What should my first layer look like?

February 24, 2013

Your 3D printer just arrived. The nearest hackerspace is 100 miles away. You’re all ready to start printing, but all you really know about the technology is what you’ve seen on YouTube videos and breathless reports on Wired, or the Colbert Report.

They never show you the bottom of the print in any of those venues. It’s always Stanford bunny this or Colbert head that, and that’s all well and good but there’s no one around to tell you you’re doing it wrong.

first layer

I was happily printing failbottom models for months before I went to Maker Faire in Detroit and saw a proper print done by some experts.

The stringy bottom on the first two prints is mostly caused by having an off-kilter heated build platform. Make sure your heated build platform is as level as possible before you start printing.

MakerBot Replicator 1
ABS, 240° C
HBP 110° C, with painters’ tape

(These are prints of my Magic: The Gathering Fungus Tokens.)

MakerBot’s leveling script never seems to work perfectly for me, but since I’m printing small objects anyway I just make sure the HBP is locally level in my printing footprint. There’s no need for the corners of the platform to be 100% level if the center’s good enough.

I often start a print and let it run for a single layer to let the print heads get to their destination. Then I abort the print, remove any plastic from the HBP, and use ReplicatorG’s homing function to home the Z-axis to minimum.

(In ReplicatorG, go to Machine->Control Panel and select the Homing menu to do this.)

Then it’s a matter of twiddling the thumbscrews on the HBP until the nozzle passes MakerBot’s business card test. When you slide a business card between the nozzle and the HBP and the surface of the card just catches on the nozzle, you’ve got it.

It takes some time to get a knack for it, so don’t despair. I find it works best when the nozzle makes an indented scratch along the card’s face.

The first company to ship an auto-leveling build platform gets a fistful of cash from me.

It’s possible to get a mirror-smooth base when printing on kapton, but I’m mostly printing with ABS on painters’ tape right now. More on that in a subsequent post.

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Sweet ABSynthe

January 1, 2012

ABSynthe is a simple brew of filament scraps and acetone. Brush it on your build platform and your ABS prints will be a lot more likely to hold fast for the duration of a print.

You’ve probably got some ABS filament ramen or failed prints scattered around your workspace. Chop them up and drop them into a jar of acetone. Feel like Walt from Breaking Bad disposing of the evidence.

Don’t overthink it, just add enough acetone to make a thin syrup. Huff not the ABSynthe.

I mix my ABSynthe in an (empty) 3.6 ounce jar of Proraso Pre-shave Cream. It’s a convenient size and the plastic top won’t dissolve from the acetone fumes. Plus, it’s imported from Italy.

ABSynthe

She’s-a-make-a-you print-a stick-a-real nice-a.

Dip a paper towel in the ABSynthe and smear it across your HBP.

Getting ABS prints to stick to a heated build platform can be an art. I’ve had excellent results with some ABS spools, where they melt just enough to stick throughout the duration of a print, but some plastics just don’t like my kapton tape. They end up going for a ride around the platform and I’m left with a big bag of fail.

Note that I’ve pretty much given up covering my entire HBP with kapton. I realized I was mostly printing fairly small things, and it didn’t make sense to spend the time ironing out all the bubbles and rending my garments when the kapton bunched up.

So I just lay one strip down the center of the HBP and I’m a much more relaxed person now.

IMG_1180

That schmutz on the kapton is the ABSynthe. I haven’t had a print slip off the platform since I started doing this. I’m generally printing ABS at 120°C.