Computer-Aided Design

The question is, how to sketch and show a product idea. Which way is most suitable and logic. We should not forget that a simple hand drawing is still the best way to find shapes and ideas. A pencil does not depend on predetermined shapes, it just depends on your creativity and ability to draw. By these thoughts I decided to draw some drafts, finding the right shape for technical and ergonomic requirements. Still, they are drafts no fixed designs, yet. I took pictures with my mobile and sent them via Air Drop to my computer. Then I decided to start with mounting them on architectural photographies in Gimp and Photoshop.


Gimp is an open source picture editing program and comparable to Photoshop. It is quiet easy to handle and to understand, I am sure it does not have the depth like Photoshop often used by professional designers. But for my issues, now, it has definitely enough tools to work with.
I opened both pictures in Gimp.
First I cut out my first drawing with the "Pathtool"Paths tool you can find it in Toolbox and dragged it over to my photo of a corridor with white walls.

To adapt the perspective you can use the „Perspective Tool“

Perspectiv Tool

easy to find in Toolbox (Bild). You click into your still activated drawing to see a mesh you can push and pull until your drawing fits to your desired perspective.
But still the background-colours were different, I had to adjust them, too. Just erasing the activated handrail layer to „background“ didn´t work out because both backgrounds vanished. After going back the command history I selected just „erase“. Now, it worked out.
After erasing I had some trouble to deselect the layer, again. Finally I found in Menue/Layer : „Anchor Layer“. Two Layers became one. May be there is a better way for deselecting an object in GIMP but I was glad to be able to continue.

A mounted flat drawing dragged into a perspective photography looks funny. I had to paint some shadows with „Airbrush“ Airbrush Tool and different coat thickness and opacity gradients. The applications have got an impressive deepness. It could have been done more accurate although it is good enough to get a first impression.
Gimp saves an image as „xcf“(experimental computing facility), but you can export as png, jpg and many more, just be aware of the lower left corner of the „Export“ window („Select File Type“). The only issue I really couldn´t find out was how to save pictures properly for web purpose. For this I saved all pictures in Photoshop.

Walking Handrail Along The Wall


My second picture I created in Photoshop. I opened another handrail drawing and chose „Polygon-Lasso-Tool“ Polygon-Lasso in the Toolbar to cut out the handrail. Then I picked it up with the „Pick-up“ tool Pick-up-Tool and dragged it over onto a wall photography. Unfortunately, my Photoshop is only in German no other languages available for me. I try to translate the tool names.

What I like very much in Photoshop is the easy to control Layer Dialog and History Overview (Protokoll). I can easily skip from layer to layer depending on my editing purposes. After mounting my drawing into the picture I had to scale it. You can find the scale tool in Menue/Edit/Transform.

To be able to show how a handrail can walk on the wall I had to paint a hole grid on a separate layer. You can find the „new layer“ icon left beside the dustbin at the right bottom of the „Layer Dialog“.NewLayer
By the way, you can find all dialogs in Menue/Window . The „Grid“ or „Pattern“ tool and a lot of other usefull tools you can find in Menue/View/Show… .

I activated the grid to set holes accurate. I like to scale the view with two fingers on my trackpad. That was not possible in Gimp. I painted the shadows with the „Pencil“ tool in an airbrush manner.Pencil-Airbrush

You can find it in the toolbar.

In comparison with Photoshop Gimp is a quiet good tool for normal use, easy to handle and to build up quick impressions. I like Photoshop very much. It is a very handsome, ergonomic tool for professional purpose and every time I work with it I feel that I use only a very tiny part of it.

Handrails on Wall

Download Gimp

Free Trial: Photoshop

For my next step I decided to draw some outlines in Inkscape and DraftSight. Both programs are open source. It is the second time I used Inkscape and every time I have the same impression, Inkscape is not useful at all for technical drawings or less for just a bit more precise drawings, where you have to indicate definite sizes. Furthermore, it doesn´t work smoothly on my computer. However, I tried to draw toothed wheels and the shape of the bases where I want to put all technical elements in: such as battery, step motors and controller boards. Even the base I couldn´t draw exactly. I had to help myself with supporting geometries and subsidiary lines. I don´t feel comfortable with his way of drawing..


Working process:
In Document Properties in Menue/File you can set paper size and snap functions and other.
In Menue/Edit/Preferences you can set all the other performances like language selection, grid size…

Choosing a regular polygon shape for my handrail base I had to set the colors for „Fill“ and „Stroke“. One can find „Fill and Stroke“ Dialog in Menue/Object. I set the number of corners (6) of my regular polygon in the upper command line.

Polygon Tool

I needed three of them, to set them in nearly properly I activated Menue/View/PageGrid.

To draw synchronized toothed wheels one should know the radian measure of tooth thickness plus gap. As I couldn´t find out, may be because of lack of time, how to do a technical precise drawing in Inkscape I decided to work with the following aid: With „Circle Tool" I created a sector of a circle with roughly the same radian as one tooth plus one gap. The smaller toothed wheel I have tried to fit through decreasing the number of teeth and creating and adapting „Spoke Ratio“. Both you will find in the upper command line.

Drawing Aid

Arm with toothed wheels:
Choose „Rectangle“ tool in the Toolbar, set the axis for the first wheel with „Circle“ tool, copy the big toothed wheel and put it on the rectangle with the axis in the center. Now, delete the unused lines of the wheel through Menue/Path/Object to Path (converting objects into paths).
Select „Edit Paths by Nodes“ in the Toolbar and pick up one wheel node intersecting the rectangle.

Choose „Break Path“ in the above command line. Do it again width the other node. Now, you can delete the segment you do not need anymore. Then copy/paste the smaller toothed wheel.
Save your drawing with Menue/File/ Save (.svg) or Menue/File/ Export png Image.


Download Inkscape File

Link Inkscape


Next, I wanted to draw a bendable sheet to apply it on my handrail.
First of all, in DraftSight you can work with calculated accurate measurements. After picking up a tool in the Toolbar you can enter your desired dimensions for x/y/z-Axis in the lower command window. Activate the command window in Menue/Window/Palettes.
I couldn´t find out, yet, how to change the length of an object. Somehow, it is deactivated in the Properties Dialog. This is a bit disturbing. But, if you know it you can handle it. That means, you need to know the sizes and positions of your drawing in advance, like a handmade technical drawing, you can´t change it very easy.

To set the preferences like Background-color, Units, Scale go into Menue/DraftSight/Preferences.
I would like to explain two tools „Trimm“ and „Pattern“, both you will find in the Toolmatrix.

Pattern:Pattern Tool
First you create a shape or line you want to multiply in a pattern. You can set this first object in a bigger object you want to fill out, if you like. Select your object, first. In the Toolmatrix you can find some sub-categories: Standard, Draw, Entity Snap, Modify. In Modify you will find the Patterntool. Click it and the Pattern Dialog will open. Choose for example Linear, then enter the Settings. Be careful with „Spacing between elements“. Here, you have to calculate the Size of the original object plus the desired space between the objects!

Trimm: Trimm Tool
After creating several Objects intersecting each other, you can unify then with „Trimm“ tool. First select all objects you want to unify through clicking. Pick up Trimm, you will find it in sub-category: Modify. Just click on these parts, lines you want to delete. Be sure that both intersecting objects are selected and activated.

Bandable Pattern

Download DraftSight File

Link DraftSight

Fusion 360

Fusion is a cloud based 3D CAD (computer-aided-design), CAM (computer-aided-manufacturing) and CAE(computer-aided-engineeiring) Tool. It combines designing, engenieering, modellin, manufacturing and simulating in one program. It is not open source although it is free for students and teachers. One can buy monthly or yearly licenses.

Designing joints. With Fusion I tested the mechanical and design characteristics of my handrail.
I created a very simple shape based on cylinders connected to each other with two joints.

The starting point in Fusion is always the same: selecting "create sketch" and determine one working plane (xy/xz/yz).
create sketch tool
The perspective view flips immediatly into a flat view. Now, one can start drawing the first sketch, for example picking up circle tool you can find it in the sketch tool

After drawing two circles, one inside the other the first sketch is ready to be extruded in third dimension

two circles

Choosing "Create/Extrude" effects that the view flips back into perspective view.

extrude tool

Through hovering over the surface of the sketch two surfaces react: an inner circle and a ring shape. The extrude panel ask you to select one or more profiles, select the ring. Afterwards, enter a dimension and hit "ok". You can modify the sharp edges through Modify/Fillet e.g.

modify tool

The second object is based on circles,too. Click an "create sketch" and create again a circle. Don´t forget to select a plane to flip into two dimensions. Draw the circle beside the first object and extrude. Now, choose "Offset" through activating the top surface. Click on it, double click with the right mouse or two fingers on trackpad, click on Sketch and select Offset.

sketch on top

Offset panel pops up and ask for selekting a sketch curve. Choose the outline and enter dimension. Modify/PressPull tool allows you to select both surfaces outer ring and inner circle. Pull up, now, you have got a thicker cylinder on top.

create sketch tooltorus1

Choose again sketch on top surface with clicking two fingers on trackpad. After another click on "sketch" select rectangle tool. Create a rectangle on the surface and change shape: Delete "horizontal/vertical" icons through activating and deleting them.


Then pick up the corner and pull them into new positions.Take Modify/Fillet to round the corners. You have got a round needle shape. Now, extrude. Take care to choose "Operation: Join" in Extrude Panel.


Joints: Choose "New Component" tool and select one Body.

new component tool

After that select the next component body. Take the Joint tool and activate the joint related centerpoint of each component.

joint tool

You can find them through hovering and keeping it visible by pushing the cmd or control button.

centerpoint At the same moment you activate the second point both objects join together by themselves. If something doesn´t work out, check Rotate Axis in Joint Panel. Finally, activate the ring shaped component in the Browser panel and with your two fingers click open a dialog and select "Ground". Now, you can turn the arm around.


Download Fusion File Handrail

Download Fusion File Needle

See Fusion360

Sketch Up

Sketch up is a quiete simple and open source 3d software. As simple it is, for cad users it is unusual and more intuitive then constructive. But this is only my opinion.

I will explain the process of creating a handrail:

After opening a sketchup page you will find a makerbox, I like to delete this box by clicking on an edge and press delete button. On the left side you will find a tool bar. Also, you have three axis in different colors red, blue, green. This helps you to find the plane you will work on, because the construction reference lines change colors appropriate axis you are referring to.

Here are some tools I used for my handrail:

planeArc tool creates arcs also tangential to an object.
plane Circle creates circluar planes.
plane Push\Pull tool shift a plane into a body.
planeRectangle tool creates a rectangle.
plane Paintbucket tool colors your object.
plane With rotate perspective you can watch your object from all sides.
plane Rotate tool rotates the object.
plane Erase tool erases lines.
planeBy a command line in the right bottom corner you can define distances, and sizes.

Now, I will explain the design process:

Create three cicles one bigger then the other with the Circle tool. Then take the Push\Pull tool to pull the face up in a way you can see below.

plane plane

Find the center of the top plane by hovering over the edge and holding alt-shift down. The center will be activated and you can create a new circle. Push this new circle down, you will get a cup. You've got one base.

plane plane

Then create the handrail with the rectangle tool and choose afterwards the arc tool you can see above in my tool list. Let the rectangle ends in half circles by finding the center point of the short lines. If you set the first point there you just have to drag to the long sides and set the second point when the arc becomes greenish, that means tangential to the lines.

plane plane

Now, you can erase the edges and you will get circular endings.

plane plane

Choose again the Circle tool und find the center, then create two circles. Select the Arc tool and create a tangential arc between these two circle lines, like above. Then drag the ring cylinder with pull\push tool.

plane plane

Activate the base with dragging a frame around it, then press hot key: command+c, then command+v and place the copy beside. Drag the handrail above. You can also hide the handrail if you want to work more on the feet. Then you press right click on the mouse an choose 'hide'. If you want to unhide again und you can't find your hidden object any more, then you can show it in menue\view\hidden geometry and now you can activate it again to unhide.

plane plane

If your object is finished, you can also paint it with the painbucket like in gimp or photoshop. You choose a color and click on the surfaces with the bucket you want to color.

plane plane

Here you can find the link for Sketch up.

If you want to download my design file, please click Handrail.skp.