Let's continue on the topic of how the filament is fed into the melting zone (HotEnd).
In the photo, the classic Reprap extruder is the ancestor of all 3D printing mechanisms for homemade people.
It is worth noting the fact that the gearbox (with a ratio of at least 1:5) Necessarily needed to drive filament with a diameter of 3.0 mm. The purpose of the gearbox is to increase the torque on the shaft by reducing the rotation speed. In other words, it will spin stronger, but slower, and we don’t really need a high rotation speed - the plastic should have time to melt.
If we are dealing with a rod of 1.75 mm or an even smaller diameter, then we do not need to make a gearbox. Although, if a very weak engine is used (for example, from an old Epson printer, which I used at first), then the gearbox will still have to be made.
The photo shows just such an engine and an extruder made on its basis from parts from old printers.
In industrial 3D printers, the extruder looks very similar:
The photo shows the heart of a printer from Stratasys - the same comrades who invented (and patented) the technology of printing with molten plastic.
There are, of course, more sophisticated options, but they are rather complicated to implement, and therefore are not suitable for independent (handicraft) production:
Since 3 mm plastic is significantly (!) cheaper than thinner options (and also more common), we will make the drive based on thicker filament. And we can “push” plastic 1.75 (and similar) with this extruder without any problems at all. In this case, only minor modifications to the hotend will be required (more on this later).
So.
First we need an engine. Moreover, it is stepper and very preferably bipolar, otherwise you will have to tinker with the controls. You can distinguish it from unipolar (another type of stepper) by the number of pins. There should be 4 of them. In this case, you can use a standard control driver (Pololu). Diagram of such an engine:The color of the wires can be absolutely any, so we check where the windings are with a tester. Regarding the beginning/end of the winding, we will determine this experimentally when connecting the engine.
In principle, you can also connect a motor that has 6 terminals - the main thing is to correctly determine where the windings are, after which there will simply be 2 unnecessary wires that can simply be cut off.
IN in this case we will have the “yellow” and “white” wires left unconnected.
You can extract a lot of useful things from old printers, but the engines are very weak, especially in new inkjet printers, so they are only suitable for use with gearboxes with a very high gear ratio. Here is an example of such engines:
Of all this variety, only the Epson EM-257 is suitable for use as a filament drive - it just has the required number of pins (4), as well as more or less good torque on the shaft. Here are a few more similar engines:
They are of course rather weak for our purpose, and, ideally, it is better to use an analogue of Nema17 (the one used in the original rap), but they can be bought for pennies on any radio market or picked out from old hardware. By the way, you should not take the Soviet DSHI-200, which are very popular among machine tool builders, as the basis for the extruder, because they are too heavy to be pulled around as a print head.
Among those available in Russia, one can highlight the website of the Elektroprivod store, which sells an analogue of Nema17 - FL42STH. I chose FL42STH47-1684A motors for the printer, which are perfect not only for the extruder, but also for driving all axes.
Now we need a gearbox.
It is clear that the smaller its dimensions, the better for us - the total mass of the print head will be less, and accordingly the positioning speed (as well as the printing speed in general) will be higher.
Initially it was planned to use a stepper motor with a planetary gearbox industrial production, like this:
But finding it in Russia at a normal price is simply unrealistic, and in China they are sold at very low prices. available means, therefore, as always, everything is done on our own.
For myself I determined (eventually) perfect option- a planetary gearbox, pulled out from an old screwdriver, converted for use with a stepper motor.
The donor looks something like this in the photo. And in disassembled form something like:
The photo is not mine, but fundamentally these planetary gearboxes are not very different from each other. Therefore, we are looking for a dead screwdriver and go ahead and disassemble it.
As before, we will need a smart turner who will help us fit the drive gear from the original screwdriver motor onto our stepper. It will also be necessary to machine the housing cover for the output shaft bearing. I'll post photos of my version later (I'll have to disassemble the finished extruder). You can, in principle, make a drawing of a cover that was machined from aluminum, although a turner usually has enough simple explanation“on fingers” what exactly we want to get from him.
It seems like it’s time to pick up the camera and start a detailed photo shoot of all the intricacies of the process, otherwise the Internet has run out of pictures that would ideally suit my description.
Each of the 3D printers has its own design features. The main thing in such devices is, it is also called the print head. The role of the head in the operation of the printer is extremely simple. Its role is to extrude plastic through a nozzle, as a result of which a pattern is formed in a three-dimensional format. A natural question arises: is it possible to do it yourself?
What are the features of these devices?
When a printer operates using 3D technology, a filament type is usually used. He is different types, but for such printers they mainly use PLA or ABS. But, big choice The source material has little effect on the design of the print head; as a rule, they are manufactured by different manufacturers according to a similar type. This is the extruder design of a modern 3D printer that goes on sale:
- Cool-end is a filament supply unit. Its design necessarily contains several gears and an electric motor. The plastic thread from the corresponding spool is removed from the process of rotation of the gears, then it passes through the heating element, where the plastic is exposed to high temperature and it becomes soft. This allows this viscous plastic to be squeezed out using a nozzle and given the necessary shape.
- Another hot-end block is a nozzle with its own heating element. Aluminum or brass alloys are used in its manufacture. This block is very high heat conductivity. The heating component contains a wire helix, two resistors, and a thermocouple to regulate the heating temperature of the device. During operation, the hot-end heats up and thereby undergoes the process of melting the plastic. Very important point The operation of both blocks is to cool the working platforms. This is ensured by a special thermal insulating insert between the blocks.
Is it possible to make a homemade extruder for a 3D printer?
If you decide to make your own extruder for a 3D printer, you need to choose a motor. But, it is also possible to use old motors from a printer or scanner (working, of course). If you are not sure which motor a homemade extruder for a 3D printer will work best with, a forum with experts in this field will help you figure it out. To secure the engine, you need a housing made of suitable material, hot end, as well as a roller - its function is pressing. To make the body itself, different materials can be used, as well as its shape, you can make it at your discretion. To adjust the pressure roller, it is necessary to use a spring, since the thickness of the rod does not necessarily perfectly meet the requirements. The material must adhere to the feed component. But it also cannot be made tight, since in this case plastic particles may break off during the printing process.
You can purchase a hot end, although this is not the cheapest purchase, in which case a homemade extruder for a 3D printer will be a good investment. Although you can find and study its drawings and make it yourself. So, radiators are made from aluminum alloy; it is necessary for removing warm air from the barrel of the device. Then you can easily avoid excessive overheating of the device during printing. It is very practical to use an LED radiator, and cool it with a fan. A hollow metal tube is used to create the hot end barrel. It connects the radiator to the heating element.
To independently design a heating element in a 3D extruder, select a plate from aluminum alloys. Drill a hole in this plate to secure the hot end. Then holes are drilled for the mounting bolts, resistor and thermistor. The resistor heats the plate, and the thermistor regulates exactly this heating temperature. To create a nozzle, as a rule, a nut with a rounded end is used. The easiest way to process a nut is made of brass or copper alloy. The bolt is secured with a vice, after which you screw a nut onto it and drill a hole in the center. This is a way to create an extruder at home or in the field without too much trouble.
For some models of such printers, the equipment includes two extruders, which makes it possible to print images in two colors or create structures from a soluble polymer. But, if you managed to make one extruder for a 3D printer with your own hands, then making a double one will also be possible.
Currently the most affordable price for plastic filament for 3D printers is more than $20 per 1 kg; the cost of filament from reliable manufacturers or with any special characteristics (color, additives) reaches $50.
Thus, when printing 3D models, reducing material consumption and its cost becomes key factors increasing the efficiency and, accordingly, profitability of 3D printing.
Liman extruder
The first public step towards this was the open source invention announced in March 2013 - an extruder for self-creation plastic filament for 3D printers. Inventor Hugh Lyman entered his machine into the competition and won the top prize from the Kauffman Foundation and Maker Faire. One of the main conditions of the competition was the price of the device - no more than $250. The winning extruder allows you to extrude a filament with a diameter of 1.75 or 3 mm with an error of 0.01 mm, and this was already the second version of the presented device, the first one did not pass the price. Lyman's invention is open source, allowing anyone to use and build on it.
Using a homemade extruder, you can save up to 80%. High-quality filament costs about $50 per 1 kg, while buying a kilogram of granules will cost only $10. And if you buy a 25 kg package of granules, then each kilogram will cost only $5.
Fisher extruder
Inspired by Lyman's extruder, Ben Fischler of San Diego, California, decided to try creating an easy-to-use version for users. STRUdittle is an ultra-compact device and can make filaments from ABS plastic with an extrusion speed of 30-60 cm per minute.
The extruder accuracy is quite high:
- Error 0.05 mm with free filament output;
- The error is 0.03 mm when using a reel that automatically winds the finished thread.
Fischler's project launched on Kickstarter in order to make this product available to the masses. Required funds have already been assembled, and the complete device is offered to participants with funding of $385. Moreover, in addition to the complete set, those who already have a similar extruder are also offered separately only a mechanism for automatic filament winding for $100. And the device itself is supplied with nozzle sizes at the customer’s choice, including without it at all - for the production of materials of non-standard sizes.
How to assemble a Mosaic printer from a set of parts from MakerGear is described in the article Assembling a 3D printer with your own hands. You probably noticed that the structure of a 3D printer is discussed in detail there, but not we're talking about about the print head. This is the topic of today's conversation.
We will look at the types of extruders and methods of manufacturing individual parts of this complex mechanism in order to understand how to make an extruder with your own hands (video about drilling a nozzle at the end of the article).
The print head of a 3-D printer pulls a rod of plastic, heats it up and pushes the hot mass through the nozzles.
Wade extruder
The picture shows a simplified diagram of a Wade type extruder. The device consists of two parts. At the top there is a cold-end (cold end) - a mechanism that feeds plastic, at the bottom - a hot-end (hot end), where the material is heated and squeezed out through the nozzle.
Bowden extruder
There is another design of the device, where the cold and hot parts are separated, and the plastic enters the hot-end through a Teflon tube. This model, where the cold end is rigidly fixed to the printer frame, is called Bowden extruder.
Its undoubted advantages include the following:
- the material does not melt prematurely and does not clog the mechanism;
- The print head is significantly lighter, which allows for increased printing speed.
However, there are also disadvantages. A plastic thread over such a long distance can become twisted and even tangled. The solution to this problem can be to increase the power of the cold engine.
Cold end
E3D-v6 assembled
The filament rod is pushed down by a gear driven by an electric motor with a gearbox. The feed wheel is rigidly mounted on the motor shaft, while the pressure roller is not fixedly fixed, but is in a floating position and, thanks to a spring, can move. This design allows the plastic threads not to get stuck if the diameter of the rod in certain areas deviates from the specified size.
Hot-end
The plastic enters the bottom of the extruder through a metal tube. This is where the material is heated and flows out in liquid form through the nozzle. The heater is a spiral of nichrome wire, or a plate and one or two resistors, the temperature is controlled by a sensor. The upper part of the mechanism should prevent the filament from heating up early and not allow heat to escape upward. Heat-resistant plastic or a radiator is used as insulation.
Feeder
First of all, you need to choose a stepper motor. It is best to buy an analogue of Nema17, but motors from old printers or scanners, which are sold very cheaply on radio markets, are also quite suitable. For our purpose, we need a bipolar motor with 4 terminals. Actually, you can also use unipolar, its diagram is shown in the figure. In this case, the yellow and white wires will simply remain unused and can be cut off.
As a rule, printer motors are weak, but the EM-257 (Epson), as in the figure below, with a shaft torque of 3.2 kg/cm, is quite suitable if you are going to use Ø 1.75 mm filament.
For a rod Ø 3 mm, or with a weaker engine, you will also need a gearbox. It can also be selected from disassembled old tools, for example, a planetary gearbox from a screwdriver.
The modification will be needed to fit the screwdriver motor gear onto the stepper and align the motor’s rotation axis with the gearbox. And the cover for the output shaft bearing also needs to be made. A gear is installed on the output axis, which will feed the plastic rod into the heating zone.
The extruder housing serves to mount the motor, pressure roller and hotend. One of the options is shown in the figure, where the red filament rod is clearly visible through the transparent wall.
The body can be made from different materials, come up with your own design, or, taking a ready-made kit as a sample, order printing on a 3-D printer.
The main thing is that the pressure roller is adjusted by a spring, since the thickness of the rod is not always ideal. The adhesion of the material to the feeding mechanism should not be too strong to avoid pieces of plastic breaking off, but sufficient to push the filament into the hot-end.
It should be noted that when printing with nylon, it is better to use a feed gear with sharp teeth, otherwise it simply will not be able to engage the rod and will slip.
All metal hotend
Hotends from E3D are widespread and popular. You can buy it on ebay.com for $92 (without delivery) or download the drawings that are freely available on the company’s official website (http://e3d-online.com/), according to which you can do it, saving a lot.
The heatsink is made of aluminum and serves to remove heat from the hotend barrel and prevent premature heating of the print material. An LED radiator is quite suitable; to enhance the cooling effect, you can also direct a small fan to it.
The hotend barrel is a hollow metal tube connecting the radiator and the heating element. Made from of stainless steel due to its low thermal conductivity.
This is what the part looks like in cross-section and with dimensions for a rod Ø 1.75 mm.
The thin part of the tube acts as a thermal barrier and prevents heat from spreading to the top of the extruder. It is important that the filament does not begin to melt prematurely, because in this case the rod will have to push too much viscous mass. As a result, the friction force increases and the tube and nozzle become clogged.
If you drilled the part yourself, you will need to polish the barrel hole. Fine sanding is suitable for rough sanding. sandpaper“zero”, secured with tape to a drill of a smaller diameter.
Finish polishing is required mirror shine(thread and GOI paste No. 1), then it is useful to fry the hole sunflower oil to reduce friction force. To prevent the plastic from heating up too early, you can coat the bottom of the tube located in the radiator with thin layer thermal paste.
Another one possible problem: Molten plastic under the pressure of the incoming rod may seep up and cool in the cooling zone, causing the barrel to clog and stop printing. You can combat this with the help of a Teflon insulating tube, which is inserted into the hotend barrel before the filament begins to heat up.
Heater
Heater plate
As heating element An aluminum plate is used. If you are unable to find a thick block of suitable size, a 4 mm thick aluminum strip, which can be purchased at building materials stores, is quite suitable. In this case, the heating element will consist of two parts. It is necessary to drill a central hole for the hotend barrel, tighten it with a bolt, and clamp the entire structure in a vice. Then drill the required number of holes for the component elements of the heater:
- fastening bolt,
- two resistors,
- thermistor.
To heat the plate, you can use a 12v ceramic heater or a 5 Ohm resistor. But for our block, two 10 ohm resistors are better suited, since they are much smaller in size, and a parallel connection will give the required resistance of 5–6 ohms.
The temperature will be controlled by a 100 kOhm NTS thermistor brand B57560G104F, with a maximum operating temperature of 300 °C. Thermistors with lower resistance cannot be used; they, as a rule, have a large error at high temperatures.
It is necessary to ensure a tight connection of the resistors to the plate, since the air gap inhibits heating. It is important to choose the right sealant here. It is best to use ceramic-polymer pastes (CPPT), whose operating temperature is at least 250 °C. For additional thermal insulation, it’s a good idea to wrap the entire hot-end with fiberglass.
Nozzle
A blind nut with a rounded end is ideal for making a nozzle. It is better to take a part made of copper or brass, since these metals are relatively easy to process. You need to secure the bolt in a vice, screw the nut onto it and drill a hole in the center of the rounding required diameter.
This can be done this way: on a drill clamped in a regular drill, secure collet with a drill of the required diameter. It turns out to be an interesting design.
A hole of 0.4 mm is considered the most successful, since with a smaller diameter the speed slows down, and with a larger diameter the print quality suffers.
Here is another way to drill a nozzle (video in English).
As you can see, making an extruder for a 3-D printer with your own hands is quite difficult. But if you know that you won’t be able to make some part yourself due to lack of necessary materials or tools, it is not necessary to purchase a complete ready-made kit; you can buy any part of the extruder separately and continue working.
Have fun typing.
Each 3D printer has design features. Main role In any device there is a 3D extruder, the second name of which is the print head. The essence of her work is simple: she squeezes plastic through a special nozzle, which is how a three-dimensional pattern is formed.
Design Features
The 3D printer uses several types of filament plastic, but the most commonly used are ABS and PLA plastics. And despite the diversity Supplies, all print heads are created according to the same principle and differ little from each other. 3D printer extruder device following:
- Cool-end block supplies filament. It includes gears and an electric motor drive, as well as a clamping mechanism. Under the influence of gear rotation, a plastic thread is removed from the spool, passed into the heater, where, under the influence high temperature the plastic becomes viscous. This structure makes it possible to squeeze the thread through the nozzle to give it the desired shape.
- Hot-end block is a nozzle with a heater. To create it, brass or aluminum are used, which have high thermal conductivity. The heating element also includes a spiral of nichrome wire, a pair of resistors, and thermocouples that regulate the temperature. During operation, the hot-end heats up, due to which the plastic melts. An important role is played by timely cooling of the working platform, which is ensured by a special thermal insulating insert between the hot-end and cool-end.
A type of print head is a Bowden extruder, which is distinguished by the fact that the hot-end and cool-end are separated in terms of location: the heater with a nozzle is located on the industrial machine that prints the hollow printer, while the feeder is located on the printer frame. The plastic thread is fed through a long Teflon tube. Its main purpose is to protect the thread from possible bends so that it is fed into the hot-end optimal speed and pressure. The Bowden extruder is good because it allows you to make a smaller and lighter print head, but on the other hand, the transfer of plastic to the nozzle is not so reliable.
How to choose an extruder?
An extruder for a 3D printer needs to be chosen correctly, taking into account several important points:
- Material. modern print heads are equipped with cast elements or created based on 3D printing. Of course, cast modifications are durable, which is especially important for areas that bear heavy loads. On the other hand, 3D printed parts are much cheaper.
- Filament supply. The quality of this mechanism plays an important role, since the filament must be fed to the heater constantly and accurately. This is the only way to ensure trouble-free printing. The plastic may get tangled on its way to the nozzle, so you need to choose printers with electric motor high power - this way entanglements can be kept to a minimum.
- Feed roller type. Very often, as a result of poor adhesion of the material to the feed roller, the thread begins to slip. Such situations arise especially often when using nylon thread on devices where only ABS or PLA plastic can be used.
- Nozzle size. The extruder can be equipped with nozzles different diameters. The purpose of the products themselves plays an important role in the selection. For example, if objects must be drawn carefully and in detail, then the nozzle is selected with a smaller diameter. The smaller the nozzle, the higher the likelihood of it becoming clogged, so the best extrusion of plastic is ensured by a powerful electric motor.
How to make it yourself
To make an extruder for a 3D printer with your own hands, you will need to select a stepper motor. However, motors from old scanners or printers can also be used in this capacity. To mount the engine you will need a housing, a pressure roller and a hot end. The body is made from different materials, and its design can be very different. The pinch roller must be adjusted by a spring, since the thickness of the bar is not always ideal. The material adheres to the feed mechanism, but the grip should not be too strong, otherwise pieces of plastic will break off.
You can buy a hot end (the purchase will cost about $100), or you can download the plans and create it yourself. The radiator is made of aluminum and is needed in order to remove heat from the hot-end barrel. This will prevent the print media from heating up prematurely. Good decision – led radiator, and cooling is carried out using a fan. The hot-end barrel is created from a hollow metal tube, which serves to connect the radiator and the heating element.
The thin part of the tube is a thermal barrier that prevents heat from entering the top of the extruder. The main thing in the hot end is to ensure that the filament does not melt prematurely, which will lead to clogging of the nozzle.
The heating element in a 3D extruder is created with your own hands from an aluminum plate. A hole is drilled in it for attaching the hot-end barrel, then more holes are drilled for the fastening bolt, resistors, and thermistor. The plate is heated by a resistor, and the task of the themistor is to regulate the operating temperature. The nozzle can be created from a blind nut with a rounded end. It is better if the nut is brass or copper - these metals are easy to process. A bolt is fastened in a vice, then a nut is screwed onto it, and a hole is drilled in the center. Thus, it is easy to create an extruder at home.
Some printer models are equipped with dual extruders - this allows you to print two-color objects or create support structures from soluble polymer. That is, two types of plastic can be used simultaneously on such a device. True, simultaneous printing is still impossible, so each extruder is used if necessary.
