Timber NC - BTL
Not version-specific
Tekla Structures
Environment
Not environment-specific
BTL - Preface
Construsoft developed and implemented several Timber NC-export tools in Tekla Structures.
Each of these export tools is dedicated to a specific Timber NC-file format, each with their own scope and definition.
The scope of some of the formats is such that Tekla can unambiguously determine the operation from the geometric information. These are categorized as basic formats. There are however also formats for which, for volumetric operations, it is not possible to unambiguously determine which operation is meant. In those cases the user needs to provide additional non-geometrical information in the form of the name of the operation. These file formats are categorized as advanced formats.
Another way to categorize the file formats is by considering the type of objects they can describe.
Next table illustrates these categorizations:
| Single-piece | Framing | ||||
| Timber NC-File Format | Type | Beam | Plate | Beam | Plate |
| BTL | Advanced | Yes | Yes | Yes | Yes |
| Hundegger-BVN (K2) | Advanced | Yes | No | No | No |
| Hundegger-BVX (SC3) | Advanced | Yes | No | No | No |
| Hundegger-BVX2 | Advanced | No | Yes | No | No |
| GT_Hechttechniek | Basic | No | No | Yes | Yes |
| HM (M311 ; HMT ; HMZ) | Basic | Yes | No | No | No |
| Randek | Basic | No | No | Yes | Yes |
| Tigerstop | Basic | Yes | No | No | No |
This document handles the various volumetric BTL-operations on single pieces that Tekla can handle and should be read in concurrence with article Timber NC-Operations - Background & general modelling aspects.
The complete BTL file format description is: btl_v106.pdf.
Click here for the Tekla Structures model "BTL-Timber Operations".
0. Some remarks beforehand
Machine-independent
The BTL-file format is a machine-independent format. It only describes geometry.
In according with this, the BTL-export tool from within Tekla Structures will only export geometry as well.
Machine-scope
The suite of operations that a BTL-machine can process, may vary from machine to machine.
Therefore, when parts of a Tekla Structures model are to be exported to BTL, it is strongly recommended to become familiar with the scope of the machine to which the BTL-data will be fed. The Tekla Structures model should also be according that specific scope.
Operation-scope
In theory, Tekla Structures allows to model freely. However, each BTL-operation has a certain scope.
Hence, the scope of the BTL-operation is leading and must be taken into account when modelling parts from which BTL-data must be extracted.
Volumetric operations
This document primarily covers volumetric operations.
1. Coordinate system of the part that carries the operation
Next image illustrates how BTL defines the coordinate system of a part.
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2. Reference Sides and Reference Edges
In Timber, initially all parts have a rectangular cross section and all parts are prismatic.
In total, initially, each part has 6 faces: four longitudinal and two end faces.
In BTL the longitudinal faces are referred to as Reference sides (RS)
- The RS are numbered 1,2,3 and 4.
- The end faces are numbered 5 and 6.
Each of the four longitudinal Reference Sides has a Reference edge.
Each Reference Side has its own coordinate system. It is this coordinate with respect to which the position of an operation is described.
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- The origin of a RS-coordinate system is at a vertex of RS on the virginal part.
- The Xrs axis is in the direction of the Xpart axis.
- The Yrs axis is orthogonal to Xrs axis and lies in the plane of the RS.
- The Zrs axis is the cross-product of Xrs and Yrs.
3. Reference point
Each volumetric operation is defined on a Reference Side and has its own reference point.
The position of this point is defined with respect to the coordinate system of the Reference Side.
The reference point has three coordinates (Xref, Yref, Zref).
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Note that the position of an operation do not influence the dimensions and orientation of an operation.
4. Operation naming convention in BTL
In BTL, an operation is referred to as a process.
The denotation has the format: G-KEY-S DES and reflects the following properties
- Group (G)
- Key
- Reference Side (S)
- Designation (DES)
The format is: G-KEY-S DES
Group
This indicates whether the process is Separating, Discrete or Profiling.
G = 1 means Separating process at end.
G = 2 means a Separating process at begin.
G = 3 means a Discrete process, position with respect to end.
G = 4 means a Discrete process, position with respect to begin.
G = 0 means a Profiling process.
Key
This is the identification number of the process.
Reference Side
This is the side on the part onto which the process is defined.
Designation
This is a descriptive string.
Example
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5. BTL parameter set for positioning the reference point
In general, the reference point has three coordinates, in other words there are three independent variables that unambiguously define the reference point of an operation.
For most BTL-operations the reference point lies on the reference plane onto which the operation is defined. For those operations Zref = 0 and cannot be controlled. For non-controllable variables BTL does not provide a parameter.
Examples
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6. BTL parameter set for dimension and orientation
BTL uses linear and angular parameters to define the geometry of an operation.
Like with position, the available parameter set for an operation defines the scope of that operation.
Examples
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7. Unambiguity and scope
Because of analogies and differences in scope and definition, there are cutouts that can be cast as more than one BTL-operation. There are however also cutouts that only suit one specific BTL-operation.
For example for a Tenon, BTL only provides one operation, whereas, in BTL, a perpendicular transversal rectangular cutout can be described by either a Slot or a Lap Joint.
Next image illustrates this:
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Likewise, a full-width partial depth cutout at an end can be by either a Ridge Lap, Lap Joint or Front Slot:
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Although a Ridge Lap operation is three-dimensional, only two of these dimensions can be controlled by setting parameters. The third dimension is calculated (P14=b) and, hence, dependent. Note that this corresponds with the fact that Ridge Lap is a separating operation (G = 1/2).
BTL also defines a Lap operation. Lap Joint provides parameters for all three dimensions.
Orientation-wise a Ridge Lap allows to set only one angle. This implies that the other two orientation angles are calculated/fixed. A Lap Joint allows to set all three angles.
Because of these, each Ridge Lap operation volume can be described by a Lap operation but not all Lap operation volumes can be cast as Ridge Lap operation.
Next image shows the parameter comparison between a Ridge Lap and a Lap Joint:
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8. Processes, type and tools
Some operations are Separating (S)
Some operations are Discrete (D)
Some operations can be either Discrete or Profiling (D ; P)
Some operations are Annotative (A)
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Next table shows the list of current available operations (processes) and their type.
| Process | BTL-name | Volumetric / Planar | Type | Tool | Remark |
|---|---|---|---|---|---|
| Cut | 1/2-010 | Planar | S | - | |
| Double Cut | 1/2-011 | Volumetric | S | - | |
| Ridge Lap | 1/2-030 | Volumetric | S | Lap Joint (j152) | Only spliced configurations |
| Simple Scarf | 1/2-070 | Volumetric | S | Lap Joint (j152) | Only spliced configurations |
| Tenon | 1/2-050 | Volumetric | S | Tenon and Mortise (j150) | |
| Dovetail Tenon | 1/2-055 | Volumetric | S | Dovetail Tenon & Mortise (j151) / Swallow Tenon & Mortise (j158) | Swallow Tenon & Mortise (j158) will generate a Swallowtail Tenon |
| Slot | 3/4-016 | Volumetric | D | - | |
| Slot Front | 3/4-017 | Volumetric | D | ||
| Lap Joint | 3/4-030 | Volumetric | D | Lap Joint (j152) | Only spliced configurations |
| Birds Mouth | 3/4-020 | Volumetric | D | - | |
| Block House Half Lap | 4-037 | Volumetric | D | - | |
| Drilling | 3/4-040 | Volumetric | D | Sunken bolts (m096) | |
| Mortise | 3/4-050 | Volumetric | D | Tenon and Mortise (j150) | |
Mortise Front | 3/4-051 | Volumetric | D | ||
| Dovetail Mortise | 3/4-055 | Volumetric | D | Dovetail Tenon & Mortise (j151) / Swallow Tenon & Mortise (j158) | Swallow Tenon & Mortise (j158) will generate a Swallow Mortise |
| Longitudinal Cut | 0/3/4-010 | Volumetric | D;P | - | |
| Ridge Cut | 0/3/4-012 | Volumetric | D;P | Ridge/Valley cut (d153) | |
| Valley Cut | 0/3/4-012 | Volumetric | D;P | Ridge/Valley cut (d153) | |
| Free Contour | 0/3/4-050 | Volumetric | D;P | Contour (m149) | |
| Marking | 3/4-060 | Volumetric | A | TO Marking Net (m116) |
Note: The prefix in the BTL-name indicates the type.
- Prefix = 1/2 indicates that the operation is a separating operation (S)
- Prefix = 3/4 indicates that the operation is a discrete operation (D)
- Prefix = 0 indicates that the operation is a profiling operation
The prefix indicates the scope, so 1/2 means either 1 or 2.
Construsoft developed some tools. The table shows for which operations this is the case and which tool can be used to model them.
9. Modelling BTL-operations in Tekla Structures: Cut 1/2-010
In BTL, a Cut is a planar operation that separates a portion from a solid.
Modelling:
A Cut operation can be modelled using a either a Fit or a Trim command.
When there is only one saw cut at an end then it should be modelled using a Fit.
When there are more than one saw cut at one end then the first Cut should be a Fit and all subsequent others should be Trim operations.
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Remark(s)
There is no parameter to control the distance over which the Cut operation stretches. Therefore, a Cut will always start and end in thin air.
10. Shape of negative volume and shape of cutout
Each volumetric operation is to be modelled using a negative volume.
Note that the shape of the negative volume does not necessarily match the shape of the cutout:
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11. Tekla tools
Some operations and combinations of operations are hard to model manually. For these, Construsoft developed dedicated tools. These tools will assign the appropriate names to the negative volumes.
| BTL-Operation | CS-Tool |
|---|---|
| Tenon- and mortise | Tenon and Mortise (j150) |
| Dovetail tenon-and mortise | Dovetail Tenon And Mortise (j151) |
| Lap Joint(s) | Lap Joint (j152) |
| Swallow tenon- and mortise | Swallow Tenon And Mortise (j158) |
| Ridge/Valley cut | Ridge/Valley Cut (d153) |
| Drilling | Sunken Bolts (m096) |
| Marking | Marking (m116) |
| Free Contour | Contour (m149) |
Tenon and Mortise (j150)
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Dovetail Tenon And Mortise (j151)
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Lap Joint (j152)
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Swallow Tenon And Mortise (j158)
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Ridge/Valley Cut (d153)
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Sunken Bolts (m096)
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Marking (m116)
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Contour (m149)
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Tekla Structures Model
The model: BTL-Timber operations illustrates the type(s) of the various volumetric BTL-operations and how they can be modelled.
The parts and operations are organized in a matrix.
- The type of operation varies along the X-axis.
- The operation name varies along the Y-axis.
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The class of the part indicates how the operation was modelled:
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Class = 12 :The volumetric operation on the part was generated by a dedicated CS-tool.
Class = 13 :The volumetric operation on the part was manually generated by a “Part cut” based on a Beam part.
Class = 10 :The volumetric operation on the part was manually generated by a “Part cut” based on a Contour Plate.