This file documents the enhancements and problem fixes provided with dbMASS version 3.8. Please read to stay up to date on these developments.
----------------------------------------------- Version / Published
------------------------------------------------- 3.80 / November 10, 1999
------------------------------------------------- 3.81 / December 14, 1999
Several enhancements have been made to extend the capabilities of the MPEX format to support additional data. dbMASS has been enhanced to handle these new features. Two new data sets have been introduced and the CLASS... data sets have been enhanced. The new data sets are "UNITS" and "STANDARD PARTS". Both are described below.
UNITS Data Set. The UNITS data set is used to specify the units of mass and length that are used in the data file. This data set should occur prior to any data that may use the units specified. Normally the units would be specified once for a data file. However, this data set can occur multiple times as needed to deal with mixed units data files. The format of the data set is as follows:
The UNITS data set format follows the same format as other MPEX data sets. The data set designator is followed by the data set label. Where it differs, however, is that the units data follows the data set designator on the same line rather than on the following line as in all other data sets. Each word is separated by a TAB character.
The brackets  are used to show that the data is optional (do not include brackets in the data).
Mass can be any one of the following abbreviations:
Length can be any one of the following abbreviations:
An example UNITS data set for data given in pounds and inches would be:
Remember to separate each word by a TAB or to place each word in a separate column within a spreadsheet.
STANDARD PARTS Data Set. The STANDARD PARTS data set is used to specify entries that are standard parts. Use this data set before the ASSEMBLIES and/or ENTRIES data sets. The entries listed in the STANDARD PARTS data set will be interpreted as standard parts when listed in these two data sets. This data set also supports defining "filters" which can be used to identify standard parts. The format of the STANDARD PARTS data set is as follows:
The STANDARD PARTS data set format follows the same format as other MPEX data sets. The data set designator is followed by the data set label. The data set label, STANDARD PARTS, has a single space between the two words. The data must follow on the line immediately after the designator. The fields in this data set are: Id, Description and Weight. Separate columns will be used for each field when using a spreadsheet. A TAB character will separate the fields in the final format. The comment line, which starts with a semicolon (;) in the first column, shown above is optional.
The import translator uses filter criteria to qualify entries as standard parts. A filter is specified by giving an Id and/or a Description which ends with the asterisk character (*) and provides a maximum weight. The filter criterion specifies what characters the Id/Description must start with. The characters preceding the asterisk are used. If only the asterisk character is given for the Id or Description, all Ids or Descriptions will pass the filter criteria for the corresponding field. If no asterisk is given in either the Id or Description field, an exact match of the Id/Description must be given to pass that fields filter criteria. All fields must pass the specified filter conditions to be accepted as a standard part. The following example illustrates the use of filters:
If an entry's Id starts with "sp" and its weight is less than or equal to 0.1, the entry will be interpreted as a standard part.
Multiple filters can be specified by adding additional rows of filter data. Each filter (row of data) is applied independently. An entry only needs to meet the criteria of a single filter to be considered a standard part. For the following example:
Any entries that have an ID that starts with "sp" or a Description that starts with "bolt" and weighs less than 0.1 will be interpreted as a standard part. The filters are not case sensitive.
When a particular entry satisfies the criteria of any of the specified standard part filters it will be treated as a standard part. However, if the entry is an assembly with sub-entries it will be converted to an assembly.
Fixed a problem with the MPEX import translator, which would cause categories from different class fields to be cross-referenced if the same description was used. Cross referencing of class categories is not allowed. Each class field is intended to have independently defined categories.
A common mistake that is easily made is to accidentally select to "copy" instead of "paste" after performing a "cut" operation. When working in the Entries or Items Windows, considerable data can be lost by this mistake because the "copy" operation overwrites the shared data buffer that will contain the data from a "cut" operation. To help prevent this from happening in the future dbMASS will now post a warning prior to performing this sequence. The warning notice is posted only if the "cut" has not been followed by a "paste" and only applies to the Entries and Items Windows. Note that the Entries Window uses a different buffer than the Items Windows, so entries and items can be stored in buffers simultaneously.
A related cosmetic display problem has been fixed. When entries or items are "cut" from their corresponding windows, the display is normally cleared where the entries/items existed and any following entries/items are moved up in the list. However, when the "cut" entries/items were on the second page or beyond and no remaining entries/items would flow onto the displayed page, the removed entries/items were still being displayed. The display logic has been updated to display the last page that contains entries/items.
A new shape has been added that supports defining a segment of a sphere. This shape is listed as "Sphere Seg." This shape can be used to model a sphere which has one side cut off by a plane. The dimensions are length (l), radius of end circle (r), radius of sphere (R) and thickness (t). The diagram to the right illustrates the relationships of these parameters.
For a specified length, either the radius of the end circle or the radius of the sphere can be specified, the other will be automatically determined. A hemisphere is defined when the end circle radius (r) and the sphere radius (R) equal the length (l). The sphere radius can be less than the length but it must be greater than or equal to one-half of the length. Note that the coordinate system of the shape places the plane of the end circle in the y-z plane at an x value of zero.
The ability to set an item weight to a negative value has always been a feature supported by dbMASS. By adding a negative sign to a calculated item mass, you can account for cut-outs in other item shapes. Once an item weight is made negative, it will be maintained negative even after modifying the shape dimensions or material type. However, performing a Database Update command with recalculated parts was overwriting the negative with the actual weight unless the weight was user defined (modified beyond just the sign). This also would occur if the Find/Replace feature was used to assign a different material. This problem of over-writing the negative on item weights has been corrected. Now a negative weight is maintained for all circumstances. The only way negative item weight will change to positive is if the weight is made either positive by deleting the minus sign or by setting the item weight to zero.
The part weight can also be changed to a negative by adding a minus sign (that is, if not already negative from summing the item weight). However, negative part weight is not maintained in the same manner as negative item weight. Adding a minus sign to the part weight is treated as if modifying the part weight (not just the sign). With the addition of the minus sign the mass properties become user defined rather than calculated. If the user defined part mass properties are later replaced with calculated values (upon user request), the minus sign is lost unless of course the calculated value is negative. This distinction between how negative part and item weights are handled is necessary because a part's calculated weight obtained by summing items is invalidated when adding a minus sign. So, if you need to maintain a negative part weight that is calculated, make the negative adjustments to the items. This will ensure that item shape or material modifications will update the part weight and maintain a negative value.