Crate Pro 6

Technical White Paper

Plywood (Panelboard) Rules


Plywood Rules determine the placement of splices in plywood panels. When the dimensions of a panel are less than the dimensions of one sheet of plywood, the Rules may modify the plywood orientation if allowed by the user.

Using Plywood Rules to create splices will assist you in assuring your container conforms to most if not all specifications while minimizing the number and length of required plywood cuts.

Plywood Rules are run automatically when a new Design is created or by clicking the Apply button. After adjusting splices manually or pressing the Apply button you can run the selected Intermediate Cleat Rule for that panel. See the Intermediate Cleat Rules white paper for details about cleating.

Crate Pro will manage up to nine different sizes of plywood pieces. Any Piece can have multiple quantities.  The plywood placement on a panel will be automatically calculated when the panel is no more than three pieces high.

To help visualize the arrangement of plywood, Crate Pro uses a spreadsheet metaphor with rows being numeric (1 to 3) and columns being alpha (A to C).  When one piece of plywood is applied to a panel it will be assumed to be in position 1A, similar to starting in the top-left corner of a spreadsheet and working outward. 

Crate Pro has a functional height limitation of 3 pieces of plywood - presumably 24' (7200mm). Although each of the three Pieces can have a quantity of more than 1, Crate Pro will only accurately calculate plywood splicing and cleating using the height field value for each plywood Piece 1A, 2A and 3A. Any quantity in that field which is greater than 1 is not considered when calculating vertical dimensions.

Piece vs. piece: It's helpful to understand Crate Pro's use of terminology before continuing however understanding the fields used in Plywood Rules can still be confusing. Specifically the use of the term 'piece'. In Crate Pro a 'Piece' (capitalized and italicized) is defined as a quantity of one or more of the same component or the portion of that component. The term 'piece' is used here in the common sense as in a tangible 'thing' that you can touch and see. The plywood of a panel may be comprised of multiple Pieces, each Piece can have a length, width and quantity. Crate Pro uses these three attributes to identify a Piece. If a panel is comprised of two pieces of plywood and both are the same dimension, Crate Pro may or may not identify them as one Piece. If, however, there are two pieces of different dimensions, then Crate Pro will identify them as two Pieces, each having a quantity of 1. A panel of a large crate will likely be comprised of multiple Pieces since it's unlikely that every piece of plywood applied can be the same size.

The number of pieces of plywood that can be used horizontally is virtually unlimited however Crate Pro is still limited to no more than 3 different widths of plywood. In theory, there is never a requirement for more than 3 different widths or 3 different heights of plywood for any one panel so Crate Pro will accommodate up to nine different dimensions of plywood per panel. These nine dimensions result in up to nine different Pieces.

Within Crate Pro's preferences, there are two options that can affect the outcome of a panel's plywood arrangement. 1) The minimum dimension of any panelboard piece and 2) OK to rotate panelboard. These options are also modifiable for a single Design. They are available from the Rules tab in the Design module.

The minimum dimension of any panelboard piece will force Crate Pro to move plywood splices when a calculated piece of plywood is smaller than the stated value. This is an exceptional feature of the Plywood Rules and of Crate Pro in general. Many specifications indicate that the minimum value is 24" (660mm) however Crate Pro's default value is 16" (440mm). If, while calculating splices, the rightmost or lowest Piece is calculated to be less than this value, Crate Pro will reduce the dimension of the leftmost or top Piece respectively to assure every piece is at least the minimum required size. For example: If a panel is calculated to be 58" wide, Crate Pro will first apply a 48" wide sheet then a 10" piece. Since 10" is less than the 16" requirement, it will modify the first piece to be 42" wide then adjust the second piece to be the minimum 16" wide. This 'adjustment' occurs before Crate Pro displays the calculated results so the user perceives this as the 'result' rather than an 'adjustment'.

The OK to rotate panelboard checkbox will allow Crate Pro to rotate plywood so if a panel can be built using a single sheet of plywood by rotating the plywood 90 degrees, it will do so. Once the height of a panel exceeds the width of a sheet of plywood, this checkbox will be ignored.

Hovering over a field will display a calculation that's relative to that field. Hovering over a horizontal field will display the calculation that includes all the Pieces that span the panel left-to-right for that row. Hovering over a vertical field will display the calculation that includes all the pieces that span the panel top-to-base for that column.

Clicking on a Piece in the matrix that appears to the left of the Piece fields will take you to the horizontal dimension field for the Piece selected. 

While it's not practical to display every possible panel design, diagrams included below represent some plywood splicing results as Crate Pro will create them.


This very large panel example shows that 48" (1220) wide plywood is a perfect fit from left-to-right however the panel is 2-1/2 sheets high. There are 15 pieces of plywood.

Crate Pro will populate the Piece 1A and Piece 2A fields with 5 full sheets each and will populate the Piece 2A fields with 5 half sheets.

(The Crate Pro interface does not represent the alternating splice pattern shown here. Crate Pro's output doesn't affect how the panel plywood is spliced.)


This panel is similar to the one above but is 40" (~1000) narrower. This would leave the right most piece to be only 8" (~220) wide; 1/2 the minimum requirement.

Crate Pro will adjust the pieces in column C to be 16" (~440) wide then will reduce the width of the pieces in column A by 8" (~220).

The result is six different sizes of material utilizing full sheets as often as possible. 

(Alternating splices are not displayed so the concept can be more clear.)

This more typical size panel would have no special adjustments made to it since Piece 1B is already larger than our minimum size requirements. You may decide to move the splice to the center so you have two pieces of the same size. After doing this you can rerun the Intermediate Cleat Rules to rearrange the cleating as may be required.

If Piece 1A of this panel starts out at 48" (1220) wide then Piece 1B will be smaller than the minimum allowed. Here Piece 1B is adjusted from 10" (~250) to 16" (~440) so the difference must be removed from Piece 1A.


If a panel is less than 48" (1220) high then the plywood can be rotated. Unless rotated, the size of this panel would have required three different sized pieces and two vertical cuts. By rotating plywood only one vertical cut is now required. Note that some standards don't allow for plywood to be oriented horizontally.

It's important to note the in the first two examples, Piece 1A, Piece 2A and Piece 3A had to all be populated even though the sizes of Piece 1A are the same as Piece 2A. Crate Pro will calculate cleat splicing using the materials in column A. If the quantity of any Piece in column A is greater than 1, the cleating Rule will assume those pieces are added to the right of one-another. The Pieces in Column A are always used to calculate height and the Pieces in Row 1 including the Quantity of each Piece is used to calculate length (left-to-right). Placing similar sized pieces in multiple Piece fields does not result in extra saw stop or otherwise affect the time results in Crate Pro.

The examples provided are intended to show sample results from Crate Pro's Plywood Rules. The results that Crate Pro produces can always be manually changed to suit your needs.

Plywood Rules are the first part of two related Rules. After you either run Plywood Rules or manually adjust plywood splices you can then run Intermediate Cleat Rules which will use the current plywood Piece data to determine intermediate cleat placement.

Crate Pro 6 does not create panel drawings. 

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