User:Callahanp

This is my user page. I use wiki user pages on wikis to explain what I'm doing and to do writing that is not ready for the main pages of the wiki. This avoids polluting the wiki's list of pages and search index with incomplete or otherwise undesirable material. I can discuss the work on the forum and interested parties can take a look and comment on my talk page or in private messages.

Why FreeCad I'll be using FreeCad to work on a hobbyist project to build a flight simulation cockpit, with instruments that are intended to be as close to the real thing as possible. I'm a member of [Framingham Makerspace ] and a regular reader of and occasional minor contributor to the [Flightgear-devel mailing list]. I do not consider myself a flightgear developer but I'm learning a lot.

What else do I use

OpenSCAD

As a programmer, I'm a big fan of scripting as a way of developing 3d models. It's a natural way of thinking for me so it fits well into my workflow. For things that have a lot of measurements and simple repetitive shapes, its ideal. It's probably not the thing to use to build a fancy [vebelfetzer] with lots of unique features and complex surfaces. But then I haven't made a fancy one in years.

Fusion 360

I had been using Fusion 360 for this hobbyist work, but have parted company with Autodesk over their restriction of the free hobbyist use of the product to a limited set of features. I do wish to thank the Autodesk team for the experience I gained using their product. Unfortunately the amount of use of Fusion 360 I would be making as a hobbyist just does not justify the cost of a license and there are free alternatives such as FreeCAD and OpenSCAD that will serve with a little effort at re-training. I wish Autodesk well in their commercial endeavour. No complaints. I saw this coming.

Some notes for tutorials:

1. The user interface for FreeCAD is a bit daunting. There are numerous toolbars, panels and menus that a new user needs to notice. There is more than one way to do a workflow, using all of these elements at once, and guidance on which to use and what the alternatives might be would help a new user who might be poking around at things in one area when a different usage might get the user's intent done easier.

2. The dreaded broken face message. Sooner or later a new user will encounter this somewhat cryptic message and will need to know what to do about it. There are a number of basic mistakes that can cause the message, and introducing the concept of a "valid" sketch early would help.

see this video on the topic. https://www.youtube.com/watch?v=WLCN0O1QZl0

Tutorials to Propose

Making a cockpit (Parts 1 to N)

Part 1 The Instrument Support Panel

This is a basic part that is basically a sheet of material with a number of holes in it of different shapes.

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  Instrument Support Panel

The model is a simple flat panel rectangle with circular and rectangular openings, except for the spline along the top left corner.

It's a very easy project I first implemented in OpenSCAD. The OpenSCAD model imported to FreeCAD with an error, but the model looks correct. Perhaps it violates some FreeCAD rule that is not present in OpenSCAD, or maybe there's a flaw in the OpenSCAD model that I'll discover.

Describe the panel and how it is to be used with a picture of the original, explain the layout and what kinds of things go in each opening. Include a hand drawing of the panel in context of the whole cockpit.

Describe different approaches to building:

Something I read led me to believe that there is a relevant distinction between CSG and Parametric Modeling. I think that's not the case and I need better definitions for the types of Modeling, parameterization and procedure based vs something else, I think the something else is not parametric. CSG has parameters just like anything else.

Explain the differences between the two. Explain how to or why you cannot switch between the two approaches easily.

Show a spreadsheet of measurements on the panel.

There's a curve at the top of the panel. Explain splines. Discuss choice of spline methods if there are such choices.

Pat