Power hammer partial noise enclosure

[Adodero]

I have an Anyang 55 and live in a residential area, I'm looking to reduce the noise somewhat to avoid neighbor complaints. We have a lot of foliage around our house and haven't had any issues so far, but I'd prefer to prevent complaints rather than respond. I also worry about it just from not being disruptive and would rather work without being concerned about bothering people. I evaluated having our shop insulated in various ways and everything I found indicated it wouldn't be very effective without stripping out the drywall. I measure ~85-87db outside our door with everything closed (I have a fairly extensive ventilation setup that lets me work with the garage door shut, but will obviously result in some noise transmission). I'm taking other precautions like sealing doors, as well.

As an alternative to insulating the whole garage, I'm considering building or purchasing a shroud or enclosure to hang around the hammer. On the purchase front, I've seen several noise reducing enclosures that use a sortof foil covered blanket that hangs around the device claiming a reduction between 10-15db for partial enclosures. I'm awaiting price quotes on this option.

On the build front, I was considering setting up studs along the outside of the hammer that would extend the full length of the hammer with enough space on either side for me to work with the dies (several feet at least). I'd put something like Rockwool Safe and Sound inside of the studs, drywall the interior and exterior of it, then use additional drywall on the outside and/or inside with Green Glue between it. I may also put some sound absorption near the back to dull the echo a bit. Where the hammer is, the end of the enclosure would only be able to extend outward from the dies ~1-2ft before it gets too close to the forge (less about heat more about having space for me to move around). One side, facing the forge, would obviously have to remain open for me to access the hammer properly.

Has anyone seen anything done like this before? Was there a noticeable difference in noise around the hammer? 

[jason0012]

Just hanging a curtain of moving blankets would cut noise. I doubt there is anything terribly special about the sound absorbing blankets. It might be worth using welding blankets for fire resistance, and they are good and heavy.

[Purple Bullet]

You might get some reduction of noise that way, and it sounds like your shop is conventional construction. Mine is made from cargo boxes with a lot of the walls cut out. These are anchored to a heavy  slab so whenever I operate either hammer it's like a bass drum when I run the 50# Little Giant or a giant snare drum when I run my jackhammer hammer. This requires social, rather than aural engineering. Make friends, do favors, show them what you're working on and don't use the hammer (any hammer) between 8 pm and 8 am. Friends that know what's going on are very forgiving. Strangers who hear mysterious thumpings are not.

[Adodero]

I think I'm putting the enclosure on hold for now in favor of addressing the echo in the garage. Interestingly, the sound coming from the hammer is less of a thump and more of a sharp "twang", so a much sharper, less dense sounding noise. From what I understand, bass noise is really difficult to mitigate, but the others can be reduced, I may be wrong though. The issue is my garage has no insulation in it and the sound just echos, which I think makes it reverberate worse. Even clapping your hands is loud and echos through it. 

I'm hanging some acoustic paneling in the garage in spots where I can, I also spoke to Oeler on the phone and they seemed confident that they had some solutions that would work to reduce echo and absorb sound on the 3 exterior walls, then a solution for the interior wall that contains mass loaded vinyl, that can prevent transmission into the house. I'm waiting on pricing but the cost isn't that high judging by their website and the materials he recommended. 

I'm also insulating our uninsulated ceiling, either way blown in insulation or, ideally, Rockwool batts depending on the price. I realized after I posted my original message that our ceiling is not insulated, but there is also an attic vent of considerable size and I think a lot of noise is leaking out that way, as well. 

If, after that, the noise levels are still too high, I will reconsider the enclosure. I'm not trying to eliminate it, just reduce it and show effort. 

Thanks for the advice on the neighbor relationship too, I've been over to chat with them a few times and may invite them over once I get everything put in. They are super nice folks and don't seem bothered by it, but I don't want that to change. 

[Frosty]

Insulating your garage will go a long way to mitigating noise. Plain old fiberglass insulation should do nicely. Your insulation companies, OF COURSE have products specifically to deaden sound and provide a heat shield for your specific situation. How much more effective than fiberglass is the issue I'd look into.

An immediate low cost alternative would be to buy or make screen panels like welding screens and hang moving blankets instead of welding screen. Fire is a legitimate concern, drenching them with a saturated 20 Mule Team Borax solution and allowing them to dry will make them a considerable fire barrier. HOT scale and pinch offs might cause a smolder as long as they're in contact and HOT but the cloth won't support flame. 

A screen type sound barrier will have the advantage of being portable and storable. 

Frosty The Lucky.

[Adodero]

Figured I'd update this since it's a somewhat common question. 

I decided to build a 'temporary' (temporary, in that it isn't attached to the house and can be moved) enclosure of sorts using 5/8 drywall panels, 2x4 8x8ft studs, and Rockwool batts. The process was a lot easier than I anticipated and took almost no time at all to get them stood up. The biggest challenge was finding Rockwool in small quantities, places like Lowes and Home Depot wanted large ($1200+) orders. I managed to find a vendor online (Acoustimac) that carried it in smaller quantities in the dimensions I was after (48x24x4in). I ordered an extra set of batts to make panels out of and hang on the walls. 

I positioned the 'walls' in a v shape around the power hammer, they are 8ftx8ft, so fairly large compared to the size of the hammer. They also cut the garage in half, which provided some nice isolation from the rest of the stuff we keep in there. Not noise related, but I painted the opposite side with chalkboard paint, so I can have some space to write on, take notes, draw, etc. 

There seems to be a noticeable reduction in noise on the other side of the panels, but not massively dramatic. I measured about a 6-7db reduction, even though that wasn't the goal necessarily. More importantly, the echo has been reduced a fair bit and it's reduced the sound of other tools/equipment in the shop (anvil, grinder, etc). 

The end result being its more tolerable in the house, my wife says it sounds more like someone knocking on the door rather than clanging pots together, so that's progress. I still haven't handled the top of the enclosure and may expand it further, but for right now, it seems to be doing its job and was considerably less expensive than a professionally assembled enclosure. 

I may look at doing something with blankets for the 'ceiling', like what Frosty recommended, but I need to take care of getting electrical sorted with my growing collection of 220v tools...