Noise, and neighbours

I’ve had a question from Craig (in California) about the implications of noise from my shed, and the neighbours.

In a nutshell, it hasn’t been a problem for me, I’ve spoken to each of my neighbours on different occasions to see if what I have been doing has been impacting on them, and none have had any complaints about the noise levels, so that’s a big part of it – communication!

Also, I try to limit my nocturnal woodworking (as much as possible), and particularly the noisiest tools in the workshop don’t get fired up after about 9:30pm as a rule (not sure what the council guidelines are – I did check them when first starting up the whole woodworking thing so I knew where I stood). I also don’t start any until after about 9am in the morning either. Doesn’t mean I don’t use the shed, I just plan my activities around those times.

The shed itself, despite being a steel echo box, doesn’t seem to let a lot of sound out of it, so what is very noisy inside isn’t necessarily disturbing everyone around. I don’t have windows, and I keep the doors shut (moreso at night etc) when really does trap the sound in.

When I have a chance (and some spare cash), I do want to insulate the roof, and obviously potentially the walls as well, and that will significantly increase the noise dampening effect (especially if I get the batts designed to absorb noise).

Finally, upgrading from a Triton Workcentre to a induction motor driven tablesaw makes a huge difference!!!

And if you do have sensitive neighbours, you can always work on improving your handtool skills! (And sharpening is a quiet, meditative process too!!)

2008 Safety Week Wrap

So that was safety week on the Wood Whisperer Network. Hope you got something out of it!

It seems from reading around, it is the same mistakes being made over and over and over…..and over and ov… (alright, enough)

What is it, that it takes a personal experience before we often will start doing the right thing? Advocates of pushsticks are often those who copped a massive kickback, machinery guards by those who have been cut, electrical safety by those who have been stung, material handling by those who can no longer lift without pain and so on. The whole OHS movement (if I can call it that) is constantly berated for being too pedantic, for making things too hard, for being too over zealous. It doesn’t do itself any favours because that is true to a certain extent, but the principle behind it is harnessing the collective wisdom to prevent injury before it occurs.

What I was talking about in the first video at the start of the week touched on this topic. Sure, safety devices are wonderful things, but they have to work for, and with the individual. If they make the job harder, less safe, are too cumbersome etc, then they will be abandoned. I don’t want myself or others to not use safety equipment, I want safety equipment to be designed to work with the activity, rather than hinder it.

Safety glasses and ear defenders are not too bad in their design and implementation, but dust masks are still poor. Perhaps the concept is too hard, or the thinking is “if you need it, you’ll put up with the poor design”. They are generally not comfortable (especially in hot weather), there are straps everywhere and more often than not it becomes a fight on the face between the mask, the glasses and the hearing protection.

There are ways to alleviate the situation…somewhat. Dust collection on the machine and dust filtering the workshop air all decrease the hazard posed.

Air cleaners such as this from Carbatec for around $370 are worth considering

To quote from their site “Once you’ve finished cutting and sanding operations and have turned off your dust extractor and protective mask, you might think you’ve been sufficiently safety conscious about protection from dust inhalation. However when you see a ray of sunlight come through window you can see that that a lot dust remains suspended in the air.” I know for a fact the same is true in my workshop, and by the end of a good day’s woodworking, my lungs are not so contented. So this is part of my workshop poor practice that I want to address.

So what else is there that suffers from the same “either the safety solution is perfect or I won’t use it at all” mentality? I’ll leave that to you to think about for your own workshop. What guards do you leave off, what safety gear do you not wear, what safety aids do you ignore because of the extra time, and hassle it is to include them? Give some thought to why this is so. If it is because they make the job harder, even increase the risk? Then don’t abandon the concept – find a better device! If your saw guard annoys the hell out of you, find a different design, if your safety specs make it harder to see what you are doing, get some new ones.

Don’t become a safety zealot only once you’ve suffered an injury. There are enough of them already (and good on them for raising people’s awareness), but let’s not continue recruiting to their ranks. Safety is much better as a preventative, than it is as at preventing a re-occurrence!

Work smart, work safe.

Main Machinery Operating Noise

As discussed in the previous post, I took a sound meter around the workshop to get an idea of the different machines and the amount of noise they generate.

To qualify these figures, the machine in use was out-of-spec, so the readings should not be taken as gospel.

A reading of 85dB or above means there is a risk of permanent hearing loss.
100dB gives a max allowable exposure of 15 minutes
110dB – hearing damage likely after 60 seconds.

Remember that the time is cumulative. I don’t know over what time period (probably in 24 hours)

A 3dB increase in volume represents a doubling of the sound energy. Because the scale is logarithmic, a 10dB increase in volume represents 10 times the amount of sound energy, which will sound twice as loud.

Shed Ambient Noise: 58dB

Tablesaw: no load 85dB
With a non-noise limiting blade that had a resonance with the TS, 105dB
During a cut: 95 – 100dB

SCMS: no load 110dB
During a cut: 120dB – 125dB

Thicknesser: no load 106dB
During a cut: 110 – 120dB

Lathe: no load 62dB

Jointer/Planer: no load 80dB
During a cut: 100dB
Forcing the cut: 110dB

Drill Press: 85dB

Bandsaw: no load 70dB
During a cut: 100dB

Router: 100dB

Circular Saw: 115dB

Nail Gun: firing 126dB
During disconnect: 124dB

These figures are not as accurate as I would have liked (limitation of the equipment), but it gives a pretty fair idea that thicknessers, brushed motors (SCMS and circular saws) and in general during an actual cut on other machines, hearing protection is mandatory.

The screaming motor of a thicknesser which is often used for quite long jobs, multiple passes will leave you with permanent loss every job.

The sound a nail gun produces may not last more than a fraction of a second, but that instantaneous sound will lead to a hearing loss that is less temporary.

Some interesting findings out of all that: Increasing the pressure during the cut can increase the sound energy ten-fold. This can move a sound from needing 15 minutes to damage your hearing to one that will take 60 seconds to do the job.

Brushed motors are bad news (my thicknesser, SCMS, circular saw)

If something sounds loud, and particularly louder than something else, the amount of sound energy required to achieve that increase in volume is huge. If something sounds loud, be sure that your hearing needs your intervention!!!!

Episode 27 Noise in the Workshop


Noise in the Workshop. This is part of Safety Week 2008, and is a brief discussion about the noise produced by different machines in the workshop.

Episode 26 Safety Week 2008 Introduction

Introduction to Safety Week on the Wood Whisperer Network 2008

A quick introduction and discussion about personal safety equipment, not only using it, but ensuring that the solution actually works for you so that you actually use the equipment when needed, rather than leaving it sitting on the shelf as being too cumbersome or uncomfortable to bother using.

Also too – the first (brief) look inside Stu’s Shed 1.7 as it continues to undergo its physical transformation.

Hearing Protection in the Woodworking Workshop

First things first. There is a HUGE range of hearing protection out there. (BTW, I don’t say ear muffs, as we had a definite opinion about what ear muffs were in the navy, and it wasn’t hearing protection, and it never got cold enough to actually wear “ear muffs”) The question has to be asked however- does the choice really matter? After all, wouldn’t wearing hearing protectors, irrespective of type leave you better off than you are without any?

Unfortunately, the answer is definitely no. It is imperative that you choose hearing protection designed for the type of noise that you are expected to encounter. To give an example, hearing protection for firearms is useless in a workshop environment. It is specifically designed for a momentary peak noise, not long hours of high frequency, loud noise. To wear the wrong type leaves you thinking you are protected, with normal frequency sounds blocked, while the damaging high frequency sounds, such as made by a router goes about its ‘job’ of wrecking your hearing.

So what are we looking for in hearing protection for the woodworking workshop environment?

  • Comfort. after all we will be wearing them for moderately long periods of time.
  • Compatibility with other safety equipment. Because of the material we work with, eye protection & lung protection is mandatory, so all three must go together without compromising comfort or protection.
  • High frequency protection- such as made by a circular saw or router.
  • Moderate volume protection. The circular saw is pretty loud at close range, and will cause hearing loss, but isn’t as loud as some other work environments.
  • Communication potential. The best situation is protection from the sounds that will damage hearing, yet still allow you to hear the person next to you talking. These are not mutually exclusive, as good hearing protection blocks damaging frequencies, while still allowing the sound frequencies associated with speech to pass relatively unaffected through the ear defenders. This would allow us to leave our hearing protection on the whole time we are in the workshop, and not have to continually remove and replace our hearing protection every time someone speaks. There are some with a built-in microphone and speaker, which transmits noise from outside the ear defenders when the noise level is acceptable, and cuts the circuit when the volume exceeds a given point.

One brand that is ideal ones for our environment are Peltor H7 or H9. Peltor H7 is the higher rated of the 2, and only costs $3 more. They are more expensive than the stock ones available from Bunnings, however it is, as always, a case of “you get what you pay for”.

With respect to headband types, the choice is yours, as reputable brands offer their ear defenders with a range of headband. There is the normal headband, the neckband, a collapsible headband, or the hardhat attachment.

So what level of protection do we need?

The following graph demonstrates the amount of exposure time allowed plotted against volume. As you can see from this, you can listen to 85dB for 8 hours, or 100dB for 15 minutes.

volume1.jpg

So how does this relate to ear defenders / muffs?

Ear defenders are rated by how much noise they block. You can buy a 10dB ear defender, 22dB, even a 31dB.

Because of the large range in noise levels that can be detected by the ear, the decibel scale is not a normal scale. Instead, a 3 dB increase in noise level, though barely perceptible, corresponds to a doubling of sound energy. A 10 dB increase, indicating 10 times the energy, seems twice as loud.

The amount of damage caused by noise depends on the total amount of energy received over a period of time, the louder the noise the faster it causes damage. A noise 3 dB greater has twice the energy output and causes the same damage in half the time.

So from this, you can see that an ear defender that blocks 28dB is excellent.

Another way of looking at this is taking the actual noise level of the equipment, and subtracting how much protection the ear defender is providing.

noise.gif

Hours of Protection

noise2.gif

From this, you can see that all this equipment should be used with hearing protection. Damage is cumulative, so even if you only use the saw for 2 minutes, then do another cut that takes 3, the use the router for 5 minutes, and finally the belt sander for 4 minutes, you have suffered a degree of permanent hearing loss. The amount of damage you do next time adds on to this, and so on.

Recommended for our work is ear defenders in the range of 28-31dB

You can buy some cheap ones from Bunnings, such as Protector, which will cost between $15 and $25.

However, my highly recommended brand is Peltor, which will cost $60 for the H9, and $65 for the H7. The cost is the same irrespective of the headband type you choose.

For excellent all-round protection in the workshop, it is hard to go past the Triton Powered Respirator, released onto the market mid 2003. It provides excellent full-face protection, hearing protection and respiratory protection via a positive pressure, open circuit air supply system. Even so, I don’t wear it all the time – horses for courses, and for many jobs it is definitely overkill. On the other hand, on days that I do decide to don the rig, I have a much better sleep that night with my lungs thanking me, in addition to having my eyes safe, and my hearing protected.

tpr.jpg

For your convenience, I have also priced the hearing aid below:

ear.jpg

Cost: $600 – $1000 per ear.

One final word about using your equipment.

High frequency sounds are substantially more damaging than loud low frequency. So beware both your router and circular saw which both generate high frequency sound. The router operating in the 10- 15000 RPM range is very damaging.

Secondly, how you use your equipment has a marked effect. If you push the work through, you can increase the volume of noise you produce by 3dB easily. Doesn’t sound like a lot, but remember that 3dB represents a DOUBLING of the sound energy, and therefore means you will damage your hearing in half the time. (eg 15 minutes when going gently, compared to 7.5 minutes if you force the work.)

So keep safe, and don’t get complacent about your hearing. Thus ends the lecture!

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