Reducing noise during run with box enclosure

[routercnc]

Skydeals,

If done correctly then it will make it a lot quieter. But there are some things to note -

The wood is a barrier to stop the noise getting through, but needs to be fairly well sealed otherwise it will only be partially effective. I assume you will add a door, and if so you need to add seals to it. I think 12-18mm ply would be fine for the box, or you could use MDF. Whatever you choose the heavier the better.

But in creating that barrier there will now be much higher noise levels next to the machine, due to the reflections from the new walls, therefore you need to line them with absorption materials such as the foam you linked too. Otherwise you won't get all the benefit.

The best absorption materials are blended fibres but these are expensive. The cheapest absorption materials are recycled felt type, but these are not very effective. In the middle are PU open cell foam types similar to the one you linked to, which still work well. The class 'o' fire rating is nice to have in case the worst happens, but does add to the cost. Given the frequencies you are trying to absorb I'd go with 20-25mm thickness.

The acrylic viewing panel is of course a good thing to have, but acoustically it will be a weak link because it will be of a much lower density than the wooden panels. You could try with say a single panel screwed to the inside of the wooden door and see if it is quiet enough - but provision for a second acrylic panel to be screwed to the outside of the door. Two acrylic panels seperated by an airgap (i.e. the hole cut into the door) will give more noise reduction than the sum of their individual effects.

If you just poke the extraction hose through a simple hole in one of the sides lots of noise will leak out. The simplest solution, and the one I'd go for, is to screw a metal flange adapter to the inside and outside of the hole to make a sealed pass-through. If you try this and it is still not quiet enough you will need to consider making a silencer, which is a bit more work.

In summary:
Wooden box of at least 12mm ply, ideally 18mm - sealed at all joints, including around the 'door'
Lined with PU open cell foam, class 'o' fire rating (as per your link), of at least 20mm thick
Extraction via a pair of metal flange hoses on the inside and outside of a hole in the wooden side

That should make a big difference to the noise levels.