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JohnFox

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Posts posted by JohnFox

  1. 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%

     

     

    Did you set infill to 100%, and if so why?  20% is usually very strong.  I guess it would help to show the model.  I have never printed > 30 hours but many people here have printed 4 day prints and longer.  I don't recommend printing something that big the first 100 prints as there is a lot to learn about using the printer.  A lot of things can go wrong and that would such a waste.  Better to do 100 prints that take less than an hour to slowly become an expert.

    Also consider breaking the print up (can you show a photo of it?) into multiple parts.

    You can change filament part way through a print.  But you should practice that.  I haven't tried it but I think you go to TUNE and then PAUSE PRINT and then while it's paused I think there is an option to change material or you can just pull it out and put in a new one and prime it.

     

    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. 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.

    While cleaning the Z-Screw, I noticed that the bed bearings are in fact sticky. The bed will stick at certain points when I'm moving it up and down and will require significant force to get it moving again.

    Could it be that I have defective bearings on the Z axis?

  3. 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

  4. 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.

  5. 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.

     

     

    Try taulman bridge - the easiest nylon I think maybe?  Actually Taulman might have one even easier - I forget.

     

    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.

     

    • Like 1
  6. Just doing some experiments on the lubrication issue. Using rapeseed oil certainly reduced friction in the bowden tube, whether it will improve prints - time will tell.

    I am going to try glycerine as the lubricant. I'm a bit worried that over time, oil will get onto the build plate and reduce the sticking effect of the PVA glue. Glycerine is water soluble, so should wash off easily.

  7. Keep the pillars really clean by wiping with a paper tissue from time to time.

     

    It is not the heat for sure because here where I live, it is really hot ( brazil :)), so I always use it with a fan blowing air underneath the printer (ahahahha).

    Update: After removing the Z axis and cleaning it very carefully with a toothbrush and an old T-shirt, I tested the linear bearings without the Z axis and it seems that the problem is the linear bearings.

    I can feel a spot where the bearings resist, just a little bit, to move near the height where I have the problem. I rotated the linear bearings, just to see if it would get better, cleaned the rods (again) and carefully tightened the screws one by one while I was moving the bed up and down (again).

    Now it feels a little bit smoother, after greasing the Z axis again, I will try a few prints to check if the problem is gone "forever". If it is not gone, I think I will have to buy/ask ultimaker new linear berings  or new rods, or both, I don't know ahahaha.

     

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