It was a bumpy road for a few months, as Cyprus-based 3D printing company Ilios 3D contemplated closing. But things seem to have turned around, especially once the company introduced its Ilios Photon 2 DLP 3D printer. We recently heard from Demetris Ruslan Zavorotnitsienko, the founder, CEO, and lead developer at Ilios 3D, and the company has been putting the printer through its paces, running accuracy, resolution, and repeatability tests.
“3D Printing, just like any other way of manufacturing parts, in our opinion should be just as accurate as the parts you want to create,” Zavorotnitsienko wrote in an article for the Ilios 3D website. “We take great pride in the build quality and components which are used in our 3D printers. Ilios Photon 2 is no different, with 16mm hardened steel ball bearing spindles, all metal slide joints and absolutely massive framing, which allows the 3D printer to create models with the upmost accuracy. We use these types of components and overbuilt constructions so that the end user spends no time in tinkering, upgrading or fine tuning the 3D printer and can expect the best possible outcome from the machine right out of the box.”
However, Zavorotnitsienko concedes that it can be difficult to prove a printer’s accuracy with just words and numbers. So Ilios 3D put the Photon 2 through a series of tests, with quality measuring equipment, to give users a real look at what the Ilios Photon 2 is able to accomplish, even with potential issues causing possible deformations at the micron level.
The company conducted tests on the three main areas during a 3D printer’s build cycle:
- Accuracy and resolution of the mechanical movement
- Repeatability of the constant movement during layer creation
- Flex as the model gains weight on the build area
Ilios 3D removed the VAT assembly from a Photon 2, which was set with default settings, and “placed a Mitutoyo Micron Dial Indicator with resolution of 1 micron (0.001mm) per step and accuracy of +/- 3 microns (0.003mm), Jeweled bearing for absolute accuracy and Shock proof characteristics.”
Zavorotnitsienko reminded users that most machine shops use a similar measuring tool, but with a ten micron resolution. A 7 mm thick steel plate covers the entire build area and a 25 x 50 mm aluminum extrusion, and the tool is mounted on the plate; this setup makes the measurements come out as accurately as possible, with no deflection, movement, or external vibrations during operations.
“The fact that the Base Plate of the Ilios Photon 2 is made from Dur-aluminium with thickness of 6mm also contributes to the overall accuracy not only during the tests but also during normal operation of the 3D printer,” Zavorotnitsienko explained.
Zavorotnitsienko said that the repeatability accuracy of a 3D printer is one of its most overlooked characteristics. As the distance between layers is determined by the lift moving up and down after each individual layer in the print cycle, this is a pretty important factor for 3D printer users to check. Generally, the backlash of cheap spindle and slide assemblies can cause a printer’s repeatability and drive train accuracy to drop, “without even considering the flex of a single point lift arm that common 3D printing assemblies have.”
The Photon 2 uses a dual spindle and slide assembly, mounted through metal junctions, causing low repeatability deviations. During the Photon 2 repeatability test, measurements were taken ten times to get an approximate overall value, and the printer’s lift returned to the same spot each time, with deviations of only 0.1-1 microns.
Zavorotnitsienko warns users to remember that each layer adds strain to the lift during detachment: any backlash in the assembly will cause all the layers to compensate by following the error. Since the printer’s movement goes through multiple assemblies with variable build quality before it reaches the model and VAT surface, a “theoretical” motor accuracy won’t truly determine the accuracy of your printer. Ilios 3D set the Photon 2’s movement to single steps during the accuracy-resolution test, and since the motors operate at 1600 steps per revolution and spin the ball bearing spindles at a 2.5 mm pitch, the expected accuracy was determined to be 1.56 microns. So for every 1 mm movement on the lift, the Photon 2’s motor will actually do 640 steps in total.
“As tests showed, the actual accuracy of the 3D printer was even higher than the specified accuracy of the tool with which we measured it,” said Zavorotnitsienko. “However since we are limited by the accuracy of the measuring tool, the result can only be stated to be within +/- 3 microns.”
Zavorotnitsienko reminds people that the quality of the machine should increase as the build volume does. If a printer can’t handle building a large model, or assemblies are built with cheap parts, each layer will displace more resin than needed from the curing area, and the lift will actually be dragged with the model and speed up warping. If you want to check your 3D printer’s “flex,” just wiggle the lift when it is static, and if you see even a little flex, that means the 3D printer’s accuracy is not what it claims to be.
Ilios 3D took a 616 gram weight and measured the Photon 2’s actual lift displacement. These flex tests showed that when force is applied at the lift’s edge, which has less support, there is a five micron flex displacement. Since most models are built in the center of the plate, Zavorotnitsienko says it’s safe to assume “that the 5 micron flex would not even show up at the maximum build volume of the 3D printer.”
“Based on the above proven tests, we can with ease say that the Ilios Photon 2 3D printer is well within the claimed specifications since similar equipment would be suited for laboratory and research work,” Zavorotnitsienko said. “Having in mind that normally a tool with 10 times the error and 10 times less resolution is used in professional machine shops, the resolution and accuracy of the main 3D printer lift is higher if not the same as the measuring tool used in our tests.”
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