(2) JNR (Mechanical)
4 Mar 02 12:57
Andrew: Hi, I just can back from Solidworoks World 2002 where I gave a presentation on design tables and spreadsheets. If you have any specific questions I can try to answer them as time permits.
Here are some pointers. First, you should never assume that the way one CAD system does it is even similar to another. They all have their methods and reasons. Usually all have advantages and disadvantages - it's not a case of "mine's better than yours" (which you hear a lot in the CAD business!). SolidWorks Design Tables are embedded Excel spreadsheets. Ie. they are embedded in a single file and only affect that file. They are used to control various dimensions and features of the part/assembly. Most often they are used in conjunction with multiple configurations of the same file. This allows different configurations to vary from eachother. This can get very creative with suppression and alternate mates, etc. in assemblies, but your question seems to be on Part files. I get the impression that you are not really dealing with multiple configuration parts (ie. "families of parts" - similar shape, but different dimensions). That kind of thing is very easy to do with DT's. In fact merely adding a new row to the DT automatically creates a new configuration, and of course multiple configurations can essentially be separate Parts (from a BOM point of view). Scott and Charley gave some good pointers, but I'm thinking you may be wanting to drive totally different parts by certain common dimensions. Scott is correct in saying the in-context features are very powerful, however I echo his caution. In practical terms you should think very carefully about using them as they can have undesirable side effects or restrictions later (sepically if you have or intend to use PDM systems!!!!!). BTW: Charley attended my presentation and suggested I make this post for you. Now for the interesting stuff.
Read the documentation on DT's very carefully. Don't "interpret" - take it dumb literally. Eg. if you carefully read the help on "Insert DT" and "Insert DT New", you will find a subtle difference - one uses rows 2 & 3, the other 1 & 2. (What the heck is that all about, SolidWorks?!) I rat-holed half a day trying to cut and paste data from one part DT via an Excel spreadsheet to another, before I noticed the difference in the doc's and it all made sense - they tell you , but don't make it obvious). Also note: that once you insert a design table it has no relationship to the external Excel file if came from.
OK, so when it says the rows and collums can't have gaps -take 'em at their word, but be curious - what happens if i leave gaps? Turns out you can do anything you want - it's an OLE Excel application - they just don't get recognized by SW to control the file. So you can do all sorts of Excel stuff and link the real DT value fields to anything else to the right/below the first blank row/collum. Simplest is just use a formula in the DT value field and have a separate chunk of spreadsheet cells below to enter you data in. I personally then hide the top rows that SW looks at - stops you (or someone else less familiar) from accidentally editing them. Note that you can use checkboxes, drop- downs, boleans, etc. ANYTHING legal in Excel. Ain't it great to have a program written native in Windows with decent OLE compatibiliy?
Next, if you want to share values (or other decision making data) between parts (or assemblies) which are not families and do not relate well to multiple configuration DT's - and you don't want in context relationship: OK, so this is OLE, right? So I should be able to have an external Excel spreadsheet and link cells in my SW DT (inside a part/assy file) to it. Works like a champ. Just Copy - Paste Special - Link. I suggest you set you options to "Open DT's in separate window. It's easier and you can have both the DT and spreadsheet open with a split screen.
You can only link from the Spreadsheet to the DT - NOT the other way (When the DT is open it has a temp name and doesn't get recognized).
You can open the Excel files in any order, for example you can Edit DT, then (in Excel Edit - Links - Open Source or change, etc.). You can leave the source Spreadsheet open while you work, all you have to do is change values in it, Edit DT - Close DT, it's that quick as it updates the instant it opens.
Watch where your source file is - Excel claims to have relative links, but they go absolute the instant you close a the spreadsheet - so they are kinda pseudo-relative.
You can't do any Excel protection inside the DT or it won't update (it's got to "save").
I have a "template" spreadsheet and set of "template files" which is used to start new projects. It contains all the optical and mechanical data and variables to configure one of our Wide field of view overhead mounted Head Up Displays for aircraft. It not only sizes and builds glass optics, it allows positioning and and cofiguration of a complex and often compound angled mechanism (can even delete and recreate links in the mechanism instantly). It makes some pretty wild geometry.
Note you may have to do some Ctrl-Q forced rebuilds at a times in assemblies.
Good luck and as I said, you can contact me for specific questions - best way to learn about anything to to try to teach someone else!!!
Senior Mechanical Engineer
Rockwell Collins Flight Dynamics.