Sound level and mufflers on small mills

[bandmiller2]

I'am as guilty as anyone,I like to hear the old diesel and the saw ,the feedback helps but probibly a mild form of hearing protection would be best.To each his own but I don't think I'd listen to tunes wile running the mill.Frank C.

[stonebroke]

The only problem that the noise from my mill in urban areas has caused, is the folks it draws in.  Pretty soon, there is a crowd.  They want to ask questions.  And out comes the cameras.  Then, with everyone watching and distracting you.......guess what  ???  Yup, you screw up,  >:(  and then try to make folks think that you ment to do that...... :D

Did I ever tell you that I love portable milling....     8)

Just view them as potential customers

Stonebroke

[stonebroke]

Just view them as potential customers

Stonebroke

[Magicman]

Just view them as potential customers.   Stonebroke 

Many times they are !!!  That's why I love it......    :D

Urban sawing has put me on the Front Page of our local newspaper.....twice...... 8)

[scsmith42]

SCSmith:
I for one am interested in your muffler accomplishment.  A sketch would be great.

As requested, a sketch is attached via an Excel file.

Here are some more details:

The design concept is to trap noise waves inside the muffler while allowing low restriction path for gas to escape.  My muffler has three sections - an inlet chamber, baffle section, and exhaust chamber.  Note that pipe outlet inside of inlet chamber faces away from the baffle assembly.  Also note that exhaust nipple exits through the side of the muffler, minimizing potential for sound waves to exit with exhaust.

The inlet chamber also serves as an expansion chamber.  It is a good idea to use a double wall on the end of the chamber, since the discharge of the inlet pipe points directly at the end of the muffler.  Doubling the end wall will reduce external heat and also increase the longevity of the muffler.

The discharge side of the inlet pipe faces away from the baffle assembly in order to create an initial sound wave trap inside the expansion chamber.  I use black iron pipe fittings for my inlet fittings, sized to match the exhaust port on the engine (typically 1").

By having the exhaust exit from the side of the exhaust chamber, rather than the end, sound waves are further captured inside the muffler.  If you need an end exhaust, consider installing a pipe elbow on the outside of the muffler (screwed into the exhaust nipple).

The I.D. of the hole in the center of the baffles should be approximately the same size as the I.D. of the inlet pipe (i.e. same size as the exhaust port).  It can be slightly smaller or larger.

I used a hydraulic press to bend a flat shim washer into my tapered baffle.  It was a simple matter of supporting the perimeter of the washer while pressing down in the middle to reform it into a cone.  The shim washers that I used were originally made for shimming bearning in heavy equipment final drives, but you can also make your own from sheet steel.

One additional goal of the muffler is to slow down the speed of the exhaust through it, as well as allowing the hot gasses to cool somewhat.  This also helps to reduce noise.

For maximum sound reduction, add a Super Trapp muffler /resonator to the exhaust port from the muffler.  I used a Model 3S with the optional resonator for my installation http://www.jackssmallengines.com/strap3s.cfm.

I built my prototype for an old Onan one cylinder generator.  The generator had a shroud around it, effectively trapping most of the non-exhaust noise from the motor.  Prior to the installation of my muffler, the generator was "hurt your ears" loud.  After installation, two people could carry on a conversation at normal levels ten feet from the generator.

Building this muffler is neither fast nor inexpensive.  It took me a couple of days to build my protoype.  As I recall I spent around fifty bucks on tubing, pipe fittings and the interior components.  The Super Trapp option alone adds another hundred bucks or so to the overall cost.  However, if you are in a situation where you have to spend a lot of time listening to very loud single cylinder gasoline engine, then the investment may be worthwhile.

My prototype has been operating for over two years w/o any problems or reduced generator power.

[Toolman]

The only problem that the noise from my mill in urban areas has caused, is the folks it draws in.  Pretty soon, there is a crowd.  They want to ask questions.  And out comes the cameras.  Then, with everyone watching and distracting you.......guess what  ???  Yup, you screw up,  >:(  and then try to make folks think that you ment to do that...... :D

Did I ever tell you that I love portable milling....     8)

A couple years back, I was sawing for a guy near a residential neighborhood. The cameras were out, a small curious crowd gathered  including a gorgeous  young college girl that made heads turn from passing motorists. A piece of wood fell from my cut onto the cutter head track. As I raced up to remove the piece, my foot hooked perfectly around the log loader and down I went.  smiley_whacko I felt goofy to say the least. I did put a smile on the young girls face. Was'nt quite the way I wanted to do that.