Scratch Built 3D Printer Goes Big

November 4, 2020 by Tom Nardi 24 Comments

There was a time, not so very long ago, that buying a reliable 3D printer was a fairly expensive proposition. Many chose to build their own printer instead, and for a few years, we were flooded with very impressive custom designs. But as you might expect, with the prices on decent 3D printers now having hit rock bottom, the custom builds have largely dried up.

Arguably, the only reason you’d build rather than buy in 2020 is if you want something very specific. Which is precisely how [Joshendy] ended up building the Big F… Printer or BFP. No doubt the F stands for Fun, or Friendly. Either way, it’s certainly something special. With a 300 mm³ build volume and heavy-duty Z axis, this fully enclosed CoreXY machine is ready to handle whatever he throws at it.

It did take [Joshendy] a few attempts to get everything the way he wanted though. In fact, the prototype for the machine wasn’t even CoreXY, it started as an H-Bot. In his write-up he goes over the elements of the BFP did that didn’t quite live up to his expectations, and what he replaced them with. So when wobbly leadscrews and a knock-off V6 hotend both left something to be desired, they ended up getting replaced with ball screws and an authentic E3D Hemera, respectively.

To control this monster, [Joshendy] is using OctoPrint on a Raspberry Pi and a BigTreeTech SKR Pro running Klipper. OctoPrint gives him the ability to control and monitor the printer remotely, complete with a camera mounted inside the enclosure to keep an eye on things, while the Klipper firmware on the SKR board pushes all the computationally expensive aspects of 3D printing onto the vastly more powerful ARM chip in the Pi. The end result is faster and more accurate control of the steppers through the TMC2130 drivers than would be possible otherwise.

If you don’t mind tinkering, a cheap entry-level desktop 3D printer is good enough for most of hackers and makers. If you need something more capable or more reliable, there’s always higher-end options from the likes of Prusa and Ultimaker. Very few people need to build something as serious as the BFP, but when the do, we’re glad they send them our way.

Continue reading “Scratch Built 3D Printer Goes Big” →

This GCode Post-Processor Squeezes Lines Into Arcs

November 3, 2020 by Sonya Vasquez 34 Comments

When the slicer software for a 3D printer model files into GCode, it’s essentially creating a sequential list of connected line segments, organized by layer. But when the features of the original model are dense, or when the model is representing small curves, slicers end up creating a proliferation of teeny segments to represent this information.

This is just the nature of the beast; lots of detail translates into lots of teeny segments. Unfortunately, some printers actually struggle to print these models at the desired speeds, not because of some mechanical limitation, but because the processor cannot recalculate the velocities of these segments fast enough. The result is that some printers simply stutter or slow down the print, resulting in print times that are much higher than they should be.

Enter Arc Welder, a GCode compression tool written by [FormerLurker] that scrutinizes GCode files, hunts for these tiny segments, and attempts to replace contiguous clusters of them with a smaller number of arcs. The result is that the number of GCode commands needed to represent the model drop dramatically as connected clusters of segment commands become single arc commands.

“Now wait”, you might say, “isn’t an arc an approximation of these line segments?” And yes–you’re right! But here lies the magic behind Arc Welder. The program is written such that arcs only replace segments if (1) an arc can completely intersect all the segment-to-segment intersections and (2) the error in distance between segment and arc representation is within a certain threshold. These constraints act such that the resulting post-processing is true to the original to a very high degree of detail.

A concise description of Arc Welder’s main algorithm as pulled from the docs

This whole program operates under the assumption that your 3D printer’s onboard motion controller accepts arc commands, specifically G2 and G3. A few years ago, this would’ve been uncommon since, technically, 3D printing and STL file only requires moving in straight line segments. But with more folks jumping on the bandwagon to use these motion control boards for other non-printing applications, we’re starting to see arc implementations on boards running Marlin, Smoothieware, and the Duet flavor of RepRap Firmware.

For the curious, this program is kindly both well documented on operating principles and open source. And if [FormerLurker] seems like a familiar name before–you’d be right–as they’re also the mind behind Octolapse, the 3D printing timelapse tool that’s a hobbyist crowd favorite. Finally, if you give Arc Welder a spin, why not show us what you get in the comments?

Thanks for the tip [ImpC]!

Sharpie Mount Brings Some Color To Your 3D Prints

November 1, 2020 by Tom Nardi 17 Comments

The average cost of a desktop 3D printer has dropped like a stone over the last few years. They went from a piece of equipment you had to wait your turn to use at the hackerspace to something you can pick up on Prime Day, which has definitely been a good thing for our community. But to get the price down, these printers are almost exclusively running single extruder setups with no provision for multi-material printing other than swapping the filament manually.

From a practical standpoint, that’s not much of a problem. But wanting to add a little visual flair to his prints, [Devin Montes] came up with a simple 3D printed mount that holds the tip of up to three Sharpie permanent markers against the filament as it enters the top of the extruder. When used with white or translucent filaments, these markers can give the final print an interesting splash of color. Obviously it’s not true multi-color 3D printing, but it can certainly make for some attractive decorative objects.

The mount is designed for the Snapmaker 3-in-1 3D printer, which is relatively well suited to such a contraption as it has a direct drive extruder and there’s plenty of clearance for the markers to stick up. The concept could certainly be adapted to other printers, but it might be a little trickier in the case of a Bowden extruder or an i3 clone that has frame components running over the top. It sounds like [Devin] is working on a generic version of the marker holder that can work on other printers, so it should be interesting to see how he addresses these issues.

Technically this isn’t a new concept, as makers were pulling off similar tricks back in the earliest days of desktop 3D printing. But this is an especially well-implemented version of the idea, and if [Devin] can really come up with a mount that will work on a wider array of hardware, we could certainly see it becoming a popular way to make printed projects a bit more exciting.

Adding Remote Control To The Elegoo Mars Pro

October 30, 2020 by Tom Nardi 5 Comments

Recent price drops put entry level masked stereolithography (MSLA) resin 3D printers at around $200 USD, making them a very compelling tool for makers and hackers. But as you might expect, getting the price this low often involves cutting several corners. One of the ways manufacturers have made their machines so cheap is by simplifying the electronics and paring down the feature set to the absolute minimum.

So it was hardly a surprise for [Luiz Ribeiro] to find that his new Elegoo Mars Pro didn’t offer WiFi connectivity or a remote control interface. You’re supposed to just stick a USB flash drive into the printer and select the object you want to print from its menu system. But that doesn’t mean he couldn’t hack the capability in himself.

If this were a traditional 3D printer, he might have installed OctoPrint and been done with it. But resin printers are a very different beast. In the end, [Luiz] had to develop his own remote control software that worked around the unique limitations of the printer’s electronics. His software runs on a Raspberry Pi Zero and uses Linux’s “USB Gadget” system to make it appear as a flash drive when plugged into the USB port on the Elegoo Mars Pro.

This allows sending object files to the printer over the network, but there was a missing piece to the puzzle. [Luiz] still needed to manually go over to the printer and select which file he wanted to load from the menu. Until he realized there was an exposed serial port on control board that allowed him to pass commands to the printer. Between the serial connection and faux USB Mass Storage device, his mariner software has full control over the Mars Pro and is able to trigger and monitor print jobs remotely.

It might not offer quite the flexibility of adding OctoPrint to your FDM 3D printer, but it’s certainly a start.

Bringing High Temperature 3D Printing To The Masses

October 28, 2020 by Tom Nardi 77 Comments

Despite the impressive variety of thermoplastics that can be printed on consumer-level desktop 3D printers, the most commonly used filament is polylactic acid (PLA). That’s because it’s not only the cheapest material available, but also the easiest to work with. PLA can be extruded at temperatures as low as 180 °C, and it’s possible to get good results even without a heated bed. The downside is that objects printed in PLA tend to be somewhat brittle and have a low heat tolerance. It’s a fine plastic for prototyping and light duty projects, but it won’t take long for many users to outgrow its capabilities.

The next step up is usually polyethylene terephthalate glycol (PETG). This material isn’t much more difficult to work with than PLA, but is more durable, can handle higher temperatures, and in general is better suited for mechanical parts. If you need greater durability or higher heat tolerance than PETG offers, you could move on to something like acrylonitrile butadiene styrene (ABS), polycarbonate (PC), or nylon. But this is where things start to get tricky. Not only are the extrusion temperatures of these materials greater than 250 °C, but an enclosed print chamber is generally recommended for best results. That puts them on the upper end of what the hobbyist community is generally capable of working with.

Industrial 3D printers like the Apium P220 start at $30,000.

But high-end industrial 3D printers can use even stronger plastics such as polyetherimide (PEI) or members of the polyaryletherketone family (PAEK, PEEK, PEKK). Parts made from these materials are especially desirable for aerospace applications, as they can replace metal components while being substantially lighter.

These plastics must be extruded at temperatures approaching 400 °C, and a sealed build chamber kept at >100 °C for the duration of the print is an absolute necessity. The purchase price for a commercial printer with these capabilities is in the tens of thousands even on the low end, with some models priced well into the six figure range.

Of course there was a time, not quite so long ago, where the same could have been said of 3D printers in general. Machines that were once the sole domain of exceptionally well funded R&D labs now sit on the workbenches of hackers and makers all over the world. While it’s hard to say if we’ll see the same race to the bottom for high temperature 3D printers, the first steps towards democratizing the technology are already being made.

Continue reading “Bringing High Temperature 3D Printing To The Masses” →

Take This 3D-Print Post-Processing Method With A Grain Of Salt

October 27, 2020 by Dan Maloney 20 Comments

There’s a lot of folklore around post-processing of prints from FDM printers. Proponents swear by their methods, which are generally intended to either strengthen the part or to improve its appearance, or both. But do they actually work?

Knowing that a collection of anecdotes is no substitute for actual data, [Stefan] from CNC Kitchen has again performed some valuable experiments, this time testing the strength of parts that have been annealed in salt. This was a follow-up to his recent experiments with baking prints after entombing them in plaster, which yielded mixed results in terms of strength gains. Viewers commented that common salt makes a good medium for annealing prints, so he set about finding the right kind of salt. It turns out that the finer the grain, the better — powdery salt packs tighter and leaves little space for the softened plastic to flow — but that powdery salt is not easier to find. He ended up making his own by pulverizing table salt in a blender. He also had to play around with temperatures and times until coming up with a good process.

The results are impressive. PETG, ABS, and two varieties of PLA prints tested with force applied perpendicular to the print layers all showed marked increase in strength after breaking, to the point of nearly matching the strength of parts printed with the layers parallel to the stress. As with the plaster, parts were printed at 100% infill; a Benchy printed at 20% was notably unseaworthy after annealing. Surface finish on the annealed parts is an interesting combination of pitting with white residue — not unattractive but still a bit weird.

Salt annealing might be a bit cumbersome, but it’s a neat method to add to all the other post-processing tricks that people have come up with for their 3D prints. Continue reading “Take This 3D-Print Post-Processing Method With A Grain Of Salt” →

Improved Flexible Build Plate For SLA Is Ready To Rock

October 26, 2020 by Donald Papp 25 Comments

The Elegoo Mars is an affordable SLA (resin-based) 3D printer, and there are probably few that have seen more mods and experimentation than [Jan Mrázek]’s machine. The final design of his DIY flexible build plate is a refinement of his original proof of concept, which proved a flexible build platform can be every bit as useful on an SLA printer as it is for FDM; instead of chiseling parts off a rigid build platform, simply pop the flexible steel sheet off the magnetic base and flex it slightly for a much easier part removal process. His original design worked, but had a few rough edges that have since been ironed out.

We love how [Jan] walks through all of the design elements and explains what worked and what didn’t. For example, originally he used a galvanized steel sheet which was easy enough to work with, but ended up not being a viable choice because once it’s bent, it stays bent. Spring steel is a much better material for a flexible build platform, but is harder for a hobbyist to cut.

Fortunately, it’s a simple job for any metal fabrication shop and [Jan] got a variety of thicknesses cut very cheaply. It turns out that the sweet spot is 0.3 mm (although 0.2 mm is a better choice for particularly fragile parts.) [Jan] also suggests cutting the sheet a few millimeters larger than the build platform; it’s much easier to peel the sheet off the magnetic base when one can get a fingertip under an edge, after all.

The magnetic base that the steel sheet sticks to is very simple: [Jan] converted a stock build platform by mounting an array of 20 x 20 x 1 mm magnets with 3M adhesive mounting tape. He was worried that resin might seep in between the magnets and cause a problem, perhaps even interfering with the adhesive; but so far it seems to be working very well. Resin is viscous enough that it never penetrates far into the gaps, and no effect on the adhesive has been observed so far.

Watch how easily parts are removed in the short video embedded below, in which [Jan] demonstrates his latest platform design.

Continue reading “Improved Flexible Build Plate For SLA Is Ready To Rock” →