In nearly 20 years of use I've sucked up everything from chunks of wood, nuts, bolts, metal parts and debris, etc., etc. even a tape measure, but never had a problem, ever, except the one time something metal pierced the side of the cyclone. My current DC cyclone (and its predecessor) was plumbed in the push-through configuration (remember all single stage DC's are set up that way!) That means dusts hits the blower which doesn't have screen on the intake and the impeller first. The cyclone which doesn't have a screen either, comes after the blower. Anything sucked up goes though the fan and impeller before being blown into the cyclone. The blower has a heavy duty steel impeller so is unlikely to be damaged. The velocity of the air and low density of dust in the air stream rapidly cool and extinguish any sparks that might be generated and prevent ignition.
My shop is above the garage. 6" ASTM D2729 PVC ducting runs along the garage ceiling. Relatively short drops run
up to the tools. The main duct passes through the wall at the right and into the motor/blower unit located in an adjoining utility room.
The motor/blower (a very old Grizz with 3 hp motor with a 14" impeller) is mounted on stilts which are lag bolted into the studs, but the weight is carried by the legs. With the help of an eyebolt screwed into the wall and some rope I can single-handedly raise and lower the blower (once the cyclone has been removed at the flange.) I've had to do that once to replace the motor bearings. I have changed the start capacitor and start switch contacts twice but can reach them using a ladder. The cyclone has a 3D cone- it length is 3 times the diameter of the cylinder- a version of Bill Pentz's (1.64) design.
The cyclone exhausts air straight up to a shop level plenum containing two 300 sq. ft Farr-style cartridge filters (from Wynn Environmental?) connected in parallel.
An old piece of inner tube and two band clamps make great, inexpensive, low noise couplings- much cheaper than a Fernco!
Since it is a push-through configuration and under pressure, I don't need a fancy dust bin or barrel and air tight lid attached to the cone. The dust collects in a standard Food Lion 39 gal. leaf and lawn trash bag connected to the bottom of the cone with a band clamp. It is extremely easy and very neat to disconnect, tie off, and carry bags to the curb! My high dust alarm had not been installed yet in the first photo. (The pink Bondo was an experiment to see if I wanted to paint it fancy- it still looks like that today!
Early high dust alarm which uses a day/night lamppost sensor and a simple bulb. It worked just fine but was replaced by a purpose-built IRLED version. I've got it wired to the DC control circuit so the DC shuts down if a high dust situation occurs. Since the sensor switch closes in darkness (absence of light), it is failsafe and there is no problem if the bulb burns out- the DC just shuts down.