darmach's blog

tech junkie

Chinese copy of E3D hotend


Today I’ve received another part of the puzzle – the hotend. It’s a chinese clone of what I believe is called an E3D Hotend. It was one of the first parts I’ve ordered, I’m afraid I bought a wrong one, but I’ll write about it later.

Build looks quite nice to me – maybe pieces aren’t ideally clean, but everything seem to be in order. Parts fit nicely, inside hollow screw is made from stainless steel, drilled to 4 mm ID, and a teflon (PTFE) tube fills the inside. It’s supposed to allow frictionless moving of the filament inside the tube – and isolate ‘fresh’ filament from the nozzle heat before it gets inside the nozzle.


Steppers arrived!

17HS4401 stepper motor

After 2 weeks of waiting, stepper motors arrived. I have chosen NEMA17 7HS4401 stepper motors, here are these pretties:

And the specs are:

Model Step Angle Motor Length Rated Current Phase Resistance Phase Inductance Holding Torque Detent Torque Rotor Inertia
(deg) (mm) (A) (Ohm) (mH) (N.cm) (N.cm) (g.cm2)
17HS4401 1.8 40 1.7 1.5 2.8 40 2.2 54

I can’t wait to power them up, but drivers didn’t arrive yet. Official RepRap wiki article about stepper motors claims that 13.7 N·cm torque should be enough, but just to be safe I decided to go with 40 N·cm. I hope they will deliver .)

Let’s get started with the design

I decided to give AutoCAD trial a chance, and start drawing a frame for my printer. It will be based on Wolfy1.1 and Nutz95 design.

I had some previous experience with 3D modelling, mostly using 3DSMax, but modelling in AutoCAD turned out to be a lot of pain. It seem 3DS Max was (waaaayyy!) more intuitive when comes to viewport navigation, or working with edges/planes/vertices.

On the other side I was able to find many 3D models for autocad  of aluminum extrusion profiles on the internet, among them extrusion 30x30x8mm which I’m going to use .)

After some time (I’m too ashamed how long it took to say it ,)) I managed to draw first few elements of the frame, and imported Y carriage bar holders from Nutz’s Prusa i3 rework.

First frame design - wireframe

Wireframe view

First frame design - render

First render

The perplexities…

Oh my god, there is so many solutions when it comes to details of 3d printing. Almost every module of the printer can be designed in many ways, some possibly better, other maybe worse…

It’s hard to make any choices, i feel that a lot of research into the topic will be necessary.

I have visited RepRap irc channel at freenode, guys in there answered many of my (probably annoying) questions, leaving me in even greater perplexity ^__^

Bowden or Wade? 1.75mm vs 3mm? Which stepper motors to choose?

Many thanks to a chap with nick Courious, he was very patient .) and it turned out we live in same country!

The beginning

Inspired by some youtube videos I decided to make my own 3d printer. I’ve decided to go with RepRap because of few reasons, big community support being one of them.

While browsing RepRap wiki I stumbled upon some chinese guy design, and I liked it immediately. It was called Wolfy 1.1 and looked way more sturdy than typical Prusa i3.

Source: http://reprap.org/wiki/Wolfy1.1

Aluminium extrusion frame looks very rigid, which might help to achieve good print quality. A pity whole page is in chinese…