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Thread: New "high tech" dust foot, opinions?

  1. #21
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    Well, yes and no. Like the old automotive adage "there is not replacement for displacement" you can say "there is no replacement for volume flow". If you have a 20 hp tornado machine the dust shoe may not make much of a difference as long as you keep the DC hose nearby. But, especially when you are power limited, the design of the dust shoe is the difference between useless and O.K. or maybe even "good". For that matter, I don't worry about 12mm bits, 9mm doc and 6 m/min with my 3hp spindle. I guess I could do that in foam, maybe

  2. #22
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    I have an Oneida 2HP cyclone and it really sucks. Most of the time, I find the Kent foot and a 5" hose is a pretty good combination to rid my shop of any trace of chips and dust. I machine a lot of plastic and this setup is perfect. I rarely have to clean up anything after 8 hours of cutting. I think the only improvement I would add is the air jet to get the chips out of the curf and move things into the vacuum flow. I would welcome a better mousetrap but I would need proof it was worth the cost and trouble.
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  3. #23
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    The issue i've had with dust collection over the years is the dust hoods running into clamps and breaking or the "unknown" of not being able to see where your bit is cutting because it is hidden under the brushes.

    I don't use dust collection as much because i like to see what's happening before catastrophe. I do use breathing protection instead..

    The problem i see is that by the time your average dust collector reaches the router bit it's suction has been deminished over the length of hose.

    I have been thinking about some type of U shaped dust hood where you could see your bit cutting, and mounted somewhere on the carriage would be some type of small powerful vacumn that would act as a strong suction primer to make up for the loss of vacumn and maybe some type of air sprayer from the front that would push the dust to the back of the dust shoe that is open in front and act as a "air wall".
    Knowing almost nothing about vacumn and suction, air pressure, ect
    am I just way off base here?
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  4. #24
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    I am new to CNC use, but I think there is room for improvement in dust boots. Mine gets in the way when changing the bit and zeroing the Z axis. Taking it off vertically presents some difficulty in getting it past the bit. I am thinking about a two piece boot. The brush section should make up for any slight mismatch. The front could have a fit that mates to the back and some simple locking feature, or it could just slide off. I'll try to come up with something in 3D and post it via a .step file if you are interested.

  5. #25
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    May 2014
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    Quote Originally Posted by Burkhardt View Post
    One thing I noticed with my own experiments, is that mostly vertical air flow is not that effective. The rotating bit will sling particles horizontally across the surface and it takes deceleration over a minimum distance to slow them down sufficiently to reverse course and go up into the DC. That means a narrow gap around the foot will have only a very short area of high horizontal air velocity and the particles may just zoom through (especially heavier ones of plastic or metal).
    That's the main purpose of the brush. To stop flying chips and contain them until they can get sucked into the hose.

    First, a 1HP collector is not really adequate for CNC use. I'd consider 2HP to be a minimum. I actually have a 1HP dust collector connected to my CNC. I also have a 2HP Harbor freight collector, and it is at least twice as powerful.

    Dust shoes are very dependent on the specific application. Or more importantly, brush length.

    For someone cutting sheet goods with a vacuum table, a 1-1/2 to 2" long brush works very well. The bottom of the bristles should be about 1/8" below the tool tip. This forms a "seal" against your spoilboard and should allow collection of just about all airborne dust, if you have enough CFM. But there will still be some dust when you cut along the edge of the spoilboard, effectively breaking the seal. On our Morbidelli at work, I can trim 1/2" off of a 3/4" sheet of MDF or particle board, at 1200ipm (20 ips), with a 1/2" compression bit, and there is no dust.

    Anyone using tall clamps will always have problems. Same thing for deep 3D carvings. In those cases, long brushes (~4-5") are probably your best option.

    If you can allow the brush to form a seal around the work, and use a 2HP or larger dust collector, with at least a 4" hose, you'll get pretty good dust collection.

  6. #26
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    Nov 2012
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    Canada
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    We've been tweaking the design constantly using all your feedback.

    We're not too concerned about the transition between the round 4" duct to the oval passage through the foot. The maths say the increase in velocity so close to the cutter will offset any reduction in total airflow (not much). The first real world prototype will shows us if this actually happens.

    For those worried about running the foot into things. We may be building it out of semi-ridged or flexible urethane. This will let the boot "give" a bit when it makes contact with things which don't normally move (clamps, workpiece etc).

    Still trying to figure out how to incorporate a way to view the cutter head while it is going. Maybe make the whole thing see-through!

  7. #27
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    would this shoe work for this...
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  8. #28
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    Gene, for what you do and for as much of it that you do, I think I'd just park the machine in a big wind tunnel and let 'er rip! Operator safety harnesses required. ;-)
    Scott




  9. #29
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    If you are just doing sheet goods, the SB or Kent foot works fine. For 3D work, unless it is shallow, dust collection is a no-go. Those who cut it on a regular basis will tell you that aside from roughing, it "ain't gonna work". There isn't enough brush length to compensate for the up & down of the Z, but the issue you run into is that the foot actually gets hung up on things like the last pic Gene shows in his examples. Since you are mostly cutting chips and not rooster-tailing when using a ball during finishing, it isn't that bad to just vacuum up the chips.

    Kudos to those making their own dust foot - you are smart enough to realize you own a CNC with infinite possibilities...How ya think Kent does it? I think he realized he could capitalize on the laziness of users...and there appears to be a lot of them out there. Good for him.

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  10. #30
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    I think he realized he could capitalize on the laziness of users...and there appears to be a lot of them out there. Good for him.


    Hey... I resemble that remark! lol

    Actually he makes a good point, in that, I have stopped using my dust boot because i don't like to not be able to see where i'm cutting in order to avoid catastrophe before it happens.
    I had mentioned earlier about a open faced dust boot with a air mist type thing to keep the chips within the confines for the vacumn to suck it up but....

    I thought about a U shaped boot with bristles around the sides and back and in the front have a plexiglass window with some LED lights to allow you to see the bit, light it up and maintain the suction. Sound feasible?
    Words of Wisdom:
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    “The biggest trouble maker you’ll probably ever have to deal with, watches you from the mirror every morn’n”
    “The only difference between a rut and a grave is the depth”
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    Just remember...when it's time for the hearse to pull up..there's no luggage rack on top!
    -----------
    The beauty of the Second Amendment is that it will not be needed until they try to take it...Thomas Jefferson

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