Hand Drawn Sketches vs Computer Aided Design

Hand drawn (sketches and orthographic drawings)

 

 

 

 One major advantage of hand drawn designs is that it does not require any special training to do unlike other processes, this means that for quick drawings in the workshop they can be completed by anyone, even if they are not a trained design engineer.

Unlike some CAD drawings, these hand drawn designs cannot be tested so you cannot gather vital information such as weight and conduct strength tests like you can when using CAD, this can have a major impact on the finished product as there is a higher chance of it having to go through redesign.

Manual calculation is needed to work out cost calculations which can be quite time consuming and has risk of human error. In comparison to other methods, manual drawings are extremely time consuming especially if you have to draw out parts that are very similar with small differences as with CAD you can just copy the parts and add the differences in with ease.               

Unlike CAD, manufacturing needs manual input as it cannot be linked up with programs for automated manufacture.

Sketching is a very quick way and effective way to quickly explore ideas in the early stages of design, while CAD may be faster for most things, sketching is better in the early stages. Hand drawn sketches or orthographic drawings can be quick to produce in the early stages and can be good for quick responses with customers

When it comes to assembly, hand drawn orthographic drawings are usually much harder to read which can lead to issues in the production processes later down the line, therefore reducing lead time. 

Computer Aided Design (CAD)

 

 Generally, CAD drawings have a lot less limitations compared to its hand drawn counterparts. The variety of commands such as trim allow you to complete drawings much faster than manual orthographic drawings, trimming allows you to get rid of unwanted lines with just a few clicks. The equivalent of doing this manually is rubbing out lines, this can often make the drawing look messy and unprofessional. A way to speed up designs is being able to use CAD parts that have been created by someone else by importing them to use in your own model. This saves a lot of time because you don’t have to draw these parts yourself. You can use this method to pass on CAD parts that your company has created to any customers that require them.

 Another advantage of using CAD is that the drawing quality is generally a lot higher, resulting in more professional looking drawings that are much more accurate and clearer to read. When using CAD you can render true to life images of the part or assembly, this can be seen in drawing to the right. The main advantage of this is allowing a complex 3D version of the product to be placed on the drawing, which can be very handy for giving information to people who will be producing this part, it can also benefit people who aren’t in the industry as it is much more easy to see the overall shape of the part.

 Another advantage is better design communication, this is due to your being able to easily send screenshots or the file itself to customers who can be across the world through email or through an image sharing website. The fact that it is 3D allows it to be much easier to analyse and visualise for a person who is not in the industry. Design flexibility is a great feature of CAD drawings as they can be quickly adapted to suit changes through the use of the dimension tool. This is much more efficient than manual drawings as with most drawings you would have to redraw the entire drawing. Material analysis and testing are often integrated into the CAD software, they allow you to import the drawing and retrieve a lot of data that will be useful in the design and manufacturing process. Cost calculation can also be automated which is quick and easy. 

To conclude I think that although CAD is a very expensive to start up and can crash or have compatibility errors, it is overall an upgrade from pictorial drawings due to the huge range of benefits. Although this may be the case I still think that sketching is a better way to get early design ideas at the start of the project as it is much faster when used for this purpose. CAD benefits the manufacturing and assembly processes much more than hand drawings as it extremely accurate and makes it easier to spot errors in the manufacturing process and will tell you before you come to assemble if any parts will not be feasible.