3D Printing Raft: When to Use it, Pros & Cons

Introduction To 3D Printing Raft:

Facing challenges to perfectly print First layer in your 3D modeling? Read on to understand the practical problems associated with it and how a RAFT can be really handy to overcome it. 

First layer acts as the foundation for the whole part and can determine the success and failure of the 3D printing. During the first layer printing, one may face problems like poor finishing, uneven layers, and the layers may even be non adhesive. What to speak of when materials like ABS are used? It makes the part twisted and creates a warp resulting in print failure.

All such problems may grab the printing interest from the user. To get rid of all such issues, this article gives you a clear cut idea by introducing a new mesh like layer called a 3D printing Raft, which will be placed on the build plate.

3D printing Raft helps you to get an ideal initial layer and also keeps the print in contact with the build platform. Since ABS filaments cause more warping, Rafts are ideal enough to overcome this problem. Rafts are also popularly known to increase the nature of bed adhesion.

What Is a Raft In 3D Printing?

The horizontal surface which is placed on the build platform and on which the print layers are deposited is called a 3D printing Raft. It is a flat mesh like structure placed or sometimes printed on the build plate, so that it’s main aim is to support the part and to provide bed adhesion.

When you try to print a part with thin legs or an object with heavy top load, then the use of Rafts are highly recommended.

When To Use a 3D Printing Raft?

Even though a Raft can be used for various causes, let’s now discuss the major ones amongst them.

  1. Improper printing or warping: As we discussed already about the issue in using ABS filaments, let’s now go through a way to control them. Take a sludge of acetone and pieces of ABS filament, then gently spread those on a heated bed. Even after doing this there are still chances of warping during the process. To weed out this issue completely, a Raft can be used for an ideal 3D print.
Warping in 3D Printing
Fig: Warping problem
  1. Imperfect bed adhesion: Rafts do not stick its base completely to the print plate, instead it is just a flat mesh on it. Being so thin and meshy,  it plays a vital role in providing surface area which in turn increases the bed adhesion. Therefore, it creates a strong foundation and does not allow the object or prototype to fail. 
  1. Pint-sized legs: While printing some parts, the base of an object might be thin and weaker. Hence it becomes complicated to the base portion to carry the rest print on it and may lead to the failure of the object. To overcome this failure you can increase its contact area to bear the load of the Rest of the print by placing a Raft on it.

Separation Distance:

The space between the Raft and the initial printed layer of the part is called the separation distance. Or in other words, the distance between the tip of the Raft and base of the object is defined as the separation distance.

Before you start up printing it is very important to stay highly conscious while mentioning the correct separation distance between the part and the Raft, because this height determines the outcome of the remaining part to be easy or difficult.

The smaller and tighter distance you give, the harder it becomes to separate the Raft and the object.

If you are doing it for the first time, then it’s better to go with a separation distance to half the nozzle’s diameter. So after two or three trials the outcomes will help you in understanding the concept about the settings modification to be done for further prints.

Normally, experienced users recommend a separation distance of 0.1mm. If you try to increase the distance, then it is easier to separate the print and the Raft. But the demerit of this increased distance is getting a poorly finished initial layer. So, it is safe and good to go with experts recommendations.

What Are The Essentials To Be Known While 3D Printing With a Raft?

Above raft speed: The rate at which the first layer of a prototype is deposited on the surface of the Raft is defined as the Raft speed. You must carefully give a low Raft speed to enable an ideal layer adhesion.

Raft top layers: As per the given value by the user the layers deposited on top of the Raft are known to be Raft top layers. In order to obtain a smooth finished surface on your part, experts advise to drop two to three layers on the raft.

Raft base layer: An initial and broad printed layer with a slow speed on base of the Raft is called a Raft base layer. The reason behind choosing this layer is that the next  layers could adhere well and lead to a good quality print.

Merits And Demerits:

As we already knew that each and every technique has some or the other positive and negative aspects. Similarly here also let us have a look at some of those.

Merits:

  • Warping can be prevented even while printing with a stubborn filament like ABS.                                                                  
  • Increased bed adhesion can be noticed, so that the part can be easily removed.
  • Output is compatible and as expected.
  • Well built initial layers can be obtained.

Demerits:

  • Poor finishing at the bottom layers of the prototype.
  • Becomes complicated while detaching the part from a denser Raft.
  • Excess wastage of the material.
  • Prototypes with tiny legs might break down or get damaged while separating from the Raft.

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