Monday, 18 January 2016

Revit Stair Component Sketch Tool Rules

Last month I posted opinions about the pros and cons of doing sketched stairs using the old tools or the new Component Sketch tools.  Now we are going to look at some of the detailed differences between the two methods:

Stair by Sketch

As I mentioned last time, when you first start a 'Stair by Sketch', it seems to be more efficient because you only need to click start and end of a run and it places all the lines for risers, boundaries and run.  From that moment on, you will start losing time to the component sketch method, as you discover how unforgiving the old sketch tool is - one tiny infringement of the rules and it will not complete the sketch.  Most likely you will spend hours trying to resolve it.
Old sketch tool - 2 click run creation

Stair by Component Sketch

When you start the component sketch tool, it does not draw any lines for you - which is why I recommend using the Run tool then converting the run to a sketch.  Once you have a component sketch, Revit is more forgiving about how you complete the line work and finish the sketch.  Revit also gives you better warning messages when the sketch is not good enough.  The rules are a little mysterious, but I have tried to learn them by seeing what I could get away with or not - so here are some of the examples:

Stair Path Lines

The stair path lines define the plan extent of the risers -  they also define exactly where the stair path arrow will go.  On stair Runs they have to be very precise, as the error message will tell you:
"Invalid stair path. Stair path should connect both start and end riser, and cross all other risers."
  • The Stair Path line must start on the first riser 
  • The Stair Path line must finish on the last riser
  • The Stair Path line cannot stop short or go past the riser lines
  • Two intersecting run lines must meet perfectly at a corner on a cranked or winder run (not cross over each other)
  • Landings also have a Stair Path line, but its only purpose is to locate the stair path arrow will go.  For the penalty of no longer having an automatic landing, you could convert it to a sketch in order to get your stair paths right.
Edit landing to create T-shaped stair path
  • In fact you can pretty much do what you like with them on a sketched landing.

Boundary Lines

Boundary lines define the edges of a stair run.
  • Boundary lines are actually displayed dark blue, but you have to zoom in really, really close to see that they are not black lines.
  • They must extend up to or beyond the last/first risers, but not stop short
Boundary line overruns OK
Boundary line shortfalls will not work

  • They do not have to join with the last/first riser, as long as they line up with the end - there can be a gap as Revit treats the riser lines as infinite (or at least very long)
Risers do not need to join boundary lines
Risers can overlap boundary lines
Stair run created from previous sketch
  • Two boundary lines meeting at a corner must intersect (cannot have a gap or overlap)
  •  Stair boundaries can be curved
Curved stair boundaries
Maybe not such a good design
In the above example it would be better if the curved lines were riser lines not boundaries

Riser Lines

It is not possible to change lines from boundary to riser (or vice versa), so you need to choose the correct line type before drawing them.
Curved riser lines
  •  Riser lines can meet at a corner, but not overlap

Warning Messages

Be sure to read exactly what the warning says.
  • If it says 'Invalid Sketch.  Can't create run from this sketch' then it is a problem with the sketch (not surprisingly)
  • If it says 'Invalid stair path' don't waste time looking at the boundary or riser lines - just check the stair path lines (you know, the blue ones!)
  • If it says 'Cannot make stair' - then it is not a sketch problem, but most likely a 3D geometry problem - maybe an impossibly thin riser element (in which case try changing it to a monolithic stair just to check).

What Can You Get Away With?

Could this possibly work as a stair sketch?

With the component sketch tool, no problem

Link to Stair Sketch Tool

Link to Stair Index Page

Monday, 11 January 2016

Weird Stair Stuff part 7 - No Array in Sketch by Component

Here is yet another crazy inconsistency and limitation in the Revit stair tool:
If you use the Stair by Component Sketch tool, it does not automatically create all the riser lines for you (unlike the old sketch tool).  So you need to create one riser and then array it.  But the Array tool is not available in sketch mode, just when you need it most !!!!
Greyed out array icon


Here are my workarounds - not that it gives the Factory any excuse for not fixing this:

1.   Convert to Sketch
  •  Use the Run Tool
  •  Select the run and convert it to a sketch
2.   Multiple Copies
  • Place two risers at the spacing you need
  • Select the second one
  • Click on the Copy icon

  • Make sure it is set to 'Multiple Copies'
  • Snap to the endpoint of the first riser (not the one you are copying)
  • Snap to the end of the second line (that you are copying)
  • It will place a third riser at the same spacing
  • Snap to it and it places a fourth one
  • Keep going until you have your 'poor man's array'.
  • Then log in to the Autodesk website and register a fault that needs to be fixed

Link to Stair Index Page

Wednesday, 30 December 2015

Revit Octopus - RTC 2012 NA Competition Winner

Octopus Hotel, Hainan
Back in 2012 this drawing was the Innovation category competition winner at RTC North America (Atlanta).  It was meant to represent the design process (on yellow trace paper and in Revit) of the Octopus Hotel designed by PTW in their Shanghai office.  The initial design modelling was done in Sketchup and 3D Max, then 2D documented in Autocad.  Then we had to start really documenting it in Revit to make sure the organic shapes were buildable. . . . .
The first task to solve was the plan layout - making sure that each hotel wing (octopus leg) had regular radius curves with smooth transitions between concave and convex curves, with a minimum number of different shaped hotel rooms.  Trying to do that in 2D was painful - lots of reference planes/lines and aligning centre-points of arcs with each other, and plenty of calculations.  If anyone made a change to the layout you had to start all over again.
To improve this process in Revit, I decided to make a flexible component that would place a number of tapered hotel rooms along an arc.  Initially I tried a line-based generic component that required the user to click a start and end point - that worked fine for linear hotel rooms.
As soon as I tried radial arrays, it became a nightmare, as they are really hard to control with parameters.  As adaptive components had recently been introduced to Revit, that seemed to be the way to go - but then I realised that they do not allow the Array command.  'Repeaters' to the rescue!
All of this required a lot of complex fomulas and trigonometry, even with using Repeaters - particularly as I wanted the end user to be able to dynamically change and schedule room areas, widths and the radius.

Area calculations for segments
Eventually I managed to create an adaptive component that had two curves (concave and convex), forming a corridor double loaded with rooms.  This was fully parametric in terms of being able to stretch the start and end points and change the two radii as well as critical room dimensions.

This would have made the design process so much easier than relying on several different programs and yellow trace paper!  Creation of this component was fully documented in my handout for the RTC events in 2012 (Australasia and North America).  When I get a chance I will try to post some of the techniques on this blog.

The 2d planning was only the start of the challenges - each hotel room had a balcony that had curves in plan and in elevation, so that really challenged Revit's ability to create organic geometry - but we did succeed in building a convincing 3D model in Revit.

Octopus hotel wing


Of course, now you might be tempted to use Dynamo to build this sort of complex geometry.

Friday, 4 December 2015

Revit Stair Sketch Tool

I have noticed that most people who want to create a non-standard stair in Revit will resort to the old stair sketch tool.  This is a really bad idea for a number of reasons.  I only know of one good reason for doing so (more on that later).
The old Stair by Sketch tool was left in Revit as a 'safety blanket' for those worried about the new Stair by Component tools.  In reality the component stair tools are much better than the old tools despite the many glitches and shortcomings.

So, what happens if you want to create a non-standard stair that cannot be done using standard components?  A tapering stair for example.  Well, the component stair has its own sketch tool:  the icon looks like a pencil with curvy line (highlighted below).  That means you can sketch just one component - say a run or landing (both have the sketch option, but Support does not).

Once you start a component sketch, you get three line types, much like the old stair sketch tools:
  • Boundary lines
  • Riser lines
  • Stair path

Once you start using these line tools, you will see that they work quite differently - each line has to be created (drawn or copied), unlike the old sketch tool that created all the lines when you placed the central run line.  This may seem like a retrograde step (pardon the pun) but it is no great hardship, particularly as there are so many other advantages.

I usually find it is easier and quicker to create a standard run or landing component that approximates what you ultimately need - then convert it to a sketch.

It will give you a warning that the process is irreversible.  Take heed, because once it is a sketch it will always be a sketch, unless you delete and replace with a component (and risk losing hosted elements).

Once a component is converted to a sketch, you need to select it in order to then edit the sketch - this seems like a needless step, but in fact it is logical.  It caught me out a few times, wondering why my converted component did not look like sketch lines.

Once you are in sketch mode, you need to remember that adjusting the central Stair Path line will not affect the riser spacing - it is just another line.  The Finish Sketch command is much more forgiving than the old sketch tools, which were very temperamental.  I will cover more detail on the rules of what the sketch command will or will not allow, in another post.

Stair by Component = Good;   Stair by Sketch = Bad

Why is it bad to use the old sketch tools?  Here are a number of reasons:
  1. Using the old stair tools means that you are missing out on new features like stair numbering - despite the shortcomings, they are useful.
  2. The old sketched stairs have the path arrow built into the stair, which means limited control on where and when they show up.  It also means very limited control on the stair arrow style.
  3. It is really bad news to mix old and new stairs together in the same project because the annotation can be extremely inconsistent between the two - particularly for stair path arrows.  This leads to confusion and messy drawings.  Refer to Stair Paths Arrows for more detail.
  4.  Stair by component gives much greater control and options for changing the number of risers, the height and location of landings etc.
  5. Stair by Component allows stair runs to go over the top of each other - useful for spiral stairs more than 360 degrees, or for stairs with 3 runs per storey.
  6. Sketching individual components (run or landing) allows other parts of the stair to remain as components, with all the benefits of that.  Stair by Sketch means the whole stair is one sketch.
  7. The list goes on . . . 

Reasons to use Stair by Sketch

There are a couple of reasons for reverting to the old stair tools, but hopefully these will be dealt with by Autodesk fixing the bugs in the component tools:
  1. "Show Hidden Lines" does not work on component stairs
  2. There are many shortcomings with the Stair Path tool for adding stair arrows, including:
  • Cannot copy and paste stair arrows between views
  • There is no "Tag all stairs" command for adding paths to multiple stairs at one go
  • Duplicating a view will not include stair path arrows unless you duplicate with Detailing, in which case you get all the other annotation.
The moral of this story is that the reasons for using Stair by Component sketching far outweigh the minor benefits of sticking with the old Stair by Sketch tools.  I wish that Autodesk would fix those bugs and remove the old tool so that people would stop using it.