Router Temperature Rise When Mounted in a Dust Collection Box - Router Forums
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post #1 of 29 (permalink) Old 01-06-2019, 08:13 PM Thread Starter
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Default Router Temperature Rise When Mounted in a Dust Collection Box

There seems to be differences of opinion on whether a router motor will overheat when enclosed in a dust collection box. Some people advocate ventilating the dust collection box so that the router motor brings in outside air that does not come in around the bit. My engineering engineering intuition says the dust collector brings in a lot more air than the router motor cooling fan. I have conducted an experiment to explore this issue and the results are attached. Let me know what you think.
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File Type: pdf Router Temperature Measurements with INCRA Clean Sweep Dust Collection Box.pdf (211.2 KB, 202 views)
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post #2 of 29 (permalink) Old 01-06-2019, 08:32 PM
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have you taken in account the the Venturi effect???

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File Type: pdf Venting a router table's motor with DC....pdf (85.8 KB, 56 views)
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post #3 of 29 (permalink) Old 01-07-2019, 06:23 AM
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I don't see how a the sawdust can be removed without incoming air. My home built router table has a plexiglass front door that has 5 - 1" holes just for incoming air and that keeps the compartment almost completely dust free. Close those holes and nothing gets removed except a very little from what small amount of air infiltrates. If possible I'd add adjustable air vents. Maybe I'm missing something here.
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post #4 of 29 (permalink) Old 01-07-2019, 07:07 AM Thread Starter
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I am familiar with the "Venturi effect" in Fluid Mechanics but do not understand what you are referring to for a router dust collection system. Please amplify.
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post #5 of 29 (permalink) Old 01-07-2019, 07:14 AM Thread Starter
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Originally Posted by sreilly View Post
I don't see how a the sawdust can be removed without incoming air. My home built router table has a plexiglass front door that has 5 - 1" holes just for incoming air and that keeps the compartment almost completely dust free. Close those holes and nothing gets removed except a very little from what small amount of air infiltrates. If possible I'd add adjustable air vents. Maybe I'm missing something here.
In my case, the air is coming into the dust collection box from above the router table. This is why it is important for the throat plate to have as much open area as possible as in the case of the Incra system that I have. The system works quite well.
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post #6 of 29 (permalink) Old 01-07-2019, 08:31 AM
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Ben I'll point out a few important facts about RT dust collection.
First is that not a single speck of dust is created below the table. 100% is created at the top of the table and up from there.
Second, most of us use insert rings in our table plates to keep the gap as narrow as possible. This doesn't allow much room for either the dust or the air needed to transport the dust to get through. The Clean Sweep rings help by allowing more air but the combined surface area of the openings is maybe 2 square inches of cross sectional area on average where as a 4" dust port is about 12.5 sq. in.
Third, the router is trying to blow air upwards through the router windings to cool itself. You are pulling air in the other direction. These two air flows tend to cancel each other out. You are also pulling air out at the intake end of the router.
Fourth is that cooling happens by transferring heat from the windings to the passing air molecules in the air stream. In a vacuum there are fewer molecules so cooling is reduced.

The only particles that would normally make it past the bit and go under the table are due to the randomness of the collisions between particles being ejected from the bit. Most will stay above the table if you don't try to move them somewhere else. So the logic of trying to suck all that dust down through that small hole by putting your router in a box that will probably compromise it's cooling while simultaneously making the router hard to get to for locking height, changing bits, and changing speed absolutely escapes me.

I'm considering building an extra pickup that will sit under the table at collet height that can capture the tiny fraction of dust that my fence mounted pickup misses but that also won't interfere with me getting at the router and that design will actually improve cooling. I'll probably mount it with magnets as It has to be able to attach on either side because I work from both sides of my table. I just haven't figured out what I'll make it out of and how yet.

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post #7 of 29 (permalink) Old 01-07-2019, 10:01 AM
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I think Ben (bfblack) has made an effort to add a real scientific evaluation here and should be commended for his sharing it with us. It shows us the importance of air flow and the huge difference there actually is when more air movement/exchanged to dissipate heat. There is no presumption here, just facts.

I also agree, that a snorkel from the end of the router to the outside of the box may help as long as you also use your DC at the same time. I presume a snorkel would cut airflow without the added DC.
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Last edited by gmercer_48083; 01-07-2019 at 10:12 AM.
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post #8 of 29 (permalink) Old 01-07-2019, 10:41 AM
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I think Ben (bfblack) has made an effort to add a real scientific evaluation here and should be commended for his sharing it with us.
I agree but I still have to stand by my comments. As a power engineer with a background in physics I didn't grasp what I said out of thin air.

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I presume a snorkel would cut airflow without the added DC.
Only very marginally. The longer it is the more impact it would have as there is some friction between the air molecules and the side of the tube but it would be over a longer distance than anyone would need to go with the snorkel. Since the snorkel would probably be much larger than the router's intake and the distance air would have to travel to get to the intake would be very short I suspect you would need some pretty good instrumentation to see the difference.

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post #9 of 29 (permalink) Old 01-07-2019, 10:46 AM
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I would like to THANK Ben for sharing that information with us!

Otis Guillebeau from Auburn, Georgia
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post #10 of 29 (permalink) Old 01-07-2019, 11:53 AM
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Quote:
Originally Posted by Cherryville Chuck View Post
I agree but I still have to stand by my comments. As a power engineer with a background in physics I didn't grasp what I said out of thin air.

Only very marginally. The longer it is the more impact it would have as there is some friction between the air molecules and the side of the tube but it would be over a longer distance than anyone would need to go with the snorkel. Since the snorkel would probably be much larger than the router's intake and the distance air would have to travel to get to the intake would be very short I suspect you would need some pretty good instrumentation to see the difference.
two independent systems..
cooling air to the router and the DC system..
the router pulls air in through the snorkel...
it then exhausts it into the box...
the DC ''pulls'' this exhausted air away from the motor...
I see it as the DC aiding in increasing clean, cooling air flow through/to the motor...
the DC is actually a plus in removing heat from the router...

@bfblack ...
Quote:
I am familiar with the "Venturi effect" in Fluid Mechanics but do not understand what you are referring to for a router dust collection system. Please amplify.
the principle is the same be it liquid or air because air is fluid... motor cars use this principle..
Ben, what were your findings for the temp readings while utilizing installed independent systems and w/ the router under extended load and not under load???...
did you use a free standing router as a baseline??...

here is a pic of a non-vented router's air intake w/ DC only after extended use...
I wonder how much swarf is inside the motor...

.
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Last edited by Stick486; 01-07-2019 at 12:23 PM.
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