Monday, September 28, 2009

The Wunnerful World of Xrefs them or hate them? In my normal course of work, I do not really need to use them because most of my drawings are of simple things. Occasionally I have to do a large layout, so instead of cluttering up the model with sectional views, I write these out to separate files, which are in turn xreffed into an output drawing.

Recently a friend got me to check out how quick my computer was printing a PDF. His drawing was full of xreffed in bits and pieces. What was interesting, was that he was xreffing back into
the components, the main layout! So, when the layout was opened, I got a message saying "circular reference detected, breaking reference". He explained that this was the clever way to ensure that components ended up in the correct place. Clever indeed.

Recently, I have had a small tank and piping job to do for a consultancy. So I thought what a good place to experiment with circular references and so on. I knew of a thing called refedit, but never used it much. On this job though, I found that if you right click, there is an option to use refedit. I'm now convinced that this is the way to go, as you can use the geometry of the other things in the layout to position parts on a component drawing.

I think sometimes you can overdo xreffing-after all: you have drawn a pump - is it likely to change? No.

The set of drawings created makes much use of viewports using conceptual shading: try it, you will like it!

I was able to make great use of pip and pipeset lisp routines for this job (see earlier posts and my website for info). Of course the first comment from someone was "Does it produce a BOM?" to which the answer is no. Maybe one day.