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Modified four vector cross product algorithm - The modified four vector cross product
algorithm is a variant of the four vector cross product algorithm in which an auxiliary
vector and two vectors on the surface are used to construct the cross product vector.
Because of its stability this algorithm was chosen to be a good solution for slicing of
curved layer models.
The modified four vector cross product algorithm was chosen as the best for
constructing slicing models, there were a few issues like self intersection and
duplication of points which needed to be addressed. To overcome this, each surface
point is to be provided with additional data. Different combinations of 1‟s and 0‟s in
the extra information column would mean the different possible motions of the
deposition head. Another drawback from the modified four vector cross product
algorithm is that when two or more points on the deposition path are repeated. Due
to this, the machine may tend to deposit more material in the repeated set of points
assuming they are different set of points. To avoid this repetition of points a module
check is developed which scans all points in each layer and compares it with
coordinates of each pair of consecutive points. During this if two consecutive points
are similar; one of them is dropped from the database.
2.4 Current method used for slicing and deposition
For the purpose of this research project, two models are chosen for producing
curved layer parts and their testing. The first of these models is chosen to explain the
concept of slicing procedure being used to print and test the part. The main part (Fig
2.13) and its support structure (Fig 2.14) are as follows:
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