Sunday, December 28, 2014

3D Print Host Log Book

What isn't always clear to the uninitiated is that 3D printing is a hobby of tinkering whether you want it to be or not. The output of a print will vary by:

  • Printer make/model
  • Revision of printer hardware
  • Revision of printer firmware
  • Host software
  • Slicing software
  • Temperature of heating element(s)
  • Speed the print is run at
  • Type of filament (PLA, ABS, nylon, etc)
  • Brand of filament
  • Batch of filament
  • Progress through a single spool of filament
  • Print surface (metal, wood, glass, tape)
  • Condition of print surface (cleanliness, presence/absence of adhesives)
  • Ambient temperature
  • Humidity
  • Nearby airflow
For better or worse there's also not a single set of conditions/settings that will make your prints successful. You may get very similar results to a given print by increasing print speed if you also increase temperature (or maybe the opposite).

Lately I've been working quite a bit at dialing in settings that work well for me. The MG Chemicals glow PLA I've been using for my train track project has been giving me no end of grief. In my setup it's all I can do to get it to adhere well enough to the print surface, let alone reduce corner warping enough to get usable output. Two different spools of Shaxon (natural, blue) work great, a spool of glow green I got from is also great. With the MG Chem I'll print a part and get good results, then print the same thing again and it will be a disaster. I've basically given up on it and switched to the filamentsupply glow green.

As an aside, my process now that's working pretty well is:
  1. Preheat the extruder to working temp +5C and let it sit so other surfaces can heat and expand.
  2. Adjust surface tape as needed. So far if I wipe with alcohol I get so much adhesion that it's difficult to sand the tape off the part.
  3. Set the slicer to run at 30% speed for the first layer.
  4. Set the slicer to produce a 3mm brim.
  5. Set the slicer to not engage the fan for the first 3 layers.
  6. Because I have my printer basically in a hallway, I make sure that there are no nearby doors open that will permit a draft.
  7. Take my heat gun and heat the surface until it registers around 110F with my IR temp gun.
  8. Start the print and watch it until the first two layers are complete. If I get there, it's like 95% success chance.
I've started keeping a log of my prep steps, settings, and materials and then recording notes on the results for the output. I expect this to be a handy troubleshooting tool.

Given that this is an inherently tinkering hobby, the host software should have this built in. When I go to do a print, it should record everything it knows. Printer settings (temp, etc), slicer settings, any calculated output the slicer provides (bounding volume, footprint, estimated volume of material, estimated print time), and actual print time. Having integrated cameras to take high-res photos every so often during the print would be amazing. It should of course provide an interface for notes so I can record anything the software doesn't, particularly observations of the output.

Sunday, December 14, 2014

Dreidel, dreidel, dreidel, I Made It Out of Polylactic Acid Plastic

3D printed dreidel body and separate handle lying on newsprint. The handle is painted with white nail polish, the body is unpainted.
3D printed in PLA with handle painted.
That's how the song goes, right? Well, in spirit at least.

We're a multi-cultural household and I have a 3D printer I'll continually need to justify buying. So, I decided to print a dreidel and see how I could do finishing it.

I'm working with 1.75mm Shaxon PLA in "natural" tone which is vaguely clear-ish. I'm using a Printrbot Simple Metal at .2mm for all layers using Reptier-Host Mac and the newest stable Slic3r.

Right off the printer it was smooth and solid. The handle did not fit into the socket on the top of the body so I first tried sanding the star of the handle. This did not progress quickly so I stepped up to small hand files. This was faster, but still pretty tedious so I pulled out the dremel. This! Was! Fast! I still had to finish with the files as even at low speed the dremel melts the plastic as much as it sands it. Some quick filing and the burrs were off and it had a nice fit that was tight enough to stay together through friction. It spins well too!

A youtube video I saw suggested nail varnish (nail polish here in The States) for finishing prints. The idea is that it's viscous enough to fill in the ridges between layers. Also, it's intended to provide a durable finish. I thought it would be a good way to test out finishing without buying a lot of painting tools. As an aside, some of this was $2 for 0.5fl oz, some was $10.50 for 0.5fl oz. This should be considered an elicit substance!

Dreidel on newsprint, glyphs are painted with white overflowing the shape of the glyph.
Glyphs painted in white.
For bulk-coating it works pretty well. For getting into detailed spaces it's not so great, at least not with the included brush. I already planned to overflow the glyphs and sand off the overflow.

This did not work as expected. The paint really does seep into the ridges which meant sanding off all the overflow would require completely sanding down the surface of the body, at least around the glyphs. Oh well, it's white paint so adding color over it should be just fine.

Dreidel lying on newsprint, glyph painted with white paint. Some of the paint is sanded off but ridges on the surface filled with white paint are still visible.
Sanded the overflow, kind of.
It didn't quite. My blue paint was kind of a blue tint with fairly subtle sparkles. The white showed through easily but the sparkles were nice. This is where I see that this is intended to be going over nails and being translucent can make for a cool effect. In this case it is still kind of a cool effect because it smooths out the layering ridges while leaving them visible. This might be really neat for some projects.

Even though the handle stays in easily through friction alone, I figure at some point I'm going to drop it, it will bang on something, and the handle will go shooting off, only to be found next time I move to a new home.

dreidel is lying on newsprint with the tip pointing up and the handle separate. The surface is a shiny translucent blue.
First coat of blue.. with sparkles!
Ultimately I'm pretty pleased with the results. I'm kind of clumsy doing fine painting but I have virtual no practice and absolutely none recently.

Dreidel is sitting tip down in a soda bottle cap. It is a much deeper blue. The handle is lying beside it.
A couple of coats in, looking snazzy!
Finished dreidel sitting tip down in a soda bottle cap. It's a shiny deep blue with white glyphs. The handle is attached and a hot glue gun is visible beside it.
All done!