Monday, 22 August 2011

Do you find Revit puzzling?

This post isn't a tip or workaround but more a simple observation which has stuck in my mind. 

During a typical working day I get lots of questions from team members regarding their Revit projects.. Some the answers I give them are quick fixes, some are simply advice tips however some are simply bad news. 

As I'm sure many of you already know, Revit can be amazing at doing complex tasks and yet sometimes it can seem almost impossible to get it to do something that the user considers a simple task. In actual fact, this is more often than not a user issue rather than a Revit issue. When this kind of thing occurs I can usually find a workaround to achieve the desired result but it often comes with bad news for the deadline panicked user.

Usually these issues are a result of a lack of forward planning when it comes to building the model or sometimes it can be a change in the user's requirements of the model. (these can be the same thing).. When this happens you often have to unpick a lot of work to be able to be able to provide a fix.. Users don't tend to like this and I often find myself the bearer of bad news.

In a recent such case and after explaining an open-heart surgery procedure for a live Revit project a colleague of mine summed up the whole thing in a nutshell. He said that it reminded him of doing a slider puzzle...

You know the one where you almost get it completed but the last two squares are the wrong way round. The only way to get it right is to go back and tear up what you have just done and rework it. Well guess what.. The same applies to your Revit projects..

Actually, I rather think a Revit Project is more like something like below but you get the idea.

I guess the lesson is to try and start with the end goal in mind. Please dont just jump in, whilst you may well get 1-13 done in record time I can guarantee you will be doing it again tomorrow if you want 14-15 the right way round.. 

Thursday, 4 August 2011

Beware of the Dimensional Rounding

This is an interesting issue i have come across on a number of projects now and therefore one i thought worth posting about. Its symptoms include not being able to dimension elements horizontally within sections. For example, your section cuts perpendicular through a wall however for some reason you cant dim to the wall edges.
To make this worse, you can see your Gridlines in section but if you try and dimension to them you get the following error message:


As the message suggests, this can be pretty serious.

This pretty much ALWAYS caused by the section not being perfectly perpendicular to the gridline. What is odd about this is the fact that Revit actually displays your gridlines even if this is true.. How can it if the view is not perpendicular? My guess is that Revit has some element of tolerance when it comes to this. The problem seems to come because the dim tools don't appear to have ANY tolerance.

So lets check the theory:

Within the file above the first thing i looked at what the relationships of the grids to each other. I threw a few dims on and it all appeared fine.

Check 01

The thing is, i have seen this a few times before so i knew what was happening here. The key is to be aware of the decimal rounding which the dim styles is applying to the angular dims in the image above.
To check I went into the dim settings via the route highlighted below:

Dimstyle -1

Initially the dim style was set to use the project settings. This was rounding to 2 decimal places.
To check the true angles of the dims i set the dim style to Degrees, Minutes and Seconds.

The results were as below:

Check 02

Oh dear..

This is the equivalent of the being 0.0001 degree out.. Seems a bit harsh doesn't it but the fact is it is incorrect.
Now the fact that the grids are not perfect is not strictly the problem here but it is the cause. In truth the crash is caused by the fact that the section is not at exactly 90 Degrees to the intersecting gridline.

Of course the correct thing to do here would be to check and adjust the gridlines and all the other geometry within the model but this is not always viable. If this error is caught early enough correcting the grids may be viable. However as is more often than not this error is not found until weeks into a project.

I guess the lesson learnt from this would be to use Degree, Minutes and Seconds as a basis for angular dims, at least for the initial project setup.

I do have a work around to ensure that sections are perfectly perpendicular to a gridline. I will try and cover this in my next post.