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JohnFox

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Everything posted by JohnFox

  1. Check for free rotation of the spool. ( just posted the same answer to an earlier thread ). A TINY smear of Z axis grease on the top of the spool holder could work wonders.
  2. Make sure the spool is running freely. Mine proved very hard to rotate at first. A TINY smear of Z axis grease on the top of the spool holder made a dramatic improvement.
  3. Thanks for the link. Did the upload and repair but for the life of me I can't download the repaired file. It seems to be a known bug. Are there any other repair programs?
  4. I can answer my own question. The problem lies with Sketchup. I was trying to make a thread with a circular cross section, changed it to a triangular one and it worked OK. Cura really does pick out the problems before printing. I don't always trust the 'normal' view but the layers view seems to be 100% correct.
  5. I have just been trying to make a threaded hole. Using Sketchup, I made the helix on its own, copied and pasted it into the object with the hole, then moved it into position. When I exported it into Cura everything worked, except that the threads appeared to be hollow, with only the outer shell on them. They seem to stay hollow even when Cura is set to 100% fill. Any ideas? Not sure if this is a Cura problem or to do with Sketchup.
  6. The end 50mm of the filament must also be perfectly straight, ( as well as pointed ). The feeder is trying to send the end of the filament into quite a small hole and if it isn't straight it hits the edge instead.
  7. Have you ever lubricated the Z axis slide pillars? I have just experienced this problem and it was due to lubrication on the pillars. The slides are ball races and need a small amount of friction to rotate. Oil the pillars and they will try and slide, not rotate, causing a jam. I removed all trace of oil and the problem has cleared. John
  8. Have you put any oil onto the Z axis slide pillars? I would remove it if you have. See my thread earlier on.
  9. I have had a similar problem, periodic wide layers and have just fixed it. After a lot of playing around I realised that I had oiled the Z axis slide pillars at the same time as the X & Y rods. The Z axis bearings are ball races, so if the pillars are lubricated the balls will try and slide rather than rotate. Some slide, some rotate and you get a jam. I removed all trace of lubricant from the slide pillars and the machine worked perfectly and has done some over about 4 x 4 hour prints. I am routinely wiping the pillars with kleenex before a run. John
  10. I think I have solved it! The problem was due to the Z axis slider bearings. The pillars should have NO lubrication on them at all. I had put a spot of light oil on them along with the X & Y slides. I eventually realised that the Z bearings are ball races and lubricating the pillars caused the balls to try and slide rather than rotate. Some slid, some rotated and that is what caused the jamming. After wiping the pillars dry, they began to slide really smoothly. Have done several prints since, all without any of the problem bands. I eventually got the nut undone but that rotated very smoothly. thanks John
  11. Thanks, I have already put a support ticket in. Unscrewed the 4 bolts on the nut but the nut won't come off, daren't put any more pressure on it. The rods look clean and true. When I slid the bearings up and down it felt like loose bits inside them, really rough. John
  12. I think the problem is the slide bearings though. I have unscrewed them from the build plate and tried to slide them up and down the pillars. Really very difficult to do, they seize every few centimetres, then work for a while, then seize again. I was expecting very smooth motion on these, occasionally I started to think they had totally jammed. Both of them seem the same. Is this correct?
  13. Is that the bearing at the back on the build plate? No obvious play on it. One of the four bearing mounting screws was loose, tightening it hasn't made any difference, ( the other 3 were tight ).
  14. I have done a complete clean of the lead screw, wiped off all the grease from the threads and re-greased. Slides a treat, the build plate almost falls by itself under gravity. However, around the area in question, 10-25mm down, there is some friction which appears periodically. At the same time, I can sometimes hear a faint grinding sound from around the bearing/slide area. The sound isn't from down below where the motor is. The lead screw looks perfect, no signs of any imperfections at all, so I am wondering if there is a problem with the slide bearings. The slide pillars look perfect, no marks on them and are lubricated OK. Hope this isn't a duplicate, I posted it about 30 mins ago and it didn't appear. John
  15. Ah, no! Will try that. Any ideas for a tool to help?
  16. Thanks, sorry I didn't respond sooner. I've changed to PLA and am getting the same charred bits. It isn't from the outside as I keep the nozzle pretty clean but I now see them fairly frequently at the start of a print, they usually are all out by the time it has printed the brim. They seem to build up within the nozzle and are disturbed when the nozzle cools down and heats back up again. I've started to do a dummy print in the same run before any important ones in order to get hem out.
  17. I would like some more ideas on this Z axis banding issue These bands cause total delamitation in ABS but are not fatal in PLA. It isn't a feed issue, as the bands occur on both the arms of the object and there has been a retraction between each arm. I am also using the PLA on a coil, not a spool, so the filament is not tightly wound. It really looks like a Z travel problem. I have re-lubricated the lead screw and when I pull the build plate up and down there are no obvious tight spots of high friction. However, the problem does tend to occur in the same region each time between 8mm and 20mm from the base, never below 8mm and rarely above 25mm. The position is random, I can build the same object with the same file and the bands can move about and vary in number. The Cura file X-ray is clean. Other people seem to see the same or similar problem but I can't see any fix which has nailed the problem. Any ideas would be greatly appreciated. John Fox
  18. I think I have fixed it! I suspect the problem is a mix of the ABS (with high warping ) and my design. The object had several right angle corners and I think these create a lot of stress which caused explosive de-lamitation across a whole layer. I have redesigned the item with radius curves on most of the corners and the latest print was fine. thanks
  19. Just had another 'event'. About 10mm vertical height printed perfectly, then one whole layer incorrect with quite an obvious gap all the way round, subsequent layers then OK until I aborted the print. Spool is OK, extrusion of all the layer seem OK, what is happening occurs to a single layer only. John Fox
  20. I am using white ABS supplied by 3D Prima, running on an UM2 at default temperature settings of 260C. From time to time I get brown colouration on the bottom two or three layers. I suspect that this is due to the ABS starting to char. Is it worth trying to drop the temperature at bit or will this lead to other problems? Oddly, this doesn't seem to occur elsewhere on the print. thanks John
  21. Just done the profile - forgot about it. I certainly have had problems in under extrusion, (something in the nozzle), that seems to have cleared now. I am about half way through a spool of filament, is it necessary to try and uncoil it? It seems to be quite highly coiled as it nears the centre. John
  22. Hello, I am attempting to print some small geometric shapes, typical dimensions are 60mm x 40mm on the X & Y and 30mm on the Z axis. Periodically and at random, I am seeing what appears to be the Z axis travel to be more than the set amount. Current setting is 0.1mm and I suspect the drop on the build plate to be around 0.15 - 0.20mm when the problem is seen. This causes an obvious band all the way round the print, which in some cases starts a delamitation. When I peel the object apart at the fault, I can see that the walls have not fused to the layer below, implying a greater than normal Z axis shift. The problem bands occur once or twice per print and always show all the way around the print with the next layers looking perfectly normal. The printer is only 2 weeks old, seems to perform perfectly apart from this. I am using ABS. Any ideas? thanks in advance John Fox
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