I have a question about exhoust.

Lasers
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1

I have a question about exhoust. I built a box that fits the back port with two 80mm fans in it. They are 12v .15a each and my power supply is 12v 200ma. They don’t move air like they should. What power source do I need? .30a?
I also tried a boat bilge blower(turbo 4000) and when hooked up to the same power supply it barely moves. I know I need higher amperage, but how high?

2

My bilge blower draws around 5 Amp

3

Do not waste your time and money on low power fans ,i use and highly recomencd this one http://www.ebay.com.au/itm/111240702828?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT

4

Try this baby. But be aware, your power supply must be able to give 4A (preferably 5A) continuously . http://www.ebay.com/itm/Brand-New-Delta-TFC1212DE-120mm-12cm-PWM-252CFM-12038-DC-12V-cooling-fan-/252119691871?hash=item3ab381325f:g:Gz4AAOSwbdpWUB7-

5

Guys - if i may ask - what flow rating is enough for the K40 ?
Will this:

http://www.canfan.nl/cfrk100.html

140 CFM generaly - be to small / just right or overkill?

6

I run at 240 CFM. A lot depends on the length of the exhaust pipe, how well sealed the pipe is, how many elbows there are and more. But 140cfm on a 20’run should suffice as long as the pipe is well sealed (use aluminum duct sealing tape on all joints) and try to minimize bends or diameter changes in the pipe.

7

I ended up with the turbo 4000 marine bilge blower, powered by Xbox 360 psu and homemade box to fit the back of the k40. Just painted it, but haven’t tried it with the machine running. It seems like it moves air way more than the stock. I will do a full test in a about a day or two and let you all know the result

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Hmm on Facebook group guys are saying that 720 barley makes it some times… I do plan on perfect sealing, just not sure what rating i should believe

Anthony do you have smell of ‘ANY’ odor whatsoever ?

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Miro G

If you have an ammetter try connecting your fan to a 12v car battery (it will be able to supply as much current as the fan needs) and just measure the consumption this way

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Of course there is a small amount of odour. Totally unavoidable as the K40 is not sealed and even with the best fan you could think of, there are places it can escape. But there is not any long lasting noticeable odour and any fumes that escape are in such a low concentration that you are safer breathing that than driving down the highway and breathing the small amount of exhaust gasses that enter your car.

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@Przemyslaw_Wilkutows Whatever you want to do, don’t go for perfect sealing. Its the worst you can do. If you do perfect sealing, then your machine will be like a vacuum. Your exhaust fan needs to be able to suck in air to blow it away. You do need holes where the machine can suck air. A good place is at the front of the machine, since you suck away air in the back. That way it takes the smoke with it and also the smell. Of course you should not have TOO many holes, but with a good fan, a lot of holes are certainly possible because the more backpressure your fan has, the less air it will move, the hotter it will become and the less efficient it will be.

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As for perfect seal i meant the exhaust system it self not a full seal on the unit but sure will keep that in mind

Ok Anthony, thanks for the info i think i know now what Fan to get

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Op tested my design yesterday and I get very faint burning smell, a lots more noise and enough vibrations to move my workpeice when the fan is running. I’m thinking about putting the fan outside and running the softer dryer vent hose to it. It moves air way better though.