Hobbed Bolts

Here's the bolt I've been using in my latest round of experiments:

Home-made Bolt
Home-made Bolt

As you can see, the teeth are crudely effective. This bolt was made with a hand-held cordless drill and an M6 tap, and it shows! Also, due to the short shank, I had to insert them backwards, with the nylock in my wade's gear and the bolt head on the back- a less than ideal arrangement. If I had a lathe I could perhaps have cut the teeth straight into the threads, but that's almost impossible with a hand drill.

Auzze generously decided to send me a preview of some hobbed bolts he's going to sell via his online shop (still under construction), pictured below:

Auzze's Bolt
Auzze's Bolt

I think these will be far more effective, and at the very least more uniform! Unlike my dishevelled creation, these actually have a groove for the filament to ride in. The position of the hob is slightly different to mine, but some washer swapping had it lined up perfectly

Between Auzze, GregFrost and the various RUGs, it looks like Australia is really starting to get its reprap on!

Experimental MakerGear Hot End

The amazing and lovely folk at MakerGear sent me an experimental 1.75mm barrel (2mm bore) for my experiments with nylon.

WARNING: when heated, nylon can emit hydrogen cyanide, a gas that's deadly even in low concentrations. osha.gov lists MAXIMUM EXPOSURE to a mere 10ppm over 8 hours! Nylon also emits a number of other noxious gases such as Carbon Monoxide. Please see a MSDS before switching your printer to nylon, and install adequate ventilation!

Having said that, this barrel should work beautifully for anyone needing higher temperatures to print at speed, or experiencing jamming issues. Read on!

Experimental SS Barrel

It's stainless steel, which has 7.5x lower thermal conductivity than brass. The notch in the middle is a thermal break, to give us a very short thermal transition from <T_glass to >T_melt, which should help massively with the jamming I've been experiencing with the regular brass barrel conducting heat far up into the insulator, as well as my hot-end having difficult achieving target temperature.

I have also added some felt insulation to my heater to help it reach target temperatures of 260°C and above:

With Insulated Heater

Even with this excellent barrel material and carefully cut thermal break, we can help sharpen the thermal transition even more by adding a heatsink just above the break.

Heatsink All put together

And does it work?

New Possibilities

So far my experiments have simply been pushing some filament through, then leaving it for a while, coming back and pushing more through. This was impossible with the brass barrel, the heat travelling up would cause the nylon to swell, and jam in the barrel without melting. With some wider testing, this barrel could be a contender for the title of "jam-proof"!

Here I am holding the heatsink while the nozzle is at 260°C! That's over 200°C dropped across a distance of about 2.5mm!

Thermal Break Is Effective

My only complaint is that it's not long enough at the top- there's no room between mounting plate and heatsink for M4 nuts, let alone a carriage. Rick informs me that they will be made longer before appearing in the shop.

As soon as my new X carriage (with room for the heatsink) arrives, I could be printing!

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Update: After almost exactly an hour, the felt turned black and started smoking. Apparently it's great at 110°C but can't take 260°C, or maybe my felt isn't pure wool felt. I may just keep heating it until it's all carbonised and see if it settles down or falls apart.

PCB Heated Bed

Overview Thermistor

Here's my homegrown heated bed. I decided to make my own because prusa's needed a bigger board than I had available.

Resistance measures at 0.9 ohms although my multimeter isn't exactly accurate with stuff like that. Eagle's length-freq-ri ULP also pegs resistance at about 0.9 ohms.

It reaches about 116°C with ambient of 10°C, a felt underlay, and my power supply's 12v rail drooping to about 11.3v despite two 12v 50w lights loading the 5v line.

Here's the eagle BRD file for those interested: Heated Print Bed.brd.

Straightening my wade's idler

Just need to add a proper surface now, and see how it goes!

First Extrusion! Working Axes!

First Extrusion! Very Exciting!

I haven't posted in a while, been waiting for parts, money, ideas to come. Over the past couple of weeks I've made significant progress though. As you can see below, my printer is no longer all wood, and so this blog is probably now rather poorly named, however I'll keep it here until I can think of a better name.

Here's the current state of my frankenprinter:

Output Side
Top View
Electronics
Z Belt Tensioner

All the axes are working, if a shade stiff. Now I need to construct a bed somehow, and I can get printing!

I have bought a piece of blank PCB which I'll etch a heater pattern onto. Here's my current design:

Heater Pattern
Please comment if you think this won't work, or will work well!

Big thanks to Mark Lagana and Greg Frost for printed parts, MrAlvin for the mega (and a ramps board not pictured- I'll use it when I get around to removing my pololus from my current board, or have to replace them), and MakerGear for a lovely hot-end

FiveD on Arduino Firmware: First confirmed print with photo!

First confirmed print

FiveD on Arduino firmware reached an important milestone today- first confirmed print with photo, reported by Markus Amsler here in the forums.

Big thanks to Jake Poznanski, Markus Amsler, Markus Hitter and Stephen Walter who have all provided heaps of patches, to those who have provided just a couple of patches to scratch their personal itch, and also to all those who have simply tried this out and reported how they went :)

For those of you just viewing this now, forum, source, wiki and I can occasionally be caught on the reprap IRC channel too.

Re-orienting towards Wooden Prusa Mendel

After a bit of a sabbatical from constructing to concentrate on firmware, I'm now at the point where I need my printer finished to make any more meaningful progress. In that time I have discovered the brilliantly simplified Prusa Mendel remix, which I think will be significantly faster and easier to make from wood. To that end, here's my first print for a long while, the prusa x-end-motor part:


Prusa x-end-motor

FiveD on Arduino - a call for testers

A while back I started work on an alternative firmware, FiveD_on_Arduino [forum thread][source][wiki]. It is designed to fit on an atmega168 (run your whole reprap from the extruder controller!) yet be upwards compatible with other chips (328p, 644p, 1280 so far) and extensible.

This firmware has reached the point where it needs wider testing. You'll need a system that has gnu make, avr-libc, avr-gcc and friends to compile as I have no idea how to wrangle the various IDEs into doing what I want. You'll also need avrdude, or some other way of getting the compiled firmware onto your atmega.

git clone git://github.com/triffid/FiveD_on_Arduino.git
git branch -r
git checkout release-candidate-triffid
cp config.h.dist config.h
### edit config.h and Makefile in your favourite editor ###
make
make program

If you have ideas on how to make this firmware easier to access, please post in the forum thread ("compile and load in my favourite IDE" a given- but what needs to change?). Other ideas and contributions are welcome too :)

Thanks to traumflug for his numerous contributions, jakepoz for gen3 electronics support, and numerous others who helped with suggestions and patches.