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JohnFox

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About JohnFox

  • Birthday 08/28/1947

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  1. JohnFox

    Massive prints (More than a kilo)

    ABS is a real sod to print. Warping and delamination are a nightmare. Couldn't you use a 3D printed shell filled with resin? On my project, ABS was the perfect material but the problems in printing with it forced me to use PLA instead and I never regretted it. Failure rate dropped from 75% to 0% What I'm printing is essentially a speaker cabinet, and it is not really possible to split it up - at least that would be a bad idea. The infill was initially set to 100% as that would by far be the best for the acoustics of the speaker, but even at 10% it still takes 6 days vs. 8 days, but the amount of material is reduced to about 0.6kg of ABS. As far as making small prints first, whilst I ideally agree, that is somewhat pointless and impossible here, since what I need for this order is the size it is, and I have nothing particularly smaller I'm in need of printing - though I have experimented some. Enought to know that the failure-rate on these fillament based printers is worryingly high relative to resinbased ones, simply due to things like the fillament not extending properly due to snags/knots on the rolls etc. I suppose an option on the Ultimaker 3 would be to use both printheads, thus allowing for two rolls of fillament - thought that does also limit the print size slightly, which could be a problem But go big or go home I guess...
  2. JohnFox

    Part start cracking while printing.

    That's a very common problem with ABS, I eventually abandoned it in favour of PLA, even though ABS was the better material for the project. Since switching, the delaminating dropped from 50% per print to 0%. PLA is SO much easier to print.
  3. Are you feeding from a spool? Maybe the coils are small and cause too much friction along the Bowden tube. I switched to buying coils of filament with a much larger diameter than spools.
  4. JohnFox

    layer alignment

    I have had this in the past, it was due to grease on the Z pillars. Wipe them dry with kleenex and the bearing should roll OK. If they are oily then the bearings will try to slide, not roll.
  5. Just seen this post - it's something quite different to normal printing. I guess the hardest part is to get viable bacteria through the print head without them being killed off by the heat. Search for the lowest temperature plastic available and print really quickly to minimise the time in the heated nozzle. A cold print bed would help. You may find that bacteria in their dormant state are more robust
  6. I have tried XTD -3D as well, found it difficult to use and didn't give good results. It had problems covering sharp corners. The real killer for me was that it isn't compatible with water at all - discoloured immediately.
  7. Bear in mind that you don't need very much oil for the X & Y bearings. The manual says 'a drop', that is a lot of oil. Just a smear is plenty. Also don't oil the Z pillars, ( unless you have really high spec bearings ). Oil on these makes the bearing balls slide, not roll.
  8. JohnFox

    Nylon finishing

    Has anyone got ideas about the best way to finish Nylon prints? I have been trying out the Taulman 'Alloy 910' which prints reasonably well but I need to remove all the little bits of stringing on some of the surfaces. My standard method of wet and dry paper doesn't seem to work.
  9. JohnFox

    Advice needed on materials...

    I simply used PVA glue, ( Prit Stick ) and a brim, the brim seems to be important. Anyone any ideas for 'finishing' Nylon prints, sanding doesn't seem to work well.
  10. JohnFox

    Advice needed on materials...

    I have just tried the Alloy 910. Not easy but I got workable parts out of it. I had to drop the temp to 245C to stop it from charring, then printed slow and at 105% flow rate. The spool it comes on is VERY small, only 50mm diameter, so the coil doesn't go in the Bowden tube very well. I uncoiled it, put it in the oven at 50C for 10mins and it 'relaxed' quickly. Not seen any obvious problems with water absorption. Very strong and the parts have less friction than PLA. However you can't smooth the surfaces with wet and dry, unlike PLA or ABS. They claim that the new Alloy 910 is stronger and easier to print than Bridge. But I haven't heard of anyone who actually tried it, so no idea, how it is different.
  11. JohnFox

    Why are my brim lines not fine anymore?

    I had a very similar first layer recently when I tried printing with some old ABS, ( 2 years old ). Abandoned the print and switched back to PLA - all fine.
  12. JohnFox

    Gluing 4mm flat object together

    I've used Araldite, it's a two part epoxy resin. You have to mix it up for each use but you have time to align the parts. The thinner the epoxy layer the better.
  13. JohnFox

    how can you improve this print?

    Maybe try outer shell speed = 30, inner shell speed = 40 and see what happens. ( Cura advanced tab ) Printing overhangs is always one of the hardest parts of printing.
  14. JohnFox

    how can you improve this print?

    Any chance of inverting the object? That would avoid those particular overhangs, although you would get problems with that horizontal slot. Otherwise try printing the shells much slower. A lower temperature may help a bit.
  15. Soap - Good heavens - whatever will they think of next! I tried glycerine as a lubricant and it seemed to increase the friction of my wiper cloth compared to rapeseed oil. Didn't see any obvious change to a print after lubrication, maybe my |Robert| feeder is doing its stuff.
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