Log in

No account? Create an account

Previous Entry | Next Entry

Printing fail in 3d

The reason I've not been posting all sorts of pics of things I've made on the 3D printer is that, other than the initial teapot, I haven't gotten anything successful.

For a while it was software issues with settings of Skeinforge, the model slicer I use. It has dozens of cryptic settings. The results are infinitely tunable as a result, but to get good, much less usable results, you have to find the "magic settings" for your machine's speed and plastruder. Skeinforge's user interface... is painful. It was obviously designed by an engineer to be able to do Amazing Things if you have a Masters in Plastic Extrusion Technology. But it's barely usable by folks who just want to print 3d objects. And the app is sloooow. If anything is going to make me spend another year of my life writing a replacement app out of frustration, this'd be it.

I also kept running into meshing issues with the STL models I was using. Blender was great for pointing out meshing errors, but I couldn't figure out how to use it to FIX the problems. The auto face add feature didn't do it's mojo on the model I was working on, and I don't know Blender's Way Of Thinking yet. In fact, it's almost actively hostile for newbies to learn, despite the numerous tutorials available. Steep. Learning. Curve. And with my general lack of memory, I end up having to go through the tutorials over and over. On a laptop without a numeric keypad, or a 3 button mouse, you have extra config setting hoops to jump though to make it even usable. Meh. Supposedly Blender 1.5 will fix a number of the more egregious UI issues. I hope so. In any case, I found another open source app called Meshlab, which Just Works and was intuitive for the most part. It let me quickly fix up the holes in the model that made it non-manifold (Not water-tight). Blender pointed me to where the holes were, Meshlab fixed them easily.

Next problem was my machine itself.. I was having backlash and slippage issues with the belt drive. I ordered thinner belts from McMaster Carr and tightened them down well, and that made a world of difference, but I was still occasionally getting slippage. I've determined that lithium grease is too viscous for my uses here. Switching to some air-tool oil for the sliders made it run much smoother on the X and Y axes. I probably should find a more permanent oil, but for the moment, I can periodically re-lubricate.

I'm starting to build up a variety of failed prints of skulls. I was originally trying to print some for Halloween, but now it's my test object. I will soon have the world's largest collection of replica skulls of people who failed to live through The Philadelphia Experiment. In fact, I seem to have just made another one. Drat.

My first (and only so far) successful print was the Utah Teapot, which tugrik posted a picture of, which I'll re-post here.


( 7 comments — Leave a comment )
Nov. 9th, 2009 12:41 am (UTC)
Have you read the pile of tutorials I posted on the Thingiverse Blog? They contain the whole of my limited knowledge on Skeinforge's zany interface.

Blender: is not CSG, and acts very very very badly if you use it remotely like CSG. I've basically given up boolean operations entirely with it. As long as you only extrude, slice, and face-merge, it's pretty easy to avoid creating holes. But naturally, this makes the tool next to useless for a wide class of problems, which is why I'm so excited about OpenSCAD.

Oil: The MakerBot guys are using 3-in-1 oil, I understand.
Nov. 9th, 2009 03:36 am (UTC)
I'd made the mistake of getting the latest Skeinforge, instead of the Skeinforge that the Makerbot folks were working with and distributing. Which appear to have drastically changed the options available and what they are named. The upshot being that when I was going through your posts, the settings just didn't match up with the settings available in the copy of Skeinforge I had.

I've since fixed this problem by getting the skeinforge that the Makerbot folks suggested in their blog. Now I'm futzing with things like enabling Towers and tweaking the size of the raft. My last three failures appear to have been because my raft was too small at the base of the skull build. The build got knocked over halfway up, when the small raft peeled up.

BTW, the latest skeinforge seems much faster than the one suggested by the Makerbot folks.
Nov. 9th, 2009 03:23 am (UTC)
For oil, there's an old workshop staple I recall being called 3-and-1 or 3-in-1 oil. Lemme see... Aha, Wikipedia has the article and it's 3-in-1. Light-weight, very little drag on parts, it sounds like what you need.
Nov. 9th, 2009 03:53 am (UTC)
Yeah, I'd have used 3-in-1 oil, but I couldn't find it in the garage, so I used the air-tool oil instead. :)
Nov. 9th, 2009 04:29 am (UTC)
That's an adorable little teapot, though. :)
Nov. 9th, 2009 11:04 am (UTC)
At some point I'll be trying to print a larger one, that maybe will hold liquid. Just not hot liquid.
Nov. 9th, 2009 05:47 pm (UTC)
ABS is pretty temperature-resistant. It might not hold boiling water, but a brief skim of propeties gives it a working temperature of 60-100 C (140-210 F), depending on composition. Absolute melting point is above the boiling point of water, but the glass transition temperature is lower (so it'll weaken somewhere around 80 C if I remember correctly).

Was the acetone trick useful for making it watertight, by the way?
( 7 comments — Leave a comment )