add unfinished hidden am8 page

input/projects/3d-printing/i3-am8.md

+title: i3 AM8
+description: Rebuild of my i3 clone with aluminium extrusions, CoreXZ, Klipper
+x-parent: 3d-printing
+x-position: 25
+x-date: 2022-02-01
+x-update: 2022-06-10
+x-comments: true
+---
+
+<!--% backToParent() %-->
+
+In February 2022 I finally decided to re-build my [CTC i3 Pro B](ctc-i3.html) with an upgraded frame and better parts.
+The following are the new integral components:
+
+ * ["AM8 - Metal Frame for Anet A8" by pheneeny](https://www.thingiverse.com/thing:2263216) on Thingiverse
+     * 2040 extrusions and nuts from [Dold Mechatronik](https://www.dold-mechatronik.de/Aluminiumprofil-20x40-I-Typ-Nut-5)
+     * [Core XZ AM8 Conversion by 93djen](https://www.prusaprinters.org/prints/131210-core-xz-anet-am8-conversion) on PrusaPrinters.
+ * [Sherpa Mini Extruder](https://github.com/Annex-Engineering/Sherpa_Mini-Extruder) on GitHub
+     * Sourced from [AliExpress](https://de.aliexpress.com/item/1005003671542821.html?gatewayAdapt=glo2deu&mp=1)
+ * [NF Crazy Hotend](https://3dprintbeginner.com/nf-crazy-hotend-a-mosqutio-hotend-alternative/)
+     * Clone of [Mosquito Hotend](https://www.sliceengineering.com/products/the-mosquito-hotend)
+     * Contact [Mellow Store](https://de.aliexpress.com/store/1531088) on AliExpress to source it
+ * [SKR Mini E3 v3.0 Mainboard](https://github.com/bigtreetech/BIGTREETECH-SKR-mini-E3/tree/master/hardware/BTT%20SKR%20MINI%20E3%20V3.0)
+ * [Fysetc Mini 128x64 LCD panel V2.1](https://wiki.fysetc.com/Mini12864_Panel/)
+     * Cloned version by [BCZAMD on Amazon](https://amzn.to/3MaaJ6T)
+
+Initially I simply wanted to re-use the mechanical parts from my old printer.
+But after talking to my friend [Tobias](https://www.prusaprinters.org/social/199673-93djen/about) about the project, he came up with the idea to convert the AM8 into a CoreXZ machine, and also immediately delivered a complete design!
+We selected the parts based on what I mostly still had lying around.
+
+<!--%
+lightgallery([
+    [ "img/am8_corexz_1.png", "CAD screenshot of whole CoreXZ AM8"],
+    [ "img/am8_corexz_2.png", "CAD screenshot of extruder / hotend"],
+    [ "img/am8_corexz_3.png", "CAD screenshot of XZ gearbox"],
+])
+%-->
+
+Other mechanical / electronical parts, like motors and the heatbed, I re-used from my previous printer.
+
+## Custom 3D-Printed Parts
+
+Mounts for PSUs, MOSFET, Mainboard, Pi, Relais.
+
+TODO links, photos
+
+## Power Supply Wiring
+
+I added two power supplies to the printer.
+One is +5V, solely for powering the Raspberry Pi, and it is always on.
+The other is +24V, for running the printer itself. This is switched by a relais module, connected to the Pi.
+
+I'm not entirely comfortable with the 220V wiring, so I <s>added</s> plan to add an enclosure that should prevent any shock hazards from touching.
+
+<!--%
+lightgallery([
+    [ "img/am8_psu.jpg", "Power supply cabling"],
+])
+%-->
+
+As a small quality-of-life improvement I put a piece of shrink wrap tubing over the indicator LED of the +24V supply.
+I don't understand why the manufacturer decided to put an unbelievably bright blue LED on there... 🤦
+
+In an attempt to avoid any ground loops and power supplies driving each other, I decided not to connect the Pi and the Mainboard using USB.
+Instead I ran a cable between them, only connecting GND and the UART Rx and Tx lines.
+This is the only place where the grounds of the +5V and +24V supply are connected.
+The mainboard is not fed any external +5V.
+
+## LCD Connection
+
+On a whim, I decided to get a [Fysetc 12864](https://wiki.fysetc.com/Mini12864_Panel/) clone.
+Only later I realized that it is not really compatible with my chosen mainboard, as it does not have the standard EXP1/EXP2 connectors.
+Fortunately this can be [fixed easily](https://github.com/VoronDesign/VoronUsers/tree/master/printer_mods/Maverick_/V0_TopHat_Mini_12864), you just need to connect the required pins to free IO pins of the mainboard.
+I decided to ignore the SD card interface, as I won't be using it and the mainboard has one as well.
+So only the LCD and rotary encoder pins are required.
+My LCD board also has some RGB LEDs, so I decided to wire them up as well.
+The other question concerns the cabling.
+The standard 2x 10pin ribbon cables are hard to route and prone to interference.
+Counting the required pins, and looking at my cable stash, I decided to simply use some Cat5 ethernet cabling.
+With 8 cores per cable I only had to use two pieces in parallel.
+
+Configuring it correctly turned out to be a bit tricky.
+Initially I thought I had [hardware revision 1.2](https://github.com/FYSETC/FYSETC-Mini-12864-Panel/blob/master/hardware/V1.2/mini12864%E5%8E%9F%E7%90%86%E5%9B%BE.pdf), based on the reviews on Amazon, with plain RGB LEDs on board.
+But I couldn't get anything to light up, neither around the encoder nor the LCD backlight.
+That's when I took a closer look and saw the WS2811 chips on the LCD PCB (and later also the revision printed on it 😅).
+Turns out I actually have [revision 2.1](https://github.com/FYSETC/FYSETC-Mini-12864-Panel/blob/master/hardware/V2.1/Mini12864%EF%BC%88RGB%EF%BC%89V2.1_sch.pdf).
+
+One thing you should check before using a display like this: the RST and KILL pins and their respective resistors.
+The push button on the front of the LCD panel can be connected to either the RST or KILL pin.
+If you do a custom cabling, like I did, it doesn't really matter which one of these you choose.
+But my display only came with R3 installed, which I didn't notice at first.
+Because I wired up the KILL pin instead of using RST, I would have needed R4 instead of R3.
+I decided to simply switch out the 0Ω-link.
+The other resistor, R1, is also important.
+It should **not** be populated, otherwise the display will feed +5V back to the GPIOs of the MCU, which are only 3.3V tolerant.
+
+<!--%
+lightgallery([
+    [ "img/am8_lcd_rst_kill.png", "Schematic of LCD reset / kill pins"],
+    [ "img/am8_lcd_pre_op.jpg", "Back of LCD, before reset fix" ],
+    [ "img/am8_lcd_post_op.jpg", "Back of LCD, after reset fix" ],
+])
+%-->
+
+To mount the LCD to my frame I used ["Mini 12864 LCD Display Housing for 2020 V-Slot" by derebbe](https://www.printables.com/model/56150-mini-12864-lcd-display-housing-for-2020-v-slot).
+You need to replace the kill button on the panel with a shorter one for this model to work.
+
+<!--%
+lightgallery([
+    [ "img/am8_lcd_front.jpg", "Front of LCD, with new button" ],
+])
+%-->
+
+TODO problems with encoder, kill button pullups?!
+
+TODO photo(s) of cabling
+
+<!--%
+lightgallery([
+    [ "img/am8_lcd_assy.jpg", "LCD mounted on printer" ],
+])
+%-->