Under extrusion during print... missing layer (PLA innofill)

Hi,

I am slowly going insane here... I have made about 100 test prints using differnt slic3r versions and variaing tempertures from 185 to 200C and the problem remains. Plastic is Innofill3D PLA in black. Layer adhesion is excellent... Bed is set at 65C and the PLA sticks well to the bed. It will print cleanly then smewhere in the print the plastic will stop flowing then pick up again. The Extruder is not skipping or missing steps. I don't get it... What do you guys think is going on? I have attached a pic...

Thanks,
Gray

P.S. At 200C this stuff is quite fluid... manual extrusion is not a problem.

Weird, measure filament in several places to see if there is big variations in diameter? or cut several sections to see if there is air bubbles inside the filament.
Chech your extruder for bent or wobbling axles and or bearings.

Let us know if you find the reason.

Edited 1 time(s). Last edit at 11/03/2014 05:45PM by ggherbaz.

A few possibilities:

1. Wires going to thermister or heating element loose and disconnect at certain points (happened to me).

2. Junk in filament. Black is most susceptible as they can throw other junk plastic in and it can't be seen. Just try another color or brand.

3. As mentioned, check size in various spots and check for it being oval in spots, this will cause jamming.

4. Take nozzle off and clean it out. Possible debris inside that keeps blocking hole.

Hi,

I switched over to PLA from Faberdashery and the problem went away... I assume the stuff from Innofil3D had water in it or airbubbles.

Thanks for the help.

Gray

hi i think im suffering for the same thing ive slowed print speed increased flow until it eats my filament then slowed it down I've tried over extruding sending 110mm when it should be sending 100mm and i give up below is a temp cheek starting at 210 going down to 170 dropping degrees every 50 layers on a 500 layer print i like the 175 temp range but as you can see i got bad layers in every temp tested

oh im printing pla

this is a single layer hollow tall cube

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ive had some small prints trun out nice and bigger prints just seem to miss filling

This looks like classic PLA starvation that is most probably due to high ambient temperature of the filament and no cooling of the feed tube at the hot end. PLA is very sticky when warm and when passing through the feed tube it can stick to the wall thus reducing the flow; the heat break between the nozzle and the feed tube is never perfect and heat leaks across to it, warming it such that the filament picks up that heat. Filament dust from the feed mechanism may also be dragged down the tube and collect on the walls making the problem worse; forcing the feed mechanism to feed can create more dust particles, so only hand feed filament when the extruder has reached temperature. I use PLA all the time and have made some challenging parts, both small and large with great success but I do observe my rules, particularly on temperature.

These are well documented problems and there are several solutions depending on the type of hot end. The E3D V6 hot end uses a small fan to cool the tube and reports are favourable; in my case I use a Velleman K8200 printer with the stock K8200/3Drag hot end on which I "seasoned" the inside of the metal feed tube with vegetable oil then heated the tube to fix the coating, which was reasonably successful but I always run the printer in a cool environment to ensure that filament ambient temperature is as low as possible. Have a look at [forum.seemecnc.com] where this topic has been aired and where I initially picked up the information, having suffered the problem too.

By the way, all my printing is done with a Kapton covered bed that I wash with a 6:1 water to PVA wood glue before printing and heat to 50 degrees for the first layer, then 30 for the rest and extrude at 195 degrees. This PVA trick is very good although large flat models will need to be carefully prised off the bed; methylated spirit will clean the bed before the next use. I use both the Slic3r and Cura engines and prefer the former for rectangular shell detail accuracy but like Cura for its speed; layer height is 0.2mm having not had much luck with finer due to the extruder nozzle being too large and worn; it most likely needs replacing but that's another day. At 0.2mm I can print overhangs of better than 45 degrees without support and with continuous cooling.

Mike

Edited 1 time(s). Last edit at 02/21/2015 02:37PM by Mike01Hu.