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Posted by Cheshire Steve on May 2, 2008, 5:04 am
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In the interest of keeping the neighbours sweet I am wondering how
best to reduce the humming noise from my mill and lathe, both of which
have cabinet mounted single-phase motors. Both have the motor bolted
to large steel plates with a pivot at one end which is in turn bolted
to the stand. I have another lathe with external single phase motor
and that is fairly quiet.
I am assuming that most of the noise is through mechanical
transmission to the sides of the cabinet which act like speakers, so I
was thinking of rubber mounting the motor on the plate or maybe using
metalastic bushes in the pivot point - and some other sort of
isolation for the adjuster on the other side of the plate.
Alternatively (or in addition) I could try and damp the movement of
the panels.
If anyone has been down this road and has some advice, then I would be
interested to hear.
Thanks
Steve
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Posted by Chris Edwards on May 2, 2008, 5:39 am
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On Fri, 2 May 2008 02:04:42 -0700 (PDT), Cheshire Steve
>In the interest of keeping the neighbours sweet I am wondering how
>best to reduce the humming noise from my mill and lathe, both of which
>have cabinet mounted single-phase motors. Both have the motor bolted
>to large steel plates with a pivot at one end which is in turn bolted
>to the stand. I have another lathe with external single phase motor
>and that is fairly quiet.
>
>I am assuming that most of the noise is through mechanical
>transmission to the sides of the cabinet which act like speakers, so I
>was thinking of rubber mounting the motor on the plate or maybe using
>metalastic bushes in the pivot point - and some other sort of
>isolation for the adjuster on the other side of the plate.
>
>Alternatively (or in addition) I could try and damp the movement of
>the panels.
>
>If anyone has been down this road and has some advice, then I would be
>interested to hear.
>
>Thanks
>Steve
Steve....as well as trying to reduce the generation of sound at
source, also give some thought to preventing the sound you *do* produce
from actually escaping from your shed/garage/workshop.......simple things
like reducing unnecessary air gaps through which sound can travel,
installing sound-absorbing surfaces wherever possible....three quarter inch
'softboard' on the walls and ceiling is cheap and very useful for this
purpose. It also helps to retain heat and prevent rust etc.
I just cranked sound proofing into Google and got 1,720,000 hits
including this:
http://www.diydoctor.org.uk/projects/sound_proofing_in_the_home.htm which
should tell you all you need to know.
--
Chris Edwards (in deepest Dorset) "....there *must* be an easier way!"
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Posted by Richard on May 2, 2008, 6:36 am
Please log in for more thread options On Fri, 2 May 2008 02:04:42 -0700 (PDT), Cheshire Steve
>In the interest of keeping the neighbours sweet I am wondering how
>best to reduce the humming noise from my mill and lathe, both of which
>have cabinet mounted single-phase motors. Both have the motor bolted
>to large steel plates with a pivot at one end which is in turn bolted
>to the stand. I have another lathe with external single phase motor
>and that is fairly quiet.
>
>I am assuming that most of the noise is through mechanical
>transmission to the sides of the cabinet which act like speakers, so I
>was thinking of rubber mounting the motor on the plate or maybe using
>metalastic bushes in the pivot point - and some other sort of
>isolation for the adjuster on the other side of the plate.
>
>Alternatively (or in addition) I could try and damp the movement of
>the panels.
>
>If anyone has been down this road and has some advice, then I would be
>interested to hear.
>
>Thanks
>Steve
Steve,
I would say you are on the right track. There are basically three
approaches 1) don't generate the noise(vibration) 2)Isolate the
vibration 3)damp the vibration where it's a problem.
You can't really attack item 1 other than making sure the motor &
pulley are (reasonably) well balanced there will always be some
residual vibration so......
It is most likely that the 'tin-work' is vibrating at its
natural/resonant frequency so isolation of the motor will help and is
a good thing to do, but it will have to be very good to really get a
major result.
You are probably likely to get better, quicker results by damping or
stiffening (ie changing the resonant frequency) of the cabinet panels.
The sort of stuff they use for sound absorbtion in car footwells might
be a possibility - some of it is sound-deadening rather than
absorbtion. It's heavy, well damped and sticky-backed. That will tend
to lower the resonant freq. Sorry I don't know where to buy it, but
try a body shop.
The other alternative is to raise the resonant frequency by stiffening
the cabinet panels - say screw some light angle iron across the
diagonals of the offending panels. Possibly glue it on with silicone
so that it is 'attached' over all its length. The result would be
similar to having a cruciform pressed into the panel (as in car boot
floors etc for just this reason).
Lastly as already noted, bung up holes in the walls/eaves and
generally do what you can to stop noise getting out of the workshop.
Richard
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Posted by Cheshire Steve on May 2, 2008, 7:07 am
Please log in for more thread options On 2 May, 11:36, Richard <sharkface-pilot at toucansurf dot com>
wrote:
> On Fri, 2 May 2008 02:04:42 -0700 (PDT), Cheshire Steve
>
>
>
> >In the interest of keeping the neighbours sweet I am wondering how
> >best to reduce the humming noise from my mill and lathe, both of which
> >have cabinet mounted single-phase motors. Both have the motor bolted
> >to large steel plates with a pivot at one end which is in turn bolted
> >to the stand. I have another lathe with external single phase motor
> >and that is fairly quiet.
>
> >I am assuming that most of the noise is through mechanical
> >transmission to the sides of the cabinet which act like speakers, so I
> >was thinking of rubber mounting the motor on the plate or maybe using
> >metalastic bushes in the pivot point - and some other sort of
> >isolation for the adjuster on the other side of the plate.
>
> >Alternatively (or in addition) I could try and damp the movement of
> >the panels.
>
> >If anyone has been down this road and has some advice, then I would be
> >interested to hear.
>
> >Thanks
> >Steve
>
> Steve,
> I would say you are on the right track. There are basically three
> approaches 1) don't generate the noise(vibration) 2)Isolate the
> vibration 3)damp the vibration where it's a problem.
>
> You can't really attack item 1 other than making sure the motor &
> pulley are (reasonably) well balanced there will always be some
> residual vibration so......
> It is most likely that the 'tin-work' is vibrating at its
> natural/resonant frequency so isolation of the motor will help and is
> a good thing to do, but it will have to be very good to really get a
> major result.
>
> You are probably likely to get better, quicker results by damping or
> stiffening (ie changing the resonant frequency) of the cabinet panels.
> The sort of stuff they use for sound absorbtion in car footwells might
> be a possibility - some of it is sound-deadening rather than
> absorbtion. It's heavy, well damped and sticky-backed. That will tend
> to lower the resonant freq. Sorry I don't know where to buy it, but
> try a body shop.
>
> The other alternative is to raise the resonant frequency by stiffening
> the cabinet panels - say screw some light angle iron across the
> diagonals of the offending panels. Possibly glue it on with silicone
> so that it is 'attached' over all its length. The result would be
> similar to having a cruciform pressed into the panel (as in car boot
> floors etc for just this reason).
>
> Lastly as already noted, bung up holes in the walls/eaves and
> generally do what you can to stop noise getting out of the workshop.
>
> Richard
Thanks,
I had thought about reinforcing the panels, but hadn't though about
using silicon so you don't get noise between the panel reinforcing and
the panel.
I suppose any empty hole will have one or more natural frequencies, so
I had wondered if I would be better using a 3-phase motor and inverter
and tuning the inverter to a quiet frequency. I have an inverter and
an old motor to try it (think they are both about 1 hp), but it will
no doubt be quite a job. Maybe it will be enough just to clamp the
motor inside and try it without worrying about the drive system.
Is a three phase motor quieter anyway, regardless of frequency ?
Steve
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Posted by Mark Rand on May 2, 2008, 8:07 am
Please log in for more thread options On Fri, 2 May 2008 04:07:04 -0700 (PDT), Cheshire Steve
>
>I had thought about reinforcing the panels, but hadn't though about
>using silicon so you don't get noise between the panel reinforcing and
>the panel.
>
>I suppose any empty hole will have one or more natural frequencies, so
>I had wondered if I would be better using a 3-phase motor and inverter
>and tuning the inverter to a quiet frequency. I have an inverter and
>an old motor to try it (think they are both about 1 hp), but it will
>no doubt be quite a job. Maybe it will be enough just to clamp the
>motor inside and try it without worrying about the drive system.
>
>Is a three phase motor quieter anyway, regardless of frequency ?
>
>Steve
>
>
Three phase motors produce a constant torque, whereas single phase motors
produce a torque that varies at twice the line frequency. This causes a lot of
the vibration with single phase motors/cabinets.
I made a very noticeable difference to my Myford cabinet by feeling which
panels were resonating and then gluing lead flashing to the panels with impact
adhesive. It adds mass to the panels and also adds damping. It did help that
I'd got a couple of yards of 300mm wide flashing left over from when I did the
workshop roof :-)
Mark Rand
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>best to reduce the humming noise from my mill and lathe, both of which
>have cabinet mounted single-phase motors. Both have the motor bolted
>to large steel plates with a pivot at one end which is in turn bolted
>to the stand. I have another lathe with external single phase motor
>and that is fairly quiet.
>
>I am assuming that most of the noise is through mechanical
>transmission to the sides of the cabinet which act like speakers, so I
>was thinking of rubber mounting the motor on the plate or maybe using
>metalastic bushes in the pivot point - and some other sort of
>isolation for the adjuster on the other side of the plate.
>
>Alternatively (or in addition) I could try and damp the movement of
>the panels.
>
>If anyone has been down this road and has some advice, then I would be
>interested to hear.
>
>Thanks
>Steve