Lix 3D pen teardown

Ok, so not really a teardown, more a why-the-heck-wont-it-feed? kind of taking apart.

As I said in the review, the Lix team have done a remarkable job of squeezing a 3D printer into the barrel of a pen.

Overall, the way the pen is constructed is pretty good. Plastic separators to hold the components in place are tethered together by slim steel rods running the length of the mechanism.

A tiny PCB connects to the buttons and motor by way of a thin ribbon cable, and it looks like power is sent over separate wires. Its neat and quite an engineering feat, but the main issue of feeding filament persists, making it an area of focus.

The filament is drawn through the pen by means of a worm drive. The worm gear itself has a sharp edge to dig into and therefore provide purchase on the incoming filament. The backside of the feed tube at this point has a tiny 'u' shaped piece of plastic which is designed to rest against the inside of the pen barrel and reduce the 'give' of the feed tube as it passes under the worm mechanism.

Unfortunately it doesn't seem to be enough to allow smooth transit of the filament through the pen.

Before the filament reaches the heated tip, it has to make a kind of 's' shape inside the feed tube, so that the molten material emerges from the tip which is on the central axis of the pen. I'm left wondering if friction from contorting this way, plus the pressure needed to extrude in the first place is backing things up.

The root of feeding problems on the Lix

Tolerances are very fine around the feed area. My attempt to place a shim behind the u-shaped piece of plastic failed - it was just too tight. I'm now thinking a coat or two of varnish or nail polish on this component might be enough to offer more purchase to the worm drive.

After I reassembled the pen I put a filament through coated in Vaseline in a effort to reduce the friction of the feed tube. At the time of writing, this didn't seem to make much difference to the feed performance of the pen, but I live in hope!

Update: After writing the above, I returned to the pen and got some consistent feeding action, to the point that introducing a new filament to the worm drive was proving to be enough to extrude the remainder of the old filament.

Result? I think so - at least for now the pen seems to be working as before. If yours is jamming try applying a little vaseline to a filament and helping it through the pen.

Update to the update: While I got through several filaments without too much bother, the pen is back to it's old ways and jamming way too easily. On the plus side, this afforded me the opportunity to take it to bits again and take better photos and at the same time try modifying the u-shaped piece in some way. Stay tuned!

Mr Fixit

As one of the office 'Computer Guys', I often get called upon to fix other people's computers. More often than not, they tend to be laptops.

This time it was a faulty Sony VAIO VGN-FZ18M.

The fault was with the GPU, a nVidia 8400GT. This is a well known fault - Sony and nVidia admitted fault and extended the warranty to 4 years after purchase.

Of course many folks may just be encountering the fault (like this example - dashed lines across the screen with a failure to boot or get stuck in a restart cycle) and may be beyond even the extended warranty.

There are few, if any, guides for stripping down this particular VAIO on the internet.

So I decided to write my own, and it can be found here (PDF). File hosted by box.com.

The guide describes how I repaired the GPU with a paint stripper. Yes, a paint stripper. It was an all or nothing fix.

Rather incredibly, it worked.