This page is about my interests, projects, and profession (technical artist in the video games industry).  Most of my hardware\software projects are coded in PythonProcessing, & Arduino.  I also enjoy 3d printing, you can find my designs for download over on Thingiverse.  More pics over on Instagram.

Find Processing\Android\Python programs\apps I’ve developed via the above title bar.

I also maintain several wikis on Maya\Python\Pygame\Processing that I update far more often than this blog.  See them on their page.

All information on this site is copyright under the Apache Licence v2.0, unless otherwise noted.  Which means you can pretty much use the information here for whatever you like, but I always appreciate credit where applicable.

Have a look around.  Thanks for stopping by.

— Eric Pavey

New 3D Print: Mini-Me

Or “Really Big Me” depending on how you look at it:

A few months ago I stopped by the “Artec3D Scanning Service and Showroom” in Palo Alto (CA) to check out their scanner tech.  While there, they offered to do a full-body 3D scan of me in their “Artec Shapify Booth” : Only takes 12 seconds, so why not?  Later that day there was a web-link to my scan, which I downloaded (for $40).

I’ve been wanting to throw something really big and complex at my C-Bot 3d printer, and this seemed like the perfect thing.  After cleaning it up a bit and making a base in Meshmixer, it printed without any (major) issues:

Lucky bonus: It was on one of two days in the whole year I had my “sexy-trucker” ‘stache still firmly in place.

Print Stats:

  • 500mm / 19.7″ tall
  • 663g of eSun gray PLA (the last of an old spool I had, purchased from ToyBuild Labs) extruded at 210 degs on a woodglue-slurry-coated glass build plate (unheated).  Only had about 5 turns left on the spool when complete, close one!
  • 35 hours, 39 minutes total print time (lol, the print estimate was 24 hours).
  • Sliced in Simplify3D, the .gcode came to 161 megs.
  • 3 shells, 5% infill, no raft, no supports : The 3 shells was to help with all the overhangs since I printed no supports, may have been able to get away with 2.
  • 90mm/sec print speed.
  • .6 mm E3d-v6 Volcano nozzle with 150 micron layer heights.

Overall, I’m really happy with it.  But, there are a few things that struck me a strange, and I believe they’re both related to the slicer, Simplify3D.

Wobbles in the infill

While it was printing, I noticed wobbles showing up in the “triangular” infill:


Watching the print, I figured out what is going on:  When Simplify3D prints its infill, when any of the lines cross, they don’t do anything to pause the print.  So in this case, since three lines are crossing, 3x the filament starts to form at the vertex.  Over time, this builds up, and the nozzle physically ‘bumps’ over it.  When it bumps, it shakes the whole machine, and those wobbles start to show up in the infill.  This is never seen since its on the interior of the print, but I don’t like that it’s happening.  Sometimes I could really hear the hot-end ‘thunk’ the vertex and shake the whole thing :(

High-res, low-quality

I’ve been seeing this in my prints recently, but haven’t yet had a good enough test case to show the issue, until now.  I’ve noticed that when I print “really high-res” mesh in Simplify3D, it tends to make the surface quality a bit like a bowl of oatmeal.  My low-res prints are nice and clean, but high-res:  Quaker Oats.  In the below images, you can clearly see what’s happening:

Click on the images to zoom in, but you can clearly see a print quality change as soon as the dense mesh layer is hit.

I’ve had this feeling that S3D is trying to print ‘all’ the detail, even though some is smaller than the diameter of the toolhead itself.  And because of this, there’s a lot of shaking going on.  I know from my years using Makerware that it specifically would ‘smooth out’ this high-frequency detail, and I noticed a major difference printing the same ‘high res’ mesh in Makerware, and S3D:  The Makerware print would look\sound nice and smooth during print, while the S3D one would try to shake the machine apart.  It looks like this is still happening, and at least I have a test case that exposes it.  If this is the issue indeed.  I’ll ping the S3D support an see what they say.

I have a few next steps to troubleshoot this:

  • Make a test print that varies from low to high-res.
  • Print this in S3D, and contrast that print in other slicers (like Makerware, Cura, Slic3r), and see what sort of behavioral differences show up.

Building the C-Bot 3D printer: Part 28 : Lighting, Ringing, Breaking

Jump to C-Bot blog index to see all the posts.

This update is a combo post on several subjects at once:

Adding Lighting

Up until now, the C-Bot has been a dark printer:  No internal lighting whatsoever.  My Replicator1 is like a little supernova next to it when the room is dark.  But no longer:  Over the weekend I added both an 12v LED strip to the top-front X-beam (pointing directly at the print-bed) and a superbright LED directly on the print-head itself:

While my buddy Mason did a slick job of wiring his LED strip directly into the Rumba board on his C-Bot, so he can adjust the lighting based on the print settings, I did not:  I ran a extra 12v lead out of my power-supply, and connected both the LED Strip, and the superbright LED (with inline resistor) directly to it:  Turn C-Bot on, lights turn on.  Nuff’said / good enough.


After I installed the lighting and turned the bot back on, the Bowden extruder suddenly started jittering:  It would no longer extrude filament.

I started by swapping a DRV8825 stepper driver from the z-steppers to the extruder stepper slot:  Try extruding, and it works.  Ok, it must be a bad DRV8825, and I have no spares.  But I do have a bunch of extra A4988‘s:  I’ll just put one in there, and updated my firmware to use it instead.  It doesn’t work:  Jittering starts again.  So I revert the firmware change, and put a ‘good’ DRV8825 back in:  Jittering.  What is going on?

Soon, any DRV8825 I put in that slot causes jittering, but they all work when plugged back into their original slot.  Drivers are good,… is my board bad?  At this point I disconnect the 4-prong JST connector running from the board to the stepper, and notice that one side is slightly melted: I remove the wires from the connector, and connect them on-by-one to the pins on the board:  Everything starts working again.

Canibalizing a connector from some other wires, I reinsert the leads, plug it into the board, and back in action.


Improving Ringing / Ghosting

I had recently printed out a “Sledgehammer Games Recognition Coin Holder” for someone at work (I modeled it in Maya / Tinkercad):  We can give out cool coins to fellow employees for doing good work, and I designed this coin holder so people can show them off (there’s four slots in the top to hold the coins).

I’d printed many on my Replicator 1 in the past, and printed this one on the C-Bot for the first time.  And what I noticed was, there was a terrible amount of ghosting / ringing happening:


Click to see the full-size that really shows the problem off.

This was printed with the .6mm E3D-Volcano nozzle, 300 micron layer heights at 60mm/sec, in MakerGeeks Royal Purple PLA.

The issue was, the prints done on my Replicator 1 had less ringing than the C-Bot, and this didn’t make sense to me:  The C-Bot has a Bowden extruder, thus removing a bunch of moving mass from the toolhead, not to mention it uses Core-XY mechanics, that is supposed to help out as well.  Why are things worse?

Posting this question to the 3D Printing Google Group, I got a bunch of good answers.  Specifically, my firmware acceleration may be too high, and the size of the printer itself could be causing too much shake, do to the lack of additional cross-members for stability.  Right now I have no surplus extrusions to stiffen it up, and my ultimate goal is to bolt the printer directly to the wall, thus really locking down any shaking.  But in the meantime, I can adjust the acceleration in the firmware.

I made a ringing/ghosting test model in Maya that would show off the issue on X, Y, and XY all at the same time.  I printed it with my default settings (3000 mm/sec), then dropped it waaay down to 800 mm/sec.  The results were pretty obvious:


Click for bigger pic

On the left of each image, is the ‘800 mm/sec acceleration’ print, and on the right is the ‘3000 mm/sec acceleration’ print.  These changes were made in Marlin’s Configuration.h:


I just set everything that looked applicable to 800.

So, an noticeable improvement.  But once I get the printer “bolted down”, I hope to be able to print even faster, with better results.

Jump to C-Bot blog index to see all the posts.

3D Printing McMaster-Carr Files

I, like many others, love McMaster-Carr.  I purchased a number of items from them during my C-Bot build:  Their shipping & customer service is always great.

While I always saw the icon, it never clicked, and it wasn’t until I was listening to a 3D Printing Today podcast (Episode 100, specifically) that I connected the dots:  You can 3D print the stuff they sell, since they have CAD files for so much of what they offer.  I was listening to the podcast at work, so when I got home I decided to try it for myself.  So easy.  On a side-note I’m not too concerned they’re going to loose much business over this:  Not sure what practical use most people will have for a 3d-printed plastic bolt…

First (if you don’t have software that can import STEP files and export STL’s), install Freecad.  I did this all on my Mac, but they have Windows & Linux options as well.

Second, go find something in McMaster-Carr to print.  Like this super-chunky Metric screw for example.  When you’re browsing their offerings, you’ll know you can get the CAD file if there’s a little green “CAD crosshair” icon, and you then click on the “Product Details” next to it:

mcmaster-carr printable

In that window there’ll be a “Save” button, and next to it a drop-down for file formats:  Choose ‘3-D STEP’, and hit the button:

mcmaster-carr download

Next, in Freecad, ‘File -> Open’ and browse to the STEP file you just downloaded.  You’ll see something like this:


Under ‘Labels & Attributes’ on the left, select the object (probably a bunch of random letters and numbers).   Then access ‘File -> Export’ and change ‘Files of type’ to Mesh formats.  Make sure the name ends in .stl, and export it.

Finally open the stl in your slicer of choice (in my case, Simplify3D), and get it ready for print:


1 hr 15 min later:


A double-sized version is printed via the C-Bot:

  • .6mm E3D-v6 Volcano nozzle.
  • 300 micron layer height printed @ 60mm/sec.
  • MakerGeeks “Royal Purple” PLA printed @ 220 deg.

Never realized it was that simple!

PS: If you’re not listening to the ‘3D-Printing Today’ podcast, you really should be.  A lot of great info in there every time.

Visual comparison of 1mm 3d printer nozzle overhang tolerance

Since I’ve been printing with a 1mm E3D-v6 Volcano nozzle on my C-Bot, overhang has become more of an issue than on my Replicator 1: The thicker the layers get, the less overhang you can support.  I could ‘sort of visualize this’ in my head, but I wanted to get it down on paper where it truly makes sense.

I mocked up nozzle diameter, layer thickness, and print/overhang angle in Maya, below are the results.  Very quickly you can see how the thinner your layers are, the better overall overhang you can support.  I did this presuming only one shell was being used.  Using two shells would support better overhang, since the outer layer would have the inner one to stick to.

1mm nozzle, 500 micron layer height:

lay500_nozzle1mm_angle45  Success with one or two shells.

lay500_nozzle1mm_angle60Fail with one shell, possible success with two shells.

lay500_nozzle1mm_angle75  Fail with one or two shells.

1mm nozzle, 250 micron layer height:

lay250_nozzle1mm_angle45 Success with one or two shells.

lay250_nozzle1mm_angle60 Success with one or two shells.

lay250_nozzle1mm_angle75 Fail with one shell, possible success with two shells.

New 3D Print: Giant ‘P’

Most of my ‘big’ prints on the C-Bot have involved vases:  Large flat bases, thin walls, print fast.  I wanted to try something more ‘structural’:  Dense & flat & strong, but still take up most of the build volume.

So I printed a giant P: (you know, for ‘P’avey)

  • 500 micron layer height, 1 shell, 2 floor, 2 roof, 20% infill.
  • 1mm E3dD-v6 Volcano nozzle printing @ 30mm/sec.
  • Fans on at layer 3, 25%.
  • 210 deg blue GizmoDorks PLA on glass plate covered in wood glue slurry.
  • Modeled in Maya, sliced in Simplify 3D.
  • Just over 4 hours to print.

Came out really well actually, only thing that could be better is the top surface quality:  I either need one more roof layer (currently 2), or I’d need to up the infill to a higher percentage so the bridging wasn’t so far.  And it stuck really well to the wood-glue slurry on the glass build plate.