Support for Lightweight Conical Objects
This system is designed to support conical burden baskets or other lightweight conical objects in storage. It can be used with open shelving or enclosed drawer storage. The system provides uniform support and avoids stressing exceptionally vulnerable and weak areas such as the rim and bottom.
University of Michigan
434 S. State Street
Ann Arbor, MI 48109-1390 USA
Tel (313) 747-0439
Figure 1 & 3 (top):
Jane E. Becker
Figures 2, 3 (center, bottom) & 4: Karen Ackoff after
Geoffrey I. Brown
The system consists of a standard or alkaline-buffered corrugated cardboard box which serves as a base, and a truncated cone of alkaline-buffered board that acts as the primary support element (Fig. 1). The box is assembled with adhesive or staples. The cone is custom shaped and joined with an adhesive.
Figure 1. Basket positioned in support cone that is mounted in a box.
The cone maintains the circular shape of the baskets which tend to flatten if stored on their sides, and can actually correct existing distortions. Using the cone or the support box to handle and move the baskets eliminates point stresses which can cause breakage. The cone and the support box also provide large areas of space for labeling with the accession number and other information, which reduces the need for direct handling.
Materials Tools Supplies
- Alkaline-buffered, paper board box, corrugated (one for each basket) or single wall, alkaline-buffered corrugated board to fabricate boxes
- Alkaline-buffered, solid core box board or barrier board, .050-.060in thickness (50-60pt or caliper).
- C-clamps, 4in, two
- Calipers, outside with blunt tips, about 18in diameter capacity
- Carton stapler (optional)
- Lumber, 1in x 4in, straight length with sharp edges
- Lumber, 2in x 4in x 16in long, two pieces
- Metal straightedge, heavy 48in long
- Polyethylene foam sheeting, 1/8in or cross-linked polyethylene foam sheeting
- Polyvinyl acetate adhesive, emulsion
- Sandbags or other weights to hold joints while the adhesive dries
- Sheet metal snips, aviation type
- Utility knife with heavy blades
- Window screen roller
- Wrapping paper, heavy or butcher paper, 40-60lb, at least 36in wide (for patterns)
- Make a pattern for the support cone by wrapping a layer of heavy paper around a typical basket. With a pencil, mark a vertical joint line on the layer of paper next to the basket and a corresponding one on the overlapping wrap (Fig. 2).
Figure 2. top, Position-ing the pattern paper to establish a vertical joint line.
bottom, Wrapping the pattern paper around the basket to determine
the overlapping vertical joint line.
- Mark a line on the paper parallel to and a few inches below the rim of the basket, and mark another parallel line several inches above the bottom of the basket. The height of the cone should not be the full height of the basket and should only span the part of the basket wall that has a reasonably straight profile. The rim area often curves out and the bottom curves in, so these portions should be above or below the support cone respectively.
- Cut out the pattern, leaving a 3-4in overlap at the joint line.
- Test the suitability of the pattern on the basket.
- Check the suitability of the pattern on other baskets of similar size. One pattern often will accommodate variations in shape with a simple adjustment of the joint angle.
- Trace the pattern onto the barrier board with pencil.
- Cut the board to form the cone with the utility knife, using a chipboard or a utility board underneath to cut against (Fig. 3).
Figure 3. Support cone is cut from board, leaving a 3-4in overlap which is then adhered along
the vertical joint line as shown above.
The curves must be free-handed. Score them lightly with the knife and then make multiple passes to cut through. Do not try to cut all the way through in one pass. Aviation snips can be used to cut this shape, or to trim cones to size after cutting them with the knife.
- To form the cone, curve the board by hand or over a table edge so that the basket is not used as a forming tool.
- Wrap the cone around the basket and adjust until it conforms to the curvature of the basket and rests at a proper height. Be sure to leave the rim exposed. Mark the end of the cone’s outside joint overlap.
- Remove the cone, and while holding the overlap in proper alignment, mark the overlap on the inside.
- Apply adhesive to the overlap area, align and rest the outside on a flat surface and apply weight to the inside of the joint until the adhesive is dry, usually about one hour. Alternatively, clamp joint between the two 2in x 4in blocks and secure with C-clamps.
- If the overlap is offset after adjusting it to the basket shape, trim the projecting points after the adhesive has dried.
- Re-curve the overlap area which will be flat from the weights.
See Confer, “Boxes from Paper-Based Materials”(this volume),
- Obtain a stock commercial box to use as a pattern
- Open this box and separate the corner joint (Fig. 4).
Figure 4. Pattern for support box.
- Orient the pattern over the alkaline-buffered corrugated board with the thinnest face ply of the board up, as it will become the inside.
- Cut the corrugated board. If the board is too narrow to accommodate the full height plus the top and bottom flaps of the box, center the pattern over the board so that the flaps will be shorter. Do not make the flaps less than half of their usual length (or one-fourth of the width of the box) or the box will be too flexible and the cone will not have enough support.
- Score the board accurately for folding, otherwise the box will not sit flat when assembled.
- Draw the handholds in a “U” or rectangular shape, about 4in long X 2in high, and centered horizontally on each of the four sides. The fold line of the hand hold flaps should be about 4in below the top of the box.
- Cut the “U” shape or rectangle for the hand holds.
- Score all the fold lines of the box sides, flaps, and hand holds using the straightedge and solid wheel of the screen roller. The corrugated board folds best when the score is on the inside of the folds. The screen roller wheel will sometimes cut through the inner paper, especially on low-density boards. If this is a persistent problem, score lightly and only on the inside of the fold.
- Bend all folds against the sharp edge of a straight length of 1in x 4in lumber so that they are accurate and do not buckle out of line.
- Adhere the corner flap of the sides to secure the joint and weight the joint until the adhesive dries.
- Fold in the end flaps of the box at one end; this will become the top.
- Adhere the overlaps and apply weight until the adhesive has dried, or staple the flaps together around the perimeter.
- With a large caliper, determine the diameter of the cone where it will intersect the hole in the box. This intersection plane should be a distance from the bottom of the basket equal to the height of the box less 2-3in (about 14in for a 16in high box). This allows for adjustment of the seating of the cone and keeps the basket from resting on the bottom of the box.
- Cut out a hole equal to the diameter of the intersection plane, and centered in the closed end of the box.
- Try the fit of the cone without the basket and adjust the hole as necessary.
- Fold in the flaps of the bottom of the box, apply adhesive to the flap overlaps and apply weight to the joint until the adhesive has dried, or staple the flaps together. The cutout for the cone in the top of the box gives access to the bottom.
- Fold in the handhold flaps.
If stock boxes are used, cut the hand holds in the locations previously described with the box folded flat. Use a scrap of board inside the folded box to avoid cutting through the other side. Score on the outside, but fold to the inside. Proceed with assembly as above.
Positioning the Cone and Carton
- Insert the cone into the base box and insert the basket into the cone.
- Adjust the cutout if necessary to accommodate misshapen baskets. Do not adjust the cone too much if the basket is distorted from lying on its side, as the gentle pressure of the cone can gradually reshape the basket.
- If the basket is in poor condition or has a very irregular shape, use a layer of 1/8in cross-linked polyethylene foam as a liner for the cone; cut the foam to the same pattern as the cone, but without the joint overlap. Pads of the foam also can be used to compensate for very irregular shapes.
- If the basket curves out significantly toward the top, cut 3in long slits in the cone at points about 21/2-3in apart around the rim to allow it to flare as well. Do not slit it too far down as it will no longer provide proper support. Notches or cutouts also can be made in the cone to allow for projections and straps.
- Mark an alignment “key” where the cone and the box cutout meet so that the position can be realigned if they are separated.
Depending on the size of the baskets and number of supports to be made, you will need alkaline-buffered barrier board with one dimension of at least 40in. MAKE A PATTERN BEFORE ORDERING BOARD to make sure that the board size will accommodate the pattern.
A box height of 16in is usually adequate and an equal length and width of 16in, 18in or 20in will cover most basket diameter possibilities.
The size of the support box at the base should be slightly larger than the rim diameter of the basket to keep adjacent rims from contacting and abrading when a number of the supports are stored together on shelves. However, a smaller base may give greater density of storage by allowing small baskets to be stored under the “overhang” of larger ones.
Some of the box sizes available commercially are given below, with the corresponding optimal flat board size required to make them in-house:
length x width x height= board size
16in 16in 16in 48 x 66in
18in 18in 16in 52 x 74in
20in 20in 16in 56 x 82in
Alkaline-buffered corrugated board is available most commonly in widths of 36in or 48in so it may be necessary to modify the box pattern by reducing the length of the flaps. Alternately, the box can be made in pieces. If this is necessary, make the box in two halves with two opposing corner joint overlaps. Board that accommodates the full length is the ideal selection, so that tedious and time consuming piecing can be avoided. In addition, pieced construction produces also a weaker support box.
For larger quantities, many local box makers will use stock supplied by you to make custom boxes, or the board suppliers can occasionally produce custom sizes.