A Lofty Ideal?

 

Or some more down-to-earth help for HPV builders some programs to help with design and fabrication. All are free.

 

 

LOFTY Simple Cad for Aerodynamic Design

 

Shapes such as velomobile body shells, fairings, boat hulls and aeroplane fuselages are often designed by lofting. Cross sections are stacked up and joined together to make a 3D shape (either physically or digitally). The panels that result are filled in to make the shape, either directly by bending them up out of some material, or made out of a composite such as glass or carbon fibre over a mold.

 

Lofty is a simple program for Windows that does lofting. From the initial shape, defined by only a few known points, you can:

 

Download free version here. Unzip to any directory and run. Sample files and more documentation are included.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Tubemiter

Version 1.3 (Dec 2008) - added DXF saving.

Version 1.4 (Apr 2009) - added inch/metric units at the request of Cyrus Vatan.

Version 1.5 (Jun 2010) tweaked display to handle large tube diameters better, at the request of John Bell.

 

A tube mitering program for Windows to print on any printer. Tubemiter takes wall thickness into account, which is important when doing small angles or equal sized tubes. It can also deal with tubes meeting larger ones such that the centrelines are offset.

 

File/Settings... puts up a dialog box. You input:

 

It paints the picture on the window, and File/Print... prints it on any connected printer. File/Save to DXF... allows you to save the drawing to a DXF file.

Glue it round the tube and cut.

 

There are two curves - the dotted one is the template you would cut if the wall thickness were zero (similar to the HyperCard program's output) and the solid curve is the template corresponding to the requested wall thickness. In a DXF file, the solid curve is in Layer 0 and the dotted curve is in Layer 1.

 

If the mitered tube diameter is greater than the second diameter, then the second tube passes through two holes in the mitered tube. This situation is handled by continuing the template on the other side.

 

Download tubemiter here. Unzip to any directory and run.

 

 

 

 

 

Spacely Sprockets

 

v1.1 Initial version, July 2002.

v2.0 Add Save to DXF option, at the request of Alaskabobb. Draw teeth in full for CNC/cutter machine input.

V2.1 Draw all teeth as continuous polyline to make CNC cutting easier.

 

This program lets you generate a sprocket of any size, round or elliptical, with any PCD. I wrote this because I ran out of patterns from my old program of many years ago, and needed some more. Also, there has been a steady demand for them. You can make nice chainrings for old non-standard crank spiders, or experiment with elliptical chainrings. Biopace chainrings are close to ellipses with a small eccentricity of about 10% (greater for smaller tooth counts)

 

There are only three menu items:

 

File/Settings... brings up a dialog box to allow you to change all the parameters. See included text for details.

 

File/Print... lets you print the pattern over one or more pages. Pages will tile. If you have an A3 printer or a plotter, so much the better (I haven't tried it with a plotter, but it makes standard GDI line drawing calls, so should work)

 

File/Save to DXF... prompts for a filename and saves the sprocket pattern to a DXF file for loading into CAD programs or driving CNC machines.

 

Download it here. Unzip to any directory and run.

 

Some samples below by Mark Pharaoh of Pyramid Composite Designs: www.pyramidcompositedesign.co.uk

Made of several layers of unidirectional carbon fibre reinforced PEEK and cut to shape on a CNC machine. The teeth are slightly modified from the program output.

 

 

Steering

http://www.eland.org.uk/steering.html has the last word on trike steering.