Technical Officer Articles

3D Printing

 

Just a simple description of 3D printing.

We use Fused Filament Fabrication as a method of 3D printing. In this thermoplastic material is heated and extruded through a nozzle. A spool of filament is loaded into the printer and fed through to the extrusion head. Once the printer nozzle has reached the desired temperature, a motor drives the filament through the heated nozzle melting it. The printer then moves the extrusion head around, laying down melted material at a precise location, where it cools down. Once a layer is complete, the build platform moves down and the process repeats, building up the part layer-by-layer.

The range of plastics include ABS, Nylon, Polyester, etc. One adjusts the printer to cope with these materials.

To make a component, one has to start with a 3D model. There are many 3D CAD programs to do that; the output from these CAD programs commonly use STL files.

Once you have a STL file, you can use that as the input file for so-called slicer programs that generate the g-code that the printers understand. We load the g-code onto a memory card which fits the printer.

We have an Ultimaker printer and they use Cura as the slicing program. There are some limitations using this printer, mainly the build volume (8x8x12"); anything too large will have be made in pieces and joined together afterwards.

Because FFF printing produces an anisotropic part (i.e. varying mechanical properties in different directions) it is important to properly orient the part.

Commonly, we use infill percentage of 20%, but for some parts we use 100% infill, based on the use of the part; 100% for parts we want to use, 20% for checking the form and fit.

It is also important to consider support materials, often made from the same plastic; wherever there are unsupported surfaces in the part, or bridges, or overhangs, then you want support to be printed. Of course this increases the build time, and expense, but does guarantee that you make a useable print.

Why do 3D Printing?

It enables us to evaluate fit and form in the Drawings Project.

It enables us to make patterns for sand or investment casting.

It allows for functional parts to be made (e.g. gearbox lever, propstand support, pinion for the speedo gearbox).

 

 

 

 

 

technical notes

The subject of engine oil often crops up; different riders have their own opinions. These range from using a monograde (such as 40W) to using a fully synthetic oil (such as Mobil 1) with a viscosity rating of 15/50W. For those only mildly interested in engine oil, it is common practice to use an available grade from the garage forecourt (say 20/40W multigrade).

Fully synthetic oils do have superior properties, such as increased lubricity, and high temperature They are expensive, though; costing almost twice the price of a modern multigrade.

One should consider the Vincent engines; they were designed 60-70 years ago. They use roller bearings in the big-end, and have by modern comparisons, clearances on the pistons, and valve guides, on the generous side. One only has to look to the Rider’s Handbook to get an idea of oil consumption; 300 mile per pint of oil! Of course, some improvements are possible (such as fitting low clearance pistons, valve guides with seals, etc.), and you may doing better than that.

If you a running an unmodified Vincent motor, I doubt that you would expect to benefit from using a fully synthetic engine oil, especially if the miles per year is limited. For in these conditions, you ought to be changing the oil yearly.

The situation is changed if you cover many miles per year AND have taken steps to avoid high oil consumption. You would benefit by running a fully synthetic engine oil.

 

 

 

 

 

 

3D printing of Series A compon

Here are some Series A components
that I 3D printed
 
  E25 Valve rocker
 
  E24mod Modified Rocker cover
 
  E20/3 Cam box
 
 

 

 

 

 

 

A visualization of the Series A Rapide engine

 

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