Downdraft Sanding Tables

[Mike Griffin]

I would like to build a simple downdraft sanding table.  Does anyone own one or have information on how to build one?

Thanks

Mike

[Mark Scarborough]

Mike, I built a simple frame of 1x4,, with a solid 1/4 ply bottom and a pegboard top, then cut an opening to fit the hose on my shop vac,,

however, since then, I have simplified, I got a window fan from el cheapo source,, it has two fans side by side. I found a box it fit in and cut the bottom out, duct taping the fan to the bottom,, then I put a good quality furnace filter on the other side of the box, ( the open or top side),,, I stand this up on the edge of my bench when I sand,, its better than a down flow in my opinion as my balsa does not get scarred up on the hard surface any longer

[Mike Griffin]

Mark that sounds like a great idea.  If you get a chance, could you post a picture of it? 

Thanks for the help

Mike

[Bob Reeves]

I was in a hurry and didn't feel like building something so bought this..

http://toolsandmore.us/shop-fox-w1733-downdraft-table.aspx

Found this at Harbor Freight and used it to cover the top so the metal top wouldn't mar balsa. Wasn't able to find it on the HF web site but my local store usually has it.

http://www.northerntool.com/shop/tools/product_389438_389438

When I ordered the table I also ordered a Shop Fox dust collector like this. Looks like Shop Fox no longer has it but found this one at Harbor freight.

http://www.harborfreight.com/13-gallon-industrial-portable-dust-collector-31810.html

It has worked out really well. The dust collector moves allot of air, much better than a shop vac but is a bit noisy.

[Joseph Patterson]

    Thanks Mike, Mark, and Bob. The question and answers were  great info. for me. I need a cheap but good dust collector, and the vac.sanding table is a piece of equipment  I didn't know about. Of course, I gotta a lotta  "Don't Know Abouts".
    Doug 

[Randy Powell]

I built one that a Jett dust collector is connected to. Used PVC piping and some pegboard in a frame for surface. Works fine, but I only really use it when doing major sanding.

[Mike Griffin]

The reason I am asking this is because I have become very sensitive to balsa dust.  It makes me cough like crazy and burns my eyes bad.  I do wear a mask but was hoping that a downdraft table or a dust collector would help.  I have seen some on line where they just take a 20" box fan and attach a furnace filter to the back side and then just set the unit next to whatever they are sanding.  I am wondering if the set up would work horizontally.  For a example build a 1 x 4 frame  with a bottom in it and then place the fan in the frame face down then put your filter on top of that with the peg board on the surface.   That might not work because the sucked in air has no place to go....If the stand up fan with the filter would be good enough I could certainly rig that up.  I do not want to get to complicated but there should be an inexpensive way to rig up a downdraft table  with a fan inside rather than attaching a shop vac to an exit port.  Shop vacs make so damn much noise that I want to avoid that....some of you engineers jump in here and figure something out.   

[Dan McEntee]

   There was an article in Model Aviation that I think Windy wrote about building a table based on a box fan for the negative air pressure supply to draw the dust away and used a common furnace filter for it. I'm thinking it was late 80s or early 90's and if anyone can get close on the date I can look it up. AMA members can view back issues of Model Aviation on line at the AMA website and you can print out the article. Wish I had room and the time to build one. I'm beginning to have the same problem with dust, any kind of dust.
   Good luck and have fun,
     Dan McEntee

[Mike Griffin]

Dan it has gotten critical with me...it literally tears me up.  I have called Tom Morris on several occasions where he answered the phone and could hardly talk from inhaling balsa dust.  It is beginning to get me the same way.  I will go to the AMA website and see if I can find that article.  If you find it Dan, please post it because I am sure there are others that have the same problem...

Mike

[Eric Viglione]

I think the box fan could be a problem for any large volume of work... unless you can afford a sealed sparkless fan motor (not cheap), you don't want to pull the balsa dust through the motor or you risk an extreme fire hazard. The shop vac is noisey, but probably the safest bet. You can always  use a long hose and put the vac away from you or out the door.

I made some very cheap downdrafts. Went to HomeDepot and in the A/C ductwork isle, grabbed an aluminum A/C filter box, a filter, and a 1.5" PVC fitting that my Shop Vac would fit over. I cut a hole in the side of the filter box, mounted the PVC threaded fitting, dropped the filter in and I was done.

This is a small one, 12x12, I think the smaller one, the small area provides greater suction for small work like hollowing this tip block but you can buy larger filter boxes as well, up to 25"x25" I think. This pic was when I first built it, I have since cleaned up the sharp edges and added a filter retainer clip instead of clamps.

Hope that helps,
EricV

[Steve Helmick]

If you put one or two 20 x 20 furnace filters on the top (low pressure side) of the box fan, the filter elements should keep most of the dust out of the motor. Fan motors always get dust in them, but keeping it to a minimum would certainly be good. Vacuum any dust off the motor when it needs it. We used box fans in the machine shops, where they'd run for 8 > 24 hours a day for months, covered with dust and oil. They didn't really like aluminum chips inside the motor very well.  Steve

[Robert Zambelli]

A few years back, I designed and built a very simple downdraft workbench with storage space and a pegboard on one side.
It was featured in CL world. If anyone's interested, I will gladly send a copy of the article.

Bob Z.

[Ron Merrill]

Bob, that is pretty cool.

[Robert Zambelli]

This design works very well, is easy to build and reasonable in cost.
It's also VERY quiet.
I use it for both sanding and painting and my shop is virtually dust free.

I also designed and built a simple dust collection system for all my dust generating power tools: bandsaw, table saw, disc and belt sander and miter saw.

  Bob Z.

[Randy Cuberly]

Not to be a fly in the ointment, but given my past experiences in explosives and explosive safety I would simply like to remind everyone of the dangerous potential for dust explosions in an enclosed area.  If any of these devices are made and used they should be cleaned often.
As posted above if fan motors are used internal to the device they will represent a higher risk factor for such explosions.
Believe me we're talking about a lot of potential energy...in the realm of serious explosives such as dynamite.
If anyone doubts this just Google "Dust Explosions" and read.
Obviously the safest ones are those that use suction or pressure external to the dust collection area...such as the Shop Vac solutions.

Randy Cuberly

[john e. holliday]

Need a separate blower that sucks the air and is belt driven so the motor is not in the dust area.   All you need is just enough air movement to keep the dust inside the box and filter. 

[Robert Zambelli]

I have to put in my 2 cents now.
If you've ever had a shop vac apart, you'll notice that it has a universal motor (Mine did) and these motors use brushes which will indeed arc.
The fan I use in my bench has an induction brushless motor which produces no arcs or sparks.

Bob Z.

[Bruce Shipp]

A few years back, I designed and built a very simple downdraft workbench with storage space and a pegboard on one side.
It was featured in CL world. If anyone's interested, I will gladly send a copy of the article.

Bob Z.

Hi Bob, I’m setting up a new workshop and want a sanding table.  Is a copy of your article still available?

Thank you,

Brucd

[Robert Zambelli]

Yes.
If you wish, I can scan the article and post it here.
It was featured in Control Line World.
Bob Z.

[Robert Zambelli]

Hi, Bruce.
The article is in Control Line world, volume 2, number 4, October 2008, page 24.

I also did another outstanding (!) article on my dust reduction techniques for power saws and sanders.
It's featured in volume 3, number 1, January 2009, page 36.

If you have access to these two issues, all the info is there.
If not, I can scan and post them here.

Both devices work very well and my shop is virtually dust-free.

Bob Z.

[Bruce Shipp]

Thanks, Bob.  Please post them here. I don’t have access to CW back issues.

[Steve Dwyer]

Mike, I have asthma so I know how troublesome dust can be to our respiratory system. I too decided I needed to do something about the dust when I work in the shop so I built a downdraft sanding board. The key to having it work best is to keep it small, remember you want good downdraft velocity. The volume of available air and area determines the amount of draft you will achieve to draw the dust away from you. I built a 24 x 30 x 8 box with a tapered bottom to attempt to reach an even airflow across the top. I do my model building in my woodworking shop where I have a central dust collection system that provides good air volume in a 4" pipe. The perforated top works best. If you plan to connect to your shop vacuum I would not build a table larger than 12 x 16 otherwise I don't think you will be satisfied. You can always reduce the open surface area with duct tape to improve the capture.

Steve

[Steve Dwyer]

Mike And additional photo

Steve

[Steve Dwyer]

Tapered bottom

[Robert Zambelli]

Bruce - here's the information I promised you.

The other dust collection system is still to come.

Bob Z.

[Bruce Shipp]

Thank you, sir.  Greatly appreciated.

[Dennis Saydak]

Here's mine. It works very well with a 3 - speed box fan and two 20 X 20" filters under the top. The top is removeable for vacuuming the dust off the filters occasionally.

[Mike Griffin]

How in the world did an 8 year old post of mine get dug up again?   LOL. 

Mike

[Robert Zambelli]

What Steve Dwyer posted makes a lot of sense.
Even if one is not an asthmatic, airborne dust can wreck havoc with our pulmonary system.
As I get older I seem to be more sensitive to airborne particles, even to where I wear a mask when mowing my lawn.

The bench/dust collector works very well and I supplemented it with a simple dust collection system for my power tools, as shown in the photos.

Bob Z.

[Dwayne Donnelly]

How in the world did an 8 year old post of mine get dug up again?   LOL. 

Mike

I'm glad it did, I'm starting to develop problems with balsa dust as well. I started wearing a respirator while sanding but of course that does nothing for the dust in the air so I'm going to need a some kind of exhaust fan. 

[Robert Zambelli]

The two devices I made remove just about all dust from the room.
You can leave the bench open and the fan on even when you're not sanding.

Bob Z.

[Bruce Shipp]

How in the world did an 8 year old post of mine get dug up again?   LOL. 

Mike

LOL.  Just the way it’s supposed to, I recon.  I am starting a shop from scratch and I want to control the dust as it is in my basement mechanical and storage room.  As many here are prone to invoke the use of the search function, I did just that.  Bobs respond to this necrothread was just what I was looking for. 

[RogerGreene]

I bought a 20 x 20 cheap fan from Walmart a 20x20 filter tape the filter to the fan intake and sand away. It's cheap and portable. The filter gets clogged replace it of shop vac it.

My two ¢

Roger Greene

[Mike Griffin]

LOL.  Just the way it’s supposed to, I recon.  I am starting a shop from scratch and I want to control the dust as it is in my basement mechanical and storage room.  As many here are prone to invoke the use of the search function, I did just that.  Bobs respond to this necrothread was just what I was looking for.

That is great Bruce.  If it helps someone, I am happy.  By the way, I did build one back in 2013 and it worked well.  It has since been decommissioned and thrown away since.  I havent built anything in over a year now.

Mike

[Skip Chernoff]

I've been having the same problem with the balsa dust. You're not alone. Cheers,Skip

[Steve Dwyer]

Going back to the airborne dust issue in our shops another thought came to mind. In addition to having a downdraft sanding table I also made a "filter box" housing a standard Walmart box fan. Initially, I bought the highest efficiency 1" thick filter I could find and installed a standard 1" furnace pre-filter thinking it would help improve the longevity of the expensive higher efficiency filter. Big mistake, the high-efficiency filter was too restrictive to flow reducing the air cleaning in the shop providing little benefit to my lungs. To increase airflow I installed the lowest efficiency pleated media filter I could find and eliminated the prefilter which was of little benefit anyway. Installing a simple telltale on the fan I could see the air volume had improved.

Since I have no instrumentation available to measure airborne particulate count I kept an eye on the dust fall out on a surface near the workspace. I also visibly monitored the "fill rate" of the filter and discovered spraying furniture polish on the face of the filter improved the dust capture as well.

Knowing a typical 20" box fan develops approx. 2300 cfm and my shop being 18' x 18" with an 9' ceiling I would theoretically achieve about 2 air changes per hour based on an estimated 1200 cfm from the restricted filtered box. To eliminate the "bubble effect" surrounding a fan where the discharged air tends to circulate immediately back into the fan inlet I installed another box fan downstream 8' in series to assure I was instead getting a circular motion throughout the shop. To help further improve complete air circulation I positioned the fans on an angle to the center of the room.

The end result has been my cough has gone away and the trips to the pulmonologist have ceased as well. Of course, I always wear an N95 mask and no longer use dope in the shop, only in the garage while wearing a respirator. Every step is essential to staying healthy when you're an asthmatic.

Steve

[Bruce Shipp]

Here's mine. It works very well with a 3 - speed box fan and two 20 X 20" filters under the top. The top is removeable for vacuuming the dust off the filters occasionally.

Dennis, I finished my table tonight, all  but drilling the holes in the top. I basically copied your idea and pictures.

What size are the holes in your top?

Thanks,

Bruce

[Dwayne Donnelly]

I've started using a downdraft table and p100 mask, I still get a running nose but no more coughing,  it's nowhere near as bad as it used to be.