darmach's blog

tech junkie

When The Frame happened.

frame3

So – finally all the frame parts arrived: aluminum extrusions, T-nuts, and I bought locally some M6 hex screws. After a little bit of screwing:

Hobbed bold hobbing

The result

One more thing I need for the extruder is the hobbed bolt. Somewhere on the internetz I’ve found an opinion (I don’t really remember where..) that hobbed bolt which teeth are cut from the threaded part of the M8 screw have even better grip than tapped one. So I got few M8 fully threaded screws, and constructed a tool for hobbing. It uses dremel flexible hose, and those thin cutting disks – 0,6 mm disks allow for a finer teeth to be cut.

Rotating disc that holds the screw have 20 holes – which are a match for a 6mm ball pushed against it by a spring. This way I could measure each step I’m cutting. And here is the final result – isn’t she a beauty?!

The result

The result

I also made a video while hobbing – a little bit shaky, but it’s hard to hold camera with one hand while cutting… …probably will have to get some stand in the future.

New toys arrived: Infill3D extruder!

extruder1

Today I’ve received printed parts for extruder – I’m making extruder designed by Infill3D, you can check it out on thingiverse. Aside from the design being very pretty – parts are amazing! Printed on industry class SLS – are actually so precise, I had problems with removing the bearings after taking pictures. I must admit I’m tempted to paint it red, as Infill’s renders on thingiverse.

Extruding quality: Bowden or Wade?

filament

I can not decide which extruder to build: Bowden or Wade. I am aware that both have their pros and cons, Wade being simpler but heavier, while Bowden allows for lighter X carriage but due to long PTFE tubing is more prone to oozing. I asked around, and got very mixed replies to that question, for Example Nutz95 uses Bowden, while Courious advised me to use Wade.

My main concern is quality, I don’t care much for the speed.

Also – which filament version to make? 3mm or 1.75 mm?

And because it’s hard to reach conclusive data, I’ve decided to create this poll.

For best print quality - Bowden or Wade?

View Results

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Final frame design

render6I think I’ve finished with frame design for now. I added few more elements from Nutz95 printer, I have remodeled Z axis stepper motors (thinner side walls) to allow them to be mounted upside down and mirrored – as I hope it will allow me to lower Y carriage more, therefore making whole frame height lower.

3D models

I’ve found a nice way to embed 3D models on the website. You can check it out by clicking on ‘Read more’ on the bottom of the post.

Whole_MK2_With_hot_end-2_preview_featured

By the way, this here is work of Infill3D, found here on thingiverse. I admire creations of this guy, first one to make not only functional parts, but pretty aswell. I think I will add his extruder to my setup, we’ll see how it goes:

You can check more here on thingiverse.

Read More

Chinese copy of E3D hotend

HotEnd6

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.

HotEnd4

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!