Easy Downdraft Sanding Box

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Project by JohnMcClure posted 12-31-2018 12:49 PM 3210 views 6 times favorited 10 comments Add to Favorites Watch

Pretty simple shop project, used scrap I had on hand.
Build a basic box, cut a dust collection port in one end, and form a ramp to encourage dust toward the dust collection end:

I used BB ply to make crosspieces to support the top. If you wanted to take this very seriously you should optimize the shape and orientation of the runners to maximize airflow; I did not.

Caulked everywhere, top secured with recessed screws to avoid scratching, painted outside with leftover paint to protect from moisture.

This seems not only useful for sanding, but also for standing up in front of dusty activities like circular saw use.

-- I'd rather be a hammer than a nail

10 comments so far

View EarlS's profile


4446 posts in 3426 days

#1 posted 12-31-2018 01:25 PM

John – thanks for posting your downdraft table. I like the design. I’ve been pondering whether to make one, or incorporate one into my assembly table so I have questions:

I’ve always wondered how much a downdraft box would help with dust if I’m using a ROS hooked up to a shop vac. I’m also curious how noisy one would be when you are sanding. It seems like it would be a big echo chamber.

What have you noticed with yours? How is yours set up? Does it sit on top of a bench? Is it clamped down? Do you use a sponge pad under the piece being sanded? Any other thoughts or recommendations?

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"

View Redoak49's profile


5234 posts in 3066 days

#2 posted 12-31-2018 01:30 PM

I built a very similar one. I ended up increasing the size of the holes to get sufficient air flow. I wanted as much air flow as possible. I enlarged the holes around the outside and some in the middle and it improved dust capture.

View JohnMcClure's profile


1254 posts in 1718 days

#3 posted 12-31-2018 01:57 PM

I hope to provide an update on performance tonight or tomorrow once I get the chance to use it.
The plan is to set it on my assembly table without clamping, but if needed it would be easy to clamp down. I typically place a piece of drawer liner under the workpiece when sanding, I expect that will do the trick with this.

Redoak, regarding hole size – I was at rockler the other day and noticed theirs (didn’t look at price) had large holes (half-inch or larger), and much fewer of them. Considering that, and your comment, my solution is probably sub-optimal by a good margin. That being said, my scrap pegboard was free and i didn’t have to put any thought into hole size or placement, so in this case, “Good enough” might just be! We’ll see!
Did you start with pegboard and just drill out some holes larger? Or start with a solid board and drill fewer, larger ones?

-- I'd rather be a hammer than a nail

View EarlS's profile


4446 posts in 3426 days

#4 posted 12-31-2018 03:06 PM

If you count the number of holes in the table and figure out the size (and area) of each one you can determine the total open area for the table. Then determine the area of inlet. You want the total area of the holes to be the same or slightly larger than the inlet cross sectional area. That ensures the table isn’t restricting the air flow.

If you have a 4” inlet – Area = pi * r^2 = 12.56 in^2
Typical peg board has 3/16” holes. Area = 0.0276 in^2
You would need 455 holes to get enough open area (assuming my math is good).

Rough count 30 rows x 18 columns = 540 so there are enough holes. Of course the further away from the inlet the holes are the worst the vacuum so if you decided to drill out holes, I’d consider the ones furthest away from the inlet. The larger holes will partially offfset the reduced vacuum in the back of the box. As you suggested, try things out and then make small changes.

I’m very interested in hearing your first impressions using this.

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"

View woodchuckerNJ's profile


1483 posts in 2712 days

#5 posted 12-31-2018 03:16 PM

I made one years ago. The holes are too small, you will need to enlarge them and chamfer them. Then it will do a better job. It needs to breathe and the small holes will starve it. Like sipping a milk shake through a bar straw.

-- Jeff NJ

View IantheTinker's profile


285 posts in 1205 days

#6 posted 12-31-2018 04:55 PM

I like that you made it from materials you had at hand. I dislike that so many others go out and purchase things for every project, especially when it is just a shop project. Looks good and I hope it works well for you!


View splinterpicker's profile


74 posts in 1230 days

#7 posted 01-01-2019 12:56 AM

I was getting ready to build one of these as part of a few major upgrades to my shop. Everyone’s feedback is helpful (thank you all)… and I can’t wait to hear how this one works!

View HankLP's profile


146 posts in 1580 days

#8 posted 01-01-2019 01:53 AM

Looks good, and you will be glad to have it. Have a similar one very close to the same size. Works great, plenty of airflow with the harbor freight DC, and things don’t fall in the small holes. Only problem is the white pegboard rubs off white paint on the item being sanded. I use some scrap to raise the item off the table, or put down some paper under the item. I also cover it with paper and use it for applying finishes. And the pegboard is easy and cheap to replace. Some day I will try the brown board and see if that also rubs off on my work.

View gailmo's profile


34 posts in 2116 days

#9 posted 01-01-2019 03:07 PM

I made one of these and use it primarily when I sand cutting boards. I took some scrap strips of wood and put 2 dowels in each piece. The dowel size is the same as the hole size of the pegboard. I then can use the wood strips to hold the cutting board in place by fitting the dowels into the holes. By the way, I also drilled out the pegboard holes to give better suction. It works pretty well – but I still have my sander attached to a shop vac and have the overhead Wen unit running and wear a mask. With everything running, it makes quite a racket—but keeps the dust down in my shop.

View Joe's profile


560 posts in 2164 days

#10 posted 01-05-2019 01:07 AM

This is a great idea, glad to see it works so well. I have a commercial version that I got at a wood tool auction. Its portable and does a good job but it only has a 2 1\2’” opening for the dust collector. It does have a black mesh material used to hold projects in place mounted over the holes, it protects the project while sanding. I have to use a reducer to connect it to my 4’ vacuum system, I’m sure I lose CFM’s. Thanks for Sharing, Joe

-- CurleyJoe, "You only learn from your mistakes"

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