Anti vibration mounts on compressor

[mrsbruce]

I was looking at anti vibration mounts, and wondered if they would make any difference to my 100 lire compressor. I realise that it would probably not make any difference at all to the noise, as it’s all mainly coming from the twin pistons but if I reduced the vibration (wood lined metal hut), would it take the edge off the noise.

I have lovely neighbours, so try not to make a lot of noise if I can help it.

 

[voipio]

AV mounts will make a difference if vibrations are being transmitted from the compressor to surrounding structures, but how much of a difference depends on the mounts themselves, the location and mounting of the compressor, and how the mount is coupled to the surrounding structures. For maximum effect, AV mounts should be as compliant as possible, and specified for the weight they will need to bear. Ideally, the mounts will be onto a large concrete block or slab, that is itself not coupled to the building which is not always possible. Quite an effective AV mount can be made using one or two mountain bike inner tubes under a slab of concrete or 1/2" steel plate, with a short piece of hose across the top of the inner tubes to allow the air trapped in the middle of the arrangement to breathe. The other main noise source in many compressors is the air intake. A silencer coupled to this would help greatly. After that, there is the mechanical noise of the valves. bearings, and slop in the crankshaft and pistons. The last sources are probably best tackled by enclosing the compressor in a soundproofed box, suitably ventilated.

 

[CoValent]

I found a big reduction in noise by building a custom air filter/intake. A box made of ply with a few baffles made an enormous difference.

 

[colnerov]

Hi, Another source of noise comes from the air intake, I've replaced my intake filter with one from a car and it's halved the noise. The main way to suppress noise is density so placing it in a box made from MDF will help. Having said that it is one of those things where it's a bit of everything, so sitting it on a softer mount than the hard floor is a step in the right direction.

Colin

 

[mrsbruce]

I had been thinking about fixing the mounts direct to the floor, bolting on a board, then sticking the compressor on top. Bit non tech, I know.

As to the car intake filter, would adapting a whole filter box be best, or a k & n type add on. The compressor fits in a corner, so I thought of lining both wall sides, and shelf on top with proper sound proofing. Adapting a complete car filter box would feed in air from outside the ‘box’.

I thought of using a couple of 4” computer fans to flow air through, to help cool it down, although the front would only have a half door.

 

[Alan Reynolds]

Alot of noise comes from the fins on the cylinders ringing. This type of thing cures it on kart engines.

https://www.tal-ko.com/tkm-bt82-fin-rubber-kit.html

You can make your own as I did on my twin cylinder.

The noise reduction is quite significant, especially if you can fir them to the head.

 

[CoValent]

I thought of using a couple of 4” computer fans to flow air through, to help cool it down, although the front would only have a half door.

I don't think computer fans would even come close. Aluminium flexible duct would probably be a good idea to link the intake with a filter box, but you may need multiple parallel ducts depending on your CFM requirements.

 

[mrsbruce]

Alot of noise comes from the fins on the cylinders ringing. This type of thing cures it on kart engines.

https://www.tal-ko.com/tkm-bt82-fin-rubber-kit.html

You can make your own as I did on my twin cylinder.

The noise reduction is quite significant, especially if you can fir them to the head.

Now that is a good idea.

I don't think computer fans would even come close. Aluminium flexible duct would probably be a good idea to link the intake with a filter box, but you may need multiple parallel ducts depending on your CFM requirements.

I have one of these buried somewhere. Slight overkill?

 

[Barking Mat]

For reference, those rubber 'engine' mounts, usually have a number stamped on them, indicating different stiffnesses. Only learnt that the other day.

 

[colnerov]

Hi, For a better understanding of the principles of soundproofing have a look at this. -

Colin

 

[mrsbruce]

Many thanks for the advice, chaps.

Ok, so my plan is to go with the floor mounts, air-box/filter, and the foam/rubber on the fins, and then ‘hear’ how that goes. That gives me the option of boxing in the compressor, as the vid says, making a room within a room for it to live.

Hopefully, I won’t need to go that far, but good to know have a workable add on options. Just to say that I fitted some little vibration mounts to the base of the motor I use for my buffing wheel. I would guess that it has halved the noise level, as it vibrated through the bench, and made my teeth ache.

 

[Wallace]

What type of compressor do you have, belt drive of direct?

 

[mrsbruce]

What type of compressor do you have, belt drive of direct?

It’s a direct drive.

 

[Afterimage]

It’s a direct drive.

There's your problem - direct drive compressors are great at turning electricity into noise.

 

[Wallace]

I used a vee twin direct drive in a friends workshop and had to put it outside as it kept making me jump at startup. The dam things just burst into life flat out and sound so angry.

There is a post on here about silencing one built under a bench or on a cupboard.

 

[Seadog]

I used a vee twin direct drive in a friends workshop and had to put it outside as it kept making me jump at startup. The dam things just burst into life flat out and sound so angry.

I had one of the cheapo little Chinese jobbies. I'm not prone to jumping at sudden noises, but every time it fired up, due to a slight leak. I thought my heart was going to stop.

 

[Wallace]

Link to Pondy's sound proofing thread.

 

[mrsbruce]

Link to Pondy's sound proofing thread.

Thanks, have had a good read, and came up with another question.

Is there any need to build a box around the whole 100 litre tank. Could a cowling just go over the engines.

Imagine the floor mounts in place, fin rubber blocks fitted, and an extended air filter, feeding out through a wooden ‘hood’ over the noisy bit, the pumps. If the base of the box where it touches the tank was also isolated with rubber blocks, can anyone see a problem with this?

 

[colnerov]

Hi, Maybe because the source of the noise if fixed to the tank, the tank will act as a loudspeaker.

Colin

 

[mrsbruce]

True, good point, but the joy of coming to this late in life, is you get to question the accepted norm of doing things, without caring if it’s a daft question.