Tuesday 16 October 2012

Type Catalogue Tips

The video below shows a method for setting up Type Catalogues so that they can be accessed from within the model.  Essentially, 2 URL parameters are added to the family. The first is pathed to a csv file, which allows much easier editing than the text file. The second points to a batch script, which will copy the csv files to text files for Revit to use as the catalogue to load from. These files must all be held in the same directory

This method is quite useful, as you can add types in situ as you are modelling. One thing that would be nice would be if Revit had the ability to reload a family by right clicking the element, as opposed to doing it from the browser window. This would enhance this method further and would also be more intuitive, as you don't have to shift your focus from the model to the browser and back again

Thursday 27 September 2012

Revit Needs to Go Back to School

Here's a simple maths problem. Take a circle of radius 10. This radius could be any unit of measurement;  millimetres,inches,light years,baby steps. To find the area of this circle, you apply the formula:


Therefore the area of our circle is 3.14159 x (10²) = 314.159

Seems simple enough?

Not according to Revit

Draw a filled region using a circle of radius 10.
Firstly, do this using metric units (mm & mm²) and you get:

Now do this in imperial units (decimal in & in²) and you get:

The metric figure is 99.98% accurate, the imperial a little closer. Big deal you may say, and in most cases you'd be correct, certainly in a small example like this. But what if I take this circle and make it bigger, then I extrude it to make some 3D geometry, then I copy this around many times, then I want to know the volume of these elements?  Small errors start to compound into more significant overall errors

pi is a constant. Revit knows this is a circle. So why the discrepancy?

Thursday 2 August 2012

Look No Hands! - Formula Free Positive and Negative Offset

The following video outlines a method for achieving positive and negative offset, using a blank(ish) nested Generic Model family. The offset value of this family, once it is nested, can then be through-linked to a parameter in the host family and under certain conditions, can then control geometry

The first part of the video demonstrates the creation of the blank 'plane' family. Essentially, the steps are follows:

  • Create a new family from the 'Metric Generic Model' template (or its imperial equivalent)
  • Under 'Family Category and Parameter's, ensure only 'Work-Plane Based' is checked
  • In an elevation view, set the reference plane running along the level line to 'Strong Reference'
  • In the plan view, put in two model lines along the reference planes and lock off. Set to 'Not a Reference'. These lines are provided purely for visual reference once the family is nested
  • Under the family parameters, add a new yes/no instance parameter 'Lines Visible'
  • Select the model lines and link their visibilty parameter to this. This will allow visibilty control of the lines once nested
This now completes the 'plane' family.

In order to use this, create a new family and load this in. This can then be placed on any workplane (ie named reference planes and levels) and the offset from workplane controlled from a parameter in the family by linking the two together. 

Above I stated that this is subject to certain conditions. Essentially, you can only control the geometry by locking the sketch work of the solid, not the solid itself. For instance, if you place an extrusion and use the solid's drag handles, as opposed to the sketch line for that edge, it won't work. The same is true for sweeps, you must lock the path sketch line itself, not the solid. The video goes on to demonstrate this behaviour in action.

Hope this helps and enjoy!

Thursday 12 July 2012

Sharp Elbows - New Revit 2013 'Structural Material' Parameter and Model Upgrade Problems

The purpose of this post is to shed a bit of light on a Revit 2013 model upgrade problem. It will also assume a certain level of Revit knowledge

The materials functions have been seriously overhauled for Revit 2013.
On the Structures side, a new built-in parameter 'Structural Material' has been introduced.

This parameter is non-modifiable and non-removable. It can only be altered from 'Instance' to 'Type' and vice-versa. The function is by design and appears to be for the purpose of using extended information for calculation and to provide a more fixed and stable platform in the structural model for third party analysis software linking

When family files are updated in Revit 2013, the upgrade elbows out any existing material parameter and replaces it with this.

However, we have discovered a slight complication with this. Take specifically families which have a nested component, and the material parameter in this nested component is linked to a material parameter in the host.

If you open the family file directly in Revit 2013, the upgrade process will 'sever' this link, but it will upgrade.

If you are upgrading a project that contains such a family, the upgrade will fail for these elements and Revit will require that these are deleted from the model before continuing. This is happening here with our Pile Cap families, which have a Pile family nested inside.

To get around this, you have to open the project model in the previous Revit version and edit the offending families to de-couple the material parameter link. The model will now upgrade in Revit 2013. You can now re-edit these families to re-couple the parameters, then reload back into the model.  You may also want to consider changing the previous material parameter to the new 'Structural Material' to take advantage of the new functionality

I trust this helps and is clear, but please feel free to comment

Thursday 2 February 2012

Adjusting the Workplane of Multiple Beams - When Revit Says 'No'

I've never quite pinned down why this happens, but on occasion, when trying to adjust the workplane of a selection of beams, the dialogue greys out

As I see it, there are three different workarounds
  • Cut & Paste by 'Selected Level'
  • Select Individually
  • Hitch a Ride in a Group
Cut & Paste by 'Selected Level'
This is the easiest option and is fine if you haven't got any annotation

Select Individually
This is fine until you hit a certain point, where the original problem kicks in. One visual indicator is that providing the 'Pick New' button is still lit, you will be able to change the workplane. If you hit the limit, just use shift+click and remove the last beam selected

Hitch a Ride in a Group
You have a view with beams that are annotated with tags.
You want to amend the workplane of some of them, while still showing the beams and maintaining the tags in that view. Select the beams and the tags and group them together. This will create a model group with an attached detail group. Change the level of the group to the required level, then ungroup and delete the group from the project browser. The beams should now be at the amended level. The tags will show, providing the new level is within the view range of the view.

Wednesday 1 February 2012

Section Marks - Some Observations

A problem that seems to come up sometimes is getting section marks to look consistent on a series of floor plans. For grids and levels, the 'Propagate Extents' function serves this purpose, but doesn't extend to section marks. In absence of this, I set out to discover the rules that dictate how section marks behave in relation to views

The Scenario

The plan on the right (Level 1) is the view in which the section mark was placed. Both views are set to an identical crop box. The extents are at the border between the pink and blue shading (more on this in a minute)  As you can see, the marks display as required

Now in the plan on the left (Level 2), the view crop is adjusted. All four sides are within the shaded areas and the section mark remains unaffected

Moving one of the crop extents outside of this shaded area, the section mark revokes to its default initial view.


In short, there is a zone of 63.5mm (or 2.5" in old money), multiplied by the view scale.
This is applicable inside and outside the crop extents. (shown here as pink and blue).  
It relates to the view where the section mark is placed and governs the display in other views. Should the original view crop extents change, this zone will amend with it. Providing all four extents in any other views are within this zone, the section mark will remain unaffected

In standalone views (ie non-dependent), the best way to control this is through a scope box. In dependent views, it is best to place and adjust the section mark in the 'Child' view, rather than the 'Parent View'.

Monday 23 January 2012

Add Spot Levels to a Topography Section - A Workaround

A slight annoyance in Revit is that you can't add a spot level to a topography in a section view. The following video shows a workaround for this. Essentially, you isolate the topography in the view and export to a dwg file. In Autocad, delete everything except the hatch pattern. This is then re-linked ('Current View Only' & 'Auto Origin to Origin') back into Revit as a 'background'. Revit will now allow you to place spot levels onto the hatch pattern. If the topography changes, you'll need to repeat the process

Get a Little Extra from a Graphical Column Schedule

The following video demonstrates a method for specifying connection types using labels in a Graphical Column Schedule. This is achieved by nesting a Generic Annotation family inside a Connection Symbol family. The Connection Types are then set up in the project under 'Structural Settings'. This is particularly useful if you need to show this information without modelling every single connection, for instance at a preliminary design stage

Wednesday 4 January 2012

Trace a Spline in a Linked Dwg File and Some Recommended Reading

The scenario. You get a dwg file for overlay. The architect has drawn a beautiful sweeping curved  edge to their building, You link the dwg file into your model and see its a Spline.

Which presents two problems:
  • You can't trace over it in Revit
  • You can't set it out. And if you can't draw it, they can't build it

Fortunately, you can use the 'Flatten' command in Autocad to turn it to a polyline of arcs. By then exploding the polyline, you are left with a series of arcs that you can pick in Revit and also set out. The following short video demonstrates this

On another note and as a supplement to this, I recently came across
'The CAD Setter Out' blog by Paul Munford. For people who regularly have to clean up third party CAD files for use in Revit (or generally), this is comprehensive and highly useful resource. Its written generally from the CNC/Fabrication perspective, but is very pertinent reading to the designer. I'd recommend the following posts as a starter

From CAD to CAM, Cleaning up 2D DWG files for CNC.

How to optimize your AutoCAD DWG drawing files

Why Setter Outs aren’t (and don’t want to be) Designers.