Part and workpiece size calculation

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One of the tasks that the furniture constructor faces is to provide dimensions for furniture parts and their workpieces in different specifications. As mentioned earlier, a furniture part is, in essence, an assembly glued from a workpiece with a fill material, and covered with cover material workpieces. Separate modelling of fill material and cover in Autodesk Inventor is a labour-intensive and time-consuming task. Besides, this overburdens a computer-based furniture model.


hmtoggle_plus1Calculation of workpiece and part dimensions according to cover material of the part


Woodwork for Inventor plug-in fixes the above problem because it has a material assignment command, which allows the user to assign a fill material to an Autodesk Inventor part and assign covers to separate faces of parts. Such a method enables the user to fully define furniture parts without overburdening the design process with unnecessary tasks. Sometimes, however, it can be unclear as to what – a furniture part or a furniture workpiece – has been modelled in the CAD system during the design process. In some situations during furniture modelling, it is more convenient to model a workpiece, while in others it is more efficient to model a part.



Construction situation

Construction situation




Different types of size calculation according to assigned cover materials

Different types of size calculation according to assigned cover materials




For instance, when modelling a drawer, it is more convenient to model the top of the container cabinet as a workpiece, later defining that the edge band of the part will be attached to this workpiece. In other cases, for example when modelling a cabinet door, it is convenient to model the final dimension of the part, by specifying that the edge band placed on the part is “sunk” within the CAD model volume. Therefore, the dimensions of the door workpiece should be proportionately reduced in the estimates.


Woodwork for Inventor provides the opportunity to indicate whether a cover should be calculated as “attached” to the CAD model or “sunk” within the CAD model volume (it is called cover positioning with respect to the CAD model). Based on the above, two sets of dimensions are calculated:


Part Size - obtained after the production of the part is completed, i.e. after the part is cut from a fill material, mechanically processed (if needed) and coated with required covers.


Blank Size - obtained and required when the part is being cut from a fill material.


Note. When assigning covers to parts, Woodwork for Inventor does not make any changes to the CAD model geometry. The assigned workpiece covers affect only the measurements calculated by Woodwork for Inventor, which are used in various reports and to generate CNC programs


hmtoggle_plus1Calculation of workpiece size according to grain direction


The above sizes may differ significantly from each other. This depends on the technology of the part production, materials used and grain direction.


During the initial material assignment, Woodwork for Inventor automatically sets the grain direction. The grain direction algorithm searches for the largest flat Face and the two longest edges on that face that are perpendicular to each other. If the search is unsuccessful, other rules are applied which allow setting the initial grain direction of the material. If the constructor is not satisfied with the grain direction that has been automatically set, he/she may modify it using the Woodwork for Inventor tools, by specifying other plane for calculation or other grain vector orientation.


Change in the blank size due to the change in the grain direction

Change in the blank size due to the change in the grain direction




Woodwork for Inventor plug-in takes into account the grain orientation and based on it automatically generates reports with required workpiece size.


hmtoggle_plus1Increasing workpiece size using oversize


When performing additional mechanical processing, there should be an option of indicating additional oversizes for a workpiece as shown in the figure below. Woodwork for Inventor plug-in has oversize control tools. Workpiece oversizes can be indicated both for fill materials and veneer covers.


Two types of oversize may be indicated for fill workpiece: sizing oversize and oversize for performing a specific processing operation. Sizing oversize is used for sizing operation, which allows the user to determine precise dimensions of a workpiece. It is important if the part has two clamping options and the precision of processing operations on both sides has to be ensured. Assigning the sizing oversize activates the sizing operation in CAM module and makes it available for use. Likewise, assigning the sizing oversize signals the CAM module that clamping options are available, which take into account the workpiece size with sizing oversize. For more information, click here.


In most cases, the required workpiece oversize is known at the time of assigning the material. Woodwork for Inventor plug-in makes it possible to specify the required workpiece oversize to be suggested at the time of assigning the material in the material description stored in the material database. Depending on the size of the part, different oversize values can be specified in the material information. At the time of assigning the material, part size is analysed and the oversize within the range of values of which the part falls is assigned. The user can edit the dimensions of these oversizes at later stages of design.



Final workpiece dimensions with added oversize

Final workpiece dimensions with added oversize



hmtoggle_plus1Increase in workpiece dimensions due to processing technology used


Woodwork for Inventor plug-in automatically increases workpiece size in case certain processing technologies are used.

1. Case - Linear edge banding machine contains equipment that allows performing pre-milling immediately before edge banding. This increase is applied when a straight edge is detected on a part, i.e. it is covered by edge band and is coincident with any one edge of the workpiece. If Woodwork for Inventor Design Settings indicate that pre-mill allowance has to be used for a detected edge, the indicated size will be added to the side of the workpiece that coincides with the edge.




Pre-mill Allowance



2. Case - Cutting of an inclined straight edge which coincides with workpiece edge is necessary. In order to ensure the sharpness of the edge regardless of the precision of the cutting operation, the size of the part has to be slightly increased. To this end, Woodwork for Inventor Design Settings provide an option to set such oversize.




Oversize for slant edge