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geert_2

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Everything posted by geert_2

  1. I do use surgical blades (scalpels) to remove blobs and strings, so I am a plastic surgeon. :-) You can chemically smooth PLA and PET with dichloromethane. This works like acetone on ABS. First remove all big defects with a knife and with filing/sanding, and then chemically smooth. One light application is best, a quick brush-on. If you overdo it, it will penetrate too deep into the plastic, and make it weak, deform and crack after a longer time. It's a solvent, so it dissolves stuff and then dries out... It smooths into a high-gloss, which feels very smooth, but this
  2. It is 20 years ago since I last selected an UPS. A few things I vaguely remember: - Find the continuous power it has to be able to deliver. See the name-plate on your machine. Multiply that value by 2x, to account for variations, little add-ons like a LED spot, and system-degradation. - Find the peak-current it has to deliver. Some devices may draw a fairly low continuous average power, but with occasional high peaks. Multiply that peak by 2x, just to be safe. - Chose the time the UPS has to hold up these values. - Look up the dimensions and the prices of UPSses. And
  3. A couple of years ago this has been discussed here, with good explanations and photos. If I remember well, the most common was that the connections at the back of the bed broke, and how you could repair them, but I am not sure. Maybe you can find these posts again?
  4. I do understand this particular situation, but generally confirmation-dialogs are there for a very good reason. On my UM2 I have occasionally pushed the "abort" button by accident when scrolling through the menus, while fine-tuning the printing. That scroll/push wheel occasionally skips to the next option while pressing the button, if you don't hold it perfectly still. I am glad that confirmation-dialog was there... Idem for deleting files in Windows. Potentially destructive actions should require confirmation. That is why in UI-design the rule is that the confirmation-
  5. I don't know your printer, but to see if there are no *mechanical* blockings, try switching it off, and move all things by hand. They all should move smoothly, without requiring brute force, and they should have no hard stuck points. In this way, you can often feel if something is wrong: broken bearings, incorrect axis-alignments, gears or belts blocked by dirt, too dry rods and linear bearings, too much play, etc... Things should have a precise fit with no play, but still move quite freely and smoothly, similar to cameras and microscopes, or like the mechanics in car engines. It are precision
  6. Or design your custom supports in CAD, as part of the design, integrated into it. Then switch off supports in the slicer. Standard supports are good for standard situations. But special situations might require special supports. You can make custom gaps between supports and model, you can include holes and other features to insert pliers or hooks to make removal easier, etc... A few examples: Custom orange and pink supports, with custom brims, that can easily be grabbed by pliers and wiggled out. These are tiny items, too small to get in there with a knife.
  7. I think that bridge came out quite well too. A bit of cement-color paint in the grooves, and a bit of stone-like paint overall, and it will look great in the landscape. I have seen far worse bridges in HO-landscapes. :-)
  8. You might get more satisfactory print results if you specifically design or redesign it for 3D-printing. I gave the idea a quick and dirty try. These wings are way more stable and should print better, with or without brim. And the eye for the wire is less likely to break off. Also, it has less steep overhangs that could cause trouble. This is a very simple model made by adding and subtracting basic shapes, and then rounding and chamfering a few edges. Created in DesignSpark Mechanical. ... Okay, it looks more like a bomb than a rocket now, but hey. 🙂 Here the STL file, and the De
  9. Thanks for that info. Yes, that all makes good sense... Is that titanium plate smooth and high gloss, or rather sand-blasted? Could you print PLA or some materials without any bonding at all, like on glass? As for a 2mm version: maybe you could glue a couple of tiny 1mm plates on the titanium plate under the clips, so that you do not have to rework the clips, but you can still use a lightweight 2mm plate (if that would be stable and stiff enough)? In this way you would still have the option to use the original glass.
  10. Maybe you could switch off prime towers in the slicer, and make your own in CAD, as part of your design? Then you can make them exactly as you want? Similar to the way I make my "dummy cooling towers" in CAD, to move the nozzle away from small objects, so they get more cooling time. The green cube here is a dummy cooling tower, otherwise the top area of the yellow part would not print well, it would deform because the heat can not escape. These models are quite small: for reference, text caps height is only 3.5mm, and text legs are 0.5mm wide. The dummy cooling tower ha
  11. For long-term stability, I prefer to design the mesh into the model in CAD. Future slicer versions, or different slicer brands, might treat infill patterns differently. Or they might give the infill a lesser density than the walls. If the mesh is designed in CAD as part of the model, it is more stable. Usually I make a solid block as the base first, and then create one hole into that block. And then I create the mesh pattern by multiplying that hole horizontally and vertically as many times as I need it, using a function "create pattern" or similar. See the sift below, for use in t
  12. Out of curiosity: is there a specific reason why you have chosen titanium? Instead of ceramics, steel, aluminum, filled composites, or other materials? And what did it cost, as titanium is not the cheapest?
  13. I usually set top- and bottom thickness equal to wall thickness. For a 0.4mm nozzle, wall thickness often is 0.8mm or 1.2mm. So maybe try that first, and adjust if required? I have no idea what value it uses when you fill-in nothing.
  14. On a standard UM2, the first layer is printed at 20mm/s, while the standard speed for the rest is 50mm/s. Speed gradually increases (at least it seems so) from this 20mm/s to 50mm/s during the first couple of layers. But at 20mm/s the material is sitting 2.5x longer in the nozzle than at 50mm/s, so it is much more liquid. And the pressure on the feeder wheel is less, making that feeder slip less onto the filament. The square pattern on the feeder wheel translates into a *diamond* pattern in the filament due to this "partial slipping". The square holes are being stretched out, which gives a low
  15. Printing multiple models improves cooling, but increases the risk of the curled-up parts being hit hard when the nozzles comes back from the other object. It depends on the geometry of the models. This testmodel was supposed to become a bridge, or table. The inverted triangles are only for support, and need to be removed after printing. It got knocked over due to the edges curling up quite a lot, about 1.5mm, and the nozzle hitting really hard: Close-up: Now with redesigned supports, and a bigger footplate.
  16. These are in transparent PET (which becomes translucent after printing, due to the entrapped air in-between the sausages, breaking the light). I believe transparent PLA should even work better than PET as it flows better, but I don't have that... If you need a higher temp-resistance than PLA, then PET or CPE would be best, I think. Translucent materials like colorFabb "natural" PLA/PHA also work with bigger watermarks, but not with such fine text as this. For fine details, you need a really transparent material, and you need to print it slow, cool and in thin layers for maximum eff
  17. Such steep overhangs curling up is normal. In my experience, printing cool and in thick layers helps a little bit, but does not eliminate it. More than half of the extruded sausage is printed in the air and has no support to stick to. So it sags when extruded, and then it curls up when cooling...
  18. I am just guessing here, so... The wavy aspect looks like the previous lines shining through. Thus: smooth previous lines will show through less than lines with big gaps. Have you checked if layer-height, speed, temp and cooling fans are the same everywhere, on all layers? Often they differ for the first layer(s). If they are all the same, I would guess that the bed is too close. At least if it would be a standard 3D-printer; hard to say about a custom one. I don't know if effects of pellets not molten enough might play? Long ago we had a plastic company in
  19. Just a question: do the flow channels have a special irregular shape? Or are it just straight channels? If straight channels, maybe another option could be to print them in a very strong material like nylon, cast the gel around it, and then pull-out the nylon strings? But this obviously won't work with irregular channel shapes... The problem with dissolving PVA could be that you need a good flow in the channels, to wash away the dissolved material, and to apply fresh water. I don't know if such a flow is possible, it may depend on the dimensions?
  20. This is the maximum I ever got. From my tests: print as slow as possible, as cool as possible, and in as thin layers as possible. The best here is 0.06mm layers, 10mm/s speed, and around 200...210°C. This is transparent PET (brand no longer available). Top row 50mm/s, bottom row 10mm/s; layer-height from left to right (mm): 0.4; 0.3; 0.2; 0.1; 0.06. Blocks are (in mm): 20 x 10 x 10, with my hollow watermark sitting halfway. Do similar small tests to dial-in optimal settings for your system and material. Sanding, polishing, or chemically smoothing with dichloromethane ma
  21. Hoi Sander, I would be interested, but I have a few questions: - Can this PETG be smoothed with dichloromethane too? How well does that work? - How transparent can you get parts, with which optimised settings? - How is UV-resistance, when sitting outside in the sunlight? - Over time, does printing with this PETG accumulate dirt in the printer-nozzle? The brand of PET that I use now, does leave a sort of glossy varnish coating in the nozzle, which is hard to remove. Contrary to PLA that rather leaves powder-like ashes that easily come off. - When parts fract
  22. Do *not* use SketchUp: this might seem to work well in the editor, but it will be an endless nightmare, as soon as it comes to printing, because it always creates defective models. Big no-no. I use DesignSpark Mechanical: this is freeware, only requiring registration. Good for geometric shapes like machine parts. It is easy to learn, and there are lots of good tutorial videos on Youtube. Not suitable for organic shapes. Other people prefer other programs. Search on Youtube for 3D CAD software tutorials, and try a program of which the workflow appeals to you.
  23. Indeed, PLA changes crystal structure into more crystaline as it ages, becoming more brittle; this is reversible. Also, it degenerates due to water-absorption, this is not reversible. I also found that if a string of filament is stretched for a longer time, like in the bowden tube, micro-cracks tend to form. This also makes it brittle. Probably this is what you have? Also, some colors and brands are worse than others. So, I remove the roll after printing, and store it in a plastic box with bags of desiccant. These bags can be re-used by heating t
  24. Yes, you can glue PET parts with dichloromethane, on the condition that they are touching each other. Dichloromethane dissolves the outer layers and makes them bond. But since it is a very thin liquid, it has no "filler" properties, contrary to epoxy glues. So the parts have to mate almost perfectly. I mate them first, and then let dichloromethane drip and seep inbetween both surfaces, using a brush. Bonding strength is comparable to contact glues: not very strong, by far not like composites, but in most cases good enough. Smoothing/bonding also helps to seal tiny holes and makes it water-tigh
  25. Mine are both: Sandisk, SDHC, 4GB, speed class 4. Any speed-class should do, as they are all faster than the printer anyway. With most of my gcode-files being 2 to 5MB, it could contain about 1000 files.
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