This topic contains 11 replies, has 4 voices, and was last updated by 
Shaun 4 hours, 43 minutes ago.
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I put this post in the technical section instead of the ‘show us your bits’, because it resulted in a problem.
Because of the type of models that I have printed recently I have begun to print without any fill. I’ve chosen models where the structure of the design itself will create its own support as a hollow object. The results are excellent and although I had thought that I would benefit from the time factor, I think that the economical amount of the filament used is probably more significant.
The picture I’ve shown here is not a faulty model. It does have a lot string-like hairs crossing the internal wall, but they’re all inside and so have no effect. I don’t see this as a problem at all. But what you see in the picture is my attempt to question the material remaining figure in AM. The set-up told me that the model would require 10g more than I had left on the reel - ColorFabb nGen light green.
I’ve noticed that quite often there’s just enough filament left to print small models, even when it shows 0g. So I thought, well I’ll risk it and if it does run out, it will eject the section in the Bowden tube and tell me to load another reel. Well it ran out as you can see, but it couldn’t eject the filament. It gave a loud painful noise and wouldn’t go any further.
I don’t like to dismantle anything if it can be avoided, so despite the options advised in the technical support for manual removal of stuck material, I decided to make use of everything in the software. I tried ejecting the filament using the button on the main screen, from the button in the maintenance section and from the button on the reel. Nothing worked. I did a clean of the nozzles and tried to do a purge, but that didn’t work either.
I was so disappointed because all the prints lately have been to a very high standard. Even on this unfinished print, the details of the hands and feet are very clear, the legs are very smooth and even the cloth, which is actually a mesh style is clearly seen as such. So I spent some more time pressing all the buttons in the hope that something would clear. Then all of sudden it started ejecting the filament from the Bowden tube into the filament reel cavity, allowing me to pull it clear.
It told me to load a new reel, which I did and then performed a purge without any problems. I’ve told myself off for taking a risk that wasn’t necessary. After all the model was not critical and I could have waited until I bought a fresh reel again. I’ve printed models with alternate colours on the same model, but I’ve completed each stage before I change the reel and there’s been no problem.
So I’ve crossed off using PLA because of problems I’ve reported elsewhere in this forum and now I’m wary about changing a reel at an incomplete stage. In the meantime all the models are printing fine so really my only outstanding feature for a 100% perfect print is the need for the dissoluble support material - i.e. a dual filament Robox.
@paulsroom If you are not able to eject material, your PLA seems to be swelling in the print head. What generation of print head do you have?
Don’t get overly excited about dissolvable support. PVA is really the only simple solution and it is exceedingly hard to print with. I haven’t been able to use it at all at this point.
I hope that you were joking about pressing all the buttons. You should be looking at this from the point of view where you are trying to solve the problem, not just mashing buttons. Look at what would cause the problem and what would solve it.
I operate two Betas and one Production Robox.
See my 3D Hub site at https://www.3dhubs.com/phoenix/hubs/ben@bhudson Yes of course, when I said I pressed all the buttons, I was just saying that I followed the recommended procedures in the route to resolve a stuck filament condition. I do analyse the problem and try to work out where it actually lies. I also understand that sometimes a situation occurs that is a first time occurrence but against the expected action.
All I was saying here was that I suspected that the filament might run out before the print completed, but that the AM software would take this into account and eject the remaining section of filament, ready for me to load a new reel. But it didn’t do this. It tried but didn’t succeed. Okay so the filament perhaps swelled in the print head and that was the cause. It was not PLA though, as I only use ColorFabb nGen now.
I activated the various buttons that all deal with filament eject and eventually it was ejected, and the printer is back in operation with a new reel of filament that purged okay. I’m using the parameters that have been tested and provided by CEL for the Robox. This makes me comfortable about how successful a print will be. I know that certain design features will cause a problem in 3D printing, so I deal with those accordingly.
But I can’t prevent the filament from swelling if the conditions are right for it to do so, even when everything is set correctly. I am increasingly aware of these situations and take as many actions as possible to avoid them. So I find that PLA slips in my printer - I can hear it doing so. But ColorFabb nGen does not and if it does, it’s very rare. So of course I’m going use a filament has the least known problems - from my viewpoint.
If it seems that my occasional posts appear to be complaints and trashing the Robox, this is far from the truth. I’m very happy with the Robox and the quality of prints it produces. But community forums like this allow me to report problems I experience. I don’t know anyone personally who either owns a 3D printer or has any interest in 3D printing. So this forum is very valuable to me. I don’t always expect a response, it’s just nice to visit a site of like-minded people - interest, that is.
@paulsroom OK, I was just checking. Some of the stuff I have seen with Robox units is why my hair is going white.
I have not seen nGen stick in an eject due to swelling, but I have had it stick because the temperature is too low for it to break off. I hear a rumor that for certain materials the eject temperatures may be changing.
While in the middle of a print if you have a failure to eject you are pretty much toast. There isn’t a whole lot you can do.
I operate two Betas and one Production Robox.
See my 3D Hub site at https://www.3dhubs.com/phoenix/hubs/ben@bhudson I’m okay with the print not completing - it was my fault after all in questioning the material estimate. I’m trying again with ColoFabb nGen yellow and from the amount on the reel, I apparently have 6g more than what will be required. That shouldn’t cause a problem. This was really a test print to see if the zero fill was okay and also no support. I had increased the perimeter number and since the legs which create the gap are quite thick, I calculated that they would meet as it printed. The print did reach these points and so proved that it was okay.
I am not sure what your comments are against dissoluble support material. The blurb against these materials in the shop site say that they provide a clean surface once dissolved. Is this untrue? I’m trying to position the prints so that the least amount of support is required. My aim is achieve a smooth surface in the critical areas. In the past I would only have printed this particular model with support, but I can just about get away with no support.
@paulsroom I simply mean that the dissolvable materials are not easy to work with. They will work, but they aren’t fun. HIPS requires a strong solvent to dissolve and that same solvent will deteriorate the ABS that HIPS is usually used in conjunction with. PVA is semi-flexible and absorbs water like a sponge. It is also soft like TPU. I haven’t been able to print PVA at all. It sticks to your fingers when you try to install it because it is absorbing the water out of your skin.
So I just mean that while dissolvable support can be good, it isn’t the miracle that many people think it is going to be.
I operate two Betas and one Production Robox.
See my 3D Hub site at https://www.3dhubs.com/phoenix/hubs/ben@bhudson You advised using PolySupport as a support material to a user a few weeks back, but I notice that only HIPS is available in the CEL shop. I presume PolySupport is easy to get hold of and the settings also available.
@paulsroom Google shows at least four resellers with PolySupport in stock in the UK and the profile for its use is included in AutoMaker and has been for at least two versions. You do not need to have this material on a SmartReel to use it.
I operate two Betas and one Production Robox.
See my 3D Hub site at https://www.3dhubs.com/phoenix/hubs/ben@bhudson The reprint of my interrupted model printed okay without any interruption. It used ColorFabb nGen yellow and I set it to print overnight while I was asleep. This is why an interrupted print has to be avoided and thus why I try to choose filaments that have few or no problems - such as ColorFabb nGen.
My point about wanting dissoluble or peelable support material is because in my opinion this is a perfect print. Maybe a different colour and a bigger size would enhance the detail, even painting it would be best, but it’s all there. The position of the figure on a base means that all the detail is pointing upwards, so it doesn’t require support. Even the gap between the legs is dismissed by the thickness and position of the crossed left leg.
But with other models that don’t have a base, need a support structure to build the layers on top. This then has to be broken off and it mostly leaves a rough surface. If the support can be dissolved or peeled away, then the perfect surface on top can follow right around the model. That’s what I’m aiming for with the dual filament Robox - when I can get it.
All of this aside, the other feature that happens frequently is a blob of filament that is coughed up at the start of printing. You might liken it to a hairball with a cat. Despite performing a full purge after changing a reel there seems to be a build up of filament that is not released in the mini-purge. It gets extruded in the printing stages. In the case of this model it doesn’t matter because it’s on the underside and if I wanted to fit a light - this is a zero fill print - I could cut a hole using the heated finishing tools.
I clean the print bed regularly and also the print nozzles, but this extraneous blob of filament is in the print head hidden from view. In this instance the blob looks if it is the residue of the previous green filament, but this appeared clear by the purge. At other times it is clearly heated up and burnt as it comes out brown. I am wondering if I should print a minimal test piece in situ with the main model using just a couple of layers. In this way the blob might be extruded onto the test piece, but I would need to ensure that the test piece printed first.
Those strings are nozzle closes across the empty area which would normally be filled. The post processor looks at the code and sees a point it needs to close, if the close can happen in a fill section it does that so any flaws are placed in the non visible part of the model. If there is nowhere it can close it can track back over the same line again but this can create a visible flaw. In your case it probably decided to close as it travelled over the fill, normally it would disappear into the fill but as you have none it has just travelled while closing. I cant remember all the ways a nozzle can close or the conditions of them but there is a couple more options it has.
Normally when the filament runs out the filament slip threshold (default 10mm³ I think) would detect it before the last bit when past the extruder gears. This means it can still control it and pull it back from the head to eject. If you saw a skip and ignored it to carry on then the material may have been passed beyond the gears a tiny bit, it can’t push it any further, perhaps your meddling managed to grab it again after a while so it ejected.
That blob on the bottom looks like a mini-purge which got trapped or perhaps something which was loose in the build chamber, maybe something which was caught on the side of the nozzle from the previous print or purge?
@pete I was actually sitting next to the printer when the filament ran out and it cried out in pain and displayed the message can’t eject material on the screen. It cried a few more times when I tried different things, but I didn’t want to release the print head and go through the routine of pulling the filament out from the back. Yes, you’re probably right that my ‘meddling’ eventually moved the filament about and positioned it to where it could perform the eject okay. I can’t see a situation where I would want to change filament in mid-stream in order to provide different colours welded together in the same model. I’d print each colour separately then glue or snap them together. So it was a lesson for me to be far more careful to check on certain aspects. With the second printed attempt there was just enough remaining filament to cover the core of the reel, so it didn’t reach a point of running out.
My mention of the stringing was really irrelevant because I fully understand what you are saying. I suppose I was just making an observation. It makes no effect on the finished model, it was more an interested observation. I often sit for some time watching the print appearing. I do check on the nozzle to see if there’s extraneous filament sticking on the outside, in which case I remove it. But this blob is inside the print head and it just appears when printing. Sometimes I pause the print and cut it off if I can, but there’s always the danger of messing up the already printed starting layers. In this case the blob is on the underside and has no visible effect.
I’ve only just started printing with a zero fill setting because I feel that many of the model I choose to print don’t need a solid inside - it’s surplus to requirement. So I presume that the volume of filament used will now decrease. Of course for flat surfaces that are in effect wide open, a fill must still be used. The only remaining feature which I’d like to resolve is getting as clean as possible the surface where support structure is necessary. That’s why I’m asking questions about the support material. Round and undulating surface print very smoothly and I can see, even on the supported parts, that this is true as well. But I cannot entirely remove the roughness caused by support material. I get close and the only option is to position the model so that the support is not in the main (front) view.
@paulsroom Perhaps there was a problem caused by a kink in the end of the filament?
Also, the tracks on the first layer of the yellow print don’t seem to merge. Is your nozzle height calibration maybe too high? Forgive me if I’m incorrect here.
Finally, wow. Those prints look great, especially the meshed fabric and the toes. Really nice.
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