String shape editing
This is a detailed look at manual stringboard shape editing, and also splitting a stringboard into separate parts, useful if a landing is present for example.
Stringboard shape editing
StairDesigner automatically calculates a curved shape for your stringboards, based on a fixed distance from the step nosing. They can also be set to straight or a sequence of straight elements.
More information:
It’s also possible to manually edit the shape of the stringboard. This makes it easy and very fast to add or refine the curve of your strings to complement your design goals.
We have a StairDesigner overview video that includes this operation, and finally, some extra advice on editing curves when we look at step shaping.
More information:
To access stringboard shape editing, switch to the display of stringboards only.
Here are the left and right developed stringboards for a quarter turn stair with a landing.
Double-click in the stringboard volume to enter editing mode.
Note that you can at any time switch between strings from the drop down menu.
One other point to note at this stage. Before editing, the stringboard will have a standard Type as shown in the Properties menu, and other associated parameters such as the width.
After the first edit, Type will change to Custom, and adjusting the thickness with the standard thickness parameter will not have any effect.
The option remains, however, to switch back to a standard type from custom.
Let’s create a curve at the base of the stringboard.
Firstly, to highlight a few features, we’ll delete some points by double clicking on them, and then click on and drag the line to bend a section of the string, and finally right click to access Convert into a line segment, all shown below:
Here’s the resulting straight line:
Let’s also delete the penultimate point from the base of the stringboard and extend the base to the right, just by dragging the anchor point as shown:
With this anchor point still selected, we have two handles (marked with circles). Dragging these allows us to define the curve as we want. The right handle has been dragged up and we’re now getting nearer the shape we want.
In this case, we’ve used the grid to ensure the handle is directly above the anchor point; this is not required but it results in a pleasing shape.
Right click now on the next anchor point and select Smooth vertex.
The following pop up window appears, we can choose whether to smooth the line by adjusting the shape to the left or right of the point, or both.
The Smooth vertex option will not be shown in all cases, but here, at the intersection of a straight and curved section, it does.
If two sections of a string aren’t smoothed, in the 3D you’ll see a line in the string.
We’ll choose smoothing to the left, here’s the final result:
This was a classic case of adding a curve at the base of the string. It’s possible to add your own curved sections at any point with the help of this feature.
Split a stringboard into separate parts
Sometimes we would like to split a string into multiple sections, as opposed to accepting the default string created by StairDesigner.
A good example is when we have a stair with a landing. Let’s take exactly the same quarter turn stair as above.
So that the join is hidden, we are going to create the cut behind the riser at the point shown below:
To do this, go back to the 2D editing window of the whole stair, and double click on the stairwell to edit it. Then double click again to add a point behind the riser (the double dashed line).
Now select the stringboard, and go to Modify > Ungroup the stringboard.
In our example, three separate parts are created because we had a point at the end of the landing too. So the single string was cut at two points resulting in three parts.
Let’s fix this by selecting the lower stringboard and then selecting Modify > Group with the next stringboard.
This merges those two strings and we have the result we need: two strings in total with the join behind the riser.
Editing continued
Let’s split the string of the 2nd flight now. We would like to position the join in front of the first step after the landing, let’s say 20mm from the nosing.
The image below shows the end landing point (exactly where the step nosing is) and then highlighted is another point 20mm to the left of it. We placed this manually, then used the coordinate system to position it accurately.
As before, the stringboard was ungrouped into three parts, then the upper two strings were grouped. Here is a developed view of the resulting two stringboards with the joining point highlighted:
Here’s the stringboard at the landing highlighted:
Let’s now change that landing stringboard to a straight string in the Properties menu:
Finally, let’s work on the upper stringboard. We could make that straight too and improve the join by changing the stringboard position or by manually editing.
Instead, we’ll keep it curved and start by adjusting the bottom of the upper string so it meets the landing string; it’s too low at present.
In this stringboard only view of the landing string, we can see the y value we need:
Back to the upper stringboard now, put this same y value (1245) in as shown:
After that, on the bottom edge, we’ve removed the penultimate anchor point and used the Bezier curve handle to create a nice curve as it meets the joint. On the upper edge, we’ve converted it to a straight line.
Here’s the result:
And in 3D:
This shaping feature, splitting stringboards into multiple parts where needed, and use of the coordinate system for accuracy, is a powerful suite of tools to design flexibly and very fast.