Building a cyclone from a 55-gallon drum.

My cost breakdown

• The Drum with removable lid was $10 at a garage sale. If the top for your drum is already gone, you can substitute a plywood disk of appropriate size. A clamp to hold the top on isn't normally needed.
• I had 3 feet of 4" PVC pipe left over from plumbing the dust extraction system ($2)
• I also had a large tube of Caulking compound ($3). Siliconized white compound works for me.
• New Metal Cutting Blade for the Sawzall cost $3 (because I only had wood ones on hand!)
• Two 10-32 x 1/2 inch long screws, with washers, nuts and fender washers ($1)
• 3 feet of flexible hose (all metal aluminum dryer vent hose) ($4)
• Beer ($5)

Tools Required:

• Electric Drill
• Sawzall, jigsaw, or other portable reciprocating saw.
• Caulking Gun

The system

Top View

Underside of Lid, first view.

Underside of Lid, at a slightly different angle.

Instructions:

1. Cut two sections of PVC pipe about 18" long each.
   
   
2. Place one in the center of the lid and draw around it to mark the hole to cut for the exhaust.
   
   
3. Mark the slot that will be cut out for the inlet tube. This slot will be like a grossly elongated D.
   
   If you have difficulty in visualizing the shape of this hole, just submerge one of the tubes in a pan of water at the angle you wish to use, and note the shape along the waterline. Draw this shape on the drum top, near the edge. You want to leave plenty of metal at the edge so you don't significantly reduce the strength of the top. Mark a line about two inches inside the straight part of the D.
   
   
4. Drill a couple of holes near your marked line in each of the holes you need to cut out. This is so you can get the blade of the Sawzall (or jigsaw) though the metal to begin your cut. If you don't have some sort of portable reciprocating saw, I imagine you could drill holes all around the cut line and file or grind the edges, but I wouldn't want to think about how long this approach might take.
   
   
5. Cut out the disc of metal at the Exhaust location. It really helps if you space the top from the floor on a couple of blocks, unless you want to buy more Sawzall blades. A fairly tight fit is good here, because the Exhaust tube is attached only by caulking...
   
   
6. Cut out the D-shaped hunk of metal at the Inlet location. At the lowest point, where the tube will be inside the lid (corresponding to the flat part of the D shape) I cut the end of the scrap off, but left a tab about two inches long with a saw cut on each side. I enlarged the saw cuts so the tubing would fit over the tab.
   
   The cuts don't need to be really exact. Any minor misadventures in guiding your saw can be hidden under caulking later. Try the fit of the tubes and cut another slice of metal as needed for a reasonable fit.
   
   
7. Now that the hard and/or dangerous work is done, pop open a beer and take a break. People that don't like beer can subsitute any adult beverage of their choice.
   
   
8. Bend the end of the tab of the inlet hole to a curve that will fit the inside of the tube, then drill and bolt the tube in place. While probably not necessary, this provides additional support for the inlet tube.
   
   
9. Block the top up about four to six inches from the table or floor, and push the Exhaust tube through so one end rests on the table or floor. It should now look more or less like the pictures above.
   
   
10. After locating the caulking gun, (why is it never where it's supposed to be?) load it up and caulk around the tubes on the upper side of the top. Note that the only thing holding the Exhaust tube in place is the caulking, so you will have to wait for the caulking to set up before you invert the top and caulk the underside.
    
    
11. Finish your beverage or have another one. All you can do now is wait for the caulking to dry.
    
    
12. After the caulking on the top is dry, invert the top and caulk the underside. When this is dry, you can plumb your new 55 gallon cyclone into the system.