How does my 3D printer work and where I can find 3D models to print?

Over the last few years 3D printers have electrified our imagination in the whole world. Many people had a feeling tha it will be possible to print everything home soon. Unfortunatelly, the reality is a little bit more complicated and complicated are also 3D printers. The first thing you should remember is the fact that 3D printing technology is a extensive issue and it’s connected with diversified processes of production. A standard, low-budget 3D printer from plastic (thermoplastics) represents only one of the technologies available on the market.

Let’s start with a defintion od 3D print. 3D print is an additive technology which consists in creating of 3D objects by putting the next layers of material – one by one. It’s a constrast to milling (a subtractive technology(where a solid model is created from a block of material by cutting  (milling) a reduntant material from it until the end result. 3D printing can be called everything what we can create “from scratch” by putting a material layer by layer.

Types of 3D printing technology

Precise printouts from resin

The first 3D printing technology which came out was stereolithography (SLA), worked out by Charles Hull in 1984. It consists in hardening of the next layers od resin with laser light. Over the next years Hull was developing his project and in the end of 80’s he comercialised it and established the first and currently the biggest company producing 3D printers – 3D Systems. 3D printers printing in SLA are charecterised by they precision witch height of 25 μm (0,025 mm). They hold up by production of specialist 3D models which require high precision and accuracy (f.e. models for jewelers, dentists, dental technicans, electrotechnicianx or production of complicated and precise industrial aplications).

In the next years the next technologies connected with hardening of resin appeared on the market, like DLP (digital light processing) and PolyJet. The first is resembles SLA, with one difference – a resin is harden with a ligh emited from projector.

PolyJet is a totally different process – a 3D printer printing in this technology resembles an ink printer – with the difference that it prints with resin instead of ink. A resin is hardened with UV.  Additionaly, a layer of wax is sprayed which is used as a support (remember that 3D printers can’t print in the air) and than removed with water in a special washer.

FDM – 3D printing from plastic

Altough 3D printing from resin is extremely precise byt has unrostunatelly a few disadvantages.  Firstly, these are resins which features differ from materials commonly used in industry.  Secondly, printing with these machines takes a lot of time (it’s connected with their precision). Thirdly – they’re extremely expensive.

At the beginning of 90’s an extremely interesting alternative technology was creates – popular FDM (fused deposition modeling). FDM was worked ouy by Stratasys, which is the second biggest company from the 3D printing on the market.

FDM – what’s surprising for many users of 3D printers, was based on 3D print from two nozzles. One of them puts a basis material – ABS – one of the most popular plastics in the world, the second puts a support material which is dissolved in a special solution. Both materials are reeled in form of line which has fixed diameter and them pulled by extruder to the nozzle. Plastic is heated in the nozzle to about 240°C (it’s semi-liquid) and put on the bed of the device. When one of the layers is covered with material, the bed goes down and the next layer is put.

By low-budget 3D printers only one nozzle is used usually which builds a model and supports. Supports are build in a specia way which enables to remove/break them off easly. A model done in this way is practicaly an exact mapping of a model created with injection moulding machine, with one difference – it’s surfaces aren’t so smooth. As opposed from 3D print from resins, in FDM a nominal layer of 3D print is about 100 – 200 μm,  so 0,1 – 0,2 mm (theoretically it’s possible to print models with a layer of 0,05 mm but in this case rinses are better).

SLS – selective laser sintering

SLS it’s an alternative to FDM as far as printing of solid models from plastic is concerned. In this techology a powdered material of  starch-like consistency is used which is spread in the 3D printer layer by layer and than selectively dried up with a laser light.

With this method you can obtain printouts in better quality which don’t have visible layers (printouts are uniform). Due to the fact that a basis material is on form of powder and and supports are done from the material which is not dried up. As a result, we are able to print models with very complex geometry, impossible to obtain using other methods and technologies.

SLS is undobutedly one of the most interesting 3D printing technologies, unfortunatelly their price (which starts from 250 €)  is a huge barrier for users. Moreover, 3D printers printing in this technology require a dedicaded room where a constant temperature and humidity have to be kept. To work with this device you have to be trained properly.

Although working with 3D printers printing in SLS technology is not that complicated like with FDM, you need a knowledge and experience to prepare models for 3D print, how to fill the chamber with printouts (in SLS you don’t print single items) and how to clean them (you need also a dedicated workplace for it).

If it’s possible to print from plastic why can’t we use a powdered metal? DMLS (direct metal laser sintering) works in a similar way as SLS, with the difference, that you use metal instead of plastic and the temperature is much higher. The next difference is the fact that during the process of 3D printing metal shrinks and that’s why you need additional supports which have to be removed afterwards what is harder than by FDM.

3D printers printing from metal are more expensive than 3D printers printing in SLS, their price begins from 0,5 mln €. These are professional productive machines which require dedicated rooms and above all – specialized personnel to operate it.

CJP – 3D printin in colour

All of the above described 3D printing technologies have one common feature – they print in one colour. Some of the low-budget 3D printers printing in FDM can use 2-3 or even 4-5 colours of filaments but they aren’t mixed and put alternately.   O ile niektóre niskobudżetowe drukarki 3D drukujące w technologii FDM mają możliwość łączenia 2-3 a nawet 4 czy 5 kolorów filamentów, to nie są one mieszane ze sobą, tylko nakładane naprzemiennie. Despite several attempts, no  one has created a device printing in full color from plastic.

As far as rinses are concidered, one of the machines from company Objet (which belongs Stratasys) offers this possibility but it’s limited with palets of colours. posiada  Full colour is possible only in kCJP (color jet printing) – it’s a 3D print from plaster, coloured druing printing.

It runs as followed – on the bed you spread a powder, after that you spray a special glue on in and a colour (like in an ink printer). After finish yoy have to extract layers of the powder which aren’t sticked together and clean them, in the end sink it in solution which safes your material from little mechanical damages.

3D printers printing in CJP  technology are used as conceptional models or f.e. in architecture to print full-colour mock-ups of buildings.

Low-budget 3D printers

Low-budget 3D printers printing in FDM are the most popular among users around the world. In spite of their disadvantages (of 3D printers and 3D printing technology) they have two undeniable advantages: they are relatively cheap and easy to use.  Printous doesn’t need additional chemical treatment and they don’t need to be kept in special air-conditioned rooms and their users don’t have to cerfified by a representative ot their producer.

That’s why low-budget 3D printers are a rational choice for beginners. You have to be aware  that’s impossible to “print everything” with them. And now the next question – what can I print?

Where can I find projects for 3D print?

It would be te best to desing something yourself and print it with your 3D printer, unfortunatelly designing for 3D printing is even more complicated than printing… Inspite of proper abilities and talent, you have to learn how to use a software to design – and it’s not a piece of cake.

You need a few months for it – I don’t mean your abilities to design a simple case for your mobile but knowledge and experience which give you a freedom of creation.

The best alternative are libraries with free projects. The biggest website of this type is of course Thingiverse where you can find hounderds thousands of projects of all kind.

For more advanced users we recommend GrabCad gathering engineer and designers, you have to remember about a conceptional character of some projects which is not proper for 3D printing.

Using of ready (and free) projects for 3D printing is the best mehtod for beginners to learn the basics about their printers and also nuances connected with 3d printing. What’s the best way to put my model on the bed, how to generate supports, what kind of project should I avoid – you have to lern it on your own – by trial and error. 

I know that it sounds like a truism (I encourage to use free projects…) but you have to know that after buying a 3D printer you have to learn how to use it and it will be necessary to create your own projects. At the beginning the most important step is to practise 3D printing.