Clamshell Case Part 2: Covering Base Tray


The base tray must be completed first to know the size of the top clamshell tray. There should be enough bookcloth left above the tray will wrap over the interior sides and about 1/2″ to 3/4″ onto the base. Once the glue on the bottom of the tray has set up, begin work on wrapping the top. 

  1. Use a 90-degree square to align at the thickness of the mill board at the corners of the tray. On the bookcloth backing, pencil in lines aligning to the interior of the mill board. You should have 2 parallel lines equidistant that equals to the thickness of the mill board.
  2. Use the 45-degree angle of the square to place point side in to the corner of the fabric. Pencil in the 45-degree angle on the backing. Do this on both corners of the tray. These slivers of bookcloth will be removed before wrapping the sides.

Marking the open tray edge

  1. Align the 90-degree angle at the base corner of the tray. Align with the thickness of the mill board at the bottom corners of the tray base. On the bookcloth backing, pencil in lines aligning to the interior of the mill board. You should have 2 parallel lines equidistant that equals to the thickness of the mill board.
  2. Use the 45-degree angle of the square to place point side in to the corner of the fabric. Pencil in the 45-degree angle on the backing. Do this on both corners of the tray. These slivers of bookcloth will be removed before wrapping the sides.
  3. Align the 90-degree angle to the front top edge of the tray. On the bookcloth backing, pencil a line vertically that aligns with the open tray edge.

Miter construction of top open tray edges

  1. Place the 45-degree angle about 1/4″ from the sides open edges intersecting the vertical and horizontal edge lines. Pencil in the guideline. It will look like a small triangle. You will cut the vertical side only of the triangle.
  2. Place the 90-degree angle at the vertical edge guideline and cut from the tray edge to bookcloth edge.
  3. Cut on the horizontal line from the intersection point of the triangle and horizontal lines to the bookcloth edge. The short side edge should have a triangular flap attached when the cutting is done. The small triangle flap will be free on the vertical side.
  4. Do this on both top edges.

Cut out corner turn-in flaps

  1. On the base and side corners, cut on the pencil guidelines to create mitered bookcloth flaps. The mitered flaps will cover the corners with is polished professional look without any fabric buildup and no mill board showing.
  2. Test your turn-ins by folding the cut flaps over the mill board edges.

Creasing the turn-ins

  1. Fold over the front and side turn-ins and crease them with your bonefolder.
  2. On the side and back tray turn-ins, there should be enough fabric material to cover the tray base by about 1/2″ to 3/4″. Use the bone folder to crease the turn-ins at the base.
  3. Position the 90-degree angle flat against the side walls over the bookcloth on the base. Be sure the 45-degree angle point fits into the corner. Cut along the 45-degree line of the angle from the corner to the bookcloth edge.
  4. Cut a miter on both side and back corner turn-ins. There should be a tiny overlap of mitered corners in the final paste down.
  5. Start with the back turn-in flap. Turn the tray on it’s back side. Place waste paper under the turn in flap.

Paste up turn-ins

  1. Paste up the back turn-in.
  2. Turn the tray on base. Fold the bookcloth turn-in over the edge. Firmly smooth the bookcloth along the back board edge, starting from the center as moving to the corner on each side for an even fabric edge.
  3. Turn the tray on it’s back. Fold the turn-in down over the side. Smooth from center out to the corner with the bonefolder.
  4. Turn the tray on it’s base. Smooth from the center out to the corners with the bonefolder.
  5. At the tray’s open edge, paste up the tray base’s bottom turn-ins on both sides.

Paste up of tray’s open edge turn-ins

  1. Turn-in the tray base’s bottom flaps.
  2. Turn the tray on it’s side and paste up the tray’s side edge turn-ins including the small triangle flap.
  3. Turn-in the side edge flaps and tuck the triangle flap over the top edge of the sides. The tucked in triangles with reinforce the edges and cover the mill board for a professional finish.
  4. The side turn-ins are the last to be pasted up.

Finishing the side turn-ins

  1. Turn the tray on it’s side. Paste up the turn-in. Fold over the top tray edge. Smooth the edge with the bonefolder.
  2. Wrap the turn-in onto the side. Smooth from the center to corner, then center to edge with the bonefolder. Go over the mitered corners with the bonefolder to be sure they are laying flat.
  3. Place wax paper and a flat weight in the bottom and set the base tray aside while you start working on the top cover tray.

Read more in Clamshell Box Part 3: Cover Tray Construction

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