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General tips around nozzle too close to print
#1
Does anyone have any general advice around the print head hitting an object and either getting stuck or causing an x/y offset and ruining the print? I've upgraded to an e3d and am very happy with it. I still have the same problem that was causing the filament jams on the stock extruder though. My first layer is great and subsequent layers are great, but at some point after a long print, the nozzle will snag on something and get stuck or offset. This happened to me 3 times yesterday within the last 10 mins of a 3 hr print. My best guess is that my first layer is too close to the bed and then the difference keeps stacking up until the nozzle is lower than the print will allow.

This is just my theory though and would love to hear other ppls feedback on this. I'm running Cura on repetier .92.
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#2
Here's an example of what I'm talking about. I'm thrilled with the layer detail and consistency, but towards the end of the print I will find the head stuck to the model, or off to the side printing in mid air.

[img]
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#3
When I have printing issue I always refere to http://reprap.org/wiki/Print_Troubleshoo...rial_Guide
I guess it is wrapping because too hot, so nozzle hit it and then get stuck - you need to slow down printing / may be decrease a little the temperature as the all model is hot like too hot bed - slow down printing will help to limit the wrapping and give more time to cool down between layers
Adding an external fan help also to cooldown
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#4
I've seen something that might be similar, printing calibration pieces. Have you checked your Z-axis calibration to make sure that the steps/mm are correct? Also, I've set up slicer to lift the print head (drop the bed) between travels. I don't remember the setting name offhand but it might be worth a try.

One other interesting thing I've noticed is that it seems that my DaVinci is very sensitive to electrical noise. I have a small desk lamp near the back panel, where the motherboard is. When I switch off the lamp, it often kills the USB connection, probably due to a power spike. I printed from SD and turned off the lamp, and when I came back, I saw that the remaining layers were offset in the Y direction.

It may be that with long prints, electrical noise interferes with your Z-axis.

Mind you, I'm running the DaVinci through a UPS, so this noise must be going to the board itself, not through the mains power.

I'm thinking about encasing the motherboard with metal mesh to make a Faraday cage, to see if that helps, or putting a choke on the mains cable incase that's where the noise is entering the system.

I have the 1.0 with the new motherboard (J37 jumper.)
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#5
Thanks for the feedback Luc, I appreciate it! That is an invaluable guide, I refer to it frequently. In my case, Im printing PLA at 195 and the bed turned off, so I dont have much of an option of reducing temp. I do have a front fan running at all times so I cant improve that either. Im printing at 40 speed in cura, with travels at 100. I will bump these two values down to see if I can finish the print. Im printing now with the object rotated opposite of what it was before. I recently switched over to cura and like it so far, but if I cant get past this Ill probably move back to slic3r and play around with z lift.
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#6
Crud, electrical interference was not a possibility I was anticipating. My first failed attempt at this model did happen when I turned the Davinci light off, from the front panel, mid print. It made a sound similar to when the steppers are disabled and then I had horrible X offset. I thought I picked the wrong menu item by mistake and didnt pay it much mind. Im going to play with speeds for now and if I cant get anywhere with that, Ill disconnect everything I have powered from the davinci supply.
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#7
I cut speed down to 35 and 90 for travel in Cura. I got further but was present to witness the problem spot happen this time. Somewhere around the head of this thing, the layer lines are "pecked" for lack of a better term. Its almost like power to the stepper is strobing, which causes blobs that spiral out of control until the job is killed. Maybe min layer time is miscalculated and tries to slow down? I see no reason for power to fluctuate on higher layers, so maybe cura is doing something funny that I cant see from the visualizer. Going back to repetier host and slic3r until I can get it sorted. Will post results.
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#8
Curling on overlaps it's a well documented problem of pla. That area it's smaller than the rest of the piece and might not be cooling fast enough. Even the 3000$ printers need cooling for quality pla printing. A fan on the side connected to the usb does the trick for my 5-6h complex prints
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#9
I gave up on the glow in the dark pla for this model. I switched to neon green pla and have since printed out two of these without issue. Well, I also switched slicer to simplify3d and the weird stuttering 75% through also went away. I may try again with glow pla, simplify, and another fan to supplement the existing object fan. Apparently glow in the dark pla from this particular manufacturer has a tendency to glob up and is generally hard to control. Simplify also let me place my own supports so there were less thin walled support columns to snag and drag all over the place.
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#10
I just ordered ABS and PLA glow in the dark filament - may I know the brand name you use to see if I may have same problem ?
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#11
Luc, this is from a large maker bot spool I found buried at a local shop for 25% normal cost. I have some other really cheap glow filament ($15/kg) from what looks like toner plastics and it's some of my favorite. The maker bot stuff oozes in a major way at 195, the toner plastics stuff does not. Now that I'm reading my own post, maybe I can get away with lower temps on the maker bot stuff after all. Wink
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