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Down Draft Question

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Forum topic by USCJeff posted 05-12-2007 05:01 PM 6598 views 0 times favorited 17 replies Add to Favorites Watch
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USCJeff

1044 posts in 2726 days


05-12-2007 05:01 PM

Topic tags/keywords: down draft dust sanding vacuum collection shop vac

I just finished up a project and am looking to make a shop upgrade before moving on. I want to create a makeshift down draft table for when I’m working on smaller projects. My shop has a row of base cabinets along one wall with a standard kitchen countertop on them. I want to cut out a small rectangular section (18”X18” or so) and make an insert for that section. I’ll probably use a clear plastic. My idea is to cut holes peg board style in the plastic. I’ll have to plastic attached to a small sealed dust collection box. I will put a hole in the box to accept a vacuum hose. I think I will dedicate a shop vac to this set up so the hose will be very hose will be very short. Will this create enough of a downwards draft? I estimate the hose will be about 6 inches from the top of the insert. Any suggestions to improve this set up? I’ve thought about putting this set up in my tablesaw where my router insert is as well, but I like the idea of the bench top better.

-- Jeff, South Carolina


17 replies so far

View oscorner's profile

oscorner

4564 posts in 2968 days


#1 posted 05-13-2007 01:57 AM

I don’t know about the downdraft question, but I feel by making your insert out of plastic you will create a static charge when pulling air across it. This will cause your dust to collect on the insert instead of passing though to the shop vac. I think you would do better to make you insert from plywood, it would be more stable and none conductive. Others may have first hand knowledge of this, I’m just going by the amount of static that is produced by my dust collection going through my seperator and hoses. Good luck on making it work.

-- Jesus is Lord!

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USCJeff

1044 posts in 2726 days


#2 posted 05-13-2007 03:00 AM

Good point, Os. I hadn’t thought about static. I liked the plastic as it is transparent and that will allow me to see the dust collection. Not a big deal. Like you said, plywood would work fine. I might skip and insert and just perforate a section of the counter top and install a box under the top in one of the base cabinets. I could keep the vac in there as well. I could install a switch to avoid opening the cabinet and turing the vac on and off. I use a lot of Walnut, and the dust irritates me more than other woods. Not sure why.

-- Jeff, South Carolina

View Bill's profile

Bill

2579 posts in 2819 days


#3 posted 05-13-2007 08:04 PM

I would say go with your new idea Jeff, and just make the holes in the counter top. Saves you one more thing to do, and should keep the counter top strong and stable.

I hear some people have allergies to various nut items, such as peanuts, walnuts, etc. Some are so allergic they can not have anything that has even a small amount. Maybe you are more sensitive to the wood because of a slight allergy to nuts? Anyway, a good thing to take precautions against.

Probably would be a good thing to have a dust mask as well.

-- Bill, Turlock California, http://www.brookswoodworks.com

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USCJeff

1044 posts in 2726 days


#4 posted 05-13-2007 09:10 PM

I need to invest in a respirator, Bill. I am good about wearing a mask, but I’ve been using the cheap surgical masks. They aren’t really meant for woodworking dust, but are better than nothing. I’m not aware of any allergies, but it makes sense as I normally don’t have any throat irritation with any other species.

-- Jeff, South Carolina

View gizmodyne's profile

gizmodyne

1763 posts in 2748 days


#5 posted 05-13-2007 10:40 PM

Here is a link to a shop made downdraft table plan. Free…http://users.goldengate.net/~kbrady/DustCollection.html#5

-- -John "Do I have to keep typing a smiley? Just assume it's a joke." www.flickr.com/photos/gizmodyne

View oscorner's profile

oscorner

4564 posts in 2968 days


#6 posted 05-14-2007 01:57 AM

Nice link, gizmo. USCJeff, I would suggest a charcol filtered mask; one made for poisons, etc. It will protect you when doing finishing as well.

-- Jesus is Lord!

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USCJeff

1044 posts in 2726 days


#7 posted 05-14-2007 04:33 PM

Thanks for the plan, John. My biggest concern is that I don’t know how much suction I need to make the down draft effective. Obviously the more of a draft the better. The air flow will be decreased as the airtight box gets bigger and as the hose intake gets further from the table top. Hole size could hurt as well I would think. I’m thinking I want to do maybe and 18”X18” area as it seems fairly small and would keep the intake hose very near the workpiece. I am using a larger shop vac for this and not the DC. I could rethink it for my DC, but I like the idea of having a good dedicated vac inside the cabinet.
~My question is, has anybody done this project, first. If yes, how would you rate the suction you are getting with your setup? Effective or Not?
~Would anyone suggest using a box fan and a high end filter over this project? That was the other idea I toyed with.

-- Jeff, South Carolina

View cajunpen's profile

cajunpen

14393 posts in 2723 days


#8 posted 05-15-2007 05:49 AM

Jeff, I know that the subject is a downdraft table, but might not hurt to take care of your lungs while you are at it. If you are having a reaction to walnut – then you can bet you are having problems with other woods also, just not as severe. I use the Trend Airshield in my shop, it’s a little pricey – but works like a charm. Very comfortable to wear and also offers a face shield.

Trend Airshield

-- Bill - "Suit yourself and let the rest be pleased." http://www.cajunpen.com/

View USCJeff's profile

USCJeff

1044 posts in 2726 days


#9 posted 05-15-2007 05:57 AM

I’ve seen those shields, and yes they are pricey. But. . . we’re talking about my lungs, so maybe I should ante up. I think I saw one of these in Mot’s shop when I was watching his tour. Might have been a different brand. He said he was on the fence about his. Something to think about though.

-- Jeff, South Carolina

View Bill's profile

Bill

2579 posts in 2819 days


#10 posted 05-15-2007 04:38 PM

Do those air shields bother you wearing them for a long time? I would think you would hear the fan running all the time through your skull, which would get a bit tiresome after a few minutes.

I was thinking of some type of air shield too, since I have asthma. Right now, I wear a dust mask, but it sometimes does not fit well over my beard. I like the idea of a downdraft table, as it will take a lot of the dust out of the air right away. That leaves less to breath through.

-- Bill, Turlock California, http://www.brookswoodworks.com

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USCJeff

1044 posts in 2726 days


#11 posted 05-15-2007 04:56 PM

I have heard the Trend is one of the more comfortable ones, but this is said with the preface that none of them are trly comfortable. My game plan is to set up my shop to reduce the amount of airborn dust so that I can get away with a normal woodworking disposable mask. There is no way that I have ever seen that would limit the dust enough to go without protection, but I think I can drastically filter the air. My shop lacks good ventilation. It is a one car garage with no windows. When the garage is open, no problem. If its closed, everything just hovers in the air. Big problem. I’ll have to brainstorm a decent way to pump out the dust. Maybe sometime of duct.

-- Jeff, South Carolina

View Bill's profile

Bill

2579 posts in 2819 days


#12 posted 05-15-2007 05:04 PM

Maybe you can build one of those box fan filters and fit it into a door? Then you can have fresh air entering, leave the garage door propped open a bit to let the air out. Or, do like jockmike did and have it recirculate from one end of the garage to the other with some ac ducting. Maybe make the intake low and the outflow near the ceiling, that would drive the dust downward.

Let us know how this goes.

-- Bill, Turlock California, http://www.brookswoodworks.com

View woodspar's profile

woodspar

710 posts in 2757 days


#13 posted 05-15-2007 05:06 PM

Jeff, one consideration that I have not heard mentioned is that there may be an amount of dust that gets deposited under the counter despite your best efforts. This, over time, might lead to quite a collection of dust under the counter. Might it not make more sense to fabricate a box that can be placed up on the counter that is sealed with the exception of the holes in the top and the hole for the vacuum hose? I also recommend that you use standard dust collection fittings (2 1/2 or even 4 inch) so that when you upgrade to “real” dust collector you will not have to retrofit anything.

-- John

View MsDebbieP's profile

MsDebbieP

18615 posts in 2818 days


#14 posted 05-19-2007 05:02 PM

I use the Triton respirator and I don’t mind it at all – but I haven’t used it in HOT weather. That might make a difference.
Battery pack is on the waist so not a problem. I don’t hear the fan at all, especially since there are hearing protectors built in. The only thing is that the dust eventually builds up on the face shield so I have a cloth nearby for a quick swipe every now and again.
I had found that working with the “fresh cut” pine was really bothering my eyes and lungs. Now – no problem.

-- ~ Debbie, Canada (https://www.facebook.com/DebbiePribeleENJOConsultant)

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Bill

2579 posts in 2819 days


#15 posted 05-19-2007 06:30 PM

Very nice review Debbie. Maybe you should blog a series on the respirator and other dust collection methods you have undertaken. I think it would be a big help to a lot of us. How well does it filter the air, how long do the batteries last, any restrictions on its use, etc.

Dust is definitely something you do not want to breathe if you can help it. The more dust you can filter out before breathing the better. If it is a respirator, or a dust collector, or working outside, whatever the method it is definitely worth knowing.

-- Bill, Turlock California, http://www.brookswoodworks.com

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