geert_2
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Posts posted by geert_2
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Hey cloakfiend,
A good starting point for searching primers might be car paints and primers for plastic parst, like for wheels covers and bumpers: they need to withstand a lot of abuse, sunlight, rain, stones,..., so they need to adhere well to various sorts of plastics (but mostly to ABS, PU, and polyester). For optimal adhesion, they should chemically bite into the plastic and chemically bond, not just cover it.
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Maybe you need 6 slots...
User neotko has good results with hairspray (spray it on a tissue and wipe the plate). And user gr5 has good results with dilluted wood glue (1 part Elmer's glue in 10 parts water, if I remember well). Still other people use dissolved old PVA-support material from the UM3, thus recycling what would otherwise be waste.
My own "salt method" does *not* work for ABS, so no need to try it. However, for PLA and some other materials it can be used. (=Wipe the build plate with a tissue moistened with salt water, until it dries in a thin, almost invisible mist of salt stuck to the plate.)
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I would suggest you have a look at DesignSpark Mechanical. This is a limited version of SpaceClaim, and distributed for free by RS Components (big electronics supplier). It only requires registration to activate it.
Its user-interface is similar to that of SketchUp, with pulling and pushing on sides or edges of models, to modify them. But it generates good STL-files for 3D-printing.
Main disadvantage: import/export module for STEP and IGES standard 3D-formats is optional and not free (actually quite expensive).
On Youtube you find a lot of demo- and instruction films. Also on the RS-website and SpaceClaim website, you find tutorials. Have a look if this is something for you.
Concerning Onshape: I tried that, but I can not get around in their user-interface: I find it all mixed-up and confusing. However, other people have made wonderful things in it, so it works. Technically, it is incredible what they can do in a standard browser, but I do not like the online-only philosopy: it reacts too slow, and no internet (or server down) means no editing. I already had an account before the recent limitations, and last time I checked, I still seemed to have the ability to store 9 private models, invisible to others. Yes, 9, not 10 as in the beginning: for some unknown reason one dropped off.
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When pushing filament manually through the whole feeding traject, I found the most friction occurs in the teflon coupler and nozzle, when near the end of the spool. Friction in the bowden tube can also be much higher than expected. Also the "unwinding force" is very high: the spool acts as a very strong spring, trying to wind-up the filament again. It is probably the sum of these that causes the problems, when using the original feeder.
With the spool normally mounted on the printer, and the filament being fed into the machine, I usually unwind 20cm of PLA, wind it in the opposite direction around a 7cm skater wheel, and release it, after which it is almost straight. Then I unwind the next 20cm and wind it around the skater wheel in the opposite direction, etc., until I have straightened a few meters. This only takes a minute or so. And it can be done easily while the printer is printing.
Then I loosely wind the filament up on the spool again (although this is not necessary, you could leave it hanging around), so now it is sitting very very loose on the spool, with a bending radius of about 50cm, and it has very little friction in the whole feeding traject. Then it does not cause underextrusion anymore.
I know, I should try another feeder. Actually, I wanted to design one myself, but I haven't come to that yet.
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To me this looks like underextrusion. If it is only in the left back corner, I would guess it is because the friction of the filament in the bowden tube, teflon coupler and nozzle is higher when bent more in this corner. This especially when printing very hard filament like PLA, and when it is near the end of the spool.
Maybe it could also be uneven build plate calibration (too much distance at the left back). This you can visually check when starting a print: is the first line equally thick everywhere?
If it was the teflon coupler worn out, or a dirty nozzle, I would guess the problem would occur everywhere?
If the cause would be too much friction, try to unwind and straighten a bit of filament manually prior to printing, and see if that helps.
I usually unwind 20cm of PLA, wind it in the opposite direction around a 7cm skater wheel, release it (after which it is almost straight), then wind the next 20cm around the skater wheel, etc., until I have straightened a few meters. This only takes a minute or so. Then I loosely wind it up on the spool again, so now it is sitting very very loose, with a bending radius of about 50cm, and it has very little friction in the whole feeding traject. Then it does not cause underextrusion anymore.
Of course there might be other causes, but these are my first guesses.
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I agree with kmanstudios: heat may be a bigger problem than water (to test water-resistance, I have made a filter for the sink in PLA a year ago: it hasn't rotten away yet). Just don't use water-soluble materials like PVA.
In addition to this, the flexibility or lack of it may also be a problem. Heavy clay or sand will deform a flexible mould due to its weight. And a non-flexible mould of course is difficult to remove after casting. But you know that for sure.
What about printing the original model (not the mould)? And then make a silicone mould around it, and a plaster or epoxy shell to stabilise the silicone? Or use a high temp rigid material to print the shell. In this way both water and temperature are no problem. Most silicones can handle up to 200°C. On Youtube there are lots of good videos on mould making and casting.
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If you have a highly directional microphone, or a modified stethoscope, that might help in locating the exact source.
I have a standard medical stethoscope (like those the doctor puts on your breast and back to listen to heart-beat and lungs), but that is not accurate enough. It does not differentiate enough between sounds from various parts.
However, car technicians use the same basic stethoscope setup, but they replace the pick-up element with a thin long tube. So in a car engine, they point the tube towards various parts (valves, waterpump, oilpump, alternator,...) and they can locate which parts or bearing makes weird noises.
If you would have access to something like this, or if you could build one (print the connectors and ear pieces, and connect some standard PVC tubing to it), this might help locating the source?
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Cool idea!
I highly disagree. Slow travel path for combin moves will cause the drip to increase and unless someone makes a math formula to actually know how much drip/mm/heat/viscosity is lost, you will get a bit of underextrusion when the extruder resumes to print.
Hi neotko,
From a theoretical viewpoint I do understand your concern. But in my tests, I haven't noticed this problem yet. But I will look out for it in the next prints.
Practically, for PLA I usually use the default speeds of 150mm/s travel, and 50mm/s printing, which gives good results. Here, a low traveling speed would have little benefits.
But for transparant PET materials this high traveling speed sometimes causes a dull line, thus an ugly opaque line in the otherwise "frosted glass" transparant appearance. So, here a slow traveling speed gave me a much better result, since the oozing-line was now also transparant, no longer dull opaque.
PET is more sticky and "rubbery" than PLA, and tends to build up on the nozzle (at least the ones I have). So, when moving fast, the "morse-code" that is sometimes left behind, accumulates on the nozzle, burns, leaks, and causes these ugly brown spots. Here too, a low traveling speed outweights the disadvantages. At least for me, but other people have the right to see things differently, of course.
So, for PET and co-polyesters, I now use the slow traveling speed, identical to the printing speed. For PLA, I use a high traveling speed.
So, in any case, this should be a user-selectable option, and not be enforced.
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Concerning the new warranty: Yes, I think the wording is now reasonable and much better: first, it is more clear, and second it reflects your "open philosophy" better. Tanks.
(Edit: clarified the context of this reply)
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If the nozzle uses roller bearings (I don't know for sure), could a broken ball, or some debris that was picked up, cause this sound?
In my case, the sound came from this belt rubbing against the flange in the photo, but then on the other side of the printer, left back side, where its home-position is.
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On one of my UM2 I had a weird sound coming from the same corner, left back. But it was rather a squeeking sound, like rubber tyres, or like chalk on a blackboard.
It was very hard to locate, as it seemed to come from everywhere around that corner. Eventually I found it came from the rubber belt (the one from the stepper motor) sliding agains the flanges of its wheels. Rubbing the side of the belt with silicon grease solved the problem. I used the thick, inert white grease that is also used in microscopes and binoculars, *not* silicon oil, and definitely not petrochemical oils (may damage the rubber).
I found it by manually pushing the belt sideways while printing a small piece, or while moving the head by hand.
Your sound is different, but maybe it could come from the teeth of the belt rubbing against the flanges?
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This is what I would rather expect from an atomic pull: see the nice orange one at the bottom. It has still a little bit of white, since I was changing colors from orange to white and back. This is from an UM2 (non-plus) with standard 0.4mm nozzle, 2.85mm filament. On an UM2+ with removable nozzle you might see some additional lines, but the general shape should be similar:
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If your model and function allow it (we can't see the inside here), another option might be to cut it in parts, and glue them back together again after printing. Or design some holes for hex nuts and screws, and mount it with screws. This might go a lot faster than other post processing, and might be good enough.
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I was about to say that neotko *does* promote hair spray and has a video of it. But he was faster.
I use the "salt method": after cleaning the glass plate with water, gently wipe it with a tissue moistened with salt water. Gently keep wiping while it dries into a thin, almost invisible mist of salt stuck to the plate.
For me, this gives excellent bonding of colorFabb and Ultimaker PLA, and still good but not perfect bonding of ICE PLA.
When hot, it bonds like cyanoacrylate. But when cold, the models come off by themselves and are sitting totally loose on the plate.
For the full manual with photos, see the PDF file at:
https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/
For ABS this does not work at all: it starts foaming and splattering, I don't know why (maybe because of the water in the salt?)
For PET it works a bit: it reduces bonding strenght a little bit, but makes it much easier to remove the models after cooling down: they don't get stuck to the plate anymore.
I also tried the dilluted wood glue method for PET: it gave a super bonding, but once tore a piece of glass out of the bed. So I am a bit reluctant to use that, if not absolutely necessary.
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Has anyone ever tried to put some (silicon?) oil on the outside of the nozzle? I'm guessing it would prevent material to stick to the nozzle.
For some unknown reason, my reply was eaten up by the system and didn't show up on the page. So, let's try again.
I use silicon mould release oil: spray it on a tissue and wipe the nozzle. This reduces build-up of molten filament on the outside, but does *not* eliminate it. It depends on the material: it works less or more for PLA, but does not work well for PET, which is much more sticky and "rubbery" when molten.
I also tried PTFE oil, which also helps a bit, but less than silicon oil.
I haven't tried any other oils.
Some time ago, there was a thread in which this was discussed, if I remember well it was about putting silicon socks around the nozzle, for the same purpose.
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I think it is a good idea to restart from fresh, in case of hard to solve problems.
To me, this looks like underextrusion.
If the filament is rather hard, as in the case of PLA, and it is bent into a tight corner on the end of the spool, try to manually straighten it. This will give far less friction in the nozzle and coupler. I usually wind it in the opposite direction around a skater wheel of 7cm diameter.
Also, I would try the following things: First remove filament and do an atomic pull to clean the path. Then manually insert a piece of filament (with cold nozzle) to see if it slides smooth through the nozzle and teflon coupler? Then insert the bowden tube, and manually slide a longer piece of filament from the back of the printer through the whole path bowden-tube, coupler, nozzle (with cold nozzle). Is this going smoothly without friction?
Then heat the nozzle, and manually feed a bit of filament through. Does it come out smoothly without too much friction?
Then start a small print (e.g. a cube of 10mm x 10mm x 10mm), and manually feed the filament while printing.
If you would have a similar printer available, you could try the exact same things there, to compare.
If all this goes well, then at least you have an indication that that part of the printer is reasonably okay.
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I am very scared to chemicals, therefore XTC was ideal for me.
XTC-3D is a chemical too. So it may also have health-risks, similar to any other chemical.
About XTC-3d, from the Smooth-On website: "Avoid eye and skin contact. Avoid breathing fumes - use in a well ventilated area. NIOSH approved respirator is recommended. Wear safety glasses, long sleeves and rubber gloves to minimize skin contact. This material has a high exotherm (generates heat). Do not mix components in glass or foam containers."
The MSDS also mentions that it could cause skin burns.
Whatever chemical you use, you need to inform yourself of the risks, and then take proper precausions to prevent any harm. It it is the way you handle a material that makes it safe or not. Even "harmless" water or air can be deadly if handled the wrong way.
By the way, water is a chemical too, even though we don't usually see it as such.
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In my experience, if the spots are dark brown or black flakes with sharply defined edges, they come from the inside of the nozzle: burnt material from the inner edges of the nozzle, or from around the area where teflon-coupler and nozzle meet. Solution is atomic pulls, and if necessary replace burnt and deformed teflon coupler.
If they are bigger and lighter brown spots, without sharply defined edges (more looking like dark honey), they come from the outside of the nozzle: material that has built up around the nozzle, and then slowly burns and leaks down on the print. Especially if you have a bit of overextrusion, have increased the flow-rate, or if the first layer is squished really hard on the glass plate.
Solution for the second is difficult: pausing print and cleaning the nozzle-outside sometimes helps, lowering temp sometimes helps, but often not.
Also, lowering travel speed to the same as the printing speed sometimes helps: then during travels, the nozzle does not drop "morse code" bits on the print, which would on the next pass get picked-up by the nozzle, accumulate, and cause this dripping. But at lower travel speed, you may have a bit more blobs when traveling through air.
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Have you tried a new SD card, or at least cleaned the contacts (blown out with compressed air)? This seems the most logical cause to me.
Else, try if all electrical connections on all boards are still okay, not loose. Also those of the mains power supply. Wiggle them.
Or maybe spikes in your 230V supply? Flikkering of lamps, motors nearby switching on or off?
Electrostatic discharge could also cause stops: I have had that a few times in freezing cold weather: I got shocks whenever I touched anything: doors, lamps, iron tables, lift, just about anything... Also when touching the printer, and then it hung up, so I had to switch it off and on again.
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Could something like this be caused by a worn-out nozzle cooling fan? So it doesn't cool enough and filament gets heated too much upwards and gets stuck? Or by a worn-out feeder-wheel, so it doesn't bite enough? Or a combination of one of these, with filament near the end of the spool, so it is wound-up too strong? If you cleaned the nozzle, did you carefully (!) poke through it with a 0.39mm needle? If burnt residus would be accumulated, it might reduce the opening from 0.4mm to 0.3mm or so? (I have sand down a standard 0.5mm needle to 0.39mm and used that.) Or the nozzle touching the aluminum cooling plate, so it loses its heat? Have you tried a small test print with a "known good" filament?
I am just guessing and thinking aloud, since it appears you already did all logical things...
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I took a look at these videos.
Very interesting project, but with the naked eye you can already see some diameter variations and deformations in the extruded filament. So I think it could give poor results in a 3D-printer when using standard nozzles of 0.4mm. Might be okay for 0.8mm, on a direct drive printer (without bowden tube), and if you accept lower quality prints.
In Europe good quality filaments are available from around 20 euro/spool, which sounds reasonable to me (from a European perspective at least).
However, to produce art and as a toy in school to promote recycling of plastic, the injection moulding stuff in these videos is absolutely great. It could teach the kids a lot. So the kids could recycle their empty coke bottles, and produce a nice piece of art with it. This is guaranteed to get their interest. Why didn't we have such things in school?
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When the traveling speed through the air is high, this easier breaks strings, and creates less chance of oozing and blobs when landing on the next part of the print. But when traveling over "land" (thus over the already printed model parts), this causes ugly dull lines, or even causes the printer to leave behind a sort of "morse code". On the next pass, the head crashes into this morse code, and it accumulates on the nozzle, and then leaks and causes hairs.
When the traveling speed is identical to the printing speed, e.g. 30 or 50 mm/s, traveling over land gives a much smoother surface, without dull lines and morse code. But then you may get more oozing through the air.
So, what about different traveling speeds for moving over land and through air?
- Traveling speed over land: 50 mm/s default, (or "0" for identical to printing speed)
- Traveling speed through air: 150 mm/s default
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An easy way around is to make a JPEG-image of every model you design, with the exact same name. Thus the corresponding 3D-model, STL, gcode and JPG-file all have the same name. By browsing through the JPG-files with an image viewer (e.g. IrfanView on a Windows system), you can easily find which file is which.
It doesn't work on the printer itself of course, but at least you can easily see which gcode-files to copy to SD-card.
In addition you could add the main parameters in the filename of the gcode (max 20 characters before the extension). For example:
- model_v33.rsdoc (native DesignSpark Mechanical 3D-file)
- model_v33.stl
- model_v33.jpg
- model_v33_pla.gcode (for use with my standard PLA settings)
- model_v33_plahq.gcode (for high quality PLA)
- model_v33_pet.gcode (for use with my standard PET settings)
- model_v33_petht.gcode (for high temp PET)
And you could add a txt-file with settings and additional info specific for that version, with the same name:
- model_v33.txt
(or Photoshop these settings on top of the JPG-file)
In these names you would replace "model" with a more meaningfull name, of course. The "v33" here is the 33th saved version of this design.
This method is not perfect due to the limit of 20 characters in the filename (the rest falls off the Ultimaker's little screen), but it works reasonably well for my hundreds of models and versions.
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I think it might be a good idea to google the BC817 specs, and test things out with a separate transistor and a test board. If it would go wrong, that is a lot cheaper than a new controller.
The very limited specs I found (but I only did a quick search), do list a VCEsat of 700mV at 500mA, which is surprisingly high. I would have expected 300...400mV. And a Ptot of 250mW at 25°C ambient temp. So, at a load of 300mA you could still go over the max power rating in a closed environment with limited airflow and cooling (thus probably 50 to 60°C in summer).
So you need to find specs that show all the power-rating curves and VCE-curves too, for given loads and temps.
My practical experience with discrete transistors (long ago in the stone age, before SMD...) is that they don't like it when you get close to their maximums. Some even didn't like it when you only got half way.
Filament waste---what to do with it?
in Materials & profiles
Posted
I use those left over ends to do atomic pulls at regular intervals.
If you would still have more left over, what about heating them with a heat gun and making toys with it for the kids? Arm bands, rings,...