Another Down Draft Sanding Box

[Sycamore67]

After I saw the other downdraft sanding box, I thought that it would be useful to post mine that I built last year.  I think the idea of a downdraft box is really good for reducing the amount of dust.  This is especially important as sanding dust is very fine and the most harmful kind of dust.  

I made the box about 24†square and 6†tall. The sides are 1/2†plywood and the top is 1/4†pegboard which originally had 3/16†holes. I got it together and attached a 4†dust collector port on one side. I tried it out with my dust collector and found that it was not pulling much air and I needed to increase the hole sizes.

Around the outside, I drilled the holes to 1/2†diameter and also increased the holes sizes in a couple of other areas. The result was increased air flow and better collection of the dust. There is a noticeable improvement in the air quality in my shop and very little escaping the downdraft box.

I am currently using it to sand some small boxes and needed to be able to sand the lid and bottom flat. I glued some old sanding belts to 1/4†MDF using 3M Super 77 spray adhesive. I also glue up a couple of sheets of sand paper the same way.  I also will cover part of the top at times to direct more of the suction to where I am sanding something.  

One note is that I did not put any internal baffles in the box and it works fine in my case without them.

I actually measured the amount of air that is being pulled through the holes and it is about 600 cfm at a static pressure of 10.3".  I am using a large cyclone dust collector.  

 

[hawkeye10]

 

After I saw the other downdraft sanding box, I thought that it would be useful to post mine that I built last year.  I think the idea of a downdraft box is really good for reducing the amount of dust.  This is especially important as sanding dust is very fine and the most harmful kind of dust.  

I made the box about 24†square and 6†tall. The sides are 1/2†plywood and the top is 1/4†pegboard which originally had 3/16†holes. I got it together and attached a 4†dust collector port on one side. I tried it out with my dust collector and found that it was not pulling much air and I needed to increase the hole sizes.

Around the outside, I drilled the holes to 1/2†diameter and also increased the holes sizes in a couple of other areas. The result was increased air flow and better collection of the dust. There is a noticeable improvement in the air quality in my shop and very little escaping the downdraft box.

I am currently using it to sand some small boxes and needed to be able to sand the lid and bottom flat. I glued some old sanding belts to 1/4†MDF using 3M Super 77 spray adhesive. I also glue up a couple of sheets of sand paper the same way.  I also will cover part of the top at times to direct more of the suction to where I am sanding something.  

One note is that I did not put any internal baffles in the box and it works fine in my case without them.

I actually measured the amount of air that is being pulled through the holes and it is about 600 cfm at a static pressure of 10.3".  I am using a large cyclone dust collector.  

 

Good looking sanding box Larry. How in the world did you measure the amount of air that was going through the holes? That has got me bum fuzzled. 

[Sycamore67]

I spent a lot of time when I got a new dust collector and developed the performance curve for it.  This is a curve of the cfm versus static pressure.  I used a hot wire anemometer to measure velocity and converted it to cubic feet per minute.  I also measured the static pressure or the vacuum with a digital gauge.  This all takes a bit of time but something I wanted to do.  For most people, this is not something that they want to do.   For your information, the dust collector is a 5 hp Oneida Super Dust Gorilla.  

 

Once I have the performance curve it is easy for me to read the static pressure at any time and then read the flow off my graph.  

 

Most of the companies that sell dust collectors really exaggerate the claims of cfm.  In my case, Oneida who made mine published a curve that was almost exactly what I measured.  There are several relatively good sources for "real" dust collector performance.  Wood Magazine has published some good data and even has the Harbor Freight Dust Collector that they tested.

[nrscroller]

Hi

YOurs is like mine only mine is lots smaller,works great with shop vac hooked to dust deputy!

nrscroller

[Sam777]

Larry,

I love what you did. The performance curve that is

Just kidding. Great job. This inspires me to do the same. I have a digital anemometer but I am not sure how to test manually test static pressure.

I think, experimenting is half the battle. who needs all this tech stuff wjen you see where the dust is going

Thank you for sharing

Sam

[Sycamore67]

The problem with seeing where the dust is going is that you can not see the fine stuff and it is the most hazardous.

 

I tried using a digital fan anemometer and it is extremely difficult to get accurate readings.

 

You can measure static pressure with a homemade water u-tube manometer.

 

If anyone is interested, I documented how I did my tests, using a water manometer, and issues/problems with a fan type anemometer. I posted a series of blogs on the Lumberjocks forum under the name RedOak49

[amazingkevin]

 

After I saw the other downdraft sanding box, I thought that it would be useful to post mine that I built last year.  I think the idea of a downdraft box is really good for reducing the amount of dust.  This is especially important as sanding dust is very fine and the most harmful kind of dust.  

I made the box about 24†square and 6†tall. The sides are 1/2†plywood and the top is 1/4†pegboard which originally had 3/16†holes. I got it together and attached a 4†dust collector port on one side. I tried it out with my dust collector and found that it was not pulling much air and I needed to increase the hole sizes.

Around the outside, I drilled the holes to 1/2†diameter and also increased the holes sizes in a couple of other areas. The result was increased air flow and better collection of the dust. There is a noticeable improvement in the air quality in my shop and very little escaping the downdraft box.

I am currently using it to sand some small boxes and needed to be able to sand the lid and bottom flat. I glued some old sanding belts to 1/4†MDF using 3M Super 77 spray adhesive. I also glue up a couple of sheets of sand paper the same way.  I also will cover part of the top at times to direct more of the suction to where I am sanding something.  

One note is that I did not put any internal baffles in the box and it works fine in my case without them.

I actually measured the amount of air that is being pulled through the holes and it is about 600 cfm at a static pressure of 10.3".  I am using a large cyclone dust collector.  

 

 

Your doing just fine with collecting dust,Great ideas!

I spent a lot of time when I got a new dust collector and developed the performance curve for it.  This is a curve of the cfm versus static pressure.  I used a hot wire anemometer to measure velocity and converted it to cubic feet per minute.  I also measured the static pressure or the vacuum with a digital gauge.  This all takes a bit of time but something I wanted to do.  For most people, this is not something that they want to do.   For your information, the dust collector is a 5 hp Oneida Super Dust Gorilla.  

 

Once I have the performance curve it is easy for me to read the static pressure at any time and then read the flow off my graph.  

 

Most of the companies that sell dust collectors really exaggerate the claims of cfm.  In my case, Oneida who made mine published a curve that was almost exactly what I measured.  There are several relatively good sources for "real" dust collector performance.  Wood Magazine has published some good data and even has the Harbor Freight Dust Collector that they tested.

i had a air flow meter given to me but i think it got lost.It was a cool device.A man that designed dust collection systems for factorys gave it to me years after he retired.

 

The problem with seeing where the dust is going is that you can not see the fine stuff and it is the most hazardous.

 

I tried using a digital fan anemometer and it is extremely difficult to get accurate readings.

 

You can measure static pressure with a homemade water u-tube manometer.

 

If anyone is interested, I documented how I did my tests, using a water manometer, and issues/problems with a fan type anemometer. I posted a series of blogs on the Lumberjocks forum under the name RedOak49

Thanks for enlightening us with your knowledge.

[Sam777]

The problem with seeing where the dust is going is that you can not see the fine stuff and it is the most hazardous.

 

I tried using a digital fan anemometer and it is extremely difficult to get accurate readings.

 

You can measure static pressure with a homemade water u-tube manometer.

 

If anyone is interested, I documented how I did my tests, using a water manometer, and issues/problems with a fan type anemometer. I posted a series of blogs on the Lumberjocks forum under the name RedOak49

 

Larry,

If you don't mind, would you please put a link to your write-up about the diy water u-tube manometer? I am a member of that forum but how would I find you document?

Thank you

Sam

[Sycamore67]

Here is a link to the Blog I created on Lumberjocks about using a homemade manometer to monitor your dust collector.

 

I have some other blogs on Lumberjocks about testing dust collectors and about my dust collector.