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FalmouthLouis

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  1. To what extent can one rejuvenate old or moist PVA? I've got four or five partial reels of PVA floating round my workshop, some of which will be 18 months old. Does anyone know how PVA ages if it's kept in reasonably dry conditions? Secondly, if PVA is just kept in a cupboard with no dessicants, how much does it deteriorate? I have a fruit dessicator, so I can heat the reels up without any problem. I saw somewhere that you should not heat PVA above 40 degrees. Does anyone have views on that? To what extent can one use heating/drying to rejuvenate elderly PVA?
  2. I'll come back to this debate later on today, as I am having to tackle a severe PVA problem. I'm trying to print a copy of someone's sculpture, which needs PVA support because Breakaway would produce too much strain on the structure when I tried to remove it. Initially, PVA flowed for about an hour but then seized up in the nozzle. I've three times done hot/cold pulls and got the PVA apparently flowing, but, as soon as I try starting the print, nothing flows again. This is despite the fact that I'm using all the tricks I know to dry the PVA. It could be that the problem is the extremely damp weather we've been having. I print in the part oif a workshop which is only partially heated, so the air will have been pretty moist over the last two or three days. Anyway, I'm going back to the workshop to see what I can achieve today. Incidentally, I am working with an Ultimaker 3 Extended, and I just use Cura settings for Ultimaker's PVA. I'll report back.
  3. I'm having steady problems with PVA failing part way through jobs. It's clearly to do with dampness, even though I am using a fruit dessicator to dry reels in advance of the job. I found the following exchange to be pretty useful. I've got a spare Polybox so I'll bring that into action. Will report back.
  4. Point taken. I've been using it for a year or so without obvious issues, but I see the danger. Thanks.
  5. Ummm, no. But I see the point you're making. What would you expect to happen/fail?
  6. I was talking about the special Magigoo for Nylon. I hadn't realised that they did a common-and-garden version as well. I like 3DLac in that I find, personally, find it easier to apply than a stick. Mind you, I tend to stay away from the printer until the fumes have dispersed.
  7. Just recently, I've been using Magigoo to support materials like Nylon. I'm still using 3Dlac for PLA jobs. Where's the crossover point. What works best for filaments like CPE, nGen etc?
  8. I've just been reminded about why I don't like PVA. I've got a commission to print ten of these handles you can see below. They need to be in nylon and whichever way they're printed, some support is needed. I've had bad experiences with Nylon and Breakaway, so decided to print these with PVA supports. My first print of three went fine. My second print of three had problems with nylon warping, probably because I hadn't done enough magigooing. After aborting, I started another print and the PVA refused to flow. It turned out that some had got stuck in the drive mechanism, so I had to disassemble that, which is a fiddly job. I did a hot pull on the Print Core just to be sure, but the PVA then loaded but wouldn't flow. I then gave it 6 hours at 50 degrees in my tame food dehydrator, and it's currently printing smoothly. The lesson from this is that PVA can get snarled up in the drive mechanism in the middle of a routine job. My conclusion is that I have to work much harder on keeping PVA dry. However, this is a hassle when PVA feeds into print core 2, which means that you have to shift the filament feeding into Print Core 1 to get at the PVA reel. ....in any case, feeding filament into UM3s is still pretty fiddly if you're pressed for space. I'll keep working on PVA because I have a job coming up with a lot of relatively fine struts and beams which would be unable to withstand the forces involved in stripping Breakaway away. PVA will be the only way forward, but these will be prints lasting days so I am nervous.
  9. Thanks P3D: A lot of the time, I'll be printing to support sloping or curved surfaces, so pausing to change some layers to Breakaway doesn't make much sense. In general, Breakaway prints pretty well, and I've just printed a marionette head which needed both external scaffolding and very light infill so that it supported the roof of the head and could be carved away. Breakaway worked fine for both.
  10. OK I think I've found the problem Problem is with the positioning of the eye sockets which are relatively widely spaced. Scaffolding clearly doesn’t like starting on a shell at the base of the structure. I found that I could get scaffolding to start when I sank the head down to give clear printbed below the eye sockets. At that point, the scaffolding emerges quite happily. However, I wouldn’t choose to split the head at this particular position. The photo below shows that I almost have to split the head in half. The alternative is a very fine infill printed in Breakaway or PVA. But that makes for more complicated post-print work.
  11. I'm printing a hollow puppet head for a client. Whatever orientation I choose, there is always a 'ceiling' which needs support. The orientation illustrated below makes most sense as it allows me to provide a hole at the bottom through which the client can insert eye units etc. The trouble is that the eye socket units are designed without any initial contact with the shell. I've instructed infill to be generated everywhere, but it just chooses to support the ears on the outside, and whatever I do doesn't seem to produce scaffolding for the eye sockets. I see I could programme a very faint infill which would be printed by printcore 2 (Breakaway), but that will make cleaning up the interior more complex (?). How do I get Cura to produce scaffolding inside this puppet's head?
  12. I've posted a couple of queries about the workings of PVA and Breakaway. In the course of this, I've been encouraged to explore the mind-boggling array of options in Cura for tweaking support structures. This would suggest that, within the Ultimaker/Cura community, there are people who have given a lot of thought to how support structures can be optimised. However, a moderately experienced operative like myself is just bemused as I look at the checklist of options. I now have a decent amount of experience with printing supports in either PLA or Breakaway. Some initial thoughts 1. It's generally easiest to print supports in Breakaway, which is easier to store (not hygroscopic) and stable to print. 2. If the support structure has relatively narrow slots/crevices/indentations it can nbe hellish getting the Breakaway out, and I have deliberately used PVA on occasions to get round this problem. 3. Breakaway does require a certain amount of force to release it, so it is not suitable for supporting fragile/thin designs. But this raises the question of whether there are choices within Cura which will reduce the adhesion between Breakaway and supported surface. There are options to do with Z distances which suggest you can widen the key gap - but just how far can one go with widening this? 4. There are a whole lot of issues to do with PVA's chemical composition. It absorbs moisture and starts printing badly as a consequence. How best to store? Does it age badly? I had past problems with clogged BB nozzles, though this may have been brought about by my inexperience. 5. Whereas I have printed support structures in Breakaway which have gone up to the 120 mm height region, I don't think I have ever got a PVA structure to print above 400/500. I've discovered an option which allows one to print a brim specifically round the support structure which may help me a bit. However, I sense that, even with a prime tower, PVA structures tend to be sensitive to sideways pressures from the printing process (some relatively narrow PVA columns have recently been knocked off the vertical pretrty easily). As far as I am concerned, there are a whole range of issues with support structures and I don't know anywhere to turn to for serious advice on optimising this part of the printing process. I'll use this strand to feed my further experiences in. I hope the Ultimaker/Cura team can provide some tips as well
  13. Geert - given the complexity of support issues (and wider dual nozzle coordination) it would be good if you could get a dual nozzle machine off Ultimaker so that you could put your massive expertise into helping us from direct experience with these systems. I understand what you are saying above, but I am generzlly taking other people's designs and creating bespoke support structures for each project would drive me insane and would be financially unsupportable. I've been poking around Cura's preferences for the support function, and there are a mind-boggling array of options. I've identified an option which allows one to create a brim around support structures, which might help my specific problem where I have narrow support towers. But I have other problems, such as difficulties in getting Breakaway to come out of slots and crevices. There seem to be options which allow one to widen the z gap between support and supported surface, but I have no idea how this will work in practice. Someone from the Ultimaker/Cura team needs to point us to settings tweaks which are most effective in getting over problems with producing effective support structures.
  14. Oliveros: there are a confusing number of options in Cura's preferences for controlling supports. I've picked a few which may help a bit and will do some experimentation. My guess is that "support z distance" and 'support top distance' could be key.
  15. Oliveros: thanks for this. I'm normally taking other people's designs so what do I do within Cura to make sure the relevant gaps are big enough?
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