Blog 15: 3D Printer: An Amazing Technology

Introduction:

3D printing or additive manufacturing is a process of making three-dimensional solid objects from a digital file. In 3D Printing, an object is created by a 3D printer by laying down successive layers of material until the object is created. Each layer can be seen as a thinly sliced cross-section of the object. The 3D printer uses computer-aided design (CAD) to create three-dimensional objects through a layering method. 3D printer codes are generated using CAD software that gives the command to the 3D printer to print. These codes are known as GnM cods 3D printing involves layering material, like plastics, composites, or bio-materials to create objects that range in shape, size, rigidity, and color.

The term 3D printing covers a variety of processes and technologies that offer a full spectrum of capabilities for the production of parts and products in different materials. Essentially, what all of the processes and technologies have in common is the manner in which production is carried out layer by layer in an additive process which is in contrast to traditional methods of production involving restrictive methods or molding/ casting processes.

In the 1980s, 3D printing techniques were considered suitable only for the production of functional or aesthetic prototypes, and a more appropriate term for it at the time was rapid prototyping. As of 2019, the precision, repeatability, and material range of 3D printing have increased to the point that some 3D printing processes are considered viable as an industrial-production technology, whereby the term additive manufacturing can be used synonymously with 3D printing

Parts of 3D Printer

Print Bed

The print bed is the surface that your objects are printed on. Typically, it will consist of a sheet of glass, a heating element, and some kind of surface on top to help the plastic stick.

Heated/Non-Heated

Most print beds are heated in order to prevent the object from warping while it is being printed. Due to thermal contraction, the plastic will shrink slightly as it cools. This causes the object to warp upwards around the edges and peel off the bed. Heated beds keep the bottom of the object warm, in order to prevent this.

Some printers do not have heated beds. This limits them to printing a narrow range of materials including mainly PLA (the material that is least prone to warping) and sometimes PET.

Bed Surfaces

The bed surface helps the plastic stick to the bed during printing but also allows it to be removed easily when printing is done. There are many different kinds of bed surfaces. Most printers will come with some kind of all-purpose surface, like BuildTak or PEI film. However, for best results, you will want to use different surfaces depending on the material you are printing. Use this guide for print bed recommendations based on the material. 

Bed Leveling

Many printers have some kind of a system for automatically making sure that the bed is level with the nozzle. Some do not, though, and must be calibrated by hand. Matter Control also has the ability to compensate for unlevel print beds with software.

Filament

This is the plastic that’s consumed by the printer. It comes on a spool. Printers use two different sizes of filament, 1.75 mm and 3 mm. There are a variety of different materials.

Extruder

The extruder is the core of the printer. It is where the plastic gets drawn in, melted, and pushed out. It is essentially a fancy hot glue gun. Extruders are small, but it is where most of the printer’s technology is located. The extruder consists of two parts; the hot end and the cold end. The cold end has a motor that draws the filament in and pushes it through. The hot end is where the filament gets melted and squirted out.

Direct Drive vs Bowden Extruders

On direct drive printers, the hot end and cold end are connected together, one on top of the other. The filament goes straight down through the cold end and into the hot end.

With a Bowden setup, the hot end and cold end are separated. The cold end will be stationary and bolted somewhere onto the printer’s frame. The filament is pushed through a long tube (called a Bowden tube) to the hot end. This means that the printer has less weight to move around.

Hobbed Gear

This gear bites the filament and pushes it down through the hot end.

Idler Gear

The idler is a spring-loaded wheel that pushes the filament up against the hobbed gear. Most printers have a way to adjust the tension on the idler so that it neither squeezes the filament too hard nor too little. 

Hot end – All Metal vs PEEK/PTFE

By not using any plastic insulators in their construction, all metal hot ends are able to reach much higher temperatures and print a wider range of materials. However, they require active cooling.

Hot end – Heat Sink / Hot End Fan

This ensures that heat does not travel up the plastic and melt it prematurely before it reaches the nozzle. This phenomenon is called heat creep and it causes jams, especially with PLA. This fan should be running whenever the hot end is warm.

Heater Cartridge 

The heater cartridge is pretty self-explanatory. It heats the plastic. It is simply a high-power resistor. Almost all modern printers use cartridge heaters, but many older printers used coils of nichrome wire (like the kind in a toaster). If you are replacing your heater cartridge, or even your entire hot end, make sure you know if your system is running 12v or 24v. 

Thermistor/Thermocouple/RTD

These are all various types of sensors for determining the temperature of the hot end. They are essentially electronic thermometers. Thermistors are the most common type of sensor, but some printers will use thermocouples for extremely high-temperature printing.

Nozzle

The nozzle is simply a piece with a small hole for the melted filament to come out of. Nozzles are interchangeable, and come in various sizes; 0.4 mm is normal, while you might use a smaller nozzle for finer detail or a larger nozzle to print faster. Nozzles can also sometimes get clogged. This is one of the most common issues with 3D printers.

Layer Cooling Fan

This fan cools off the plastic immediately after it is deposited by the nozzle. It helps the object hold its shape. The slicer will turn this fan on and off under different circumstances, depending on what material you are printing. It is not to be confused with the heat sink fan, which cools the hot end itself and not the printed object.

Motion Control – X, Y, Z Axis:

Delta VS Cartesian

Cartesian printers move one or two motors along each of the X, Y, and Z axes, and the name was derived from the Cartesian coordinates system. They typically have a rectangular build area and the printers themselves tend to have a cube-like shape.

Delta printers have three arms that come together in the center to suspend the extruder above the build area. Deltas also use a Cartesian coordinates system to move around. Still, instead of moving one motor per axis at a time, all three arms move at different rates or times to precisely move the nozzle with triangulation.

End Stops (one for each axis)

The end stops are how the printer knows where it is. They are little switches that get pushed whenever an axis moves to the end. This is how the printer finds its starting point before printing. Most printers use mechanical switches, but some are known to use optical sensors.

Threaded Rods / Leadscrews

These are usually used on the printer’s Z axis. They rotate, thus forcing nuts to move up and down. Inexpensive printers will use simple threaded steel rods, which are essentially extra-long bolts. Higher quality printers have smooth chrome-plated leadscrews designed to minimize backlash.

Belts

Belts move things. The X and Y motors have sprockets that drive the belts. Most printers also have some way of adjusting the tension on the belts.

Stepper Motors

Unlike regular DC motors, which rotate continuously when given power, stepper motors rotate in increments. This gives them precise control over their position. Most printers use NEMA 17-type motors with 200 increments (steps) per revolution.

Frame

The frame holds everything together. Early printers had frames made out of laser-cut plywood. Printers now have frames made of sheet metal, aluminum beams, or plastic. Many parts of the frame are often 3D printed themselves. The more rigid the frame, the more precise the printer’s movement will be.

Enclosure

Enclosures for 3D printing are used for safety. There are moving parts and heating elements that users will want to protect themselves from. If your printer does not offer an enclosure it is easy to construct your own. Something as simple as a cardboard box could suffice.

Electrical Components:

Power Supply

This takes the 120V AC electricity from the wall and converts it to low voltage DC power for your printer to use

ATX Power Supplies- These are the same power supplies used in desktop computers. They have been repurposed for use in many printers. They are very beefy and efficient and have separate lines that provide power at a variety of voltage (12V, 5V, 3.3V).

Voltage – some machines run 12-volt systems, while others run 24-volt systems. This becomes critical if you are going to replace components – especially your heater cartridge or hot end. Make sure you order the appropriate parts. 

Motherboard/Controller Board

The motherboard is the brain of the printer. It takes the commands given to it by your computer (in the form of G-code) and orchestrates their execution. The motherboard contains a microcontroller (essentially a tiny, self-contained computer) and all the circuitry needed to run the motors, read the sensors, and talk to your computer.

SD Card Slot

Some printers also have an SD card slot from which they can load G-Code files. This allows them to run independently without a computer.

Stepper Drivers

These chips are responsible for running the stepper motors. They fire the coils of the motor in sequence, causing it to move in increments. Many motherboards have the stepper drivers built in, but some also have them in modules that can be unplugged. By balancing the power fed to each coil, the driver is also able to divide steps up into further increments. This is called micro-stepping and allows more precise control over the motor than is normally possible. The stepper driver also controls how much electrical current is fed to the motor. More power makes the motor stronger, but also makes it run hotter.

Screens and User Interfaces

Some printers have an LCD screen so they can be controlled directly without hooking them up to a computer. These can be basic black and white displays like the VIKI 2 or advanced enabled touchscreens like the one included on the new Ultimaker S5 3D printer.

A few Applications of 3D printer:

• Consumer products (eyewear, footwear, design, furniture)
• Industrial products (manufacturing tools, prototypes, functional end-use parts)
• Dental products
• Prosthetics
• Architectural scale models & maquettes
• Reconstructing fossils
• Replicating ancient artifacts
• Reconstructing evidence in forensic pathology
• Movie props