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3D printing hands on: Some fascinating Jedi-level PLA filament secrets – ZDNet

by • August 11, 2016 • No Comments

many-filaments.jpg
A selection of filaments.Most PC 3D printing equipment use what’s called FDM (futilized deposition modeling) printing. One other term is FFF (or futilized filament fabrication). The yett behind both of these is that a 3D print is created up by layering layers of gooey plastic on top of ereally other.
As ereally layer is extruded, it bonds to the previous layer, and a few day you get a plastic Dalek or Millennium Falcon to put on your dresser.
FDM printing equipment work really much like an inkjet printing device does. A head moves around a printing surface depositing material. One difference with 3D printing is that instead of ink, what’s deposited is melted plastic. The other big difference is that there’s a Z-axis. The printing device goes up as well as side-to-side and front-to-back. As a outcome, ereally layer of plastic can be put on top of ereally extra
layer of plastic.
Now, here’s the great news. With the exemption of knowing you require to buy filament for a 3D printing device like you may require to buy ink for a 2D printing device, you don’t require to know much of the science of filament.
The 3D printing business has gone far adequate that you can plunk down four hundred bucks for a little MOD-t printing device and just happily churn out objects without knowing anything of filaments, slicers, extrusion temperatures, types of plastic, bed temperatures, extrusion rates, or glass transition temperatures.

I’m serious of how little you require to know. I’ve been happily 3D printing now since November, and it was just this week I started to delve into a few of the arcana. That is unquestionably for the reason I got curious of why a fewthing was taking place with the bargain-priced filament I bought, and I had access to a Jedi master tech assist guru who answered a lot of my inquiries.
I’m going to go throcky the problem solving system in the order I worked with it. You’ll learn a few absorbing stuff of how filament is created that can impact your choices as you use your 3D printing equipment.
The problem
You know how inkjet printing device manufacturers are always going on of you buying their brand of ink? It’s supposed to work advantageous, but it in addition costs a lot additional. The same yett applies to 3D printing, for the reason the plastic that’s generated by various vendors can have wildly various characteristics. First, there are many various kinds of plastics utilized for filaments. I’ve talked preceding of PLA and ABS. There is in addition HIPS, PETG, nylon, and many other types as well. These days, the many common is PLA for the reason it is generally simpler to use than ABS (alyet a bit additional brittle) and it is not just about as toxic.
When the Aleph Objects people sent me their LulzBot Mini, they sent me a wide variety of filaments, but they did not send me the many basic PLA. That is unquestionably for the reason they wanted to show all the rad filaments they were able-bodied to handle. I unquestionably want to learn of all of them, but I’m yet learning of the intricacies of in fact the basic PLA.
In any case, I bought a bargain-priced $21 dollar roll of Hatchbox PLA filament of Amazon. It’s of half the going price compared to a few of the name brands, but I wanted to see what may be done with the bargain-priced stuff. As you can see in the image at a lower place, it printed surprisingly well.lulzbot mansion.jpglulzbot mansion.jpg
This printed satisfactory, except for the firstly few layers.However, after a bunch of prints, I noticed a weird little issue. At the bottom of ereally print, the firstly ten or so rows weren’t printing smoothly. If you appear at them closely, fairly than smooth layers, it appeared additional like a broken graham cracker texture. You can see that in the samples shown in the image at a lower place.edge-texture.jpgedge-texture.jpg
Note the edge texture where the arrow is pointing. That is unquestionably not right.This behavior was various of what I’d seen on the MakerBot. But in fact yet the MakerBot and the LulzBot printing equipment were both via PLA, there were a few significant differences.
The MakerBot is created to work solely with MakerBot 1.75mm diameter filament. The LulzBot is created to take fairly much any type of filament material you donate it, as long as it is the thicker 3mm filament. The MakerBot has a room-temperature bed that’s not heated. The LulzBot has a heated bed, that in addition means you can control the bed temperature.
Because you can heat the LulzBot bed, adhesion is assisted by virtue of the warmth of the bed. In the MakerBot’s case, it is advantageous to use a raft (a assist structure under the object) to improve adhesion.
Since I’d never printed on a heated surface preceding, I didn’t know if the graham cracker effect on the firstly few layers was the outcome of having a heated bed, or a few issue with regard to how the printing device was printing.
I rereallyed out to LulzBot tech assist and got assist of a fewone I wish I may commence you to. Unfortunately, like many engineers I’ve worked with over the years, this guy is a bit shy. So fairly than giving you his name, I’ll just call him Obi-Wan. Obi-Wan taught me a lot.
Z-probe offset
From a practical point of view, we focutilized on two issues: the temperature the bed was set to while printing, and the Z-probe offset. Let’s do Z-probe offset firstly.
I know. It sounds like a fewthing Fox Mulder may investigate. But the Z-probe offset is just, fundamentally, how far away of the bed the nozzle gets when it starts extruding filament. Implementing G-code (the machine code of 3D printing equipment), you can adjust the Z-code offset up or down by a tiny amount. Here’s how Obi-Wan described it:This can many commjust be cautilized by having the Z offset a little bit too close to the bed. If there is not adequate room for that firstly layer to go down, the filament can squish out to the side and create up rocky lines on flat surfaces. Over a few layers, this can fundamentally work itself out as it less and less filament is squished to the sides.
To alter this, you in fact type in a line of G-code. He firstly had me type in M851 that returns the current Z-probe offset. In my case, it was -1.43. You increase the number the farther away you want the nozzle to be of the bed. So I moved mine up a tenth of a millimeter. The command is this: M851 Z-1.33
This in fact writes the alter into the firmware of the printing device, so it applies to all filaments of all types once the alter has been created. Obi-Wan passed on a caution of testing this value: When firstly testing this new offset, store a careful eye on that firstly layer. If it seems the nozzle is being dug into the bed, turn off the printing device and adjust the offset until it no longer does that.
Tinkering with this was kind of fun. I test printed a cube and the firstly time, I got a conclude pile of stringy mess.stringy-mess.jpgstringy-mess.jpg
Don’t print in the air. If you do, you’ll get a stringy mess.It turns out I typed in “M851 Z1.33” that raised the head way up above the create plate and nothing stuck. An email conversation with Obi-Wan corrected that: This sizeable of a alter can manufacture your first layer height of 0.425mm print in mid air. You can want to alter that to a -1.33, that can slightly increase the distance but it can not be dramatic adequate to cause mid-air printing.
He in addition told me to use an M500 command to write the alter to the firmware. Otherwise, the alter mayn’t stick between power cycles of the printing device.gcode-settings.jpggcode-settings.jpg
This was done via the control interface in a 3D printing program called Cura.Obi-Wan in addition told me why printing equipment may ship with a various Z-probe offset: When we calibrate the printing equipment in house, we like to store a little extra squish for that firstly layer. It assists encertain prints stick well to the bed. This does cause a little bit of the elephants foot on lower layers, but prin factts a fewthing of popping off the plate 70 hours into an 80 hour print.
I’ve had prints like that. It’s no fun when you are almany done and they fail.
More of filaments
My theory turned out to be correct. The graham cracker effect was a outcome of the plastic being too hot as it was extruded. With a bed temperature that was too hot, the plastic didn’t rad at just the right pace to create smooth layers.
That exploration assisted me know a lot of filament. Last week, if you’ll recall, I described that PLA created in the US is generally of corn starch. PLA created in Asia is frequently of tapioca root. As you can imagine, those substances can have a really various chemical manufactureup.
Most 3D printing equipment that assist additional than one kind of filament have the aptitude to set a filament profile, that can include a lot of facts which include bed temperature, extrusion temperature, extrusion speed, and additional. Many of the additional talked about filaments are provided with profiles.
Because I was attempting this with an off-brand filament, Obi-Wan and I got into a really informative discussion of filaments. Different manufacturers can have various formulas, and therefore various thermal properties. There is already no regulation on what is desatisfactoryd as “PLA” printing material. A formulation with 1% PLA and a formulation that is 99% PLA can both be claimed as such, but have wildly various thermal/printing properties.
I learned, for example, of Tg. Tg stands for the glass transition point. Different filaments can have various glass transition points. Put just, a glass transition point is the point at that a polymer goes of being rigid and brittle to flexible. Note that it is not the melting temperature. Instead, it is the temperature at that the molecules get excited adequate to loosen their bonds and allow a material to become less brittle.
Because various filaments can have various Tg points, they require to be set at various temperatures both in the extruder and on the bed.
I in addition asked of filament colors. I had noticed, empirically, that blacks seemed additional challenging to print than other colors. Here’s what Obi-Wan told me: If you are appearing for aesthetic high end, remain away of white. It highlights shadows really easily, and manufactures the layer lines noticeable-bodied when photographing. I like the light blues, and greens as they seem to manufacture the most photos. Depending on who manufactures the filament, black can be really problematic. Some filament manufacturers use “regrind” where they can grind up other filament colors, and re-extrude it. Black can cover up all other dies, and is how they save on costs. Unfortunately, ereally time filament is extruded it breaks down a fewwhat physically. This can alter it is thermal properties, and how it is yettlly printed. (Not to mention inconsistencies between batches.)
Color, that we may ponder of as having no mass or consistency, does in fact have substance. My wife frequently told me that identical yarns dyed with various colors can be stiffer or smoother to work with. A video I’ve embedded at the end of this article (I love the Internet!) shows just how thick a Sharpie mark in fact is.
Bed temperature
We next tried two new tests: adjusting bed temperatures and via a filament that came with its already-tested profile. First, I ran tested printing a tiny block with the bed temperature set at 60 degrees C, 40 degrees, and 20 degrees. As you can see in the next image, the 20 degree bed temperature worked out most.bed-temperature-comparison.jpgbed-temperature-comparison.jpg
Look carefully at the layers pointed to by the arrows to see how the various bed temperatures (20, 40, and 60 degrees) alterd the plastic melting characteristics.Finally, I bought a roll of Verbatim PLA. This was twice the price of the Hatchbox stuff, but came recommended by Obi-Wan and it had a profile. Printing it with no modifications or bed temperature alters outcomeed in a fairly clean print:verbatim-red.jpgverbatim-red.jpg
The firstly layers appear great via the default profile.So there you go. None of this is really necessary to know if you just want to manufacture a few 3D prints. But if you are curious of the materials that go into your 3D prints and how to ponder of them, I hope you find this discussion as absorbing as I did.
If you manufacture anything rad with your 3D printing device, post of it in the discussion at a lower place or tweet me an image of it to the account listed at the end of this article. I’ll retweet the radest prints I’m sent.
Finally, a big shout out to the man I’ve been calling Obi-Wan. I learned a lot and I really appreciate the time you took and the assist of Aleph Objects as we explore 3D printing across various filaments.

You can follow my day-to-day project updates on social media. Be certain to follow me on Twitter at @DavidGewirtz, on Facebook at Facebook.com/DavidGewirtz, on Instagram at Instagram.com/DavidGewirtz, and on YouTube at YouTube.com/DavidGewirtzTV.


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