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How to select patterns for 3D surfaces

This page has particular relevance to the Pattern Reference, but I include it in the Technical Reference as well because it primarily relates to the geometry of engine turning. It is an attempt to explain what will fit where and avoid us being given impossible briefs!

Matching Patterns to suitable Surfaces - pattern groups.

Using the diagrams on this page you can see which patterns will work on which surfaces. Don't Worry if all this seems too complicated, just tell us what effect you want to achieve and we will show you what can be done at the appropriate price for the market the goods are intended for.

Each of the basic primitives from which all surfaces are defined (e.g. an egg would be included with the dome primitive as would be a doughnut ring) are represented as icons. Arrows indicate the direction you could cut on these surfaces without difficulty. I have not included such things as spiral cutting on tubes, cones and spherical shapes: consider them to be imaginary purple arrows: difficult and expensive but not always impossible.

It is also very well worth noting that most complex looking shapes can, with a little imagination, be resolved to a part of one of these primitive shape groups, or reasonably closely to it. We have always been particularly well known for our ability to engine turn even the most complex surfaces to a very high standard of quality.

The basic icons. Arrow colours are arbitrary here.

The Primitive Icons represent the following shapes in the order illustrated above: This is the explanation of the icons. This list is NOT the pattern group list! See below.

1. Cylinder - Tube of any profile, (non round more expensive),boxes, bangles, rings etc including SLIGHTLY tapered tube as for a pen body.
2. Cones - from tapered tube to shallow angles like a shallow round roof point.
3. Curved Cones - from large bases to narrow stands and trumpet shapes (beware not too concave!). This can also include convex curved cones.
4. Domes - All Spherical shapes such as eggs, curved bases, mudguard shapes, doughnut shapes.
5. Flat or nearly flat Surfaces with approximately parallel cutting in whatever direction, or with circular cutting.
6. Flat Surfaces with Sunray Cutting - cut direction radiating. If the surface is not quite flat then complete sunrays are as Red or Blue Arrows.

The colour of the arrows indicates the possibility of cutting the pattern in that direction.

Red indicates that the pattern is geometrically unsuited to the surface and would either be prohibitively expensive or impossible to do with a reasonable chance of acceptable quality. It is possible that there also might be some stretching of the pattern.

Blue indicates that the pattern can be cut with certain restrictions - e.g. a sunray pattern can be cut even on a domed surface but there would be problems completing the last few cuts as the guide would have to pass over the first few cuts, (the guide being on the right of the tool and progress of cutting lines from left to right on the work) as you get back to where you started! There may or may not be some stretching of the pattern. Often there are ways in which this problem can be solved, though the solution can be expensive.

Light Brown indicates that there is no problem technically with this direction on this surface and it can usually be done economically. However it must be born in mind that the pattern will stretch and be distorted as it covers the surface. This applies to all circular patterns (where the cuts are either concentric circles, wavy circles, or arcs and wavy arcs of circles)and sunray patterns where the cuts radiate from a point on or off the workpiece. The Radial element in a circular design (e.g. the amplitude of the waves) is the same at all diameters and the number of waves in a circle or the number of cuts in a sunray remain constant (though they may swirl around the centre). All sunray work falls into this category because the pattern is always distorted by its radial nature.

Green indicates that the pattern will look similar to the illustration on the surface in the direction indicated.

Scaling

There is some ability to scale all Low Relief type patterns and all patterns cut on the CAD/CAM system, but most ordinary 2D engine turning (on a flat or a 3D surface) is effectively same size to the pattern bar or diametrically related to the rosette for a circular machine. However we often have many sizes of bar for a particular straight line pattern and therefore we include the scaling icon: where there is a possibility of cutting the pattern in various sizes though we may not necessarily have every possible size available! For important jobs or volume production we can make any pattern bar or rosette to match anything that has ever been done as well as new designs with the limits set out in the technical reference.