Overhangs and Bridging
Overhangs and Bridging are two of the hardest things to accomplish in desktop 3D printers based on the FFDM process, and the Overhang Print Test, 40mm Cube with holes, and Stepped Pyramid Bridging Test are all designed to test these parameters to the max. This is where the printer will really prove its worth or show to be just another mediocre desktop printer.
Up first is the Stepped Pyramid Bridging Test, which is designed to test the printer's bridging capabilities over various length spans. This is a really good test and shows just how well the printer handles thin bridging, the hardest bridging to achieve.
Second, we will test the printer's ability to handle concave overhangs using the 40mm Cube with Holes model. This model is based on a 40mm cube that has had spheres cut out of its side with 9 holes punched through each parabola.
Finally, we will test the printer's ability to tackle overhangs of varying degree using the Overhang Print Test models. These models are designed to test the printer's ability to print overhangs from 12 degrees to 45 degrees with a total of 10 different overhangs.
The Stepped Pyramid Bridging Test shows some very good results when it comes to bridging. The longest bridge is 50mm, while the shortest is only 9mm. While the 50mm span showed some sagging, it all but disappeared around the 25mm bridge, and was clear the rest of the way up. Bridging is something that is very finicky, and this could be improved if the user were to spend some time fine tuning the bridging parameters in Slic3r.
Up next is the 40mm Cube with Holes. This object is one of my favorite to print and show off to students and spectators at outreach events as they are usually mind blown by its complexity. Here you can see that the cube is very square and the concaves look like you took a perfect ice-cream scoop out of each face. I do not have a photo of it, but the cube measured in at 40.02mm, which is consistent with the accuracy we saw on the 5mm Stepped Cube print.
For the most part, the holes are uniform and round as can be when you consider that they are formed by leaving voids in the layer being printed. There is some layer splitting about halfway up the cube, but I attribute this to a temporary drop in the extruder temperature. There is layer banding present in this print as well, and I think it may be a flaw in the model slicing as it is not present in other prints you will see in this review.
Now we come to the first of two of the Overhang Print Test models. This particular model varies the overhang from 15-degrees to 45-degrees in 5-degree increments. The Ord Bot Hadron appears to handle overhangs up to 25 degrees quite well, with curling beginning to form at the 20-degree and 10-degree levels when unsupported. On the right-hand side, we see that the supported overhangs actually pass the test with flying colors.
Here is another angle that better illustrates the curling that begins to occur at the 25-degree mark. Also note that the supported side remains flat, but you are able to see some minor lifting of the supports that begins around the 15-degree mark. This was likely due to a hot-spot on the heated bed as PLA actually sticks less to glass the hotter it gets.
Taking a look from the bottom, we can see that the layers were uniform, but the higher overhangs simply stretched them out too thin without enough overlapping to properly prevent curling.
Moving on to the smaller Overhang Print Test model, we can see that the 18-degree level did not curl for some reason, but the 15-degree and 12-degree overhangs were just too thin to resist curling. Just like the larger test, the supported overhangs fared well.
Another angle showing the curling of the 15-degree and 12-degree levels.
From the bottom, we once again see uniform layer thickness, but the longer overhangs curl from a lack of sufficient overlapping of layers.
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