I want to build a downdraft table to collect sanding dust from my palm and random orbital sanders.
I’ll use a furnace filter, 20″ x 30″ as primary filtration and slope the interior of the box to increase efficiency.
Will an old fan from a microwave have enough oomph to do the job? I don’t know how much air it moves, but it is from GE’s largest built-in unit and has two speeds.
Would using my Shop Vac be better? Buying an Onida system is somewhere in the future, but the CFW, (Chief Financial Wife), has to OK the “capital outlay”…
Replies
After quite a bit of experimenting in the Fine Woodworking shop, I've come to the conclusion that a downdraft table isn't the best way to control sanding dust. To work at all, a downdraft table needs a large airflow, the kind generated by a 1 1/2 to 2 horsepower blower and even then some dust may still drift away.
The secret to good dust control is to buy a sander with good dust pick up built in and to hook it up to a small shop vac. This set up collects virtually all of the dust before it even gets a chance to go airborne. The vac can be a small inexpensive shop vac such as a Ridgid brand fitted with an after market HEPA style filter.
If you look on page 81 of the March/April 2007 issue of FWW you will see, in the top right corner, a picture of a sanding table I built for our shop. It is a downdraft table, but I found that hooking up the sander as shown to a small vac in the base cabinet completely controlled the dust and there was no need for the slatted table surface and a blower.
John White, Shop Manager, Fine Woodworking Magazine
I agree with john- go with the vac method, it gets the nasty before its in the air(and your lungs). That said we have a downdraft table in our shop that was built last year. It work great with our enourmous dust collection system( think 4 80 gallon bags).The secret is that you need a DC that moves A LOT of air. CFM. My probleems with the sanders are not dust but noise. If they figure out how to quiet down some of the pnuematics I'll finally be able to hear myself think...
north,
Not to rain on your parade but even if you could get the microwave fan to work, where is all the dust going? To get enough suction to pull the dust down, it has to be captured somwehere.
Another advantage to the shop vac approach is that you aren't tied to one place in the shop for sanding operations.
Regards,
Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
NH Guy,
Buying an Onida system is somewhere in the future
Are you speaking of the Oneida Dust Deputy?
If so, you need to convince your wife to let you pull the trigger. I bought one about 3 or 4 months ago. I have emptied the small drum 3 or 4 times. The finest dust I have ever seen - and not a speck in my ridgid shop vac filter. Your lungs will thank you - explain to your wife that it is more of a safety purchase than a tool purchase.
I would also agree with John WW - the downdraft table needs a very large blower to suck in the airborne dust. Think very large squirrel cage blower. I don't think the micro fan will do the trick.
Lee
If you have Porter Cable sanders with the round plastic filter, removing that will reveal a tube that looks like it's about 1" in diameter. I have one of their sanders and found a washing machine hose at Home Depot that fits perfectly on the sander's outlet. Better still is the fact that the other end fits perfectly onto the end of the small hose of a Shop Vac. No mods needed at all. This hose is light gray and corrugated, There's a plastic piece that snaps on, to form a curve that hooks over a stationary tub. This piece comes off and it's a lot less than the $29 Porter Cable charges. I think it was about $8
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