By Martin Harris.

Drum Sander Dust Collection

A drum sander needs a real dust collector. The drum sanders I looked at from JET, SuperMax, and Grizzly all use a 4 inch dust port, and their makers ask for roughly 400 to 600 CFM at that port. CFM means cubic feet per minute, the volume of air moving through the hose. A shop vac cannot move that much air, and a small collector at the end of a long hose often cannot either.

This page covers the manufacturer numbers, how to size the hose and duct so you actually get that airflow, and how to handle the fine dust a drum sander makes. If you run other kinds of sanders too, my sander dust collection guide covers random orbit and benchtop machines.

What the manufacturers ask for

The best starting point is your own sander's manual. The makers know how their dust hood is shaped and how much air it takes to clear it. Here is what four drum sander manuals and support pages say.

Figures as published by each maker. These are airflow targets at the sander's port, which is different from a collector's rated CFM. Check the manual for your exact model.

Two things stand out. Every one of these machines uses a 4 inch port, and the airflow targets are higher than many people expect for a sander. SuperMax adds that some jobs will need more than its 600 CFM minimum. My sander page quotes WorkshopCalc's reference chart at 350 to 450 CFM for drum sanders. The manuals run a bit higher than that, so I would plan around the number in your manual.

Plan the power side too. JET's listing for the JWDS-1632 calls for a 20 amp circuit at 115V for the sander alone. If your dust collector shares that circuit, you can trip the breaker when both motors run. Put the sander and the collector on separate circuits.

Why drum sander dust is harder to catch

A planer throws heavy chips that fall into the hood on their own. A drum sander makes powder. Most of it is fine dust, and fine dust rides the air instead of falling. Particles in the 10 to 30 micron range are big enough to see and settle fairly fast. Particles under 10 microns stay in the air much longer, and those 2.5 microns and smaller are the ones that matter most for your lungs. A micron is one thousandth of a millimeter.

The drum also spins across the full width of the board, so dust comes off along the whole contact line. The dust cover over the drum works as a hood. When airflow is too low, you see a haze of dust drift out of the infeed and outfeed openings, where the board goes in and comes out. That haze is the fine dust you most want to catch.

OSHA's wood dust guidance names local exhaust ventilation, meaning collection right at the point where dust is made, as the main engineering control for wood dust. On a drum sander that means strong airflow at the dust cover. My page on whether sawdust is dangerous covers the health side in more detail.

Rated CFM versus CFM at the sander

A collector's rated CFM is measured with nothing attached. Your hose, duct, fittings, and filter all slow the air down. Woodcraft's article on dust collection for a one-man shop measured this. A 1 HP collector rated around 650 CFM delivered about 420 CFM through 6 feet of 4 inch flex hose, and fell below 300 CFM after a 25 foot run of 4 inch pipe. Several 1.5 HP collectors rated around 1,200 CFM measured roughly 470 to 500 CFM through similar hose.

Compare those numbers to the table above. A 1 HP collector parked next to the sander with a short hose might reach JET's 400 CFM minimum. The same collector across a garage will not. SuperMax's 600 CFM figure points toward a larger collector with a short, wide duct run.

The resistance that slows air down is called static pressure. It is measured in inches of water column, written as in. w.c. The more hose and fittings you add, the more static pressure the fan has to overcome and the less air reaches the sander. My guide to dust collector static pressure explains it step by step, and the dust collector size calculator lets you run your own shop layout. If you are still choosing a collector, see 1 HP vs 2 HP dust collectors.

Sizing the hose and duct

The 4 inch port is the bottleneck. Air speed in a duct equals CFM divided by the duct's cross section area. Air speed is measured in feet per minute, or FPM. OSHA gives about 2,500 to 4,000 FPM as the duct speed needed to keep wood dust and chips moving. Faster than that and you pay for it in static pressure, because resistance climbs quickly as air speed goes up.

Here is how much air each duct size carries at about 4,000 FPM. The numbers come straight from the area of the pipe, and they match the capacity figures Bill Pentz publishes.

Calculated from duct cross section area (CFM = FPM times area in square feet). Capacity at 4,000 FPM matches Bill Pentz's published duct figures.

Pushing 500 CFM through 4 inch hose means about 5,700 FPM. At 600 CFM it is close to 6,900 FPM. That is well past the useful range, so a long 4 inch run will choke the airflow your sander needs. The fix is to run 5 or 6 inch duct as close to the sander as you can, then drop to 4 inch only for the last few feet. My comparison of 4 inch vs 6 inch dust collection goes deeper on this choice.

Flex hose is where most drum sander setups lose air. Oneida's static pressure data, measured at about 4,000 FPM, puts 1 foot of 4 inch flex hose at 0.280 in. w.c. and 5 feet of 4 inch rigid pipe at 0.285 in. w.c. So 6 feet of 4 inch flex costs about 1.7 in. w.c., the same as roughly 30 feet of rigid 4 inch pipe, which is why flex belongs only on the last few feet at the machine.

Setting up the connection

1. Give the sander its own blast gate. A blast gate is a slide valve that opens or closes a branch. Close every other gate while you sand so all of the collector's air goes to the drum sander. See how to install blast gates.
2. Run the largest rigid duct your collector supports. Bring 5 or 6 inch pipe to within a few feet of the machine.
3. Reduce to 4 inch at the machine. Put the reducer close to the sander so the narrow section stays short.
4. Use gentle fittings. The SuperMax manual says straight pipe is the least restrictive, and that wyes and elbows restrict airflow less than tees. My dust collection fittings guide compares the options.
5. Clamp the hose to the port. A loose connection pulls room air in at the port instead of pulling air through the dust cover.
6. Start the collector before you feed the board. Let it run for a moment after the last pass to clear dust still inside the cover.

Why a shop vac usually falls short

A shop vac is built for high suction through a small hose. It moves a small volume of air very hard. A drum sander needs the opposite: a large volume of air through a big dust cover. JET's older 16-32 Plus manual allowed a shop type canister vacuum of 16 gallons or larger, but only for short periods of sanding, and only with the hose reduced to 2-1/2 inch. The maker treated it as a stopgap.

The math shows why. A 2-1/2 inch hose at about 4,000 FPM carries around 136 CFM. Even with the vac pulling harder than that, it stays far below the 400 CFM minimum in JET's current spec. The dust cover is sized for a collector, so a vac leaves most of that space with weak airflow and the fine dust drifts out the openings.

If a vac is all you have for now, sand in short sessions, put a cyclone separator such as the Oneida Dust Deputy Deluxe ahead of the vac so the filter does not clog in minutes, and use a HEPA filter. My dust collector vs shop vac comparison explains the tradeoff, and my best shop vacs for woodworking page covers the vacs that handle fine dust best.

Filters, separators, and bins for sanding dust

Sanding dust is hard on filters because almost all of it is fine. On a single-stage collector, everything passes through the fan and into the bags, so the upper filter bag loads up fast. A loaded filter adds resistance, and the airflow at your sander drops even though nothing else changed. A pleated canister has more filter area than a bag of the same size, which helps it hold more dust before airflow suffers. See canister vs bag filters and 1 micron vs 5 micron filter bags.

A cyclone separates most of the dust before it reaches the filter, which keeps the filter cleaner for longer. It costs some airflow in return. Oneida suggests budgeting about 2 in. w.c. for a cyclone as a starting figure. If a drum sander is your main machine, that trade often pays off. My best cyclone dust collectors page covers the options, and how to clean a dust collector filter covers upkeep.

Common problems

• Dust drifting out of the infeed and outfeed. Check for an open gate on another branch, a long flex hose, or a loaded filter before you blame the collector. My weak suction troubleshooting guide walks through the checks.
• A small collector on a long 4 inch run. Woodcraft's measurements show a 1 HP unit dropping below 300 CFM over 25 feet of 4 inch pipe. That is short of every manufacturer figure in the table above.
• A full bin or bag. Airflow drops as the collector fills. Empty it before a long sanding session.
• No room filtration or mask. Even good collection lets some fine dust escape at the openings. Run an air cleaner and wear a respirator for woodworking during long sessions. My air filtration roundup covers room units.

Recommended gear

For a collector with enough headroom for a drum sander, start with my best 2 HP dust collectors roundup. For how a drum sander fits into the rest of your shop, see my guide to dust collection for small shops.

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