showroom space for you know who.

I digress, saw many a mower come through my doors and often found myself telling the prospective customer "that's your project". I was more than willing to offer advice or even special order parts, but there's a point where fixing costs more than replacement and I didn't want folks in our small town saying I ripped them off on a repair regardless if it was the actual cost of doing it.

Don's diss pop-rivets though, I still have a small stash of Monel rivets left over from when my dad built his airplane. If you can't get behind something to buck a regular rivet there's few better alternatives.

John

 

[graham-xrf]

In the same general category of do it regardless, moving the air compressor to a cubby on the outside of the shop is now on my list. Wife is tired of it drowning out her audiobooks through her headset while she’s working out there.

You may have to do more than just move it outside. It may pay to put some design thought into deflecting and/or absorbing the sound.
I am also into this issue, and I have been scheming for weeks. I also plan not to have the compressor inside the shop using up space and making noise. One can get "quieter" compressors which inevitably are lower power, and possibly shorter life. If you need the odd squirt of air to blow stuff clean, the needs are different to if you want to have even a small shot blast cabinet, want to go spray painting, or plasma cutting.

I have researched the various air compressor types. For me, it was a choice between oil-less types, and the more traditional kind which need various oil and water removal stages. They have the benefit of much longer life and less maintenance than the oil-less sort, and, of course, they have the higher CFM flow capability, but are noisier.

There are a whole bunch of YT videos on compressor noise reduction boxes, and there is a lot to be gained by getting ideas from them. If you look at the one linked here, which is about why the guy does not recommend going this route because of the time and effort involved to get an adequate sound reduction, you get the real deal.

If you don't already know, a change in noise power of 3dB represents a doubling, or halving. It is a logarithmic scale of ratios. Our ears noise perception is also logarithmic, which is why to hear equal increments of noise change needs a doubling, and re-doubling. A reduction of -15dB is making 0.0316 of what it was previously. Down to 3% sounds impressive, but if the compressor was 90dB to begin with, the new 75dB will still be louder than people speaking. Here is where you can place a value judgement on how much a given dB noise is worth vs lower flow and air cleaning/drying kit. If the end noise is at 50dB level, you will be hearing other stuff like the birds outside

By all means, evict the compressor, but be prepared to do a bit more. I will be wanting perhaps 50 Litres tank, and up to 8 or more CFM flow.
Anyways, if you haven't already, have a look at a few videos from our favourite information source. You will see the links anyway.

I know he says "don't do it", but I am into "do it regardless", and my design will have two fans, and a different method of sound trap internal surfaces, and the machine will be suspended on bungees. In the end, I can forcibly shut the thing up, even if it's in a "box within a box"!

Do not build a sound insulated enclosure for your noisy air compressor!

 

[rabler]

You may have to do more than just move it outside.

Thanks for the suggestions. I've done video conference room technology at one stint in my life. The audio portion of the design was always more comlicated than the video, so I have a pretty good idea of acoustics and noise power. My wife usually wears over the ear headsets when working in the shop. She likes to refinish furniture. Problem is her workbench is right next to the compressor. That proximity is the killer. If she doesn't have to rewind her audio book every time the compressor runs, she'll be happy. The challenge is not the continuous noise of the compressor, but the cycling. Fortunately her headset provides about 15 - 20dB of attenuation to outside sound, so that makes the problem much more feasible. I too aften wear a headset, part of my PPE, whether in the shop, or out working with farm equipment.

We already have a suitable concrete pad behind the shop for the air compressor, isolated from the shop pad. It is right behind the current compressor location. I need to frame in an enclosure, and run the power and air line straight out through the wall. There is a significant difference between boxing in a compressor or moving it to a cubby outside that only shares one wall. Fiberglass insulation on the inside of that enclosure will do a pretty good job of absorbing sound, as would shag carpet. On my list is also a muffler box for the intake, which is the source of much of the noise. While that alone wouldn't suppress the sound enough, the combination certainly will.

It is a 60 gallon tank, don't remember the CFM rating. But there is also a safety factor in having that tank external to the workspace.

Obviously we put the pad in some time ago with this in mind, there just has been other priorities. We had to replumb the house (polybutylene piping) over the summer. New ductless HVAC throughout the house. Still need to rip out the carpet through much of the house. Build a new front covered porch. Not to mention we're building a new shop, although the woodworking and compressor problem won't be solved by that. But if I want to enjoy shop time, it's prudent to be sure she can too. And she will be helping with the work of moving it outside. We work well together, met on the job. She was involved with the video conference work too.

 

[graham-xrf]

I have to be impressed with the amount of energy/activity going into building on your house. Mine was once like that too, building while living in it. Not so easy. When I did it, I could not get another mortgage, because I lost my job along with about 50 others, so I had to DIY a lot of it as I became self-employed. That is why it took so long, and even now, there is stuff to do. While quite a lot of fitting out my external workshop building will be DIY, it can be at my own "retired" pace, because I paid a construction firm to make the foundations and raise the blocks and basically build the main structure of it. Stuff inside the main house like "new kitchen & utility room", and upstairs en-suite bathroom are still down to me, power tools, and making it up as I go along.

I have provided a duct going across under the patio-style paving around the workshop to carry water, power, air, etc. Initially, it was fore-thought for the "coiled black pipe under E-glass" type of solar pre-heater", but it's obvious use is also to get across to an external concrete pad which can mount the compressor.

From what I know about not making a racket in the country, I can tell you that regardless of the outside enclosure, just fixing simple surfaces inside only 1/2" away from the walls, all around the noisy thing, makes a baffle that causes pulse component of sounds to reflect back and dissipate pinging back and forth inside. You can, of course, have the normal sound insulation against the inner surfaces of the enclosure anyway, but the isolated baffles just adds -dBs to the performance. If the baffles are also covered in sound absorbing stuff, like old carpet, it works better.

Most of the "make a box" type of soundproofing projects for shop-vacs and compressors miss the trick that you have for free if you make a brick enclosure outside, that being the inability of impinging sound to shake the blocks. This is not the same thing as how efficiently sound goes through the ceramic if it is directly pinged, like whacking it with a hammer. Builders of high-end hi-fi loudspeaker enclosures will even make up (heavy!) double sided things, and fill the gaps with sand. If they cannot de-couple the sound, they make the wall unresponsive.

Probably moving it outside will go most of the way for what you want. Working on US gallons being 3.78 litres, a 60 gallon tank is at least 227 litres, which is just huge. I would be contemplating only 50 litres, or 100 litres at most. (about 26 gallons). Like you, I also have to use ear protection all the time when using power tools. If I let it get going, my tinnitus will start ringing, and it can take up to 20 minutes or more to die out.

Maybe post a picture when you have got it built.

 

[rabler]

We ended up buying this house in a pinch, our plan was for me to work a few more years and build a house. So there are a lot of things that need fixing to be up to our somewhat odd standards.

My current shop is all drywall walls and ceiling. My brother in law thought I should put up metal interior walls and especially the ceiling. Easier, yadda yadda ... But I can't imaging working with power tools inside a completely metal walled interior building. Might as well call it a drum.

I'm working on laying out the utility feeds to my new shop. On the list is power, fiber optics, natural gas, water, and a compressed air line between the two shops. Ordered the pre-terminated fiber yesterday. Trying to get everything in hand before I start digging as I need to cross the driveway.