FalmouthLouis

Brulti: I'm using the latest version of CURA, so was dealing with a circular prime tower, and had it in the middle of the right hand side. I take your point about toughening the tower up. I still have this worry that, after a certain height, it sounds as if the nozzles start brushing against the print surface, suggesting that the print has expanded slightly. I'm fairly careful about printing with brims, so I don't think we would be talking about warping on the plate.

I've found the ooze shield setting. I still can't visualise how it works. I'll try a test print today.

Iam trying to do variations of an identical item. Today, I tried to have one print operation print one item with 20% infill and a second one at 40%. I set the underlying settings to print at 20% and loaded two models to print and the slicing told me that the combined job would take 11 hours to print. I then highlighted one of the models, brought up the "per model setting", chosse modify infill setting - at which point the slcing tells me the job will last 5.5 hours, and whatever I then do I never seem to be able to get it to time this as a two item print job, though the second item is never "greyed out" to indicate its unprintable. It's just coloured as a slightly washed out version of the underlhing yellow. IIn the Layer view, only one of the items is actively modified as I check how things will print. I click on infill density and then close. That allows me to change infill density to 40% and I'm left with the picture below, but I can't see any other action that I can take to get Cura to recognise there are two items to print. It makes no difference whether I tell it to print one at a time or simultaneously. Is there anything I am missing out?

smartavionics: thanks for this, but I still don't quite visualise this. I can see that we are dealing with choosing within the 360 degree option. Would [0,180] give me straight lines up and down the print bed? How would that affect something like the grid infill setting? What would your [0, 60,120] produce? Would that be a set of triangles?

What does your ooze shield look like?

Do these 3DSolex cores work without hassle? I ask because I've just come across a discussion thread which suggests that a 3DSolex printcore may be causing problems with UM3s because they have some settings within the printcores which can interact problematically with UM3 machine settings.

As I've printed using UM2s, a UM3 and, most recently, a UM3E I've noticed that, as prints rise in height, the nozzle(s) seem to start catching on the print surface, in that I can hear a sort of thumping noise as the print head does rapid movements across the print, and tall thin structures can sometimes be knocked off balance. Most recently, I've done an 80 hour print on the UM3E of a copy of a sculpture involving a lot of support material. (I used Breakaway and have separately commented on how well that has performed). The overall print ended up 15 cm high, but the prime tower was knocked over at around the 9 cm level. This happened overnight, so I didn't pick up any advance notice of anthing going wrong. This led to a mess where the machine tried printing over where the tower should have been. I slowed things down and monitored more closely so managed to get a completed print, but, once again, I sensed that the nozzles seemed to be hitting the top of the print - which meant that I throttled right back to 50% print speed. So, a couple of questions. Might the volume of a print slightly increase during the course of a long print,thus leading to an upward creep of the relative printing surface? Is there any reason why the mechanics of shifting the print bed downwards should deteriorate over tall prints? What can one do when a prime tower gets knocked over during the course of a tall print? How much would the quality of my print have suffered if I had printed without a prime tower? I'm tempted by the idea that one could have a mechanical replacement ready to put in place if the prime tower fails. I see something which could be carefully calibrated upwards until the print heads start putting a firm print down again. That may sound excessive, but printing for 30-40 hours with the machine printing birds nests where the prime tower should be is not fun.

The print eventually took three and a half days. I had to slow it down because the Prime Tower got knocked over about half way through the job leaving some messy attempts to print where the tower should have been. Otherwise, all went very well. Breakaway continued to print clearly right to the end, and the design called for a lot of support. See the first image below. Using the tools in the fifth image, it took me 20 minutes to clear the model of Breakaway. It involved quite a lot of work with pliers and I had to use quite a lot of force, but that was mostly to do with cutting/crushing the material into manageable sizes. I had quite deliberately toughned the walls of the model, but I didn't sense that I was ever in danger of damaging it. The beak and head of the bird was heavily encased in Breakaway. Once I had cleared the bulk of the support material away, it was relatively easy to carefully clip the remaining material away. The second and third pictures show that the surface of the model ended up in very decent condition. I shudder to think how long it would have taken to dissolve the equivalent amount of PVA My verdict is that Breakaway performed admirably, but I wouldn't want to use it on particularly delicate structures or ones involving complicated internal designs.

For experimental purposes we want to check the impact of moving away from the default 45 degree setting in Cura. I understand I need to use the "Infill Line Directions" option. I'm looking at the square brackets, which are inviting some numbers. We want to test the impact of printing at a zero orientation - ie straight ahead on the print plate.

SandervG: I've just started a three day print involving lots of Breakaway, so I will have lots to report back on after that. It's of a bird, perching on a book lectern, looking down. 15 cm high. It will be using nearly 30 cm of Breakaway. I don't have the photos you want, but it seems to leave flat surfaces spotless. Where I did have a few issues was with an irregular egg-style design which I printed on an end. Breakaway supported the print absolutely solidly, but when I came to break the support away, I was left with strands of Breakaway around the bottom of the print which, though not massively important,were quite tricky to clear. Towards the end, I was having to use tweezers to pull away individual strands. For some jobs, I've been able to clear Breakaway just by using my hands, fingers and occasionally finger nails. After that, I've pliers supplemented by tweezers. If photos will help, I'll post some once I've finished the three-day print.

Geert_2: thanks. When thinking about the marine environment, I have been aware of the importance of things like UV sensitivity. The trouble is that my colleague can only get limited access to the testing facilities, so we've had to zero in on a single issue - tensile strength. If we get decent results from this round of tests, we could see if there was funding for a next generation set of tests. Incidentally, I like your point about under and over extrusion.

GR5 - many thanks for all that. Have now got to get down to a talk aimed at artists in St Ives. They are interested in a much different set of issues, such as filaments with tactile qualities. Am just going to experiment with prints in Bronze and SteelFill. Should be fun. I'll get back to tensile issues early next week.

Understood. However, we probably only have 24 variants to play around with, so we might only be able to do something like test out three differing PLA @ 20% infill versions which would at least give a sense of how different brands of PLA can produce different results (or not). Whatever we're doing is not going to allow anyone to claim that brand X can out-perform its competitors.

kmanstudios: probably Faberdashery for PLA, Colorfabb for Nylon, 3DGBIR for an advanced co-polyester. Resins probably through the Photocentric setup. The point is that there are now so many filaments out there that it's pointless trying to be scrupulously precise about the differences between filament A and filament B. We want to be pretty precise when charting what happens as we experiment with different print setups using one filament (probably PLA since that is what most of us start of using). When comparing the different materials, we just want to be able to give a general sense that shifting from PLA to the likes of Nylon will produce a perfomance improvement of around so much. If you have views about brands etc, feel free to make suggestions. Within our various constraints (financial, plus the fact that my Exeter University colleague needs to finish her work by a specific date) we are trying to make this exercise as useful as possible to general users as well as the community who come on to this site. I'm an Ambassador for CREATE Education, so am part of the Ultimaker community, hence my willingness to work with 3DGBIRE.

SandervG - I'm interested in the views of you guys in Ultimaker as to how you think the various infill designs will affect tensile strength. Assuming infill density is kept to 20%, which infill design should be the weakest and which the strongest? Do you have any other expectations as we play around with the options? By all means feed me with any questions that you think we could throw some light on. My colleague has produced two variants of a testable design - one 8mm deep, one 10 mm deep. We can afford to test something like 24 variants of these designs. What issues do you guys think we could most profitably test within that 24 variant constraint? Remember that we need to focus on issues which matter to real life practitioners like myself and their real life clients. This all started because I am doing a bit of printing for the marine sector and I needed to be very clear in my head about how best to give commercial clients like that the structural toughness they might need, without going over the top in terms of printing unnecessarily in exotic materials.

I'm very impressed with Breakaway. I've done around 10 days of intensive printing of items which have all needed support. I would say that Breakaway has indeed come away 95% completely at the first attempt, while the remaining 5% has pretty well all come away with a bit of fine tweezer work. In about a third of the cases, some strands still get left which need some very careful work to remove. Compared with PVA, Breakaway is a joy to use. .... and it's a vast improvement on what you can hope to get with scaffolding produced by a single nozzle machine. There have been a couple of times when Breakaway did not bind cleanly to the print bed when starting a new job immediately following the removal of the previous one. I ended up doing a material change and then clipping off 10 cm or so of the Breakaway filament before re-feeding it into the system. This worked for me, though I don't know if there's any genuine rationale behind my "solution". Obviously, PVA is still going to be needed when handling sensitive internal structures and, since removing Breakaway involves a certain amount of force, I wouldn't want to use if when supporting particularly delicate structures. Having been so positive about Breakaway, are there problems around it? Will it continue to perform well after sitting around for some months?

Just to let you know that I'm working with an investigator from Exeter University to do some serious tensile testing on around 20 variants of a standardised design. We will look at four contrasting materials (PLA, Nylon, Resin and a strong co-polymer), but also at varying print orientations, degrees of infill, infill patterns and so on. At the end of this, I would hope we can produce a guide to the ways of improving tensile strength, starting from PLA at 20% infill, which is the standard entry level setting for most of us. If people are still monitoring this strand, I'll feed results back into it.

Every so often I get the notice about "detected printcore height". Quite often (as happened this morning), I merely restart the print process and the automatic levelling this time lets the printing go ahead. What might be happening here, when I have done absolutely nothing but set up a new printing attempt?

Sometimes I find there's small amount of residue on one of the print heads. Clearing that normally clears this problem, when that's the cause.

Cura now allows one to choose between an interesting variety of infill patterns, including 3D ones. Is there any evidence about the performance impact of the various approaches? The literature has quite a lot of emphasis on the impact of different raster directions, but Cura offers a choice between grids, lines, zig zags, 3D concentric, tetrahedral etc. Keeping life simple, suppose I am interested in optimising tensile strength, what's the sequence I should follow to move from a relatively weak print to a relatively strong one?

My anti-virus programme, Norton 360, removes Cura 2.6.2 on the grounds that "it is not safe". I had the same problem, if I remember right, when I tried downloading a beta version of 2.6. I've had no problems with 2,5 and earlier version, including some beta versions. I'm very reluctnat to disable Norton in order to install 2.6.2 . Does anyone have ideas about what the issues might be?

Was talking about these issues with a venture capitalist yesterday. The ability to print with chocolate would be extremely interesting. I've seen a chocolate printer which can only really handle two dimensional printing. To be able to print lattice-style structures in chocolate would interest our local hotel and tourist sectors