ToyREP/fr
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Release status: working
Description | Printer inspired by Prusa i3 Y-frame, CARP Box X and Y axis and Z axis of Printrbot or Wallace. Extruder is based on Wade's Geared Extruder.
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Contents
Introduction
La ToyREP est une imprimante 3D de petite taille et au coût très réduit conçue comme un démonstrateur technologique ou un jouet pour enfant. Le volume d'impression est de 100x100x100mm (125x125x100 avec quelques modifications) elle dispose d'un lit non chauffé en polyacrylate, le hot end est une copie de l'E3D diamètre 1.75mm. Elle utilise des moteurs pas-à-pas très peux cher, les 28BYJ-48 hacké en bipolaire pour tous les axes ainsi que pour l'extrudeur, un Arduino Mega 2560 avec une RAMPS 1.4, des DRV8825. elle est conçu pour être alimenté avec une alimentation pour LED de 40W qui est installé sou le lit. la consommation électrique est de 40w quand elle chauffe et de 15-20W pendant l'impression. la ToyREP à été conçue en juillet 2015.
Dimensions
Les dimensions extérieur de la ToyREP est de 255x245x295mm et un volume d'impression de 100x100x100mm. il existe une version plus grande de 265x265x295 de taille extérieur et un volume d'impression de 125x125x100.
caractéristiques
Cette imprimante est essentiellement conceptuel, conçue pour utiliser des moteurs pas-à-pas 28BYJ-48, pour vérifier la possibilité de les utiliser dans de futures imprimantes 3D. ils sont utilisable dans des démonstrateur technologique d’imprimante 3D à depot de fil ou de jouet ce qui lui vaut son nom de ToyRep toy = jouet, REP=Replicator. actuellement l'imprimante peut ce déplacer entre 10 et 12.5mm/s sur les axes X et Y et 0.25mm/s sur l'axe Z sans problemmes. elle peut éventuellement être poussé à 30mm/s sur les axes X et Y mais cela échauffe les moteurs et peu les endommager.
l'imprimante est créer pour être auto-réplicable, économique, facile à construire, simple à utiliser, avec un faible coût d'utilisation et transportable.
It is sort of a repstrap too, as the vitamins are mostly spare parts or in case of rods, leftovers from my previous projects.
Although it shows very high steps per mm ratios, precision was not a main goal when printer was designed. It is mostly a side effect of 28BYJ-48 (changed to bipolar) with 1/16 or 1/32 microstepping. Such high microstepping is used mostly to make current control less square. Extruder is rather designed for 0.4-0.6mm nozzle, so thicker layers can be used to speed up printing a bit. Theoretically the printer have a resolution up to 1.5um in X, Y axis and 24nm in Z axis but those numbers are only virtual. There is a major deviation caused by the gearbox and threaded rod backslash and melted plastic flow. Still overall performance is may be a bit better than of a common RepRap it the terms of resolution.
Pièces mécanique
Pièce imprimé
la plupart des pièces sont imprimé. certaines pièces sont disponible en plusieurs verions, à vous de choisir en fonction de la configuration voulus.
Liste de pièces:
Les vignettes utilisé sont des images téléchargé depuis thingiverse.
Vous pouvez télécharger les STL sur Thingiverse. à l'heure actuel il existe deux taille de ToyREP. La plus petite avec une alimentation de taille 111x78x36mm et 100x100x100 de volume d'impression et une plus grande avec un alimentation de 129x99x38mm et un volume d'impression de 125x125x100mm. Choisissez les pièces à imprimer en fonction.
Also You can either suspend threaded for Z axis from the top bearings or let all the weight rest on the motors, but you will get less wobble. If you are going to use E3D clone bowden hotend there is actually no bowden extruder for 28BYJ-48 motor. You will have to use some NEMA17 extruder instead.
Vitamins
For complete list of accessories and screws see BoM in ToyREP Buyers Guide.
Electronics
Controller Electronics
Mounting is prepared for Arduino Mega 2560 with RAMPS 1.4.
Stepper Drivers
In above mentioned electronics, Pololu drivers or its clones are used. There are two most common drivers.
- Allegro A4988 based driver - up to 16 microstepping, maximal current 2A, voltage 8-35V.
- Texas Instruments DRV8825 based drivers - up to 32 microstepping, maximal current 2.5A, voltage up to 45V.
Both needs at least passive cooler for longer prints. Although DRV8825 may look like the best choice, very low current (around 100-150mA) required for 28BYJ-48 is harder to achieve.
Stepper Motors
All stepper motors are unipolar 28BYJ-48 5V, 0.15mA?, 0.03Nm with 1:64 reduction gearbox. They are changed to bipolar by a simple hack: http://www.electronicsmayhem.com/?p=13 Be carefull when removing the blue plastic cap, as you can break tiny wires coming from coils to the PCB!
Motor can operate safely at 10-12V when bipolar. After the hack, motor has ca 2048 steps per one revolution of the shaft. This number varies as many available motors do not have exactly 1:64 reduction, but rather 1:63.7 or so. This does not matter because during the calibration the amount of steps per mm will get adjusted.
Motors with 1:64 reduction are strong enough not only for movement in all axis, but even for direct drive extruder. Be careful though because high static load can damage the tiny teeth in gearbox.
The major disadvantage is their shaft turning speed around 15RPM. Although you may hand pick some that are capable of 36RPM, they cannot be used at such "high" speed for too long, as they will overheat and their coils will burn. The motor it self without the gearbox can do 960-2300RPM. Maybe motors with 1:16 reduction gearbox may be a good way to go 4 times quicker, but they will have much lover torque. This yet have to be tested..
Extruder
The printer have a remix of Wade's geared extruder adjusted for E3D clone and 28BYJ-48 motor. The gear ratio is 1:4. Fan holder at the hot end serves also as a extruder mount on X carriage. Hyena M8 hobbed bolt is used to pull the filament. Hotend have 0.4mm nozzle, 12V 40W ceramics heat cartridge and 100K Ohm thermistor. It can be operated as 10V to match motors, only heating will take a bit longer. Be careful when using original E3D, as they have a bit shorter aluminium coldend and may not fit inside this fan mount.
Heated Bed
As I am printing mostly ABS, this printer is using polycarbonate plate 120x120x3mm with mounting holes 105x105mm apart. Printer can also utilize 145x145mm plate with mounting holes 130x130mm apart. With Polycarbonate first layer have to be extruded at very low temperature (ca 205-215°C) so the model can be removed form plate when print is done. You can use your favourite print surface instead.
For hotbed 12V 40W PCB board should be just fine. This is still on the to-do list.