Construction parts for 3D modeling and prototyping

Modern additive manufacturing has gone far beyond the creation of simple figures and souvenirs. Today, engineers and designers use the 3D printers for the manufacture of functional units that require subsequent assembly in complex mechanisms. That is why understanding what details are needed for a full 3D modeling is a critical skill for any person skilled in the field. Without the right components, even the most perfect geometry can be useless.

In the design process, it is often necessary to use standard elements that are either too difficult to print or economically inefficient to produce by additive method. BearingsScrews, nuts and specialized profiles make up the skeleton of most devices. Ignoring their characteristics during the digital prototype stage leads to the fact that the physical sample is not assembled or works incorrectly. It is important to consider the integration of these components in advance.

This article aims to systematize knowledge about the different types of parts used in conjunction with additive technologies. We will look at materials, fasteners and methods of their implementation in your projects. This will allow you to create more reliable and durable products, avoiding the typical mistakes of beginners. Immersion in the topic will begin with the fundamentals of material selection.

⚠️ Attention: Do not use parts made of ABS plastic for units exposed to aggressive solvents, as this can lead to rapid structural collapse and loss of leakage.

Basic materials for printing functional parts

The choice of material is the first and most important step in the chain of creation of the part. For functional units that will carry loads or experience friction, conventional PLA plastic is rarely suitable due to its brittleness and low heat resistance. Engineers are more likely to pay attention to nylon and PETGThey have excellent impact strength and chemical resistance. These materials allow you to create parts that work in real operating conditions.

Particular attention should be paid to composite filaments. Adding (carbon), fiberglass or Kevlar to the base of plastic drastically changes its mechanical properties. Such parts become stiffer, lighter and better keep the shape under load. However, abrasive fillers require the use of hardened steel nozzles or tungsten carbideOtherwise, the equipment will wear out catastrophically quickly. This is a technical nuance that cannot be ignored when planning production.

For high-temperature environments, polymers such as PEEK or PEI. They can withstand heat up to 200 degrees and above, making them ideal for the automotive and aerospace industries. Working with them requires printers with a heating camera and a high-temperature extruder. The cost of such materials is high, but justified in specific tasks.

• 🛠️ Nylon: Ideal for gears and bushings due to the low coefficient of friction.
• 🌡️ ABS/ASA: Good heat resistance, but requires shrinkage control when printing.
• 💎 Carbon-plastic: Maximum rigidity with minimum weight of the structure.
• 🛡️ PEEK: Extreme strength and resistance to chemicals for aerospace.

Standard fasteners and metizos in additive design

No serious project is complete without the use of standard fasteners. Screws, bolts, nuts and washers are the universal language of engineering. When modeling parts for them, tolerances must be strictly observed. For example, a screw hole M4 PLA may require a diameter 4.2 mmHowever, ABS may be required. 4.3. to 4.4 mm It's because of different shrinkages. Accurate measurements and test seals of calibration lines are mandatory.

There are two main approaches to integrating fasteners: the embedding of nuts when printing and the use of self-rotting screws. In the first case, the model is suspended on a certain layer, inserted into the cavity nutAnd the print continues on top of it. This gives a very reliable threaded connection. The second option is simpler, but less reliable when repeatedly assembled and disassembled, since the plastic can “float”.

Thermoinserts (therm inserts) are also used to create reliable connections. These are brass sleeves with threads that are pressed into heated plastic. They provide a connection that withstands high torques. Use of the heat-insert significantly increases the repairability of the product, allowing you to repeatedly unscrew and twist screws without damaging the plastic base.

Bearing units and rotational elements

Mechanisms involving movement cannot be imagined without bearings. In 3D modeling, standard series ball bearings are most often used, such as: 608zz (Popular in skateboards and 3D printers) or 6200 series. When designing seats under them, it is critically important to take into account the printing accuracy class and shrinkage of the material. The gap between the shaft and the inner edge of the bearing should be minimal, but without tension, unless a press fit is provided.

It is often tempting to print bearings entirely from plastic. This is only permissible for mechanisms with very low load and rotation speed. Plastic “bearings” wear out quickly, warm up and lose geometry. For serious tasks, always use metal components, and leave the plastic for housings and holders. Sliding bushings Bronze or graphite composites are an excellent alternative to ball bearings where compactness is important.

When calculating the shafts and axes, remember the beat. If the shaft is fixed in the printed part, make sure that the walls of the hole are thick enough so that they do not rupture when pressed. The use of composite shafts or shafts made of grinded steel is preferable to the use of conventional nails or spokes, which can have a significant curvature.

Type of node	Recommended material details	Type of landing	Note
Ball bearing	ABS, PETG, Nylon	Moving (H7/g6)	High accuracy of the hole is required
Sliding bush	PLA, PETG	Press	You need lubrication in the process.
Tooth gear	Nylon, TPU.	On the shaft with veneer	The accuracy of the tooth profile is important
Support unit	ABS, ASA	Screw-strengthening	Rib reinforcement

⚠️ Attention: When designing seating under bearings, avoid thin jumpers, as when pressing a metal ring, the plastic can crack due to internal stress.

Electrical components and their integration

Modern devices are often mechatronic, that is, they combine mechanics and electronics. Details for 3D modeling in this context include enclosures for Arduino, Raspberry PiBattery holders and cable management. The main requirement here is the exact compliance with the dimensions of electronic boards. Even millimeter deviation can make assembly impossible.

It is important to consider the heat generation of electronic components. If you are designing a housing for a powerful controller or driver, you need to provide ventilation holes or installation spaces. radiator. Plastic is a thermal insulator, so it should not prevent heat from being removed from critical nodes. In some cases, it is worth using materials with increased heat resistance.

Cable management is the art of laying wires. 3D printing allows you to create unique clips, channels and fixers that fit perfectly into the geometry of your device. Use flexible filaments (TPUs) to create latches that won’t break when opened repeatedly. This will add a professional look and reliability to the device.

Secrets of printing enclosures for electronics

When printing cases for electronics, always leave allowances for the thickness of the walls. A standard 1.2 mm wall may be too brittle for latches. Increase it to 2-2.5 mm or add internal stiffness ribs. Also consider the tolerances for screws, which the board will be screwed to the bottom of the case - the holes should be slightly wider than in the drawing, due to the "inflows" of plastic.

Specialized profiles and connectors

Aluminum profiles are often used to create frames of robots, machine tools or furniture, such as: V-Slot or T-Slot (2020, 2040). 3D printing allows you to create adapters, angular connections and movable nodes that dock with these profiles without complex metalworking. It is democratizes the creation of complex designs for home workshops.

There are a huge number of ready-made solutions for connecting profiles. Corner brackets, couplings for connecting shafts, engine holders - all this can be downloaded and printed. However, when designing your own connectors, it is important to remember the direction of the printing layers. The load should not fall on the tearing of layers, otherwise the part will break under the weight of the structure.

Use of the eccentric It allows you to create adjustable connections, which is especially useful for wheel pairs or guides. These parts require high accuracy printing threads or the use of metal inserts. The combination of aluminum profile and 3D printed parts opens up limitless possibilities for design.

• 📐 Aluminum profiles: The basis of the frame, requires accurate slots in 3D detail.
• 🔗 Corner connectors: It should be printed with maximum filling (infill).
• ⚙️ Clusters: Connect the engine shaft with the mechanism, require rigidity.
• 🚄 Guides: Wheels for V-slot profiles are often printed from ABS.

Tools and tooling for assembly

Not only the final product, but also the process of its creation requires specific details. 3D printers allow you to produce unique equipment: drilling templates, conductors, clamps and fixers ("third hand"). These auxiliary parts are often made from cheap PLAs, as they do not carry an operational load, but are critical to the build quality of the main product.

It is also worth mentioning the calibres and measuring instruments. You can print your own calibre (albeit with limited accuracy) or a set of calibres to check for gaps. This is especially useful in the field when there is no professional tool at hand. Templates. To check the angles or radii of the rounding helps to control the geometry of other parts.

The organization of the workplace is another area of application. Organizers for screws, holders for coils with filament, nozzle storage systems - all this creates a comfortable environment for the engineer. A well-organized table increases productivity and reduces the risk of losing small but important components.

Frequently Asked Questions (FAQ)

What material is best for printing gears?

For gears experiencing load, it is best suited nylon or PETG. They have the necessary elasticity and wear resistance. PLA is too fragile and can split under load, especially when heated. For high speeds and loads, consider carbon-nylon.

Do I need to make allowances for holes under screws?

Yes, I will. Plastic when printing "floats" to the walls of the hole, reducing its diameter. They add 0.2-0.4 mm to the diameter of the screw. The exact value depends on your printer, the slicer settings and the type of plastic, so it is recommended to test the calibration plate.

Can the whole bearings be printed?

Technically possible, but such bearings will work only at very low speeds and minimal loads. Plastic has a high coefficient of friction and wears out quickly. For functional mechanisms, always use metal ball bearings or bushings, embedding them in the printed case.

How to strengthen the 3D part for installing screws?

The best way is to use heat-set inserts. They are pressed into heated plastic and provide reliable threading. Alternatives are nuts or wood/plastic screws, but they are less durable when disassembled frequently.