Test bench for some technical solutions for a 3D printer

Actually, I decided to write the article not so much for the sake of demonstrating the possibilities, but rather as a source of some technical solutions, possibly interesting to the community. Yes, this is not a full-fledged review of the device, but, as it is written, an announcement of a future review. But then I will finish the project 🙂

So what do we have. A year and a half ago I got a piece for free … Um … Well, that is, the Wanhao i3plus 3D printer. I must say I chose this device myself, and I chose not for those. characteristics (let’s be frank, all devices of this price range have, to put it mildly, so-so), but I was attracted by the color touchscreen display from the company DWIN, or rather the operating system on which it is built. Well, customization there and all that … Come on, who am I kidding, of course, fell for the whistle deals.

In general, I played around for a couple of months. I made a heat chamber for him, in the photo below

I drew my firmware for the display:

I played a little more. And killed the analog inputs of the controller, to which the resistive touch panel is connected. The printer itself works, the display shows, but the sensor is dead. Well, okay, you can send it to print from your computer. Well, in this way, I scored on the device until better times.

The best times came a month ago and I decided to upgrade it a little and I got carried away. Only the filament feeding motor, a couple of carriages, belts, and screws with dowels remained from the former device, the rest is completely new. However, the project has not yet been completed, but I want to share some interesting solutions.

First, a few words about the device itself. Cartesian system Z table, XY extruder. Along the Y-axis, the X-axis moves two motors connected in parallel. The X-axis motor is mounted on the extruder. I understand that this is bad for the weight of the latter, but, oddly enough, I need a heavy extruder, more on that later. A couple of pictures of the site:

It is assembled from aluminum profiles of all possible types and sizes, tongue screws, 8mm cylindrical guides, blue electrical tape and cat hair. It has a closed, heated chamber with an inner aluminum box and outer PVC. The plastic spool is hidden in a pull-out tray under the camera. The tray is equipped with its own microclimate system, more on this below. Electronics 32bit MKS Sbase 1.3 + MKS TFT 7.0 Display. Actually myself display such:

A 7-inch fool with a resolution of 800×480. The choice of such a display is due to the fact that it is built on a standard ssd1963 chip that is controlled by an STM32F407 over a standard DMA bus. In short, I can download my firmware to it without any problems, which is what I need. And in general he is credited. By the way, a funny story is connected with him. So he came to me, I unpacked it so beautifully, went nuts from the size, turned it on, went nuts again, climbed into the Wi-Fi settings (the whistle is standard ESP8266, it is stuck in the back as standard) and … nothing works. It took two days, it turned out that the metal frame of the display scratched the protective mask of the board and shorted it with its ground to the reset pin of the Wi-Fi. Blatant handcrafted by the manufacturer! Okay, let’s move on. The extruder feed clamp was taken by the notorious MK8

Well, it really had to be completely reworked, but I won’t go into details. I implement the autoleveler of the table on a piezo under the table. It is triggered on a ‘knock’ with a pip on the table. Everything is standard here: piezo – operational amplifier with frequency filters – operational amplifier in comparator mode – pin on the board for autolevel. Whatever triggered the ‘knock’ of the solidified plastic sticking out of the pipette, the extruder first heats up to operating temperature, then wipes the nozzle on the felt and silicone barrier. Also standard. So that it doesn’t get completely boring, I’ll throw a couple of photos of the frame:

I bought these curtains in a shop near the metro … What am I talking about … Oh, yes. Then I selected the internal volume of the print area and sewed it up with 1.5mm duralumin sheets. How I hesitated to cut this light. First, with a paper knife, on both sides, he left deep grooves on the sheet, then he was bent there-court until a crack appeared, along which I moved until the sheet broke completely. I know about the existence of a jigsaw, but a jigsaw does not know about the existence of straight lines, and scissors twist the metal into the steering wheel. In short, a paper knife, steel ruler and a couple of cut fingers give an effect comparable only to laser cutting. Arcs are really tricky. In short, I sheathed the camera and bungled uh … I don’t even know what it’s called. In general, a thing that heats the air inside the chamber to a certain temperature and drives it along a closed circuit. A kind of air heater. Actually, the photo of the camera itself:

Two holes are visible at the end of the chamber. This is the outline. In one hole the air is sucked in from the other comes out already heated. Here’s a bigger one:

A powerful server fan is installed in the right hole for suction. I installed a nichrome heater inside. I wanted to buy a ready-made one, but within a radius of 50 meters from the house I could not find a suitable one in terms of parameters, I had to go to Chip and Deep for a piece of mica and nichrome wire. I assembled a roughly similar structure and shoved it inside the contour:

I will try to post the original photo in the full review after the end of construction. In the meantime, the outline itself is below in the photo:

This oblong box contains a heater and a fan. A piece of the protective grill is visible on the left. In the middle is the Z-axis motor. If anything, this is a photo of the bottom rear of the printer. A pull-out tray for a plastic reel is also installed below. The tray is needed not just for convenience, I already wrote above that a microclimate suitable for storing plastic is created in it. Everyone knows the problem of hygroscopicity of plastic. Usually, it is fought with sealed silica gel bags and this is a normal solution. I haven’t “invented” a tremokamer for my Wanhao yet, I have always used the following method – I didn’t completely break the bag with a coil of plastic, but made a small hole through which I pushed the end of the plastic. Something like a similar design protected the coil. But what if I have my mom’s hands and the plastic is already wet. Normal guys fry it in ovens, dryers and other devices like them. Output? Output! Thus, I made the tray airtight, inserted a slightly modified thermal device from the heat chamber into it, stuck in the thermal moisture sensor and cut a container with silica gel into the circuit. The algorithm of work is as follows: Open the tray – insert a spool of plastic – load plastic (semi-automatic – more on that below) – close the tray. Automation detects the fact of replacing the coil and, if the tray is closed, cold air begins to drive inside. If the plastic is wet, the sensor will detect this and turn on the heater. The heated air passes through a silica gel filter. All this crap works until the humidity reaches the set values. The procedure can be performed manually from the menu. About semi-automatic loading of plastic. I haven’t decided yet. In the first version, I had an additional plastic feed motor installed directly in the tray. That is, it was enough to push the end of the plastic into the receiving hole, as the motor immediately picked it up. But in this case, it is not a fact that there will be enough space. Okay, enough text, here is a photo of the non-sheathed frame of the tray:

In the front of the tray, a heating circuit is visible – the flow, as it were, continuously envelops the coil. In the middle of the circuit is a compartment for a silica gel filter. Then a disc under the spool will be installed on the thrust bearing. In general, I propose that this feature be adopted by the community. Now another feature. In the heat chamber itself, the temperature can be quite high; engines will not like this, of course. This means that the engines must be taken out of the heat chamber. Extruder including. I implemented this in such a way, as you can see in the photo:

These are aluminum plates with cutouts of different sizes, laid on top of each other in a special way. This design allows the head to move along two axes without disturbing the internal microclimate. This is how it looks from above:

In the center, the extruder without kinematics lies on square sheets of aluminum. Yes, it’s aluminum. Yes, I see the text. No, I have not read what is written there. Because these are sheets from printing apparatus… I bought it from Do It Yourself. No, not expensive 🙂

In fact, it is not enough to simply place everything as in the photo above, it is also necessary to tie the corresponding corners of all sheets with an elastic band or a spring, then the sheets will not rotate and their movement will be linear. In the photo below, next to the heater block, a hole is visible in the aluminum sheet:

This is for blowing off the part. Here I took a not quite standard approach. Time will show the correctness / incorrectness of such a decision, but for now I will describe the very essence. Perhaps someone noticed that a water block is installed on the extruder and not a regular cooling fan. Well, that is, the use of water cooling is implied. The point is not at all that I’m going to load aluminum wire into the extruder and I need a cooler and more powerful one. Not. The task is to try to cool the long bridges and the first layer of the part on the support of SOUL cold air. Bridges that would not bend. The first layers do not stick to the support. VERY cold air (relatively of course) I will receive with the help of a Peltier element, which does not so much cool as it creates a temperature difference on opposite sides of the element. Accordingly, in order to get a VERY cold first surface, it would be necessary to thoroughly cool the second surface, for which I use water cooling. And again the pictures:

From left to right, layer by layer: water block, Pelte element, homemade radiator, MK8 feed mechanism, bracket, feed motor.

From right to left in layers: water block, Pelte element, homemade radiator, MK8 feed mechanism, bracket, feed motor.

The crap I ran into when making all this crap was that I couldn’t find a suitable radiator. I had to work on a collective farm from an aluminum profile. But the worst thing is that it had to be not only cut into the desired size, but also soldered. Aluminum. Solder. Soldering iron. So I went to look for fluxes and solders for aluminum. I actually bought a bunch of everything. Three liquid fluxes, two of some kind of powder, and two solders with cadmium (In general, I am the type of person who perceives warnings about danger something like this: “Hmm. It says here that if I look at this powder, then I have the ass will fall off, then the horns will grow and in 12 seconds the inevitable death of the brain will come. Well, I convinced you, I will not add it to the salad. “What would you understand, when I make boards, I degrease them, of course, in alkali. nothing will happen to them in ten seconds of rinsing your palms in alkali. But alkali is a slippery thing, so then I neutralize it by dipping my hands into acid after alkali. is still alive, but if you suddenly solder the luminka with cadmium solder, do it ALWAYS under the hood!) In short, it didn’t work … If you don’t want to head on, we’ll go the tricky way. I made a galvanized bath, re-energized the vitriol with electrolyte for batteries, dabbed at my mother from non-ferrous metal extension cords, connected it all to a charger from a mobile phone and deposited a layer of copper on aluminum parts. Now you can solder. I got this beauty as a result:

It can be seen that he did strengthen the corners with cogs-tongues, but the middle radiator is soldered together.

There is still a lot of work to be done. It is necessary to collect all the individual elements and mechanisms into a single device, place the electronics, conduct an electrician, sheathe the tray, attach the door (by the way, it slides up on the guides, the screen is also placed on it) and the whole thing is sewn up with an external casing. The current work on the printer killed 3 months of time, a couple of fingers on my hands and a jigsaw. As I wrote above, here we are not talking about boasting: “Look what a cool fat I did”, but first of all I wanted to talk about the applied technical solutions. The experience of using a closed heat chamber unequivocally speaks in a positive direction regarding the printing of ABS and other plastics that shrink. As for blowing SOUCH cold air, fine adjustments are still needed.

Well, that’s all for now. Thank you all and I hope someone will be interested in the ideas from the project.

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