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Speaking of Toxic dust (down draft table)
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Author:  LanceK [ Thu Dec 20, 2007 11:31 am ]
Post subject: 
I am looking to buy a good down draft table, does anyone have any opinion on this one?



I thought about getting a fein shop vac to attach to my ROS, but that does not address the "hand sanding" issues. A DDT would.

Any thoughts? Pros, cons and other options welcome!
Thanks!
Author:  LanceK [ Thu Dec 20, 2007 11:33 am ]
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Here is the link to Grizzlys site.

Down Draft Table
Author:  Bill Greene [ Thu Dec 20, 2007 11:43 am ]
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Lance, a buddy of mine has a big DDT like that one. I'm fairly certain it isn't a Grizzly, but it looks very similar. He's a master woodworker. Builds grandfather clock cases, custom shadow boxes, stuff like that.

Anyway, his is ducted with 6" pipe, and an impeller that, literally, came off a battleship. You can stand near the thing and feel the air movement. They work fantastic IF you have the ability to move high volumes of air through'em.

Bill
Author:  joe white(old) [ Thu Dec 20, 2007 11:47 am ]
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Lance, Last spring I went to a tool expo in Shipshewana Indiana. They have them quite often around here with all the local Amish woodworkers. at any rate, there was a gentleman there that was making a very nice downdraft table, different sizes and whatnot. They are made in Mishawaka or Elkhart and the guy even said I could come by sometime for a tour during production. I will try and dig his card out, I think they had a web site.
Author:  Hesh [ Thu Dec 20, 2007 11:58 am ]
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I wanted one too for a while until I discovered that they require a major air cleaner to move tons of air to work properly - but you have that already Lance so you are good to go there.

And you know that My ROS and vac are Festools and this is with HEPA filters.  Highly recommended by the way and several OLFers just bought these combos too.

These days I just place a portable air cleaner on the bench near where I am sanding and it all gets sucked into that.

My only concern, and this is probably not an issue for you, is that these tables are one trick pony's - they take up a lot of space regardless of if you are using them or not.  Have you considered a down draft table insert that you build into a bench, plumb to your dust extractor system, and cover and use the bench for other things when not in use?  Several good looking systems are available and they are far cheaper too.  Plus you get the added benefit of another work bench when not sanding.
Author:  LanceK [ Thu Dec 20, 2007 12:22 pm ]
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Hesh, this unit does not plug in to a dust collector. It has a big fan that sucks air, and its filtered through an exhaust back in to the shop.

I have a delta down draft table that plugs in to my cyclone and its not worth the space it takes up. It is pretty much worthless.

Here are some details on the Griz.
Suction Capacity: 1600 CFM
Filter size: 16" x 25" x 2"
Filter micron: 0.5
Author:  DannyV [ Thu Dec 20, 2007 12:29 pm ]
Post subject: 
Lance,
Just wondering what the cfm movement on your cyclone is? I've looked at
the Delta's and wondered how they would work or easy enough to build your
own to plug into your dust collection.

Best of the Season
Danny
Author:  Jon L. Nixon [ Thu Dec 20, 2007 1:32 pm ]
Post subject: 
Rockler sells down-draft table plans and a kit with the fan and other parts. It looks well- designed, although I have never talked to anyone who has built or used one.
Author:  Jon L. Nixon [ Thu Dec 20, 2007 1:49 pm ]
Post subject: 
Link is:
http://www.rockler.com/product.cfm?page=10169&filter=downdra ft.

Sorry, left this off of my previous post.
Author:  AndrewGribble [ Thu Dec 20, 2007 3:10 pm ]
Post subject: 
Lance, I too am curious about your current Delta table (what model
#?).  Does it just not suck?  I think I saw a similar table
at the local place though they had sold out of the sale model before I
arrived.



That Grizzly model looks really nice, but I imagine it might take up a lot more space the the Delta.  But I bet it definitely sucks!


Author:  Kahle [ Thu Dec 20, 2007 7:18 pm ]
Post subject: 
Looks like it might take up some real estate in the shop but who says you
can't cut a carpet square and a piece of 3/8 ply that fits the top and use it as
another small bench when it is not in use.
Author:  LanceK [ Fri Dec 21, 2007 12:38 am ]
Post subject: 
[QUOTE=Kahle] Looks like it might take up some real estate in the shop but who says you
can't cut a carpet square and a piece of 3/8 ply that fits the top and use it as
another small bench when it is not in use.[/QUOTE]

My thoughts exactly.

Andrew, its the table found at Lowes. Or at least that is were I found it. I thought it was my smallish dust collecter at first, but after getting a Penn Ind Cyclone installed, its still pretty worthless.

I have seen the smaller grizzly table in person and it looks and works great. Just to small. So I think this larger unit would be perfect.
Author:  sharp_custom [ Fri Dec 21, 2007 1:34 am ]
Post subject: 
Lance: I like that down draft table a lot for the price and would recommend it. The Delta ones from lowe's are horrible. Obviously the Grizzly DDT will take up a lot more space but I think it's worth it!
Author:  sharp_custom [ Fri Dec 21, 2007 1:56 am ]
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Oh, I forgot to mention that I am going to purchase a Denray DDT. I like their new tubular filtration system. It drops most of the dust into a "Drawer" that makes cleaning filters a lot easier and less frequent. they're a bit pricey but I really like the features and specs.
Author:  Wade Sylvester [ Fri Dec 21, 2007 2:20 am ]
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Just curious. Does anyone know how noisy these DDTs are?

Wade
Author:  uncledave [ Fri Dec 21, 2007 3:16 am ]
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Hey guys,

http://BillPentz.com/woodworking/Downdraft.html

A fine discussion on downdraft tables, and other parts of his site deal
with dust collection in general. He is well thought of (and linked to) by
the company that Tim McNight's mini cyclone collector came from.

Check it out

Dave

PS I'll go back into lurk mode now,,,
Author:  Chas Freeborn [ Fri Dec 21, 2007 4:19 am ]
Post subject: 
The type of air movement is different from a DDT with a blower or large
diameter fan and a dust collector. I had it explained to me by an
"industrial hygenist" friend once and I'm sure I'd mix up the terminology-
something like "static pressure, vs cfm, velocity vs volume, measured with
a manometer.... In simple terms it has to do with pressure vs volume. You
want to move a large volume of air, but not necessarily very fast. For a
DDT a you want volume which is better acomplished with a blower.
Anyway, like Lance says the dust collector/table top units are pretty
worthless.
I built my rig very hastily with a yard sale blower, a scavenged 1/3 hp
motor and filters I got from my local filter supplier. (yes, Grumpy we have
stores that sell nothing but filters around here!)
While building it I learned alot about filtration and air flow, so I'd do a
number of things differently.
My friend and fellow local builder Mike Doolin has his built right into one
of his benchtops. He'll leave it running constantly during dusty days to
filter the shop air.
The grizzly unit looks good. The only concern I'd have is import motors,
having toasted a few, but this isn't a high load situation so it should be
okay.
If there's enough interest I'll draw up a design for a shop made unit. I
-C
Author:  Steve Saville [ Fri Dec 21, 2007 4:40 am ]
Post subject: 
I've been thinking about making one and hooking it up to my 2hp dust collector. It is listed at 1550 CFM. If I make the table large enough for a guitar body, it seems that it would work. A couple of sheets of ply wood and a couple of hours of work should do it.
Has anyone tried this?
Several years ago I made a vacuum table for screen printing from MDF that work great. I small fan provided plenty of suction.
Author:  Howard Klepper [ Fri Dec 21, 2007 6:11 am ]
Post subject: 
The Griz H2935 is another viable option at 23" x 31". Not big enough for a whole guitar, but OK for separate body and neck. I see that there are three different filter efficiencies on the Grizzlys; some are 5 micron, other 1 micron, the one Lance showed and the 2935 are .5 micron. I'm thinking to put one in the new shop next year, but I will have a good central collector, so it would probably be more economical to run a duct to a passive table. Thing is, I don't want to spend much time on it; I'd rather buy one that is well designed for the airflow, etc. So how critical is the inside design for good airflow? Is it just a box with holes in the top and a duct somewhere on bottom, or does the interior need to be some kind of cyclone or something?
Author:  PaulK [ Fri Dec 21, 2007 6:23 am ]
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[QUOTE=Chas Freeborn]If there's enough interest I'll draw up a design for a shop made unit.


Chas, I'd be interested in seeing a design for a shop made unit. Would a squirl cage fan from a furnace be of any use in one?


Paul
Author:  Howard Klepper [ Fri Dec 21, 2007 6:27 am ]
Post subject: 
Putting it a bit differently: How do you empty the dust out of a unit like the Griz? The website shows filters, but no bag. Do you get a big pile of dust in the bottom of the box that has to be scooped or vacuumed out? That would be a big PITA. Seems that a good table would have a cyclone action that dumps most of the dust in bag that is disposable or easily removed and emptied, with a filter for the really fine stuff that passes the cyclone. Does anyone sell a table with an internal cyclone system?
Author:  LanceK [ Fri Dec 21, 2007 6:36 am ]
Post subject: 
Howard, I was orginaly looking at that smaller model, but for 100.00 more you get the larger table, and the motor is a 1/2 hp instead of a 1/3. Plus it pulls 1600 cfm. The smaller unit is rated 1300 cfm.
Not a bad bargin for another 100.00
Author:  John How [ Fri Dec 21, 2007 6:41 am ]
Post subject: 
The cadilac of downdraft
Author:  Chas Freeborn [ Fri Dec 21, 2007 7:17 am ]
Post subject: 
Howard- there's a little drawer that catches the big chunks that you pull out
and empty. Pretty straight forward, and compared to emptying the can on
my cyclone, super easy. The fine stuff gets caught in the filter.
My design uses two stage filtering, with a relatively cheap pre-filter that
gets the worst of it.
I'll draw it up when I get a minute this weekend.
Not sure about a HVAC blower- I'll measure mine and report back.
-C
Author:  j.Brown [ Fri Dec 21, 2007 8:12 am ]
Post subject: 
Looking forward to seeing that, chas
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