3D Printing, an Art Versus a Science

Creality Ender3D Printer

One of our cherished holiday traditions is to craft homemade gifts for family members. My now 22-year-old son, when he was ten used his Erector Set to make a fishing pole for my dad, complete with working reel, fishline, and lure. Dad was big into sports fishing, and although he passed back in 2012 that rod is still on display in my mom’s FL Keys home. This year my son returned from college bringing his Creality Ender3D printer, an entry-level product he purchased this fall in kit form for about $250USD. He wanted to print several gifts he’d been designing, but hadn’t had time to while in school. 3D Design and printing is something he’s been into for the past six years on various projects and thought it was about time to have one of his own. If you’re not familiar with the Ender3D it’s a fundamental design where the print surface moves in one dimension (forward and backward) and the single printer head moves in the other two directions (left or right and up or down). Both the print bed and the print head have controllable temperatures, as well as cooling fans designed to cure a print rapidly. This enables the printer to utilize the most common plastic, PLA, but also many other more exciting materials like TPU, a sort-of plastic/silicone blend which is both flexible and resilient. On the surface this sounds awesome, we can printer whatever we like from things we’ve designed to those designed by others and posted to sites like Thingverse. Who wouldn’t want this remarkable capability at home, right?

It’s not so amazing though, as 3D printing is still very much an art more than it is a science. For those not familiar with this subtle distinction, when something is a science it must ALWAYS be reproducible, while when something is an Art there remain significant variables under control of the artist, and sometimes nature, which makes the process nondeterministic. Everything we print, of any size above an inch or two, often takes several attempts to produce a final product. Sometimes even that final product results in a print that is unfortunately unusable as a result of the process settings (not the design). For example last Monday morning, after two failed attempts we finally succeeded in printing a mobile phone case using TPU. The two prior attempts failed due to a break down in the adhesion of the print job to the build plate, the most common class of failure. Since this is an entry-level printer, it isn’t aware of a failure, so it continues printing until it jams or the job completes.

Epic Print Error – Ball of PLA Behind Print Head

This lack of intelligence or feedback into the system results in some epic messes. The previous Friday night we returned home to find a PLA print job had broken loose from the build plate, and the print head had shoved it off onto my desk. It was only 1/4 complete and a blob of PLA the size of a jawbreaker was riding the back side of the print head like a tic on a dog. Did I mention it was still printing, perhaps an hour or more after the failure? The phone case discussed above, which we’d been printing using TPU, finally finished successfully on the third attempt. It removed cleanly from the build surface. To increase our chance of success for the third attempt, we added a “raft.” A “raft” is several extra layers of print material which are laid down as part of the print process. The “raft” has a slightly larger footprint than the print itself, and that footprint has 100% coverage using a tightly weaved pattern to ensures that plenty of material is applied to the build surface to secure the print until the job is completed. We’ve never had a problem with PLA prints separating from their “rafts” but as mentioned TPU is far more flexible and resilient which made it impossible to cleanly separate the “raft” from the case, rendering the case unusable.

One of Four Puzzle Pieces Making Up
5×7 Photo Frame Gift
Note Extra Tape to Avert Curling

As mentioned previously build plate adhesion is the single biggest problem making 3D printing today an art. Various build plate materials are available from aluminum to tempered glass, and PVC, all with their unique bonding characteristics with different build materials. Tempered glass works reasonably well with TPU, provided the build plate temperature is set correctly and consistent within two degrees Celsius. With the third print, we opted to lay down a thin layer of diluted Elmer’s white glue to provide adequate binding of the print to the build plate. Something we do now as a regular process when printing with PLA.

The second problem, which impacts print adhesion to the build plate, is temperature control. Here there are three variables, the temperature of the head, the build plate, and air flow from fans designed to cool a print in process. PLA shrinks as it cools, so often prints larger than an inch tend to curl if they cool too quickly. This is where the bed temperature needs to be just right at the start then cool slowly as successive layers are applied. Peeling with PLA has been a problem for some time, so “rafts” and a little extra glue on the raft early on often solves this.

Stag Coral Bud Vase with Scaffolding
Looking Like Something a Spider Wove

Another problem is the supports created by the program that compiles your 3D model into your print file that you can then send to the printer. These supports often called “scaffolding,” are required if a print needs to expand much beyond the printed surface below it. 3D printers are akin to hot-glue guns with excellent control over print material placement. With that in mind, you can’t have the printer squeeze out a bead of plastic with nothing below it for very long before gravity takes over and introduces chaos into your print. The print programs are aware of this, and they have tricks to prevent this from happening. Imagine you are printing a capital “T” as you see it on this page. Normally you’d print this T laying flat on its’ back or even upside down to limit wasted material and ensure a successful print. For this to print properly standing up, the print program inserts temporary scaffolding under both arms of the “T” as it starts building the base of the “T.” This provides a structure onto which the printer can then print the more solid arms of the “T.” This holds especially true if you’re a grandson whose custom designed a “stag coral bud vase” with many outstretched branches as shown below, or a phone case where the protective lip touches the front glass. With PLA the scaffolding often removes pretty easily once the print is complete, and if not a Dremel can be used to clean up any remaining mess. With TPU some scaffolding can never be removed.

Same Stag Coral Bud Vase
After Removing Scaffolding

More expensive dual head printers, often starting around $800USD, can utilize a water-soluble plastic to print the scaffolding in parallel with the primary print material. Once a job has finished printing you just remove it from the printer and drop it in a tank of water overnight. On returning in the morning you find a clean print with no supports. Single head printers don’t have this technique available to them.

Other materials like wood, metal, and ceramics can also be printed on these printers, but these exotic materials require even more of a craft approach to printing. We’ve attempted a wood product several times, but have had no success to date as it’s jammed up multiple print heads. This product is VERY finicky when it comes to temperature, too low it jams up, too high and you end up burning the wood. As for metals, you can even print simple circuit boards; we’ve not yet experimented with those.

Exercise #5 of 20 in In Learning 3D Design

Another craft aspect of 3D printing which I’ve not discussed yet is the area of designing something to be printed. Design programs like SolidWorks or Fusion360 by Autodesk, the leader in this market, enable you to create practically anything you can dream up, sometimes even more. That doesn’t mean though that what you design is always in-fact printable. Shown to the right is one of the twenty exercises my son assigned me to design in Fusion360, a little role-reversal. With a single head printer if you want to create something that requires different materials or colors you have to design it for assembly post printing. Most single head printers don’t allow you to stop mid-job to change out a spool of black PLA for white PLA. Designing something for assembly, post-printing, requires considerations be made during the design process which would not be necessary if you were using a dual-head printer. Most dual-head printers today pause the job and notify you a spool needs replacing, like back in the day when your plotter needed another pen to draw with green.

Final Stag Coral Bud Vase

If you live on the bleeding edge sometimes you get cut, or in my case lately a little scorched, by the technology you’re looking to wrangle. Perhaps you might like to learn a bit more, please consider listening to this recent podcast we did on this subject. If you’re one of those out there who thinks 3D printers are something that will soon be gracing the shelves of Target, then I’d love to hear your perspective. *Note all the above pictures are clickable if you want to see things in a bit more detail.

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