Tuesday, October 18, 2011


left click to enlarge

This is a completed drawing of three valve gear components on the K36. This rendered drawing is 3-d and can be rotated to view from any angle. All the dimensions are accurate to .0312, or 1/32nd of an inch. This is a good as it will get.

This link yoke was the most difficult component to draw... dozens of different X,Y,Z coordinates for the UCS to create the proper planes for all those curves.

The rest of the valve gear is there, but on different layers that are turned off.


Unknown said...

This is really impressive work. It's hard to believe you're doing this in AutoCAD... But it looks fantastic!

Bob said...


AutoCad has a feature called "render" that makes a 3-d drawing look like the above, but like everything else in AutoCad, it's got loads of conditions to meet: Background light, foreground light, ambient light, multiple spotlights that require position data, color, hue and intensity.

It takes a lot of fiddling around to get things right, but the results can be pretty neat.

As Ellen Finklestein said in her almost 1,300 page book "AutoCad 2000":

"Rendering is a multistep process. It generally requires a good deal of trial and error to get the exact results you want."

No kidding. I consider that a classic understatement.

If you are an AutoDad user, Ellen's book is an absolute necessity and absolutely worth whatever you pay for it.

Unknown said...

So is this 3D model separate from your 2D drawings?

Bob said...


2-d drawings are flat plane drawings of any particular elevation - left elevation, top view, front view, etc. They have only two planes, X and Y, but they provide exact dimensions.

A 3-d rendition is pretty as all get out, can be looked at from any direction, but you can't get a single accurate measurment from one. You can make good guesses, but that's about it.

I use my 2-d drawings as a base for my 3-d efforts. They provide me with the necessary dimensions to create an accurate rendition.

Of course, adding the 3-d third axis - the Z axis - requires that I have the needed dimensional measurements missing in a typical 2-d drawing.

An X-Y drawing may look fantastic as a highly technicial engineering drawing. But it contains zero information about depth.

An X-Y-Z rendition is like a photograph - eye candy - but just like the one I posted, it can provide physical information impossible to ferret out of a 2-d drawing.

Unknown said...

Have you ever tinkered with SolidWorks or other solid modeling program? The way they are supposed to work is that you build the 3D model and then you make drawings (projections of your 3D model). You can then send your drawings to a machine shop, but if something is unusually complex you might just send the CAD model and they will CNC fabricate it straight from the model file.

These solid modeling programs kinda work like a virtual machine shop. You can drill, mill, and lathe into a block, but you can also extrude (add material). One, called Alibre CAD, has a personal use version available for $200.

Bob said...

My son once showed me a program similar to what you describe, but I have never personally used one.

At this late date(for me), I don't plan on diving into another complex program such as AutoCad.

It takes too damn long to beoome proficient enough to demonstrate any level of skill.