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Thread: Total newbie trying to avoid death by sawdust

  1. #16
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    Weather-stripping around the lower door and some foam where the blade comes up out of the lower cabinet also help to improve the airflow.

  2. #17
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    Quote Originally Posted by Bill McDermott View Post
    Chris, I have a short piece of flexible tube sliced open a bit and placed around the blade, under the table. The end on the outside has a fitting on it for my vac. Bungee cord and duct tape. It works really well. Maybe you can experiment in that direction. Also, if you don't yet have a "dust deputy", you should get one. That will improve everything you do with your vac.
    I would definitely try something along these lines, or Rob Cosman's PVC idea which is similar. I also second the notion to add a pre-seperator to the shop vac, either a dust deputy or a shop-made Thein baffle type. It helps keep the suction level constant over time by keeping the filter clean. And I second all comments regarding getting and wearing a good respirator, and I'd also add that a shop air cleaner is something to consider. With those, you can still work safely even if your collection at the tool is sub-par.

    Now for some meanderings on bandsaw dust collection...

    I've been thinking and experimenting with my Laguna 14bx. This saw has (2) 4" ports on the lower cabinet, one on top and one on the bottom. I have a 2 hp cyclone DC with a 6" line run to the saw that splits into two 4" hoses. With one or both hoses connected to the lower cabinet ports, the lower cabinet stays clean but the area around the upper guides collects dust, and quite a bit ends up on the table (and in the air, presumably, although its not that noticeable). To be sure this is far better than with no DC, but can be greatly improved. I'd prefer the lower guides stay reasonably clean, and the dust buildup on the table is annoying. The more of that I can eliminate, the less dust should end up in the air as well.

    In thinking about how a bandsaw generates dust, as the blade is in the cut the dust is trapped in the gullets. When the teeth emerge from the cut, they are full of dust, which immediately starts to fly out of the gullets below the table. This is where the buildup on the lower guides comes from. As the teeth move into the lower cabinet, more dust is flying out of the gullets, which would accumulate in the lower cabinet. This is where most of the dust would end up, but typical bandsaw DC designs are good at catching this if you can supply enough CFM. Most of the dust is probably out of the gullets by the time the teeth go around the lower wheel and exit the lower cabinet, but there will still be some left. Some of this dust ends up in the upper cabinet, and the rest settles down onto the table (and into the air).

    So the key is to remove dust from the gullets, ideally as soon as possible after the teeth emerge from the cut. I took one of my 4" hoses and rigged an under-table dust port to catch the dust flying around under the table- this was successful in eliminating the sawdust building around the lower guides, but apparently there is not enough airflow (I mean air velocity more so than total CFM) to remove the dust that is still trapped in the gullets, as I still get a little buildup in the upper cabinet and on the table. It will pick up any dust that was going to fall out of the gullets anyways, but can't extract dust that is still stuck.

    This is where I think a shop-vac could potentially outperform a typical DC if it were setup correctly. With a small diameter hose or pipe crossing perpendicular through the blade, you can get a very high velocity, violent airflow right through the gullets. You shouldn't need a lot of CFM, just high velocity, which a shop-vac is well suited for. If you can get all of the dust out right there there is no need for a DC hooked to the cabinet, and there should be very little dust to deal with on the table (there will always be some from the beginning and end of a cut, but I don't think that can be helped).

    For the time being I'm going to stick with my DC setup, but I'm thinking of adding a mechanical means of clearing the gullets. My plan is to aim a stiff bristled brush right into the gullets, at a location just below the throat plate. If the brush can knock loose the trapped dust, then the under-table DC should be able to collect it. I'll add an additional brush in the lower cabinet, directly in front of the upper 4" port where the second DC hose is connected, to remove any dust missed by the first brush. I've seen metal cutting bandsaws with a brush to remove chips, but I don't think I've heard of one on a wood saw, so it will be interesting to see how it works, and how well the brushes hold up.
    Last edited by Robert Hazelwood; 05-05-2017 at 6:43 PM.

  3. #18
    I will just add that you shouldn't use the stock bags on the HF DC. Your shop vac filter may be too leaky too. If you use a shop vac or DC with a filter that is pretty open, you capture the big stuff that won't hurt you and blow out the fine stuff that might. I like a HEPA fabric filter on the shop vac (not HEPA rated but has the same filtering material). For a DC, I like a cartridge filter that is at least close to HEPA level - or discharge outside. I used stock bags on a Delta DC I later sold. It contaminated my shop badly with fine dust. I then used shaker felt bags and it was a lot better but I think the dust level continued to build, just at a slower pace. Then I got a cartridge filter. I think it worked a lot better. But I didn't do measurements.

    I don't have a bandsaw at the moment - got rid of one when I moved. But when I get one again I will try the shop vac first. Mine is pulling through a dust deputy and is using the "fine" stock filter. That is overdue to change. I think a shop vac can work but it may take some messing around with the setup.

    With respect to your health concerns, I would search for the posts about Dylos readings for shops and outside. The bottom line I get is that shops are not terribly dusty, especially if you are using a DC or shop vac. Outside air may be dustier. With reasonable measures the shop may be no dustier than your house. We don't normally worry that outside air is going to make us sick. I think it is appropriate to take measures that keep the dust controlled but I don't think that most of us require 5hp DCs that pull enough air to make the shop better than typical homes in air quality. People with unusual sensitivities need this (like Bill Pentz) but most of us, fortunately, do not. But if we don't keep the level reasonable, we may later have that sensitivity too.
    Last edited by Jim Dwight; 05-05-2017 at 6:57 PM.

  4. #19
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    I get the best result gathering right under the table. I don't even use the other collection points on either of my bandsaws. Here's some ideas . . .

    G0513X-DC-Add 002.jpgG0513X-DC-mod 002.jpgG0513X-DC-Add 003.jpgG0513X-DC-mod 003.jpgBAND SAW TEE.jpg

    all of course require a dust collector.
    "A hen is only an egg's way of making another egg".


    – Samuel Butler

  5. #20
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    Dust collection is the most important power tool that you'll put in your shop.

    Like John, I have an online friend who is an incredibly talented woodworker who recently became sensitive and has had to curtail his whole business due to intolerance of wood dust that quickly became extreme...even with personal protection and good dust collection. A local locksmith I met a few years ago similarly had to stop carving due to a sudden intolerance brought on from sanding walnut. (I can't even handle bubinga at all and that was after only one project)
    --

    The most expensive tool is the one you buy "cheaply" and often...

  6. #21
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    Quote Originally Posted by James Morgan View Post
    Weather-stripping around the lower door and some foam where the blade comes up out of the lower cabinet also help to improve the airflow.
    WRONG! that is exactly opposite to what the lower cabinet needs. ALL bandsaws apart from one (Minimax) that I have seen all suffer from the same problem, they stall the dust extraction because the the cabinet has no inlet to supply air. Because the inlet does not exist the cabinet gets emptied of air and when the air stops flowing the dust stays in the cabinet. There needs to be a port added to the cabinet to supply make up air to keep the dust in suspension and that part needs to have an area of at least 1.5 times bigger than the extraction port. Some people have managed to prevent the dust getting into the cabinet by very good under the table collection and an above the table duct as well. Instead of adding a duct on a saw the quickest way to prove that make up air is needed is to leave the bottom door opened a bit to allow air in.
    Chris

    Everything I like is either illegal, immoral or fattening

  7. #22
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    Quote Originally Posted by Chris Parks View Post
    ...ALL bandsaws that I have seen...suffer from the same problem, they stall the dust extraction because the cabinet has no inlet to supply air...There needs to be a port added to the cabinet to supply make up air to keep the dust in suspension and that part needs to have an area of at least 1.5 times bigger than the extraction port. ...
    Chris, come visit and check out another possible exception, my 18" Rikon setup. (And bring some of that great local wood!) I agree the lower cabinet needs sufficient air intake to keep the dust moving. However, the 1.5x port area you mention is not necessary here. With two 4" ports on the lower cabinet of my Rikon, 1.5x would require about 37 sq inches of air inlet - I just measured and including the 1/8" gaps at the hinge side and at the bottom of the doors a generous estimate gives only 15 sq inches. Even with that intake area less than 1/2x the extraction port area no dust accumulates inside.

    I suspect what may help is the strong suction from my 5-hp cyclone pulls in sufficient air at a higher speed. In addition, the turbulence created may actually keep dust suspended and help the ports remove it. I originally planned to add an air inlet port somewhere in the lower cabinet but found it unnecessary. Additional inlet area may be needed for a lower suction from a smaller DC and/or for a bandsaw with a different design.

    (BTW, ClearVue has a video showing the 5-hp cyclone snatching up a 30' measuring tape and dumping it in the bin! I've lost sandpaper and small turnings at the lathe.)

    I've never seen the Minmax you mentioned but another possibility for success with the Rikon: could they have copied or improved on the Minmax design?

    Also, while good collection under the table (or with the Rikon, at the top inside the lower cabinet) may prevent a lot of dust from entering the cabinet, I think any ABOVE-the-table collection will have no effect on dust entering the cabinet. If the blade is surrounded by wood on three sides as with a normal cut, the sawdust has no where to go except be pulled straight down by the gullets to below the table.

    The above-table flex duct I use catches only some of the dust "sprayed" on top the table by skimming cuts, where one side of the blade is exposed while skimming a tiny amount of wood from the side of a wood. I do this a lot to clean up turning blanks after they dry for a few years to remove warp and reveal the color and figure of the wood.

    The whole topic of optimizing dust collection for bandsaws and other tools might make a great PHD thesis research topic for someone.

    JKJ

  8. #23
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    Jordan, good to see at least one saw maker using multiple ports on an otherwise sealed cabinet. It is a problem that few recognise and Laguna in one video even made a point of putting better seals around the cabinet door when they should have put more holes into it. I introduced and sold Clearvue in Australia for a few years and they definitely make a good product that simply works.
    Chris

    Everything I like is either illegal, immoral or fattening

  9. #24
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    I don't see the advantage from sealing up the lower cabinet either. On my 14bx I only hook up to the upper 4" port and leave the lower one open, so it becomes an air intake. This is enough to eliminate all dust buildup from the cabinet. Hooking up to both ports could only reduce the airflow, the way I see it. So the second hose is better served collecting from under the table.

    One reason for this is that there is not much of an opening in the top of the lower cabinet where the blade comes through. If there were a bigger opening there, it might make sense to seal up all other openings so that there is significant airflow coming down through the lower blade guards. From what I can tell the minimax saws have this sort of design.

  10. #25
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    Quote Originally Posted by Chris Parks View Post
    WRONG! that is exactly opposite to what the lower cabinet needs. ALL bandsaws apart from one (Minimax) that I have seen all suffer from the same problem, they stall the dust extraction because the the cabinet has no inlet to supply air. Because the inlet does not exist the cabinet gets emptied of air and when the air stops flowing the dust stays in the cabinet. There needs to be a port added to the cabinet to supply make up air to keep the dust in suspension and that part needs to have an area of at least 1.5 times bigger than the extraction port. Some people have managed to prevent the dust getting into the cabinet by very good under the table collection and an above the table duct as well. Instead of adding a duct on a saw the quickest way to prove that make up air is needed is to leave the bottom door opened a bit to allow air in.
    YMMV. I have a Powermatic that had all sorts of gaps to allow air into the lower cabinet, as will as a perforated insert plate. Originally, dust collection through the built-in rear port was miserable. I added a port at the lower front of the bottom cabinet, weather-stripped around the door, and sealed up most of the original port. I see little to no dust accumulation in the lower cabinet.

  11. #26
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    Quote Originally Posted by James Morgan View Post
    YMMV. I have a Powermatic that had all sorts of gaps to allow air into the lower cabinet, as will as a perforated insert plate. Originally, dust collection through the built-in rear port was miserable. I added a port at the lower front of the bottom cabinet, weather-stripped around the door, and sealed up most of the original port. I see little to no dust accumulation in the lower cabinet.
    You still had make up air entering the cabinet though. A lot depends on the capability of the DE being used, a one HP DE is not going to require the air entry of a Clearvue cyclone of course. Any cabinet that is sealed with no air entry is a dead end for dust extraction.
    Chris

    Everything I like is either illegal, immoral or fattening

  12. #27
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    Quote Originally Posted by Jim Becker View Post
    Dust collection is the most important power tool that you'll put in your shop.
    Agreed. Many approach dust collection as secondary to woodworking, therefore less essential and important. Could not be further from the truth evidenced from those that have had to give up WW due to reactions to short term or long term exposure.
    NOW you tell me...

  13. #28
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    You can't sell safety unfortunately and dust collection is not picking up the big chips but capturing the sub 5 micron dust that escapes when we machine wood. Give a person a choice between buying and installing a table saw or a dust extractor and guess what wins? I had a woman ring me one day and order a system because she was sick of laying in bed at night listening to her husband cough and he still didn't get the message and point blank refused to install dust extraction. Unfortunately bag type dust extractors pick up the big chips and recirculate the dust that does the real damage.
    Chris

    Everything I like is either illegal, immoral or fattening

  14. #29
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    Quote Originally Posted by Chris Parks View Post
    You still had make up air entering the cabinet though. A lot depends on the capability of the DE being used, a one HP DE is not going to require the air entry of a Clearvue cyclone of course. Any cabinet that is sealed with no air entry is a dead end for dust extraction.

    Agreed, starving the DC system for air can only be detrimental.

    My goal in sealing some gaps in the cabinet was to better direct the air stream. In my intuition (which may be faulty, given my lack of expertise in aerodynamics or fluid mechanics), dust collection is best served when the flow moves from a point at or near the origin of the dust (i.e., where the blade exits the cut) to the collection port rather from some more diffuse set of air inlets. Also, accelerating the flow at that point of origin (via some sort of venturi)may help to entrain dust in the flow.

    -- Jim

  15. #30
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    Quote Originally Posted by Chris Parks View Post
    You can't sell safety unfortunately and dust collection is not picking up the big chips but capturing the sub 5 micron dust that escapes when we machine wood...
    Some time ago I came to realize that some people think this way. But I beg to differ.

    To me, there are three levels: Chip collection, dust collection and air purification.

    Chris, you seem to be addressing the air purification level, which is of course the highest level. But this is not the only level that one might want in his shop.

    Air purification would be capturing sub micron particles. Not the goal of chip collection or dust collection, in my opinion.

    There may be one higher level I suppose: do not filter anything, just dump all the air collected by the system outside the work space. Then ALL particles sucked up by the system, of any size, are eliminated. This may be the ultimate solution if one is concerned about sub micron particles. But then it does not address whatever is not sucked up by the vacuum system. So the story never ends! 😀

    At at the end of the day, if we all understand the options we are in a position to make a decision, to do what makes the best sense for each of us.
    Too much to do...Not enough time...life is too short!

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