jbeale
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Posts posted by jbeale
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It is very nice that you are making renderings from OpenSCAD files uploaded. However I wonder what version of OpenSCAD you are using, because it doesn't match my model. Compare what I see:
with what your software rendered, below. Colors don't translate, OK; but I see the screw heads are missing. Also, the cylinders modelling the caps and toroid on the PCB have the wrong (much too small) diameter. The cylindrical screw bosses in the case top & bottom are completely gone. I am using OpenSCAD version 2014.10.02 (beta) but this file also renders properly in OpenScad version 2014.03 .
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Maybe OT since I have a UM2 which came with a glass bed already. Anyway, after using a thin receipt slip paper for levelling, and setting first layer to 0.1 mm in Cura, and using a vanishingly-thin layer of glue stick for PLA adhesion, the bottom surface quality looks quite good to me. Practically like an injection-molded part: https://www.youmagine.com/designs/28byj-48-mounting-bracket
My only mod is a fan shroud which I think improved overhang performance slightly, but I think careful extrusion temperature and speed adjustment is the more important factor.
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If you are going to machine something, the isolator might be a good application for a machinable ceramic like Macor: http://en.wikipedia.org/wiki/Macor
It is stable up to 800 °C and being a glass ceramic it has much lower thermal conductivity than metal: Aluminum: 205 W/(m.K) Macor: 1.46 W/(m.K)
Macor is a somewhat exotic and expensive material, but you only need a small piece.
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I am playing around with some "deep groove" ball bearings. I have read that "Deep groove ball bearings mainly take radial load as well as moderate axial load." But what does that mean exactly?
For example, one particular bearing (6203Z, OD=40mm) has a spec for static (4.8 kN) and dynamic (9.55 kN) loads but I think that is radial only. Since there is no spec number provided for axial load, is there some rule of thumb for "moderate" like 1/10 or 1/100 of radial load, or should I assume it really cannot handle any axial force at all? Pushing in on it just by hand, it feels pretty solid, though. This size bearing is used in some machine tools, motorcycle crankcase, etc.
http://www.amazon.com/Bearing-6203Z-17x40x12-Single-Shielded/dp/B002BBAWUE
EDIT: Ok, maybe this is my answer; 1/2 to 1/4 of rated static load Co:
If deep groove ball bearings are subjected to purely axial load, this axial load should generally not exceed the value of 0,5 C0. Small bearings (bore diameter up to approx. 12 mm) and light series bearings (Diameter Series 8, 9, 0, and 1) should not be subjected to an axial load greater than 0,25 C0. Excessive axial loads can lead to a considerable reduction in bearing service life. -
However, best thing one can do with a 3D printer is to remove any material around the printer which can easily burn such as cardboard etc. And don't put it close to curtains or other textiles...
Certainly something to consider. I believe the printer that caught fire was enclosed on 4 sides with acrylic. Some people are doing that to stabilize buildplate temperatures, but like many plastics, acrylic is flammable. Plexiglas (a brand of PMMA or poly(methyl methacrylate), a form of acrylic) starts softening around 102 C and ignites at 300 C, according to http://www.plexiglas.net/product/plexiglas/en/about/faq/Pages/fire-behavior.aspx
PLA filament self-ignites at 388 C according to http://en.wikipedia.org/wiki/Dust_explosion
Plastic shards and dust can build up whenever the extruder grinds the filament. I guess the plastic would melt before it burns so it wouldn't be dust anymore, but still seems an argument in favor of the UM design, separating the feeder from the hot end.
Some people put a 3D printer in the garage or workshop, where smoke detectors should not be used because car exhaust or dust from power tools can set them off. You can however use a heat alarm mounted somewhere near the ceiling, which triggers both at high temperature, and high rate-of-rise of temperature. Amazon has them for about $25. Just on general principles, having a fire extinguisher on hand is not a bad idea either.
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And by the way, don't assume that a 3D printer will not cause a fire, because one already has. The house was lost, along with a pet. http://www.soliforum.com/topic/6608/beware-your-3d-printer-they-can-cause-fires/
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With my UM2 printer, I oversize holes by 0.2 mm in diameter and they generally come out very close to correct. Print head 225 C, bed 60 C and then 45C after the first few layers, speed 20 mm/sec, "Ultimaker Blue" PLA filament.
The very first layer is set to 0.3mm thick and gets squished out more, so I do have to ream out holes but it's mostly just that first layer edge.
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If something is smoking, that's obviously a safety hazard. I often do long and unattended runs on my printer, sitting in a room with no smoke detector but I'm going to change that right away!
Meanwhile, a photo of what bad connector wiring looks like, would help. I assume the clips are not fully inserted in the connector, so the wires can short out as the cable flexes when the platform moves up and down the Z axis?
Is there no overcurrent fault protection on the heater? Or, given that the heater power seems to be 150 watts or so, maybe just the normal current when concentrated in a small area by wires touching, causes the damage.
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Neat collection! I had a look at the Kepler spacecraft- looks tricky to print since there isn't one flat surface to use as a base.The solar panels are flat, but many fine details protrude beyond those planes. Cut in half and assemble it, I guess.
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The benefit of youmagine is simply there are higher quality items posted on average. It hasn't reached the user level where people are constantly uploading anything they were able to scrape together in a free cad program.
It would certainly be good to have smart filters that show you only the "good stuff", although that depends on your interests... For example, I am working more often with functional mechanical parts as opposed to art and I am mostly interested in models with OpenSCAD source provided, because I usually want to change some dimensions to suit the project at hand, and I don't have access to SolidWorks etc.
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I think YouMagine is improving in user base size. My most popular design that is on both sites shows a 3:1 ratio of downloads, and 7:1 ratio of like/favorites, when comparing Thingiverse:YouMagine.
https://www.youmagine.com/designs/universal-joint-with-bearings
(80 D/L, 10 favorites)
http://www.thingiverse.com/thing:392828
(264 D/L, 70 likes)
Maybe not directly comparable, but certainly different from the 100:1 ratio that IRobertI reported back in January. If I hadn't posted it on Thingiverse, I wouldn't have been able to proudly reply there when a comment praised the surface finish in my photo and asked me what printer I used. :smile:
Note: this forum has an annoying bug that HTML links get merged together with any following text on the same line, and mangled in the process. So any link must be the last thing on a line. It would be nice to see that fixed!
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Excellent guide, by far the most useful thing I have come across yet in these forums. Every UM owner should have this link.
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I have heard that not everything can color PLA filament well, but just FYI the first thing I tried worked OK: metal layout dye. I didn't use paint, because I didn't want to increase the diameter of the part. I tried it on an 8 mm shaft I printed and the fit remains the same, so I think the dimension did not change more than 0.1 mm anyway.
This fluid comes in only a few colors, most frequently blue or red. I tried some blue on the light-blue PLA that came with my UM2. It turned it a nice dark blue-purple. The color was not entirely even since I brushed it on, but that might be improved with some more care.
Be aware the smell is somewhat annoying, although not awful. The label says it contains Ethanol, Butyl Acetate, Isopropanol, Nitrocellulose, 1-Butanol, Propyl Acetate and to use with adequate ventilation.
The exact product I used was Dykem 80300 BLUE from http://www.amazon.com/gp/product/B0018ACR6G/
and they also have it in red color.
Another brand is Beechem who have blue, red, green, black, purple, yellow and orange. http://www.shelbygemfactory.com/KelleyBeechem-Labs_ep_34-1.html
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As far as I can tell, YouMagine is first cropping my original rectangular image into a square in the upload preview window, loosing the right and left edges. Then, after confirming the upload, the main page crops the image again into a smaller rectangle, this time removing some from the top and bottom, so it has been double-cropped by the time it appears on the user page. I don't think that is what you want or intended. I had to first swell my image with a 130% blank border in photoshop before uploading, to get around this. Not a great situation, so a fix would be welcome.
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I thought this article was very interesting, and the results look convincing:
http://3dprint.com/3340/ulimate-filament-colorer/
Is this possible with UM2? It uses 3mm instead of 1.75mm filament (need larger diameter marker?) but it also has a bowden tube; would that make a difference?
Apparently it works better on "natural" color filament, than "white" for some reason.
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You can get a power strip that will automatically turn off the power when it detects that the device plugged in has dropped into an idle mode, drawing less than XX amount of current. Has anyone used such a thing with the UM2, and does it work OK?
With overnight print runs, the head fan ends up running quite a bit longer than necessary. I don't think it uses much power, but it makes some noise, and it will probably wear out eventually, so it would be nice to completely shut off power once the print is done (well, and the head has cooled off, so maybe a 5 minute delay...)
I am thinking about something like this device:
http://www.amazon.com/Smart-Energy-Saving-Autoswitching-Technology/dp/B000P1QJXQ/ref=pd_cp_e_1
it has a switch to adjust the sensitivity (threshold of current draw before shutoff).
I'm wondering if it would not work because the power draw during "on but not yet printing" might be the same as "finished printing", so it would turn off before I could start.
Or maybe a custom build of firmware could be used, which controls its own power when connected to something like http://www.adafruit.com/products/268
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And, the firmware change for this has already been added.[...]
Our electronics guy also proposed to note down a small schematic so people could wire this up themselves if they want. We still have spare pins in the board that could be used for this. (It should just be a transistor and a few resistors)
I would definitely be interested. I assume the fan turns off whenever the head heater is OFF and also the head is below XX C temperature(?) I replaced the metal side-fan bracket with a duct printed in PLA, so I don't want to turn off the head fan until things are cool enough not to start melting the duct. But I don't like the always-on fan noise at idle, and I'm sure it will eventually wear out.
I can do the switch circuit myself, just let me know which pin number the FAN-ON signal is coming from. (Also, how much current at what voltage, goes into that fan?)
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My 2-week old UM2 developed a distinct and regular ticking sound several days ago (only during printing, not while cooling off after a print). This was a new sound that did not happen before. It seemed to me to come from the filament feeder. I dis-assembled the feeder this morning and blew out some PLA dust, and reassembled it without changing anything in the feeder (not intentionally, anyway). The occasion was changing the stock metal fan bracket to a printed version https://www.youmagine.com/designs/fanduct-another-idea
Anyway, the ticking noise is now completely gone. The new fanduct seems to be an improvement but I haven't done careful tests- at least it is not worse. I think the fan noise also may be reduced (which makes sense; I'm sure plastic resonates less than sheet metal).
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I received my UM2 direct from ultimaker.com a few weeks ago. I decided to try my first change, using a different fan duct, https://www.youmagine.com/designs/fanduct-another-idea
which I hoped would help overhangs. To install the new duct, I first had to remove the existing sheetmetal fan bracket. I removed the bracket from the head, but before I touched the fan screws I was so surprised by their condition that I took a photo (see below).
Was yours like this? Do the UM2 factory assembly instructions actually read "torque the fan screws to destruction" ? Surely not intentional, to discourage modifications? All eight screws, around the two fans looked this way. Fortunately I was still able to remove them, but re-installing the fans on the new duct was difficult with the stripped heads- at this point I need new screws.
I suppose I should not complain too much as the UM2 as delivered does work as-is, but I am just not used to this kind of factory assembly practice.
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Sure enough, holding the filament in my fingers between the reel and extruder I could feel it was slipping (not advancing) in one specific area on each rotation of the extruder stepper motor, causing a regular pattern of under-extrusion on larger fill areas. I increased my head temp from 205 to 210 C, and also slowed down the mm/sec print speed. After that, I did not notice any slipping, and the extrusion appeared nearly perfect with a setting of 105% flow rate. Lesson learned.
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Here is another part I printed with the same problem, although not quite as bad. On this one I had it around 105% extrusion and on the front face of the part (which was against the build plate) you can see in some places there are just separate threads laid down, instead of a solid surface as intended.
There are a few white patches, where a little excess glue stick on the plate stuck to the part.
https://www.youmagine.com/designs/pololu-37d-motor-bracket
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Ultimaker blue is probably the worst fillament that we sell. The only reason we sell it because it somewhat resembles our company color.
Seriously? so it's just bad filament? The odd thing was, though that later during the model print it gradually extruded more and I eventually dialled back to 105% extrusion. But the bottom few mm of the print definitely needed more than 200%.
So what is the recommended best PLA filament that I should be using, if the part that came included with the printer is the worst?
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One thing I'd like to see is the current Z-height of the platform, sometimes I want to watch for a feature to appear which I know is x mm up from the surface.
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Not sure if this is the right place to post this, but anyway: my 10-day old UM2 works OK on very small pieces, say 1 cm across. Right now I decided to try a larger print, this one https://www.youmagine.com/designs/fanduct-another-idea
and I notice what should be a solid surface is not, it's thin crisscrossing lines. I can make it solid by going in the "tune" menu while it is printing and adjusting the flow rate up to 230% where it started at 100%. That seems like a very large adjustment, when I didn't need to do any adjustment on the smaller pieces. Is this normal and should the adjustment be so large?
I am using Ultimaker blue PLA with 0.1mm layer height, 25% fill, 25 mm/s print speed, Head 205 C, Bed 60 C, fans 100%. Using Cura 14.07 to generate the gcode.
OpenSCAD images do not match my model
in Coffee corner
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Colors would be nice to have, but it is secondary. The more important problem is that most of the cylinders were rendered incorrectly, or not at all.