This article has been written with the novice or beginner designer/inventor in mind.
The intent of this article is to hopefully guide you through some of the various minefields that you’ll encounter, and to also look at the major challenges that any design has to face – from conceptualization to the realistic possibility of your idea being put into production.
In this article we’ll explore how you, as the novice designer/inventor, can help to facilitate this process, so let’s get started…
What’s the difference between an idea and a design?
About $100,000.00 minimum in my experience. Seriously, if your design is complex or has multiple elements and/or components to it, it’s going to take a chunk of money to see it to fruition.
I don’t personally know any independent industrial designers who have that type of investment capital to gamble with, so the key is to do everything you can with the resources that you have, in order to make the best possible presentation to the money men.
You simply can’t expect to be left alone in your shed or study and churn out all of these amazing designs… If you can’t sell it to the ‘money’ then the ‘money’ won’t be able to sell it to the market. So learn how to market yourself – use every software tool you can lay your hands on, from Power Point to Blender.
Ready to start designing and stop sketching?
Any design starts with an idea, and then that idea is usually placed on paper in the form of a sketch. If you’ve become a crack shot at hitting the waste paper basket, then you should seriously consider CAD (Computer Aided Design) drawing and modeling software.
It’s time to become a bit more organized, and quickly… there are many aspects of designing a product that aren’t in the least bit glamorous, in fact they are tedious, repetitive and boring, but they’re also essential. If you don’t institute a effective regimen from the start, you’ll end up in a complete mess with all sorts of different iterations and part files lying around, none of which integrate with each other.
Apply a version to all your different design components and assemblies, and do this from day one. This is important, trust me on this…
CAD can really help you in many different ways, such as the ability to draw different parts and then assimilate them into an assembly containing all of the parts. It’s then very easy to see what is actually going on in your design.
CAD/CAM modeling software doesn’t have to break the bank. In fact some programs are available as open source (free) software and it will really enhance your ability to effectively communicate your design. Don’t be afraid of it, but if you really are stuck with a pencil and paper, then just be sure to communicate ALL the required dimensional information on your drawing to the people who will turn it into reality.
Think very carefully about what you have put on paper – are any further dimensions/ measurements/tolerances required?
The engineering shop that you go to will certainly use a CAD program, and they will use this to facilitate the construction of your design.
The old Acronym of GIGO (Garbage In, Garbage Out) is particularly apposite for prototyping any proof of concept design.
So which is the best program? The reality of any CAD program is that with repetitive use comes familiarity, so when you ask any CAD designer which program they prefer, the answer will almost always be that of the program that they use on a daily basis.
And as a last note on this topic, it’s very easy for a new CAD user to draw something that is either impossible to make, or extremely costly and/or impracticable. Don’t be afraid to ask people who might know more about this than you do.
So, what’s the next step?
Your design concept – things to consider
A concept is simply an idealised ‘perfect world’ model of your design – it can exist on paper as a sketch or illustration, on a computer, or as a physical model.
Most complex concept physical models don’t actually work, they’re simply there to keep the designers ‘eyes on the prize’.
The reason why most concepts don’t end up in production is that there is always an element of compromise in designing anything – the task is to combine functionality and aesthetic appeal with realistic costing and manufacturing processes. This triumvirate of conditions is very rarely met with equality for any product that is intended for large scale production.
So be prepared to sacrifice something.
Nothing should ever be sacrificed in it’s entirety, but certain elements of the ideal will almost invariably be lost, however, it is extremely important to have that ideal concept, as it is the cornerstone for all future efforts in your design.
Don’t be afraid to alter the concept either – one of the great benefits of a concept drawing is that you can use it to garner opinion, and this opinion, when properly collated and assessed should be influential to your concept.
Tolerances
This is an extremely important factor that you have to consider in any mechanical design – no manufacturing process is perfect in its ability to replicate the nominal dimensions that you specify. So it’s your job to design something that can be easily repeated time and time again, even with these imperfections in the manufacturing processes.
So wherever possible, be as generous as you can in specifying a tolerance. This is actually a fairly complex topic and falls outside the scope of this introductory article, but Google the topic and read up on things such as Maximum and Minimum Material Conditions – you’ll learn much that will save you an awful lot of money that would otherwise be wasted on multiple design iterations.
Proof of Concept – The prototype phase
There is usually more than one way to make a design, and this is the stage where you can effectively explore which is the most efficient, cost effective and aesthetically pleasing way of constructing your concept.
There are many pitfalls in this stage of your design – in fact, it is very easy to make a simple mistake at this stage which may have serious financial implications further down the line, even to the extent of the whole thing being canceled due to spiraling costs.
The golden rule is to follow two simple precepts;
Make your prototypes using the same, or as close as possible to, the materials and manufacturing technologies that you intend to use for the finished product, or if this is not possible as will quite often be the case, ensure that you have a good knowledge of the industry specific capabilities and the cost of replicating your prototype in a production environment.
An example of this could be something such as a design for a plastic part – the logical thing to do is to prototype this using a 3D printer. But a 3D printer doesn’t require a split line or draft angles – a plastic injection mould does. The two halves of the mould have to be able to separate and eject the part.
3D printing is a wonderful technological development that has progressed in huge leaps over the past 5 years, but it is still a long way from being a cost effective mass production process – so the lesson here would be to model your parts using the draft angles required to eject the part from an injection mould, and to also ensure that the overall shape of the component allows it to be ejected from the mould.
Another example could be that of a prototype laser cut sheet metal part;
Although lasers are generally very versatile machines, they do have limitations, one of which is that of the time required to cut large, complex or thick parts, resulting in them being quite expensive to mass produce some components.
Punching the part out of a metal sheet is therefore a far more cost effective way of mass producing the component and for simple parts this would be the way to proceed, but punches have limitations that lasers do not have, one of which is the inability to form complex sharp corners or profiles through a material that is thicker than the radius of the edge/vertices of the component without severely degrading the lifespan of the tool.
If you don’t take this sort of thing into consideration right at the start, your design probably won’t make it off the piece of paper, at least not in its current form.
There are obviously countless other examples, but the purpose of illustrating the previous two is to provide you with a couple of samples of some of the dangers that lie before you..
So, don’t be afraid to ask – this will become a recurring theme in your life as a designer, and if it isn’t, it certainly should be.
There is no shame in being a beginner or novice, any shame will only occur when you look back at what you could have done, but didn’t, simply because you thought you knew it all…
I’ve been doing this for 20 years, and I realise that today I ask more questions from a supplier in a single day than I did in a whole month, 20 years ago.
Our entire technological environment has quite simply exploded in the past 10 to 15 years, to the extent that individual knowledge has become much more of a small fish in a much larger pond.
You, as a designer who wishes to make their way in this extremely technologically convoluted environment, need to know when to ask for help.
People actually enjoy sharing their knowledge, and as an example, that’s why I’m writing this…
So make full use of that sharing appeal, but at the same time keep the ‘both feet on the ground’ filter switched on. Any ‘know it all’ should be given a wide berth in all circumstances.
Concept development – you’ve now got some bits and pieces in your hands. What next?
It’s very easy to just look at the nice shiny parts you have, but now you have to determine some data from these parts – what’s the best way to do this?
Well, firstly, do they all fit together as they should? If they do, congratulations, as you’ve achieved a world first.
The fact is that although they may well all fit together and interact with each other acceptably, the chances that they are correct in their entirety, are extremely minimal.
This goes back to tolerancing – something may work well as a sample, but as soon as you start to produce it in any quantity, it stops working, and this is usually because one or more of the specified tolerances is incorrect.
So the correct approach is to comprehensively and accurately measure all possible dimensions of your prototypes, and it’s also important to have as many prototypes as possible, in order to provide a sample that is statistically relevant.
You then need to compare these real world results with your nominal (perfect model) dimensions.
I know that the word ‘statistics’ is enough to make most peoples eyes glaze over, but it really is a very important tool that can manage how your design can be profitably produced.
Excel spreadsheets can do all number of wonderful things, including a ‘at a glance’ warning of out of specification tolerances – it’s just a simple input to make this happen, and a bit of tedium to record all the measurements on the spreadsheet. But it will greatly assist you in determining what your manufacturer can consistently achieve, and what they consistently cannot… You can then modify your design to accommodate these realities.
A note on prototyping.
Don’t fall into the trap of Patents and Non Disclosure Agreements unless you feel it is absolutely necessary – if you have a design that requires the services of a machine shop, a 3D printing facility, a laser cutting business etc, then the simplest way of initially protecting your intellectual property is to split different elements or components of your design between different businesses.
As Elon Musk, the MD of Tesla electronic vehicles recently stated, and sagely in my opinion, obtaining a patent is akin to buying a lottery ticket to a lawsuit..
The people that work on these elements of your design will in general have no interest in what it is – although this will change as you start to develop a more solid relationship with your suppliers. So take the opportunity to ask these people (who have a wealth of real world expertise in their individual areas) everything you can – and I assure you, people enjoy the opportunity to express their knowledge. This is true in every walk of life, but it’s particularly true of the manufacturing sector.
If you put your pride on the shelf, you’ll obtain so much more invaluable input than you otherwise would.
However you choose to prototype your design, you should keep it as close as possible to the intended finished product in all of the essential aspects. A simple example of this could be as follows;
You have a frame that is designed as die cast, in Zinc (as I write this, I’m looking at a disassembled hard drive lying on my desk). Within this frame there are components that have to be located, some of which are static, and some of which have a shaft that both locates and rotates in the frame.
You obviously can’t spend the money to have a Zinc die cast pressure mould built for your prototype, but you could have a plastic model grown on a 3D printer, right?
If you do this, then within your design model for the prototype frame you should incorporate some cylindrical cavities that allow for some cheaply machinable press fit, or glued in, inserts of Zinc. These inserts will allow you to do a real world assessment of the friction and tolerances between the frame and the shaft that rotates within it.
Of course, this is an overly simplistic scenario, and wouldn’t be appropriate for a drop test for example, and nor would this model be an accurate prototype for any form of Ingress Protection test, so for any complex design, you’ll probably need more than one prototype iteration, each one to test specific features, loads or compatibility of your model.
Things can start to become very complicated, very quickly, and that’s why you should take every advantage you can, from every possible resource that you can.
You’ll also have to use your own judgment, as sometimes well intended advice can have potentially dire consequences. In general, avoid the ‘man in the pub’ and seek advice from someone you are paying money to – they usually have a vested interest in your success, as this equates to more business for themselves.
There is also a wealth of information on the Internet, in the form of data sheets, articles or design calculators for everything from springs to load deflections.
And don’t forget group input, such as the Mechanical Design Forum. This is a classic case in point of knowledgeable people who enjoy imparting their knowledge.
The best way to get a good answer is to ask a good question, but sometimes that’s not as easy as it sounds – here’s a hypothetical example;
Your design includes the requirement for a gearbox. It may be for a car, or a watch – doesn’t matter which.
What you know is the reduction requirement of the gearbox. You want the first (input) gear to turn at 100 RPM and the last (output) gear and shaft to turn at 10RPM, but you’ve only got the space (in whatever dimension) for 3 gears.
You could ask, ‘how do I calculate the individual gear modules of a 3 gearbox with a reduction ratio of 10:1?” and you’d get lots of well intentioned and informative answers that probably won’t help you in the slightest.
This is because a gearbox can be configured in different ways – if you’ve ever seen a vehicle gearbox, you’ll know that it’s quite long, whereas a mechanical watch which is basically a gearbox is very flat in comparison to its diameter.
So, rather be more general and inclusive – let other people do the work for you.
Ask something like; “I’ve got a space of X by Y by Z – what do I need to know about gears to make 3 of them turn 100RPM into 10RPM”
Again, mechanical design is such a wide ranging field that any example in this article can only be generic, but the principle remains true – ask what you actually want to know, not a question that elucidates an elusive hint.
And don’t give up until you know in your heart that it’s time to do so. Sorry, but that’s true. Lots of people will tell you to ‘follow your dreams’. These same people will normally not financially support you whilst you attempt this.
Some designs work, and some don’t. If yours doesn’t, then go away and design something else – and don’t ever give up on that dream…
K.I.S.S.
