Using LSPP as STEP viewer

I have talked previously about free CAD editors and one of the big winners was DesignSpark Mechanical 2, where FreeCad was close. These two software packages are very good but also very different. DS Mechanical 2 is a direct modeller and FreeCad isn’t (yet). Basically DS Mechanical 2 works like moulding clay where you push and pull surfaces. On the other hand FreeCad requires a sketch, dimensions defining the sketch, and everything is linked together through actions history. These are real editing softwares and require installation and are heavy…. But if you just want to see a STEP file or a IGES file?

You can use LSTC LSPP. It’s available in all the major flavours (including MAC).

Here is an example:

Clip Pins in LSPP
Clip Pins in LSPP

Chair – Legs and IKEA

Yesterday I went to the mother of chairs and found so many design approaches that I got overwhelmed by it. It’s about purpose, function and creativity, ahh and some color.

Real examples of my previous figure were there! That was expected! I know….

4 Straight Leg Chair Design
4 Straight Leg Chair Design

Since I am a visual person I will show it any way… If you look closely 4 legs the central seat but pay attention to how the legs connect to the seat. This is the primary detail that holds everything together. Although materials change from metal to plastic, shaft diameter changes also but also important is how we consider this connection and how we simplify it. And which one will I study? It looks easier compared to the spider but not similar to the small table I shoed before.

Side Legs Chair
Side Legs Chair

Heres another shape.

Cross Legs Chair
Cross Legs Chair

Another design approach that has the advantage of folding.

I Leg Chair
I Leg Chair

Here the typical IKEA office chair. This chair can have different height levels.

The purpose of this post was to show there are many designs available and all of them try to solve a particular problem. There is no such thing as bad in any of the designs, maybe more a question of taste and function.

 

My Donuts and some wonderful work Wikipedia. Let’s help!

While strolling around NY (New York – Manhatten) I noticed a really pretty donut looking at me. I got really impressed with it’s design and colour set. This donut remembered me my, Advanced Math course back in the days I was studying, where we represented mathematically a torus. I opened my phone and viewed it’s equation without any cost. It was free and imediatly available in wikipedia. For me, one of the most marking human accomplishments in my life time. Everyone knows it! And in some direct or indirect way we use it (our children use it).

Torus cyclesLet’s all give some help and donate! 

My Dunkin Donuts
My Dunkin Donuts

So many types of things we can sit on

When we think of something to sit, we think on something we can rest on. These things are around since forever. However for the same function we have imagined a diverse set of designs that get things done. Every design has it’s advantages and disadvantages, probably material strength will play an important role here. The stronger the legs are the thiner they can be and more weight they can withstand. Bellow are a few representations os seats or tables (why not?) in 2D. Some imagination is important from here on. On my office I have I Rise Legs approach and a side legs design, on my living room I have a more classic straight legs design. Probably during a days work I will view many of these designs and probably you will too. Many reasons will determine the design from cost, function and requirements but I will be focusing on the open legs and straight leg variant. Differences? Maybe many, maybe not…. From intuition I feel that straight legs will be stronger but with 120 Kg on top….

Types of tables
Types of tables

Modelling, Seeing, Imagining & Photography

I believe that to understand a model we need to experience it, feel it even if it is in some very different way…. The more we experiment the more we can imagine and this is probably our way of modelling what we don’t know through our life inputs or the data we collect. Photography is all about the experimentation and imagination that make us build imaginary portraits that we materialize through a shot. My first photo experiment that I place here was the bokeh effect.

Bokeh effect
Bokeh effect

Round and creamy a mixture of color that gives a yummy taste on the nightly environment full of color and sparkling lights. Why are night shots so captivating that we forget everything around us?

4 leg chair the chalenge

Continuing my divagation through chair design and analysing the previous chair/seat post.

4 Led Table Front view
4 Led Table Front view

The purpose of this design is to serve as a support for objects. All 4 legs are tilted in a square fashion pattern at the bottom and are closer to each other near the table surface.

Tilted table
Tilted table

It’s not my intention to replicate the design of the table completely so my first simplification is the junction of the legs to the table.

4 Led Table Bottom view
4 Led Table Bottom view

Every design has it’s strengths and weaknesses. It’s purpose and function. This design is particularly sensitive to edge force since leg is supporting the table center. For a table this size the table will work comfortably with the objects we place on top, however as a seat considering an average weight of 80Kg.

So here starts the challenge:

  • Withstand 80 Kg to 120Kg
  • Use a clean, light design

Everyone probably already has an idea and the first one that comes up my mind is a straight leg chair (the simplest form of this design).

So why do we bother inventing new ideas??? The answer is that not all people are made equal. Some like simple chairs, others like edge design chairs, some others are in between and the rest probably don’t care.

Looking for over the edge designs, challenge our notion of possible or not possible. And maybe let us feel in some way better either for simplicity or because of blending in room design…

Why NetGen Why!!

This time around I am presenting a alternative mesher to gmsh. The application is called NGSolve/NetGen it’s installable both in Mac and Windows which made me very happy at the beginning. Afterwards I opened a step file with no issues and generated a default mesh (on the windows version).

NGSolve/NetGen mesh in windows
NGSolve/NetGen mesh in windows

I really liked the visual display and the mesh quality. This is a default mesh.

NetGen Close up mesh
NetGen Close up mesh

The close up rendering mesh shows good image detail and the mesh elements geometry look more uniform and the circular shape looks well represented through the mesh.

At a first view the mesh seems much better compared to gmsh. There is however a problem. I could not open step and iges files through my mac. This was a frustration…. It seems that the windows version already has a binary file for open cascade which is the library that allows the NetGen software to understand these formats. On the other hand there is no easy way to install the open cascade library on a mac neither it seems to have been tested in detail with netgen.

This is a big frustration point for me.

Free simulation package Gmsh

Free simulation package Gmsh – Geometry – Mesh – Result

I have posted previously a list with many comercial simulation packages. These packages have numerous features, are very robust and have active development, however they are expensive and their source code is closed. A free alternative is growing day by day, although the user interface isn’t as user friendly and are feature reach as comercial packages they allow for some level of calculations or the same but with an added patience requirement to understand how they work. Many packages developed so far tend to solve individually each simulation requirement from geometry creation to mesh generation, a solver to calculate results and finally a display environment to view the calculated results. Gmsh tries to combine all in one in order to work in a similar fashion as Ansys APDL or LSPrePost. It still has a long way to go but the ideia is there and with time the user interface will grow to be even better. Just wish it was easier to work with.

Gmsh pin mesh
Gmsh pin mesh

The image above is a slightly refined mesh. I did’t play much with the meshing parameters.

The good thing was that I could run it with Windows and Mac with no installing issues.

Mac 3D STEP viewer

For me the best so far free STEP file viewer is LSTC LSPrepost for mac. This software is a simulation pre and post processor for LS-Dyna and basically works on system. Rendering quality is great.

This software also provides a good image exporting feature to produce great quality step figures.

4 leg seat in LSPP
4 leg seat in LSPP

 

Improving Rendering in DS Mechanical 2.0

Some time ago I was noticing some rendering quality degradation on my screen. I noticed that maybe my customization values had change. In order to have nice graphics one just needs to change on the options menu the following.

Improving Rendering In Design Spark
Improving Rendering In Design Spark