****, but that's loud

[marktp1967]

anybody have any suggestions on how to quiet a planishing hammer. i have a cp that is rattling the blacksmith in the next shop. he says the cp is louder than his 25 lb. little giant power hammer. don't know about that but it is really loud. any help would be appreciated. mark

[Gene_Olson]

Hang some Industrial felt around it several layers , punched to provide channels for the sound to trap in. Mount that in a wood box , or a piece of concrete form, lined with sheet lead (hung so it can move, not glued on) The felt or other sound absorbing materia can be glued to the lead. Maybe a layer of felt between the lead and the box.

I don't have a hammer like that, but that is where I would start.

There is also special heavy, open cell, Urethane foam, that is designed to absorb sound energy.

Another thing that can be done is to hang sections of old carpet from 2x2s on the ceiling. Just short curtains of it that are up out of the way. That heavy old wool stuff would be better than synthetic. Resiliant mass that can trap the sound is what you need. Hang it like a curtain by the door. They have felt panels like powered window shades hanging above false ceilings in concert halls to tune the sound absorbtion.

GoM has two blacksmithing demonstrations in the same building at our fall conference and we hang several old carpets and an old canvas tarp between them. It helps a LOT.

Jerry Frost wrote the following about quieting a tumbler where he worked. It may or may not be applicable, but it might set you thinking



We have a machine in the soils lab that is basically a really heavy duty tumbler, 30" in dia. by 24" long by 5/8" wall, with one 4" lifting flange running the full length, mounted on the inside of the door. The thing is charged with 6,000 grams of aggregate and 12, 1" steel ball bearings. It is horrendously loud, physically painful with ear plugs and muff type hearing protectors both and way above safe noise limits through four insulated walls. I was asked to see if I could quiet it down to the point they wouldn't have to house it in a building of it's own.

I wrapped it with 1/2" felt, just glued to the outside. I was stunned, it just thumps now, you can work in the same room without hearing protection at all. It's only making about 60 db instead of over 300 db.

Let us know what works.
I am sure there are a lot of people here who would like to solve the same problem.

Gene

[Wray Schelin]

Hi Gene,

Great post! One of my customers has a noise reduction consulting company. I've never thought to ask him for some ideas on air hammer noise reduction. Next time I talk to him, I'll see what he has to say.

Wray

[marktp1967]

gene, thanks for the info. the cp is a pedestal mounted unit so i will also put a 1/2 inch piece of rubber between the base and the floor to start. i am going to try wrapping it up with some 1/2 felt and see if there is any reduction in volume. that seems like a simple and clever way to resolve things. i will keep you posted on the results. thanks again, mark

[James(Western Canada)]

I seem to recall reading (possibly in Fay Butlers book?) that some have filled their frames/pedestals with sand to try and dampen the frequency somewhat. Shouldnt be a bank-breaker to try out anyway....


James(Western Canada)

[Gene_Olson]

I seem to recall reading (possibly in Fay Butlers book?) that some have filled their frames/pedestals with sand to try and dampen the frequency somewhat. Shouldnt be a bank-breaker to try out anyway....


James(Western Canada)

James,

When we had our repoussee class, Wendel Broussard's spec for the workbench stations was a tube frame filled with sand. They even welded a pipe fitting into the frame so it could be refilled after settling.

Gene

[marktp1967]

on this cp the pedestal is also an air cylinder but i wouldn't want to fill it up with sand. maybe lay some sand bags on the base? thanks for the ideas. mark

[marktp1967]

hello folks,
last saturday i wrapped the cp with 3/8" industrial felt and zip tied it. it made a noticeable difference. i don't have a db meter but it seemed like it cut the loudness by almost half. if you speak loudly you can talk to the person next to you when it is running which was impossible before. give it a try, it might help you out.