DIY Twin-Size Trundle for an Under Bed

Retrofit Wooden Frame

• 1

  Measure any used, standard-size twin-bed frame you already own from head to foot along its length, to ensure it's less than 76 inches long.

• 2

  Examine the bed frame to determine how the legs attach. Use the appropriate tool to remove the legs, such as a standard screwdriver for slotted screws, a hex wrench for hex-drive screws or a socket wrench and a pair of locking pliers for bolts and nuts.

• 3

  Label one of the 4-foot ends of the plywood "A," and the other 4-foot end "B." Label the 8-foot sides "C" and "D." Measure 75 inches from the A end of the plywood along sides C and D, and mark each point with a carpenter's pencil.

• 4

  Snap a chalk line across the plywood, passing through the two marked points. Cut the plywood to length on a table saw, and set the scrap plywood aside for a future project.

• 5

  Measure 39 inches from side C toward side D, 6 inches from side A -- and mark that point with a carpenter's pencil. Repeat that same measurement and marking, 6 inches from side B.

• 6

  Snap a chalk line from side A to side B, passing through the two pencil marks. Don a painter's dust mask, wraparound eye protection and ear protection. Cut the plywood to the correct width on a table saw.

• 7

  Repeat steps 1 through 6 on a second sheet of plywood for the XL twin-bed frame, using an 80-inch length instead of 75 inches.

• 8

  Smooth all ends and sides of each plywood sheet to remove burrs and eliminate splinters, using coarse and medium sanding belts on a belt sander, in that order.

• 9

  Face side C of the plywood sheet. Snap a chalk line from the left-hand corner of side C to the right-hand corner of side D. Repeat to snap a line from the right-hand corner of side C to the left-hand corner of side D, creating an "X" from corner to corner.

• 10

  Lay the 39-by-75-inch plywood sheet chalked-side down on top of the cut-down regular-size twin-bed frame. Align the edges of the plywood sheet with the sides of the bed frame.

• 11

  Drill 1/16-inch diameter pilot holes every 6 inches around the perimeter of the bed frame, 1/2 inch to 1 inch from the outside edge, depending on the width of the material used to construct the original frame. Drill 1 inch from the edge, for example, if the original bed frame was made from 2-by-4-inch stock lumber.

• 12

  Countersink all the pilot holes by drilling straight down into the wood 1/8-inch to 1/4-inch deep. Secure the plywood to the original, cut-down bed frame using 1.5-inch long, 1/8-inch-thread diameter wood screws.

• 13

  Flip the frame so it lays plywood-side down. Position a caster 2 inches along the chalk lines from each of the four corners of the bed frame.

• 14

  Mark the screw positions according to the type of caster you purchased. Drill pilot holes the same diameter as the fasteners supplied by the manufacturer, and secure the casters to the bed frame according to manufacturer's instructions.

• 15

  Position the remaining two casters 24 inches from sides A and B, so that a line drawn between them passes through the point where the diagonal chalk lines cross. Secure them to the bed according to manufacturer's instructions.

• 16

  Repeat steps 8 through 14 for the XL twin-bed frame.

• 17

  Sand the entire surface of both bed frames. Stain or paint the frames as desired. Allow the stain or paint to dry overnight between coats. Apply three to five coats of clear acrylic wood sealant, allowing at least 12 hours of drying time between coats.

• 18

  Drill screw positions for two drawer pulls or drawer knobs into side D of the cut-down bed frame. Attach the knobs or drawer pulls using manufacturer-supplied hardware.

• 19

  Place the standard twin mattress on the cut-down bed frame, and make the bed with standard twin-size sheets and blankets. Repeat for the XL twin bed.

• 20

  Push the cut-down bed, which is now your new trundle bed, under the XL twin bed.

Welded Metal Frame

• 21

  Don wraparound eye protection, ear protection, a NIOSH-approved respirator and heavy leather work gloves. Cut 32 pieces of 2-inch wide, 1/8-inch-thick bar steel, 39 inches long, using a chop saw. Deburr the ends of each piece using a 24-grit wheel on a right-angle grinder.

• 22

  Don a welding helmet over your primary, wraparound eye protection. Replace the leather work gloves with welding gloves, and don full leathers.

• 23

  Clear all observers from the area and weld in a well-ventilated area, preferably outdoors or in the doorway of your shop or garage, with all doors and windows open and an industrial-size exhaust fan running.

• 24

  Position the first bar across the width of the smaller bed frame, with one edge flush with the outer edge of the head of the frame. Use a 100-volt gas-less MIG to fillet-weld the bar in place. Weld only where the bar crosses the frame below it, along the side of the bar that is closest to the center of the bed.

• 25

  Position the second bar across the width of the smaller bed frame, with one edge flush with the outer edge of the foot of the frame. Use a 100-volt gas-less MIG to fillet-weld the bar in place, along the side of the bar that is closest to the center of the bed.

• 26

  Space the remaining bars evenly between the first two, and weld them all in place.

• 27

  Repeat steps 4 through 6 for the XL twin-bed frame.

• 28

  Use the 24-grit wheel on the right-angle grinder to smooth all the welds after the metal cools for at least 12 hours. Switch to the 80-grit flapper wheel and run it over all surfaces of the entire bed frame. Switch to the coarse wire wheel to create a brushed-metal finish.