Intro: Easy DIY Downdraft / Sanding Table
Ok, so we have all been there, we finish a project that has had us totally tunnel visioned, engrossed in completion, only to look around your shop and realize that your shop has about an inch of dust on everything. I just finished a big project a couple days ago that involved bondo and LOTS of sanding, and needless to say, there is several square feet of bondo dust all over everything. I have tried many different methods to try to minimize the dust that is created when sanding something, but nothing really seems to make it better.
I decided that I needed a sanding table. Space is at a premium in my shop, bench space is at an even higher premium, like super premium, or something like that. There is an area in my shop close to my laser cutter that I built an exhaust. Basically just a Y-gate that diverts the exhaust from the laser to a home-built paint-booth that I built long ago. But if I am being carefull I will sand in this area. The paint-booth carries some of the airborne dust outside, and this room is isolated thereby semi-Quarantining the dust "virus" to one room. So I have the area picked out where I wanted to build it. Now I just needed to know how. I looked at many shop-vac style vacuums. But the amount of actual air (cfm or cubic feet per minute) was great for a 1 1/2 inch dia. hose, but not so great for a sanding table. I dont know, maybe I am wrong, maybe a shop-vac would work great. But I was not willing to buy a shop-vac for this purpose. It just seems like it would be underpowered.
So I looked for a way to create a large amount of suction. Or maybe just a way of moving large amounts of air. That is when I thought of a leaf blower. I figured that if it blows out a large amount of air, then it would suck an equally large amount of air, right? Then I would just need a way of attaching the sucking part to the bottom of the table, and something to collect dust. In my search for a leaf blower I ran accross the black and decker that I ended up using on amazon. It already had an attachment for suction, had great reviews, and had a bag that I could use to collect dust. I figured I would give it a try, so here we go.
Step 1: Parts
This is the parts that I used to make this project.
Parts and Materials
1. Black & Decker BV3100 12amp Blower/ Mulcher/ Vacuum -- Here is a Link to it on Amazon
2. 3' x 3' 1/4in MDF -- I got this from Menards a long time ago for something else and didn't use it.
3. 10ft pine 2 x 4 -- I had this left over from another project as well.
4. Window and Door Sealant -- Bought from my local Ace Hardware.
5. 4 M5 x 35mm Hex Head Bolts -- Here is a Link to it on Amazon
6. 8 M5 x 16mm Hex Head Bolts -- Here is a Link to it on Amazon
7. 4 M5 x 25mm Hex Head Bolts -- Here is a Link to it on Amazon
8. 1 1/2" wood screws, I used a lot of these, didn't count -- Bought these at my local Ace Hardware.
9. 1/4" Wood dowel -- Here is a Link to it on Amazon
10. 1/4" Birch Plywood -- Here is a Link to it on Amazon
11. 1/8" Birch Plywood -- Here is a Link to it on Amazon
12. M5 Washers -- Here is a Link to it on Amazon
13. M5 Nylon Lock Nuts -- Here is a Link to it on Amazon
14. 8ft Extension Cord -- Here is a Link to it on Amazon
15. SPST Light Switch -- I had this left over after converting my shop to smartthings. But anyway here is a Link if your not sure what they are.
15. Heat shrink for wiring splices -- Here is a Link to it on Amazon (This kit is awesome, I will not use another from now on)
Step 2: Preparing the Leaf Blower / Vaccum
I needed to prepare the leaf blower to make it so that I can attach it to the bottom of the suction box. It has a spring-loaded cover that will be in the way, so the first step is to remove that. I used a nail set and a hammer to easily hammer out the hinge pin so that the cover fell off. Next I measured and cut the vacuum attachment to be much shorter. I just used a sawsall to cut it ant it cut no problem. That is all I did to prepare the blower. Now I need to make an adapter to make it so that I can attach the vacuum end of the blower to the bottom of the suction box.
Step 3: Making the Adaptor
I needed to make some sort of adapter to make it so that the blower vacuum side would attach to the bottom of the sanding table. I decided the easiest thing would be to laser the part. I measured the parts and designed it in coreldraw. I designed it in many pieces so that I would not waste material. Because I wanted everything to match up when it was assembled I put 1/4in holes in the four corners so that I could just put it together and drop a 1/4in dowel in the corners so that when it is glued it will be perfect. This turned out to work perfect. I will definitely be using this technique again in the future.
I cut the parts on the laser out of 1/4in birch plywood and glued all of the parts together. I also designed a top plate out of 1/8in birch plywood that will go on the suction box to attach the adapter to. Once the adapter was all glued I sanded off the excess glue and cleaned it all up. Now it was ready to bolt onto the blower. First I used window and door caulking on the blower and then slid the adapter over the vacuum attachment.Then I used M5 x 25mm hex bolts to attach the blower to the adapter.
I included the adapter and top plate files below if you would like to make it yourself.
Step 4: Prepairing the Surface
I have used this bench for many years so there was many years worth of stain, poly, wood glue, and every thing else imaginable all over the surface of the bench. So I sanded it down with 150 grit paper to give me a flat clean starting surface.
Then I mapped out where I wanted the sanding table part of the bench to be, and how big I wanted it to be. If I made it too big I was afraid that it would not have enough suction, too small and it would not help out as much as it could with the dust plague. I settled on a 26in x 36in box and I cut my 3'x3' 1/4in MDF to that size. This would be the bottom of the suction box. I set the bottom of the box on the bench and lined it up and traced the edges with a pencil. Now that I know where I wanted the box to be, and the size of the box, I took a ruler and drew a 1" x 1" grid inside of the box that I traced on the bench.
I had everything marked out where I wanted it to be, in order to make sure that I put the box underneath in the same spot I drilled 4 1/4in holes just inside of the 4 corners, then pushed dowel rods down the 4 corners so that I could use them as guides when installing the suction box to the bottom of the bench. In preparation of getting the box installed I countersunk screw holes around the edge so that it would be easy to attach the suction box.
Step 5: Building the Suction Box
Now that I have the bottom of the box made I know the measurements for the box. I grabbed a spare 2x4 that I had and cut it on the miter saw, then layed it out on the drawn box on the bench to make sure everything was the size that I wanted it to be. Then I glued and screwed the four corners to make the edges of the box. I let the glue dry for a few hours and came back and put a layer of caulking on the 2x4 square that I had now and then added the bottom of the box and screwed it on. Now I had all sides except the top, which will be the bench itself.
Next I set the top plate that I cut before on the middle of the MDF and marked and cut with the jig saw. I did this because I did not want to have the adapter just hanging from the MDF because the MDF is pretty week and will break fairly easy. So, cut the hole, another round of caulking, then layed the top plate on and drilled holes and bolted it down. Then I could finally put a little more caulking and bolt on the adapter and vacuum attachment. Now the box itself was done and just needed to be screwed to the bottom of the bench.
Having the dowel rods in the 4 corners made it really easy to screw the box under the bench. I applied a layer of caulking around the top of the suction box, then I just lined it up, and then stuck something under it so it would stay and screwed it in from the top.
Step 6: Making the Downdraft Table Surface
Now the suction box is in place, It is time to drill lots of holes. This is where the grid pattern comes in. I used a countersink bit because I like the taper that it has, but the only hole bit for it I have is a 1/16in bit, which is too small. So I went back over every hole and drilled the holes out to 1/8in. It was a lot of drilling, 704 holes, drilled twice. After about 300 holes your arms start to hurt, lol. I also went around and filled all of the screw holes with wood filler, just to make it perty.
Step 7: More Sanding
This final sanding is just to remove the pencil marks and to make everything baby smooth.
Step 8: Wiring
I wanted an easy way to turn the table on and off. I went through one of my bins and found a SPST light switch that I had replaced when I installed smartthings in my shop. So I dissected an 8ft extension cord and snipped the black wire and ran it to the switch. I sacrificed a computer power cord that had the same gauge wire to reach the switch. I made sure to heat shrink every connection and put tape over the switch terminals, just in case. then I mounted the switch under the bench so I don't bump it when I am walking past it.
To clean up the cabling I used a few screwed cable mounts and tidied up the wires.
Step 9: Final Thoughts
I used the table for the first time. I definitely seems to cut the dust quite a bit. 100% better without a doubt. I think I will be replacing the bag that came with the blower for something specifically made for dust. But for now it works great. I am really happy with the way that it turned out. Thanks for taking the time to check this out.
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