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Thread: Router cooling in table

  1. #1
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    Router cooling in table

    I have a PC 7518 motor in a Woodpeckers Precision Router Lift (the older one not the V2). When I bought the set up, I purchased the Woodpeckers router table with the dust collection housing. The dust collection housing has not seemed to work all that well (and with the connection pointing down it is hard to connect). I have come to not expect much from router table dust collection, but my concern is whether the housing restricts airflow enough to affect cooling of the motor. The only intake is the space between the ring and the bit. I noticed things being a bit warm after running about 25 ft of 3/8 roundover for my father (slats for a wooden swing). I am wondering if I should remove the housing. I notice it is not on the woodpeckers page anymore.
    Router dush collector.jpg


    John

  2. #2
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    I have the same router, but a different dust collection housing (I think its from Rockler). The router runs much hotter if i leave the door to the enclosure closed and I dont connect it to a vacuum hose.

    The dust collection works pretty well even with just a shop vac attached. The router makes a huge mess without it, but just leaks a little dust around the bit when the vacuum is on. I would be inclined to try and get the dust collection working on your router table rather than remove it. My housing has a bypass grate, and the system runs a bit better if the grate is open a little to increase the CFM in the hose.

  3. #3
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    Quote Originally Posted by Scott DelPorte View Post
    My housing has a bypass grate, and the system runs a bit better if the grate is open a little to increase the CFM in the hose.
    For efficient dust collection you have to let air in to the enclosure in order to get good flow out. Pulling negative pressure inside your enclosure makes the shop vac work harder and actually decreases the effectiveness. Basically with your shop vac running, when you connect the hose to the enclosure, you should hear no change in pitch from the shop vac if your air inlets are large enough. If the pitch changes, you need to have more openings to let air into the enclosure. This will also provide cooler air for your router which will prolong it's life.
    Lee Schierer
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  4. #4
    Quote Originally Posted by Lee Schierer View Post
    For efficient dust collection you have to let air in to the enclosure in order to get good flow out. Pulling negative pressure inside your enclosure makes the shop vac work harder and actually decreases the effectiveness. Basically with your shop vac running, when you connect the hose to the enclosure, you should hear no change in pitch from the shop vac if your air inlets are large enough. If the pitch changes, you need to have more openings to let air into the enclosure. This will also provide cooler air for your router which will prolong it's life.
    This is good advice, except I think your shop vac will use the least amount of power with the hose completely blocked-at least that is how my dust collector works (checked it with an amp meter)

    To the OP-that looks like a decent dust collection design, I would just try to get more air flowing through it.

  5. #5
    sucking air out of the bottom?
    could be the problem
    the fan on my router motor sucks air in from the bottom (when router is inverted in router table) to cool the motor
    so i have an air intake underneath the router and suck the air/chips/dust out of the top of the enclosure
    Carpe Lignum

  6. #6
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    John, have the same router but in a Bench Dog table and cabinet with a dust port at the lower side of the router (5 inch) and a 2.5 inch port on the fence. The only air inlets are a small gap between the doors of the cabinet and the hole in the router plate. I can run the router for long periods with fairly heavy loads without a lot of heat being generated. There is almost zero dust left behind in the router cabinet and the top of the router plate stays clear.

    It looks like part of the issue could be the size of the enclosure in your case. I'd probably remove the existing enclosure and build a larger one from sheet goods using the table legs as a framework - then cut at least a 4 inch dust port in the side. This assumes you are using a regular DC and not a Shop Vac or similar

  7. #7
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    Would it make any sense to run the exhaust from the shop vac back into the router enclosure? If it's too much volume you could make a bypass damper with a tee on the outside of the enclosure.
    Confidence: The feeling you experience before you fully understand the situation

  8. #8
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    Ken, The shop vac uses less power when airflow is blocked because once the air begins to cavitate, it is not being moved, thus no "work" is being done. The increase in pitch is the removal of the load from the motor, so it will spin higher rpm and use less energy, it just won't be moving air as well.

  9. #9
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    Quote Originally Posted by Jerry Bruette View Post
    Would it make any sense to run the exhaust from the shop vac back into the router enclosure? If it's too much volume you could make a bypass damper with a tee on the outside of the enclosure.
    If the shop vac pulled the air out of the enclosure, hooking the exhaust back to the enclosure would not introduce any more air than was pulled out. It would however recirculate the router motor heat and any heat generated by the shop vac motor if it is cooled by the same fan that is creating the vacuum.
    Lee Schierer
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    My advice, comments and suggestions are free, but it costs money to run the site. If you found something of value here please give a little something back by becoming a contributor! Please Contribute

  10. #10
    I think the right way to pull from the cabinet is to put a hose inside to suck from the top of the router motor, around where the bit is. That way, you help the fan on the router instead of fighting it. For routing that is not on the edge, like making a dado, the fence vacuum attachment gets very little, the connection inside the cabinet gets the debris. I made my lift and have the hose this way. I need to switch it to a 2.5 inch hose now that I got rid of my DC. It currently is 4 inch.

  11. #11
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    I see a couple of issues with this setup:
    1. Dust collection through the bottom draws the chips through the motor - bad idea.
    2. When routing dados or otherwise blocking the too small air intake renders the whole system useless and let's the motor run in the dust without cooling.

    I have 2 1/2" d/c on the fence and a 4" port under the table near the very top on the back, the key to make it work properly is a floor heat register mounted in the top front of the box that can be adjusted to draw a certain amount of air horizontally across the box near the table top above the router motor. I don't have a dust port on the bottom of the box, only a 1 1/2" hole near the bottom front, and only need to clean the box out when I forget to adjust the crossflow.
    Last edited by John Lankers; 06-12-2016 at 6:25 PM. Reason: spelling

  12. #12
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    Lee nailed it IMHO. There should be equal return air to that being drawn. If there is no vent on that housing other than the space around the bit (which I try to keep to the minimum possible while still allowing spoil collection) then it is poorly designed. I keep my bit throat close and have venting on the side of the enclosed space. Collection is good and the enclosed space stays pretty clean (other than the natural snow-drift effect that nooks and crannies cause). I have never noticed the motor getting hot at all; no smell, no sense of warm to touch when changing bits, etc.
    "A hen is only an egg's way of making another egg".


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  13. #13
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    Some of the discussion confirms my concerns.

    It seems I might be better off taking the shroud off the bottom, since the router cooling is blowing up through the router plate. Using the downdraft as designed pulls the opposite direction of the cooling flow. I have an 1100 cfm dust collector that I hook to four inch port, but the clearance around the bit is small definitely not supporting 1100 cfm. Looking around the Incra version of the dust cabinet has extra slots for airflow, but not compatible with the PRL lift.

    I really did not give this much thought when I bought the table package over 10 years ago, but I haven't had to run a whole lot all at once.

    So the issues with this design
    1. Air flow of the dust collection is opposite of airflow for cooling
    2. Clearance on insert of PRL not sufficient to support high cfm of dust collector
    3. pain to make the connection at the angle

    So I think I ought to remove the housing. Just need to figure out a good switch option. I would like one of the paddle off switches.

    John

  14. #14
    Quote Originally Posted by John Stankus View Post
    1. Air flow of the dust collection is opposite of airflow for cooling
    So I think I ought to remove the housing.
    John
    Can modify the enclosure to have another port on top housing to connect to your dust collector?
    Carpe Lignum

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