CAD Challenge of the Day #006 – Beginner

Regular geometrical shapes where invented by the ancient Greeks and although they might seem simple for the human mind if we know the rules that govern them, it is sometimes hard to build them in a CAD system. Let’s try to build a regular octahedron with a 10mm edge. Making it with as few features as possible earns you extra points for this challenge.

This part was designed in Onshape.

Google Drive – CAD Challenge of the Day #006

Dropbox – CAD Challenge of the Day #006

CAD Challenge Of The Day #005 – Beginner

The secret to complex models is the ability to decompose a design into smaller pieces. Build them together like puzzle pieces and you should be able to obtain pretty complex manufacturing parts. If you combine the features from previous challenges like extrude, revolve and holes you can easily obtain the model below.

This part was designed with Onshape.

Google Drive – CAD Challenge of the Day #005

Dropbox – CAD Challenge of the Day #005

CAD Challenge of the Day #004 – Beginner

Holes with threads are the easiest way of fixing parts together. They also have some advantages of being removable, as opposed to welding for example. For this challenge you should try to make a hole and add a standard metric thread to it and also add one external thread. If you manage to do that, you will have another very important tool in you CAD belt.

This part was designed in Fusion 360.

Google Drive – CAD Challenge of the Day #004

Dropbox – CAD Challenge of the Day #004

CAD Challenge of the Day #003 – Beginner

Pad/Extruding is not the only operation you can use on sketches. The revolve feature is extremely useful for axis symmetric parts, manufacturing them on a lathe is really easy to imagine. Again, you have a choice, either bring the radii directly in the sketch, or add some fillets afterwards. While drawing, why not try to add some tolerances to our dimensions.

This part was designed with Onshape.

Google Drive – CAD Challenge of the Day #003

Dropbox – CAD Challenge of the Day #003

CAD Challenge of the Day #002 – Beginner

After we started with a simple sketch-extrude/pad design in the first challenge let us now learn how we can reuse the same geometry in different places with patterns. You could either complicate the same sketch by drawing all of the four pockets, or you could just build one and reuse the pattern, I would recommend the latter.

I used Fusion 360 for this component.

Google Drive – CAD Challenge of the Day #002

Dropbox – CAD Challenge of the Day #002

CAD Challenge of the Day #001 – Beginner

I want to start a series of daily CAD Challenges for the beginners in the field of design engineering. For each new challenge I will supply the 3D model in STEP format and also the drawing as PDF. Today we will start with a basic model that I created in Fusion 360.

The sketch is the first building block of every 3D model. Let’s start with a simple sketch that we can extrude/pad for 20mm to obtain our model, and while we learn how to do that, adding some holes in the same sketch should not be that difficult. The outer radii could be added inside the same sketch or afterwards as fillets, your choice.

I will provide Google Drive and DropBox links for each challenge. Good luck!

Google Drive – CAD Challenge of the Day #001

Dropbox – CAD Challenge of the Day #001

NYC CNC – Weekly Machine Shop How-To Videos!

If you are like me, then you feel that what you learned about machining in school might not be enough for your daily activities. This channel is exactly what is needed to understand the day to day activities of a machine shop. Tips, how to videos and also Fusion 360 tutorials, you can see the whole life of a part, from CAD to the finished product on this channel.

Thank you John Saunders for sharing your experience in your awesome machine shop!

NYC CNC Youtube channel

NYC CNC website

NYC CNC on twitter

Material Behavior – Georgia Institute of Technology on Coursera

grid-wire-mesh-stainless-rods-rods-raster

I just finished this course on Material Behavior on Coursera and I can say that it was a great experience. If you want to freshen up on your materials knowledge or you are currently studying this and want a different perspective, I recommend you take this course.

The course is offered by Georgia Tech and it is taught by Thomas H. Sanders, Jr. (Regents Professor). I have to be honest: although the course is full of information it might seems rather slow and boring sometimes and if you do not pay attention or even write down the important topics, it will be hard to pass the tests at the end of every week. The course goes through the most important aspects of materials like atomic structure, crystalline structure, defects etc.

We all know that these massive online open courses are sometimes just marketing schemes for unknown universities from around the world that do not offer a lot of value. This course is not like that, and everyone that will make it through to the sixth week will have a deeper knowledge of materials.

The student effort is listed at about 2 hours and 30 minutes for most weeks, and I have to say that was not enough for me, I guess for someone new to the material behavior, this course might well take up 4 or 5 hours a week with a little internet search on different topics mentioned by the professor.

In conclusion, I highly recommend this course and I found it to be one of the best open courses floating around on the internet.

Material Behavior – Georgia Institute of Technology

Materials Science

Material hardness tests

Material science tests

Wikipedia describes hardness as: “a measure of how resistant solid matter is to various kinds of permanent shape change when a compressive force is applied. Some materials (e.g. metals) are harder than others (e.g. plastics). Macroscopic hardness is generally characterized by strong intermolecular bonds, but the behavior of solid materials under force is complex; therefore, there are different measurements of hardness: scratch hardness, indentation hardness, and rebound hardness.”

According to my sophomore undergrad year material sciences textbook there are three widely used hardness tests: Brinell, Vickers and Rockwell. Fortunately I found an excellent YouTube channel where we can see each of these tests performed. Enjoy:

The Brinell method

The Rockwell procedure

The Vickers method

External resources:

Guidelines to hardness testing by Hegewald & Peschke

Wikipedia links page of the three hardness tests above and many others

MaterialsScience2000 YouTube channel