There is a lot of hype in the media at the moment about 3D printing with many articles focusing on only the positives of this ‘brand new technology’ (that has actually been around for nearly three decades). There are however many drawbacks and missunderstandings that are either ignored or miss-represented by many sources on the internet and elsewhere.
This section of the site has been put together by professional users and not salesmen of the technology and is aimed to give you a more realistic guide of what is possible without any sugarcoating. Please read on to have some of the hype translated into reality….
All these points have come from articles we’ve read, and enquiries we’ve had over the last two years.
The Myths and Misunderstandings explained…
3D printing is cheap....
Yes, 3D printing is cheap, when you:
Compare it to other methods of producing one off items.
With 99% of manufacturing methods, relatively expensive setup and tooling costs are involved. These are generally cost for making moulds, tooling up a machine or creating a jig etc. This setup generally costs a bit, and takes time, resulting in longer lead times and more expensive products if you are only ordering one or a few. However generally this tooling means that you can produce items really cheaply once the tool has been made, meaning if you are making a lot of the same item it may end up cheaper to make the tooling – this is called economy of scale.
In 3D printing, there are no tooling or set up costs, only material costs, meaning that you don’t have to spend hundreds or thousands on set up or tooling, you only pay for the materials that you use…. But…. The materials are generally a lot more expensive, so you’ll never get the same price from a 3D print than you will from a mass produced item.
Make things small
Because the cost of 3D printing is based on volume of material used, one main rule applies to cost – that is:
Small = Cheap, Big = Expensive
It does not matter how complex the part is, it is simply the amount of material used that determines the price of the part. This means that a brick, ironically, is the most expensive thing you can produce (at that size), but an incredibly ornate model train of the same size would probably be a tenth of the price as it uses far less material.
So ‘What is small?’. Well, if you can fit it in your hand, it’s probably going to be under £100, if it is bigger, then it is going to be more. One of the more frequent questions we get is ‘How much to print my own head?’ – Answer, Generally £1,000. No prizes for guessing that printing a table is probably going to be a bit too expensive.
You already have the CAD model.
One of the hugely overlooked parts of 3D printing is the fact that you need a CAD model to print from. This is generally a very time consuming and specialist job. If you don’t have any CAD skills, you can either try learning with numerous free CAD programs that are out there, but it’s not the easiest thing in the world, so you could get one of our trusted CAD companies to do it for you.
3D printing is strong...
Depends on your material
The first factor is that there are lots of different types of materials, ranging from plastics to ceramics to metal to glass (we only do Nylon and Resin in white). Things like plaster (from the full colour printers) are by nature very brittle and have no flex. The resin we use is relatively strong, described by the suppliers as ‘similar to ABS’ – I disagree, it is NOT as strong as ABS.
If you are looking for strength, definitely, definitely use our Nylon material.
3D printing is a layer by layer process – this means that you effectively have a grain – and where there is a grain, there is weakness, especially on thin features. The easiest way to visualize this is imagine that your part is made out of Lego. If you make your wall very thin, you cannot easily break the wall by adding pressure from the top or down the length of it, but if you push from the side of it, the wall will buckle easily and break. This is the same with 3D printing – to get around it you can either orient the part at a different angle (being humans, we will always do this for you if we notice a weak point on your model, though it is not guaranteed that we will notice everything, and extra support material charges may be incurred if you are using the Resin printer), or you can thicken the wall up considerably – just like if it were Lego!
You make things thicker than the minimum
We have minimum wall thicknesses, but these are minimums, not for strength. Personally, I make all my walls 2mm or thicker if I can – there is no point in making everything as thin as possible, even if it is cheaper – it becomes a complete false economy – you are much better spending a hundred pounds on something that works and lasts than seventy pounds on something that could break at any minute!
Example – the Nokia 820 case released to the world – sadly it paid no attention to wall thicknesses and broke. This is a good example of how wall thicknesses can be strong in the XY axis and very weak in the Z axis, demonstrating both the importance of wall thickness and the effect the layers have on the strength of a part.
You can 3D print from pictures
Here is a picture of my dogs, how much to 3D print it? Well, believe it or not, you cannot 3D print from a photograph. You need a CAD model to print from which can be the biggest challenge, especially with organic or living items. If you want to 3D print your dog/friend/car and you have no previous CAD skills, then expect to pay £500+ for a semi-decent CAD model of them before you can even consider paying for the 3D print.
There are apps such as 123Dcatch for iPhone and Android that you can create 3D CAD models for free by taking photos of the object, but these are very abstract once you remove the pictures from them…
An example of a scan and print from a photo based scanning app (left is the printed item, right is the original that it was scanned from!)
You can just 3D scan it then 3D print it
Yes you can, but there are a few things:
Firstly 3D scanning is expensive, and if it is cheap, it’s probably not worth it.
Secondly, 3D scanning can only scan the exterior of an object, and is very bad at scanning holes and hollow cavities etc, this is especially important for engineering parts.
Thirdly, if you are scanning and scaling something up, every imperfection in the scan gets magnified.
Lastly, Scans are much harder to edit than CAD models, so whenever possible, get the part drawn up in CAD.
You can 3D print anything you can see on screen
Despite 3D printing having far less design rules than other manufacturing methods, it still has rules! You have to stick to all the max and min wall thicknesses and build sizes.
You really have to be careful about this, especially if you are buying files from the internet. Many files may look appealing, but are highly likely to be unprintable. Remember, many 3D files are generated for animation, rendering and computer games, and not for manufacturing. These files are likely not to be printable!
You can Print in colour
First of all, we don’t offer this service Second of all, yes you can, but you can only print in full colour in a plaster material or in a paper 3D printer (yes a paper 3D priner!). You cannot print in colour in plastics other than in a mix of a few block colours on some machines, but generally, if you want a durable plastic part, it will be printed in one colour, generally white.
Full colour printers produce rigid and brittle models that can only really be used for visual representation and cannot be used for any functional testing in our opinion. Nine times out of ten it is better to 3D print in a strong white plastic and paint after if colour is required.
Can I have a smooth gloss finish?
The Objet resin printer does offer a gloss setting, but this is only where there is no support material in contact with the part. There is always support material on the underside, so you will always have a matt finish on one side, meaning your options are full matt (a layer of support material covering the whole model) or half gloss (matt where support material is in contact with the build material, gloss where it is not).
This replacement radiogram knob has a gloss finish on the front face, but a matt finish on the underside (the ridged part and the smaller cylinder) where it has been in contact with the support material. It is not possible to print it completely gloss, and the half gloss setting is only available on the resin printer. FYI, this part has been drawn up in CAD, not 3D scanned.
You can print mechanisms pre-assembled
You may have read about the the amazingness that is ’3D printed mechanisms’ where you can print a full working gearbox, a bearing or a bike chain all in one print, pre-assembled. Well, this is true, you can, but in reality, they’re rubbish.
Why? Because you have to leave a (in engineering terms massive gap) between these moving parts. This gap is to prevent the parts fusing together when you print them. This gap has to be around 0.5mm between moving parts. This may sound a little, but if you’re talking about efficiency on a gearbox, it’s terrible! You can get a little closer on higher detail machines, but these machines generally work with brittle resins, basically giving you another problem whilst not really solving the first one.
It is always better to manufacture the parts individually and then assemble them after. Even better, buy off the shelf gears from a supplier and 3D print the box that holds them all together.
This heart gear is a model that has been downloaded from thingiverse.com and modified to reduce the tolerance to make it fit tighter and turn smoother.
You can print any file you download from the internet
A great example of this is the Raspberry Pi laptop case – the ‘Mobile Pi’ – Don’t get me wrong – this is a fantastic piece of geek-tech, which is exactly what we stand for here, however, it has not been designed very economically for 3D printing! The part has a total volume of over 500cm3, which even on our economy price Nylon will cost over £500! You can however build this on a makerbot for other personal 3D printer for a lot less….. you just have to own the machine in the first place!
However, we still think it is awesome!
You can 3D print big things
3D printing is fast