geert_2
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Posts posted by geert_2
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If this is Ultimaker or colorFabb PLA, have you tried my "salt method"? Also read the section about cleaning.
See: https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/
I have printed quite a lot of long models with holes, similar to yours, without any problems. They usually are 100 à 150mm long, 10 à 15mm wide, and 3 à 6mm high, with sharp corners.
The only things I can not print are inverted pyramids and prisms, with a very small base and huge overhangs. Here the warping forces are to high for the very small base.
(Actually, I thought you were printing in ABS, with that amount of warping..., and my salt method does not work for ABS.)
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If Ultimaker makes *very* sure that all Cura-versions can work parallel, also early developer versions, without influencing each other's settings, then doesn't that solve the problem? When they are installed in totally different directories, based on version number and sub-numbers? I think this is already the case, although I don't know about the very early experimental versions?
Then you can just keep a couple of the most stable older versions on your system for production. And you can freely experiment with all new features in the nightly builds, and give feedback.
A version that is stable enough for my production models, might crash or miss an important feature for someone else. And vice-versa. So anyone can keep a couple of "good-enough" old versions in parallel on his system, as his "personal stable branch".
The advantage is that the newer features get tested well in the field, and that no extra manpower is required to maintain and develop several old branches in parallel.
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After is easy: just measure the weight of the model. If you regularly compare this real weight with Cura's estimates, then you will get a good idea of its accuracy for your type of models, and for the requirements (spare amount) before starting.
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If you want/need custom supports, I think it is best to design them in your CAD program. Then you can design all fine details as you wish.
"Custom" supports can not be automated anyway, due to the zillion different shapes, materials, requirements and personal preferences. If Cura has to do this, then this would divert developer attention and manpower from "trying to develop the best slicer", into developing a mediocre 3D-editor + slicer bloatware. At best in Cura there could be options like "place additional supports here" and "remove supports here". But this still doesn't give any real custom features such as holes for inserting tools, special top surfaces, tree-like structures in some places but not in others, etc...
Have a look at these support features, which I use often. Here they are shown in simple test pieces, but in reality they are part of complex models and often closely surrounded by other model features.
Edit: short explanation of the support features:
- Left-center and right-center: these extensions allow to use pliers or hooks to pull out the support. There is not enough room between the model and support to insert a knife: this damages the models too much, as they are quite small and fragile, only a few mm. This would be very hard to automate.
- Bottom-left: this allows the support to be peeled off layer by layer. Sometimes useful.
- Bottom-right: the small overhang of the support gives a better first layer of the model above the support. The tree-structure allows to insert pliers.
- The ribs on top of the support allow a smaller gap between support and model, giving a better underside on the model, and make removal easier than when using a flat plate. Usually I make the ribs 0.5mm high and wide, with 1mm gaps in-between.
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Obviously, hardware stores can't beat that ebay price.
Last week when walking through a Brico shop, I took a quick look at the prices. An "industrial" bottle of 20ml cyanoacrylate costs 13 euro (Belgium, Europe). Compared to 6 euro for 2 little tubes of 3ml of the same product, next to it. I think the brand was "Bison".
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I have no answer for your question. But if you would find one, you might run into other problems, depending on the size, nozzle temp and print time of each of these extensions. If these extensions are too small or the print temp rather high, it might not get enough cooling when the nozzle is staying too long in the same area. So it might deform as in the photo below.
I think your dimensions are on the edge of what can still be done: I guess it should go well if you print rather cool. So I suggest you first try if such deformation happens by cutting the model in pieces, and only printing one extension, just for testing.
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I think you also need to specify which bonding method you use (also describe how applied), how you clean the glass bed, which printing materials you use, and how you calibrate the bed. Because these might be the problem.
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If your model consists of geometric shapes, you can do this in DesignSpark Mechanical. This is a freeware 3D-editor for geometric shapes. I have used this feature once to rotate text around a cylinder. It uses the "project" feature, but I don't remember the exact procedure, so you will have to google a bit. There are training videos or tutorials around the internet showing it.
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When it finally started running, did the fan run smoothly? Or does it make a lot of noise and a sort of grinding sound? If the latter, its bearings might be worn out, preventing it from starting? After a while, it does start, but only at low speed, and wobbly. I have seen this quite often in computer fans, in the old days of Windows 9x and Pentium I, II, etc...
If it are the bearings, replace the fan. You could lubricate the bearings to get a few more days/weeks/months out of it. I have done so by making a small hole in the silver cover plate with a needle, and then injecting a little bit of oil into that hole.
You could also pinch the cable and break it while reassembling the nozzle on an UM2, if it gets stuck between the metal parts.
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I once tried welding 2.85mm pieces manually. It works, but it is cumbersome.
First, you need to design and print a sort of clamp or guide in which you can keep both ends of the filament aligned nicely. So that they match well while welding.
Then, cut off both filament ends in a 90° angle. Insert them in the clamp/guide. Heat a metal plate, and old knife, or a spatula in a flame until well above melting temp of the filament. Insert that hot metal inbetween both filament ends. Push the filament against the metal slightly, so it melts. Remove metal plate, push filament together, and let cool down. (So, obviously the "clamp" needs to keep the filament ends in place, but it also needs to allow sliding them. It should not be a tight clamping, but rather a sort of guide. And it should be one that you can operate with one hand, while keeping the hot metal plate in the other hand.)
Finally, cut away, sand, file or machine away the inevitable flanges. To minimise these flanges, don't melt too much filament, and don't push it together too hard. A hotter metal plate works better, as it takes less time to melt the filament's ends.
It works: it gives a strong bond and feeds well. But the removing of the flanges is very time consuming, because the resulting diameter on that spot should be close to 2.85mm. Too thick or irregular, and it will get stuck. Too thin, and you get underextrusion.
This is the "clamp" or guide I used. Clamping and sliding is done by pressing the filament down with my fingers. Very primitive, yes, but it was only ment for a quick test, not for production. For better results the filament should have been clamped over a longer distance, and with a top clamp too.
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This was my oversized design. Although technically it worked, the uglyness did outweight the benefit, as you can see.
The original button raised 5mm also does the job well enough.
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I think super glue (cyanoacrylate) is already one of the cheapest glues, since you need only very little to get the job done. The thinner the layer, the stronger the bonding.
I don't know any glue that bonds better on PLA. Cyanoacrylate seems to melt the upper layer of the PLA a little bit: if I break apart a bonding, it often fails in the PLA, not in the glue.
Maybe you could instruct your students to design special "bonding areas" into their models, so that you can get a maximum bonding strength with minimum amount of glue? How to do that, will depend on their models, for example a few flat mating plates? Or some sort of dovetail system, like in old wood works?
Here in Europe, cyanoacrylate tubes usually are little tubes of 3 grams or 3ml. But they do exist in "industrial" packaging too, for use in industrial production lines. This is a lot cheaper per volume. Maybe that could be part of a solution?
For bonding ABS you could use acetone of course, on the condition that you have good vapour extraction. Put the parts together, and let some acetone drip into the seams. Keep parts together for quite a while, until the acetone dries out.
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Concerning outgassing, it is not only the material itself. 3D-prints do contain lots of small holes and "channels". These voids may contain air, gasses from the plastic when it was still hot, glue, hair spray bottle gasses, alcohol from cleaning the glass plate, or water vapour from removing and washing the model, or water vapour from absorbing moisture from the air. If it is a vacuum clean room, these are going to come out too.
So I don't think anyone could give valid official specs. If the model should not outgass, maybe you need to put it in vacuum for several days, prior to use? Not sure what this would do to the chemical structure (as some composites get destroyed when put in vacuum, if their chemical structure contains bonded water, and that is dislodged in the vacuum, for example glass ionomer cements).
At least, FDM prints generally do not smell, so they probably do not outgass very much at atmospheric pressure. Other 3D-prints, made by lasers or UV-lamps solidifying a liquid resin, do smell very strong for months and months. This indicates that there is a substantial amount of uncured resin present, that is outgassing. I have some models that still smell very strong after two years, in UV-cured resin.
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What you could do: measure the axis width and length with calipers. Then make the hole slightly smaller (0.1mm or so). Then manually heat it up with a tiny hot air gun and push it on while the plastic is still weak. Or file it out, or scrape it out with a knife, until it fits. If you give the hole the same depth as the original, minus 1mm, there should be no problem activating the switch.
I also designed a different knob, one with two areas, like in very old radios: a much larger diameter for finetuning, and a much smaller diameter (extruding 1.5cm from the other) for fast rotating. Although it did work a little bit better than the standard knob, it looked way too ugly. I couldn't get over that. So I removed it again.
Now I have put a little piece of PVC tubing inside the hole of the original knob. So the standard knob is now protruding 5mm from the panel. This makes it much easier to rotate the knob, and it does not harm the visual beauty of my printers (UM2). This is a good balance.
If you take a piece of small, hollow PVC tubing (like used in laboratory equipment) and cut that to size, you can still pull it out later if it would not give the desired effect. There is no permanent damage.
Or you could design a little stub, print that, and put that in the original knob's hole. Make sure you design a hole in the stub, and make an M3 thread into it, so you can always pull the piece out again.
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So do you have "just" an optical mouse or a laser mouse? The difference is that laser mice are capable of tracking movements on transparent materials, normal optical mice are not. It does have to be a laser sensor for the filament.
Probably it is just an optical mouse, as it has a red lamp illuminating the surface. A simple Logitech M 100, price 10 euro. I can't imagine this thing having a laser, beam splitters and all that stuff, for just 10 euro. I looked it up, but the official specs on the Logitech website don't tell:
- Tracking technology: Optical (no more details specified)
- Sensor Resolution: 1000 (no units specified)
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During the test phase, if not done yet, I would suggest that you not only test if it works correct. But also how it works incorrect. So, try to abuse it and try to crash it.
For example:
- Upload huge files or huge amounts of data.
- Log in with as many people as possible at the same time.
- Try to spam and hack it.
- Random click on functions and buttons in fast order, or press all keyboard keys at once (often surprising how much programs crash on this).
- Upload wrong filetypes, or damaged files.
- Try to harass other people (with their knowledge and agreement of course).
- Try older and newer browsers (preferably including Pale Moon, a Firefox derivation that still uses the menubar).
- Try browsers with and without extensions (e.g. with "no-script" and anti-banner or anti-popup extensions).
- Try mobile devices.
- Try attacks with bots (only in a separate safe environment, not connected to anything else).
- Etc...
I don't know how it is at Ultimaker, but sometimes this aspect, "resistance against abuse and idiocy", is overlooked during development, because developers generally are sane and clever people who do things right. Otherwise they would not be capable of developing things. The problem is not the general public here either, which are also developers and clever technicians and hobyists. But the thing has to be foolproof against abuse from the rest too, like spammers, all sorts of bots, and harassing.
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Out of curiosity, I just tried the "optical sensor approach" with my mouse (standard Logitech mouse, with a red light), and moving short pieces of filament in front of the sensor. Then the movement of the cursor on-screen - or the lack of it - clearly indicates whether the mouse sensor sees the filament or not.
Results:
- colorFabb white and red PLA/PHA, opaque: detected very well, cursor moves smooth. These filaments have a rather rough surface.
- Ultimaker pearl PLA: detected well. This filament has a smooth surface, but sort of internal glitter particles for the pearl effect.
- ICE PET (or PETG, not sure), transparant yellow, smooth filament surface: detected very poorly: cursor jerks occasionally, but often no movement.
- same ICE PET, but with indents from the feeder wheel: detected very well. Big difference compared to "undented" filament.
- Ultimaker nylon, transparant clear (no indents): not detected at all, could not get the cursor to move, even not jerk. This seems too transparant to reflect any differences in light during movements.
So, to have a reliable detection, the sensor should sit behind the feeder wheel and shine on the indents caused by that wheel. At least for this sort of optical mouse sensor (I don't know if and how a "laser mouse" differs from a standard optical mouse?). But when sitting after the feeder wheel, it would not detect out-of-filament conditions, since the filament is not advanced anymore once the feeder wheel is empty, so the sensor would always see filament, except after unloading. The sensor would detect a non-movement condition, but it would not know the cause: out of filament, clog, filament stuck on spool (due to kinks, or end not coming loose), or stuck elsewhere?
If I had to design it, I would probably go for a mechanical microswitch, with a little roller wheel and rather large travel. Similar to those used in compressed air cylinders to detect when they reach end-stops. This for the out-of-filament conditions. Maybe combined with an optical sensor shining on the indents (behind feeder wheel) to detect no-movement conditions (clogs, stuck).
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Also, keep in mind that (if this is normal PLA) this thing is probably going to deform and maybe melt when you take a hot shower!
You should not subject standard PLA to temperatures above 40 à 50°C. Also don't leave them in your car in the sun (in Australia probably even not in winter).
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I do the leveling (UM2 non-plus) the "gr5-way". First adjust the nozzle until the plain white laser A4 printing paper has a bit of resistance, but not too much. Yes, it is very subjective and not standard indeed. But at least you can get about the same calibration on all three spots.
Then print a test model with a lot of skirt lines. And manually adjust the three leveling screws to get the most even distribution. Because sometimes when the corner is perfect, an area halfway is not, and is 0.05mm or less off. It is not much, but it is visible in the first layer when using low layer heights (0.1mm or 0.2mm). So the easiest way to level this out is is visually.
Edit: just realised that I hadn't answered your original question. A piece of plain white paper is 0.11mm here. This is standard "80 gram" A4 laserprinter paper. I measured it on about 20 papers of different brands and batches, which were laying around here, mostly printed (thus having been through the printer's heater and rollers).
Measured with good quality professional digital Mitutoyo calipers with 0.01 mm resolution. Thus theoretically the result could be between 0.10 and 0.12mm, but since the calipers were zerod well, and since the final size was displayed very stable (no blinking last digit), and since it are small values close to the zero-point calibration, we can safely assume the value is between 0.105 and 0.115mm, thus averaged and rounded to 0.11mm. This was for all papers I tried.
Thicker, better quality paper, like for company letters, is 0.12 to 0.13mm. This might be "100 gram" paper, but not sure.
Things could of course be different in other parts of the world.
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This looks a bit like when you manually extrude silicone paste in a circle: it sags, and it pulls the previous layers sideways due to its own unstability and flexibility.
Could that be here too? Maybe: temperature too high, walls to thin, material too flexible (for the size of the object), or some sort of mechanical wobble in the model due to inertia or resonance?
If I had to print it, I would print it as slow and cool as possible. With thick walls. And with a layer height of only 0.1mm: a thicker layer height needs more time to cool, and might easier be pulled sideways than a thinner layer, I think. But this is a guess.
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In all spools that I have used, the beginning of the filament was fixed in a hole in the spool, and bent around the corner. So, even when running out of filament, that end can not come off the spool, and the "empty-sensor" would never trigger. The feeder would just start grinding on the stuck filament.
Even if it would come off the spool, the sharp corner would cause that end to get stuck in the feeder anyway.
To detect this, you would need an intelligent optical solution that watches the remaining amount of windings on the spool also. But then, that would not work well for people who put the spools on the floor, or in a box with disseccant, or people who use loose unspooled filaments. And it would not detect if the filament somewhere gets mangled. I had that once: it sort of flipped 180° and there became a kink in it, which of course got stuck in the feeder. I did not see it happen, so I don't know how it occured exactly.
I think the best way is to put a high-res webcam, and maybe a LED-spotlight, on the feeding traject, and monitor that from wherever you are? The most intelligent solution is the human mind.
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I think by far the simplest method is like ahoeben says, but then you are going to have quite visible layer-steps, like stairs, especially in the center.
If you want less visible steps, maybe printing it vertical might be an option? But then you would need to design a sort of support beam structure around it, for good adhesion to the glass and for stability. If your printer has no Z-axis issues, this should give a smoother surface and require less post processing, I think. Of course the support needs to be cut off afterwards.
Would be interesting to compare both methods.
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Also, check if your bed temp indeed reaches the set temperature. If not, try in steps of 5°C more or less.
I had no problem printing NGEN on an UM2 (non-plus) with the default brass nozzle. So brass should work. It can be printed on bare glass without lifting (and even without brims), on the condition that the fans are off. With fans on, for models that do have overhangs and need more cooling, I need to use glue, otherwise I have warping. I used dilluted wood glue (about 10% white wood glue dissolved in water), which worked perfectly.
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Abrasive materials are: 'metal'-fills, glow in the dark, carbon fiber filaments. Did I miss anything?
You missed stone-fills.
I found that plain white (colorFabb) is also slightly abrasive. On one of my printers I only printed colors (mainly orange, red, natural, blue, pearl, from both Ultimaker and colorFabb), and on one I printed almost only white. After about 800 hours of printing on both, the "white" nozzle is clearly worn: the flat area at the bottom of the nozzle is larger than that of the "color" nozzle, which is still fairly original. The inner diameter of both nozzles has increased from 0.39mm to about 0.41 or 0.42mm. I haven't counted the amount of white spools I printed: maybe 6?
I guess this is due to the filler particles used in the white, to get a thick opaque color. But I have no idea which particles they use: talcum? Titanium dioxide? Other?
So, nothing to worry about if you print only a few spools of white. But if you print white for 24h/day, you should keep an eye on this.
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The original button raised 5mm also does the job well enough.
Stumbling through the forest of 3D Modelling - what software for newbie?
in Design for Additive Manufacturing
Posted
SketchUp is good for getting an idea of how to use a 3D-modeling interface, since it has a very simple and intuitive interface. Use the last free versions (was that 7 or 8?). But do *not* use it for 3D-modeling for 3D-printing, since the models contain too much defects. The walls don't close and are not "watertight", so these models are not considered solids, but hollow models with infinite thin walls, and obviously you can't print that: it is a mess.
I use DesignSpark Mechanical since it came out. It is excellent for geometric shapes, thus based on straight lines and curves, such as machine parts. There are a lot of video tutorials, although you may have to search a bit (try Youtube too). You can also use the tutorials of SpaceClaim, if you keep in mind that DesignSpark Mechanical only has a limited set of these features, and that there are small differences in cosmetics. But the modeling concept is the same.
The biggest advantage of DSM over much other 3D-editors is that you can keep modifying models easily: just select a surface or an edge, and pull on it, or move it.
For organic shapes, Blender might be better, but that has a high learning curve, definitely not easy.
Also, Form-Z (from the company AutoDesSys I think) is good in organic shapes and architectural designs, but it is not free. The interface of Form-Z is much more like that of DSM and SketchUp, thus much more intuitive than Blender. Have a look at demo videos on Youtube.
I tried OnShape too, but I have problems with the interface: I can never find the features I need, and I can't get them to work. I can't find previous designs, can't save and export them, etc., without consulting the manual every time. This may be my problem, as some other people can create fantastic models in OnShape. But their phylosophy obviously isn't mine: it's all in the wrong place for me, unfortunately. Some things are too slow, due to the internet. Further, in the free OnShape versions, I think you can not hide your designs anymore: they are visible to the whole world. You should check this. Originally, you could have 10 private models (although for some weird reason, I can only have 9: somewhere some invisible model seems to have gotten stuck beyond reach). Apart from that, it is a real achievement that they can get a 3D-editor to work in a browser.
FreeCAD also works if you know exactly what you need, before you start. But it is very hard to change a design later: you often have to restart from scratch. Thus not suitable for me.
So I would suggest you try DesignSpark Mechanical first. It is free and only requires registration. Also watch demo videos and tutorials of all programs, to see if the workflow is suitable for you. Everyone has different preferences and requirements.