What does the barcode represent? I am having a hard time understanding the barcode's relationship between the camshaft and the crankshaft. Would not the tolerances be different for each part? Do the first 7 digits represent a group that share the same tolerance?
To display the part number group, you could include the Left() function in a query as an alias and then JOIN on the alias. So, work through most of your problem in queries.
Something Like
Code:
MyAliasName: Left([TableName].[PartNumberName], 7)
Just remember that what the Left function returns will be Text. So if you want to do some math on it, you will need to convert it to the proper data type.
Once you have the alias, you can display that information to the User in a Form. If you need to do additional queries on the 7 digits, you will need an additional, well, query. So, maybe you need another query object that JOINS your first query on the MyAliasName. Your second query could include its own Alias that employs the Left() function. Use the alias' to JOIN the two.