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My father needed to change the oil in his Toyota truck about 6 months ago, but unfortunately he couldn't find his oil filter wrench. I too thought I could be a
by sgnelson 10y ago
My father needed to change the oil in his Toyota truck about 6 months ago, but unfortunately he couldn't find his oil filter wrench. I too thought I could be a hero, and show him that the money I spent on this 3d printer wasn't just for a lark, but it was a useful tool. I found a model of the exact tool needed on Thingiverse, printed the model out (it took about 3 and a half hours if my memory serves me correctly to print the part, all the while my dad was waiting).
Finally, being incredibly proud, I handed my dad the tool, and expected success along with much congratulations from my father for solving his problem.
It was about a millimeter too small to fit around the filter. I had failed. My printer had failed. He went and bought a new oil filter wrench at a car parts store.
One of the problems with STL's is that they're unit independent, they don't care if the part is measured in millimeters or inches. (they also ignore the internal structure of the part, but that's a rant for another time.) And one problem with the 3d printer community is that with all these different printers, there is a wide variety in the tolerances/accuracy of the printed parts. Even with well set-up printers, changing one setting, such as amount of infill, may change the size of the final part. And even if you have a precisely calibrated printer, the person who made the model you're about to print may not.
In this particular case, I don't believe the model was off, but rather to make the tool incredibly strong, I printed with ABS plastic and included extra support and extra shell layers, which I believe may have produced too much material and effectively over extruded plastic, making the part just a bit too small. But I took the part and slammed it into the driveway as hard as I could, and the part didn't even think about breaking, it was quite strong, even if it was useless.
- Daneel_ 10y agoSurely a flat file would fix that though? If it's just ABS it should file quite easily. The tool is far from useless.
- WalterBright 10y agoA file is one of the most under-appreciated tools. I find them incredibly useful.
- sgnelson 10y agoI tried. I worked on it for about 30 minutes and then just gave up. Printed ABS is actually surprisingly difficult to file/sand, it's rather tough stuff. I find it's easier for me to file 6061 Aluminum than it is to file ABS. And as this was a piece with a ~3 inch diameter, and many skinny, flat internal angles, filing wasn't successful.
- qarioz 10y agoThat's why people of the ancient times invented sandpaper.
- Animats 10y agoThere's about 15% shrinkage in extrusion printing with ABS. Most of that occurs during printing (which is what causes lamination cracks), and some of it occurs during cooling after printing. It's just not a dimensionally precise process.
- burfog 10y agoAn STL file is made of floating-point triangles. You get X,Y,Z for each of the 3 corners. It should be integer tetrahedrons. You'd get X,Y,Z for each of the 4 corners. Tetrahedrons let you fill the middle. Each tetrahedron should have fill data, for the whole thing or corner-by-corner for gradients. This would allow variable density, elasticity, conductivity, opacity, hardness, etc. Integer math solves the problem of variable rounding that often screws up STL files. Being unit-independent is much better than having one particular unit. You may think millimeters are great, but to others this might as well be angstroms or chains or twips or rods or parsecs. Unit conversion introduces rounding error. I could go for an optional free-form text field that suggests a unit to use, with the software defaulting to the suggested unit if recognized. Software should let you define the unit.
- sgnelson 10y agoI agree with the unit-independent part, and you hit the nail on the head, I would prefer a text field, or anything that's part of the file, to give an indication of what unit of measurement the part was designed.
- dsfyu404ed 10y agoI've never seen an oil filter a screwdriver and a hammer couldn't get off...