Sunday, September 26, 2010

Blocks versus lines and things

I have been playing around with some joinery details, and it came to me that whoever drew them was thinking as he drew, with lines and so on. Once he had those lines, he saw no reason to alter them. Which is fine.

Only problem is, that he wanted to generate more sections based on them, things got a little messy, to the point where he must have said to himself:

"Funny? That dimension should have been is not actually that, on this model....oh well, let's just do a quickie here and alter the dimension text to read what I want instead of what it actually is".

Where's my big hammer?

The trouble is, when you are designing, it is wonderful to use lines etc, but once you have zeroed in on a particular size, make it into a block, so you don't inadvertently stretch it, plus you can reuse it, confident in knowing that it is a set piece of geometry.

I'm thinking here of a sectional view of a window sash.

Saturday, September 18, 2010

Video Productions and old 2D lisps

Once, long ago, last century I posted a heap of supposedly useful lisp routines on an old web site (now long gone). I have gone through these and reposted them on:

I have also posted some ancient 3D ones on:

It struck me that some of these are hard to use(!), so I have done a few videos, creating a special page for them at:

It was a bit of a learning curve doing them - they ended up with huge file sizes, so I downloaded a free converter and condensed them a bit.

Before 2000, I was interested in Virtual Reality Modelling Language (VRML) and sort of expected that this would evolve into something useful around about now. It appears not....although maybe I have not looked hard enough. I looked at all the old sites and most of them seem to be stuck around 7 years ago. Octaga seems to be the only one still chugging.

Saturday, September 4, 2010

Revisions...the last post...I promise! and Working with XREFS

Revision File Naming

About a year back I raved on about revision problems created by the fact that a drawing file might contain many layout tabs, where sheet 1 might be rev B and sheet 2 might be rev D.

My approach for the last year, which I now admit is one that has a major fault, was to remame the actual drawing file name so it reflected the fact that it was a later revision. For example 150283D.dwg. The "D" would represent the most advanced revision. Into a folder marked "History" went the old files, for record purposes.

This worked well until the man in charge of maintenance requested that we go back to the old format of 150283.dwg, because he had that number listed in his database package called Mainpac.

My new system, from here on, is to saveas the drawing into the History Folder as "150238 as at 12Aug2010", and keep the current one always as "150238.dwg". Always a brain strain to remember to saveas!

As well, the principle of Xreffing goes astray if you start changing file names. Xreffing is something I had avoided because people in the future would come unstuck if the masters of IT ever changed a name of a drive. (They would never do that....would they?)

If they replace me in the future, then part of that person's job is to understand the concept of xrefs and how to fix them if the drive is reanamed. With this in mind, I have started to use them sparingly.

A Different Way of working, using xrefs

We have a 3D models of the plant in a folder marked "Plant-3D Models". Each major building has a name, eg "Melthouse" and the file name is the same as the building name.

My idea is to gradually build these up so that they represent a true and more or less accurate model of what is currently there. In these models, there are section tools, which write out 2D sectional views to the appropriate folder.

Our setup is further complicated because we have 2 sets of drawings-One for proposals and one for things actually built. So if something went from a proposal to reality, I would have to change my xref paths. A further gotcha is my 3 step method:

  1. Model with section tool.
  2. Outputted section file.
  3. Presentation drawing with outputted section file xreffed in.
The benefit of this seemingly overly complex method is that the process of updating the Presentation file is quick and easy: Change the model, write out the section file, reopen the Presentation file and everything is updated more or less automatically.

I have mentioned this in previous posts, but not in the same format!

At the moment this system seems to work, but sometimes the model gets cumbersome. For instance I might be working on the basement area, and you tend to trip over all the other stuff just looking at that. I'm thinking of a lisp routine that freezes layers according to their names- for instance Level1-Plant might get hidden when I want only level2 stuff showing. Yes, this can be done with layer filters and the layer manager. The trouble with the layer manager is that it seems to choose to turn off layers and not freeze them. As well, if you create new layers, you have to update the layer definition in the layer manager.

There are other problems: The detail required of a large plant layout is usually better to be of a low level, whereas for say a tank, I usually make this quite detailed. How to mix and match the two? I don't have an answer as yet. Possibly the answer lies in a 64Bit machine with 12Gigs...?

Wednesday, September 1, 2010

Handrails and Stairs....Lisps

Turns out only 2 people requested the handrail routine I offered for free about a year ago.

If you wonder what these may be about, check out Utube, with bilroCAD in the search box.

Kind of makes me wonder what planet I was on when I thought maybe I could make a small amount of money doing this sort of thing.

Maybe the problem is that if you look hard enough, you can get all sorts of stuff for free.

So I have decided to not be so precious about them and have stuck them on my web site at

If you delve into them you might find (if you are a purist) that some of the programming looks a bit ham fisted. However, they do work most of the time! What do you expect for free? Just to add to the fun, looks a bit shonky when you see that I have put "these do not conform to any known standard"!

I have just spent about 2 days trying to get the handrail one to work with R2011. After much harrumphing I created a special one, just for R2011.

I'm pretty pleased with the handrail one, but the stair one could do with all sorts of things added:like footplates, top-plates, handrails and a sytem for variable depth treads, and some way of tying it in with the New Zealand Building Code. It produces stairs which have a rise x going of 46500, which is not how the NZBC does it, so this lot is going to have to be revisited big time soon!

I like to have just one version of Autocad, so it is quite annoying to have things that work on one version but not another.