Saturday, June 19, 2010

Skeinforge settings vs Great Rafts

In short: a raft is a printable, flat thick layer to even out your build platform. Through testing and whatnot your build platform takes a couple for the team and in time becoms uneven (holes, scars). The raft is there to make sure the build surface is flat, and also tries to assure good first layer adhesion to the platform.

My first rafts were thin candy string like threads that offered virtualy no support and actualy did the opposite of what it was supposed to do. The fatter base layers and the thinner support layer didn't assure first layer adhesion, except on very small builds.

A raft is important when you're printing with the standard build platform, and to a lesser extent when you're pinting on a heated build platform. Since printing with a heated build platform is very different from the standard, there's a separate post devoted to just that.

First off, i've learned through trial and error and many comments on the google makerbot operators group that the interface layer (thinner threaded 2nd raft layer) isn't necesary by default. If you learn how to make a nice fat spread base layer that's all you really need.

To get the raft you see here on the right, you need to manualy reposition the z-axis on the first line that's going down when the raft starts printing. Position your nozzle about 1mm above the build platform and start your print, then just lower the nozzle by hand untill your raft lines touch each other, but make sure they don't overlap. If the lines overlap you will see a very thin (like a hair) thread on top of the raft lines. That could mess up your first layer, but could also strip out your filament. By making such fat lines you could end up blocking the extrusion by feeding more into then the nozzle can lay down. So make sure the lines don't overlap. It'll take a couple of tries, so start out with a small raft to get the hang of it.

Thursday, June 17, 2010

Feeding the Filament... with a spool!

Jared Spool : "Good design, when it's done well, becomes invisible"

Let's say that for the 3D printer jared's argument isn't always necesarily true. For quite some time i had filament strips that had two main reasons. Not having adjusted the idler wheel deep enough, and not feeding the filament 'smoothly' enough. Adjusting the idler wheel was obvious - but i kept looking past it for a few weeks because i was convinced i had set it correctly.

The ABS filament i got with the deluxe kit was a mess. I had no clue how to handle it and reasoned it's a spool - and if it goes haywire i'll just rewind it. This might be so for electrical wire, it isn't so for ABS. That stuff has no organisational qualities. The way my filament went into the cupcake was all tangled, twisted and what not. Didn't really catch my eye untill one day it stripped cause it bent almost double.



You don't have to be blond to be stupid, as illustrated by the above. Browsing around in thingiverse i found quite a number of people with spool variations. Some clever, some highly ingenious, some so wonderfully simple!. So i decided to go with KISS (keep it simple stupid). What can be more environamentaly friendly then to make your stuff out of cardboard! The user charlespax on thingiverse came up with a cardboard spool made from pizza boxes. I however used an old box from a computer i had lying around. Which is good thick cardboard. The build is really really simple, and surprisingly sturdy. You would need a spool holder for your shiny new toy, i made mine from a cardboard box. I inserted a metal rod through the spool, and hold the spool as a whole inside a cardboard box that's deep enough. Just make two holes in the box and tadaaa you have yourself a DIY - no effort spool holder.

enjoy!

Howto: level your z stage

“Vertigo is the conflict between the fear of falling and the desire to fall.”
is what Salman Rushdie said.

We've all seen our Z stage crash into the build platform. The Z stage design is frail and prone to flaw. If you haven't payed allot of attention to the horizontal level of your stage, reconsider. Some print errors can come from a miss calibrated stage.

The problem with the z-stage comes from two issues:
- The nuts that hold the stage horizontaly in place

- The differing height variation between those 4 nuts respectively.

From personal experience i've found that leveling the z-stage horizontaly as a whole compared to the build platform is not 'THAT' important. I've found that the build stage can be off by millimeters and still result in a good print. What IS important however is that the nuts support the stage on all 4 points. The Z-stage can not have a tilt in it or it will result in bad prints. When all four nuts support the z-stage, the stage itself can (even visualy) look slanted - provinding there's no more then 5mm (give or take) height difference between the nuts. If you end up with more, you'll have to take a closer look at your build.