Handwheel.

Not real complicated this component or so it would seem. The rim of this handwheel has a shape that must be created using construction geometry and is positioned relative to the rear of the hub and the rims finished shape not the geometry that is used to create it. A typical example of many situations experience in real draughting, the rim must be drawn first then the hub on a board else you may have to re-draw one or the other.  In AutoCAD (2D), who cares which is drawn first, as the ‘Move’ or ‘Stretch’ commands will fix any problem! Should a similar problem arise after it has become 3D it’s the same issue less ‘Stretch’.

The other twist to this component is just that a ‘twist’; it is to be found in the sides of the spokes.  Absolutely no problem in describing this in 2D and having it made by a competent pattern maker prior to casting, but 3D modelling this correctly creates some work.

Again the image you are looking at is an AutoCAD solid and this exercise amongst all we have done was done only once using the AutoCAD-MDT team and is very easy to do, much the same as Block ‘A and B’, and has been done in Inventor so many times I am sure even the software has learnt what I am up to.

It is also the only one of the tasks shown in this Gallery that I turned to others to ensure that my results were a fair representation of the facts. Inventors ‘inflexibility’ slowed this job to all but a crawl and I have done it a number of times and different ways.  Inventor made this is a more difficult job than it should have been and it does show clearly what a normal user could suddenly face and how software’s ‘inflexabilty’ can considerably reduce the profitability of a particular job or project.

One of the fastest methods (if you want to persist with Inventor) is to use AutoCAD for the initial shape description turning the 2D over to Inventor (as we did in MicroSolid and AutoSolid) to model and complete the task.  At no stage even using this faster method of shape description and positioning could I equal the time this job was modelled in Mechanical Desktop there is simply are too many steps to be made and too much additional construction that must be created by Inventor to pull this job off and again what we end up with is a model with which we can do much less!

A final point, the drawing calls for a fillet of 4mm at the intersections of the spoke with the hub and rim, AutoCAD did this with no trouble Inventor cannot go much larger than 3mm.  Not such a small point this and does show why you need to test.  Fillets often cannot be compromised in a design and software needs to work for us not the other way round.  I consider this a critical fault and one that is none to reliable!

Again as we had found in MicroSolid and AutoSolid all those years ago, for CAD software ‘FLEXIBILITY’ is the key and path to profitability not constrictive rules.

This pattern is going to be repeated over an over now just as the software developers and vendors releasing and re-releasing software each time forgetting,  not realising or ignoring, for some reason, what they should be doing, and you the end-user are paying for each of these sideways steps.
 

R. Paul Waddington
cadWest.