Shop vac again.

[sunnybob]

ok, lets see if this works.
Pic 1 is the mdf box, with the lower baffles, all loosely covered with old blanket.

pic 2 is the upper baffle, shown upside down before laying it over the lower baffle

pic 3 is the baffles in place, and you can see the slot at the rear base that the air travels down to the baffles through

pic 4 is the vac inside the cabinet, with the padded lid fitted, and the padded door ready to be fitted.

pic 5 is the box sealed and the cyclone connected up. job done.

So the air travels down to the back of the cabinet, and goes over and under the baffle plates before exiting at the lower slot.

all you have to do is slow the air down, all of the noise is air moving incredible fast. Slow it down, and all you can hear is the muffled motor.

 

[Doris]

I really like that. Does the baffle help with overheating too? My vacuum is a blower as well as a hoover and i think it blows hot air out.

Have you measured the before and after with a decibel meter at all? I have a very small workshop so i wonder if it will have as big an impact as your workshop looks at least twice as big as mine.

 

[katellwood]

all you have to do is slow the air down, all of the noise is air moving incredible fast. Slow it down, and all you can hear is the muffled motor.

One Question

If you are slowing the air down in a confined space does this not have an effect on the amount of suck

 

[sunnybob]

Doris... My "workshop" is a single car garage 5 metres x 3 metres. All the woodworking stuff is on one long wall. It looks bigger because i have roller doors at each end and on that day the doors were up.
Dont have a decibel meter or any way to record the sounds. but i can promise you that before it was enclosed it was so loud it was louder than the bandsaw cutting wood. Now its a very low background whine, like hearing next door hoovering through a partly open window. i went from being unable to talk with it on, to now having to check that I did actually turn it on if I am using the bandsaw or mitre saw.

Hot air comes from the motor. the suction is pulled through the motor to cool it and then exhausted away. There is NOT a heater inside. This box makes no difference to the air being pulled in so there is no difference in temps on the motor.


Katellwood.... the exhaust isnt a confined space when compared to the 3 or 4 inch inlet pipe. The motor still pulls the same amount. Once the air has exited the motor casing, it now has the whole box to expand into. The opening on the bottom is 24" x 5" (125 square inches) compared to the inlet pipe of 3" diameter (maths is not good this time of the morning, but i think thats about 9 square inches?)

The proof of the pudding is in the eating. i have been using this for almost a year with not a single moment of doubt, and you have to bear in mind I live in Cyprus. i work in the garage at anything up to 43 degrees c air temp which is why I have both doors open at times. It does NOT overheat.

 

[DiscoStu]

I too would be concerned about it over heating but it's good to see it doesn't. I'd probably be keen on putting one or two small computer fans at the exit to help pull the warm air out. Especially when the vac isn't running but you've still got residual hot air and a hot motor inside. I guess it also depends on how long it's run for at a time.

Very interesting post though and something I may well have a go at as my vac is noisy.


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[screwpainting]

That will do me Sunnybob, I will copy that, anything that keeps the noise down has to be a good idea.

Nice one.

 

[Doris]

I too would be concerned about it over heating but it's good to see it doesn't. I'd probably be keen on putting one or two small computer fans at the exit to help pull the warm air out. Especially when the vac isn't running but you've still got residual hot air and a hot motor inside. I guess it also depends on how long it's run for at a time.

That's a good idea. I may have to do that myself.

Sunnybob. Does the thickness of the box have a crucial part to play or is it the actual soundproofing that matters more? I have some thin sheets of MDF I could use but I wonder if I would just have to double them up instead.

 

[sunnybob]

mdf is the densest material cheaply available. Much better than plywood. But go too thin and youre not insulating the noise. Noise is transmitted through vibration. A thin board will vibrate, a thicker board wont.
I used 22mm. Bought a sheet and had them cut the sides and top. around £20 or less.

DONT put fans in!! The whole point of the box is to stop fast air escaping. Why would you then make holes in the soundproof box? Its not soundproof any more. You would just have directional sound like hi fi tweeters.

If you are a weekend warrior and use the vac for 45 minutes or less at any one time. this is all you need. Remember, if you really are concerned about heat (and I'm the EXPERT on heat, try 40 degrees sometime while youre working), every time you switch off, the motor starts to cool. If its a half hour before you use it again, wheres the problem? And if it does by some amazing set of circumstances get too hot, all modern motors have a thermal overload on them anyway and will stop all by themselves.

If youre commercial and have the thing running 8 hours a day, then you should have a larger bag system anyway, or you could just build a bigger box, or put a bag of ice cubes in there.

 

[pike]

I'm using the SIP as shown here http://www.amazon.co.uk/SIP-Saw-Dust-Co ... B005T0A69Q

Its pretty good for the stuff you want to do. I run it through a cyclone and 62mm piping to my machines, it copes with everything except the big bandsaw.
if you want it portable you can make a wheeled dolly for it easy enough.

That looks like the same one I have and it handles my Record BS400 perfectly. Maybe I just don't cut the same sort and amount you do sunnybob?

 

[sunnybob]

Pike, I dont have a quick answer. i have had a long email conversation with axminster (i have their 350N) who have shown great interest even to the point of sending videos to each other, but it does not take away enough. Their video showed a huge double bag suction machine, mounted next to the saw with only 2 metres of 4" hose between. the saw cut without any dust appearing. To be honest, with the size of that dust collector, I'm surprised the saw didnt get sucked up there as well. Is yours mobile? is it next to the saw when cutting?
I have a 5 metre run between saw and vacuum. Axminster say they are going to change the specs on this machine after our conversation and state that it requires a 4" extraction pipe. The problem appears to be the gap between the table and the extraction port is too big, allowing any cross draught to defeat the suction and just dump the dust at the bottom of the saw.
I am building a collection tray to fit underneath and connect to the angled port. Thats a work in progress.

 

[sunnybob]

carrying on from the above. Today I opened the cabinet and checked everything.
In the bottom of the canister was a tiny, tiny amount of waste. Not enough to even take a picture of.
But the filter around the motor was very blocked with fine dust. So much so that it had started to collapse inwards. Took me several minutes to brush and shake away the fine dust from this filter, but it has been at least 7 months since I opened the cabinet last. It has a noticeably stronger suction now.

So I've put a sticker on it that says "clean in sept". Every 6 months will do me fine.

 

[DiscoStu]

DONT put fans in!! The whole point of the box is to stop fast air escaping. Why would you then make holes in the soundproof box? Its not soundproof any more. You would just have directional sound like hi fi tweeters.

I wasn't suggesting putting a hole in the box to put fans in as that would indeed defeat a lot of what you're trying to achieve. I was suggesting that where you have the baffles for the air to flow that putting a fan in could help with airflow and cooling. I've used fans previously and they are very quiet. Still if heat isn't a problem then that's good.


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[sunnybob]

ok. i misunderstood.

But to a degree, if you accelerate the air through the baffle, then the noise level will rise a small amount. i have a piece of acoustic transparent black foam across the outlet, purely to deter the wildlife from nesting there (small lizards are everywhere, you just cant keep them out), it moves very slowly when the extraction is running, so there is no back pressure in the system.
And as I say, my workshop is ambient 30c plus for over half the year, before turning anything on. Just to make you jealous, its been 25 c for two weeks now.