Going nutty

Hi all,
Have had my printer for 9 months or so now I suppose.
Was going OK but now I can't print anything - have lost my printing mojo.
Some prints look good and then crumble apart (too cold?).
Some prints have failed half way thru leaving a sandpapery top layer (too hot?)

Have so many different batches of PLA that I don't know which is which anymore.
Dont' seem to get any really nice thick healthy looking extrusions anymore.
Am totally confused at what temp and speed i should be using.
How can I work out the correct temp to use for each batch of PLA I get?
Should I set a temp and them manually push through hot end until I get a good flow?
Any other ideas. There seems to be such a huge stated range for PLA 180-220???
Thanks,\\Roger.

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Prusa 'Explorer' (3dStuffMaker), GEN6, J-head Mk III-B, Bowden Extruder, Marlin 1.0.0 RC2, Repitier-Host V0.84 and Slic3r 0.9.8, PLA. Live at Victoria, Australia.

Start off by printing slow, like half of your current speed and figure it out from there. weather can be warmer, changing the hot region of the hot end, making it longer, causing feedstock to require greater force.

also if hobbled bolt is clogged then you will need to remove debris because cooled down pla is really slick. Clean hobbled bolt with a torch or a barbeque lighter, then remove fine debris with needle.

Also stick with a brand that you trust. This is one area that I have sometimes been baited to save a few bucks, but it usually costs me down time, and a purchase of additional extruders or parts costs to make my own.

Run thru a couple of test prints with pla until you know how good the pla color and brand is. Ideally run your printer a little slower, like at 50-75% of its max flow rate only on infill and about 1/3 to 1/4 of max speed on perimeter. This allows for your printer to work with the variance of feedstock without calibration. Yes some feedstock may work faster, but others may tear, or be harder to push at the current working temp.
Good luck, and this is my opinion only. Others may have better tips

hi james thanks
yes did have some good white PLA.
but then they sent me some brittle white PLA - no good
then they send me some clear PLA to replace that - no good
then there was a 8 week wait (still waiting) for the (hopefully) original PLA
in the meantime I order some more PLA from an australian supplier (instead of straight from india)
all these didn't seem to work as good as the original white.
now have so many can't figure which ones are OK or if I have changed some setting
in my attempts to get this going.
used to print at about 205 now have been up to 230 just to try and get something coming out
then have to blast it with a fan to cool it down again. arrgghh.
I have cleaned my hobbled bolt (just with a wire brush will try your suggestion) but the whole extruder
seem to struggle (creaks and groans) so not sure if it it is the extruder or because the hotend is not doing its job and so putting the extruduer and extra strain.???
i am bit lost in general.
have lowered my speed to 15!! in attempt to get things going.
the plastic just doesn't look right - used to be a big thick looking line now is shiny skinny ugly looking thing.
could the hotend be blocked because I went so high on the heat. pulled it apart the other night
and cleaned it out a bit. but did not take out the resistor - looked a bit scary.
can you 'wash' the hot end bit out with something??
roger.

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Prusa 'Explorer' (3dStuffMaker), GEN6, J-head Mk III-B, Bowden Extruder, Marlin 1.0.0 RC2, Repitier-Host V0.84 and Slic3r 0.9.8, PLA. Live at Victoria, Australia.

first with heat on to nozzle, clean it out with a small needle. remove any thing that is possibly stuck in there. then try to manually push pla thru. if it now goes, then you successfully unclogged it.

but actually sounds like a hot end issue where pla seeped where it should not go around the ptfe sleeve, are you able to disasemble your jhead, and remove excess pla. it sounds like your ptfe liner raised up, creating a blockage.

have had lots of instances where the nozzle blocks, i pause the print, pull the filament out (sometimes hard to do), cut off the semi molten bit, then feed it in again and will get good flow. seems the 1st layer being squashed into the deck causes this blockage. (any higher and not good adhesion)
then the 2nd layer burbs and farts along - some good thick lines and then skinny ones

just need some good tips on how to separate the two - determine if it is the nozzle of the extruder (or both) that are the issue i think.

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Prusa 'Explorer' (3dStuffMaker), GEN6, J-head Mk III-B, Bowden Extruder, Marlin 1.0.0 RC2, Repitier-Host V0.84 and Slic3r 0.9.8, PLA. Live at Victoria, Australia.

will try to check the extruder (cold end) by just running filament thru it and try to push the filament back into it ie. apply a bit of resistance.
check that it extrudes the correct amount of mm/min for different settings, etc.
if that is all OK then start to look at the nozzle.
roger

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Prusa 'Explorer' (3dStuffMaker), GEN6, J-head Mk III-B, Bowden Extruder, Marlin 1.0.0 RC2, Repitier-Host V0.84 and Slic3r 0.9.8, PLA. Live at Victoria, Australia.

hi
have tried the above extruder test and noticed that the extruder would 'slip' when pressure was applied and so not all X mm
of filament came out.

got down to the point were I have the servo off the extruder (see photo) and grabbed the little gear with my fingers
(pretty tight but nothing crazy).

the servo (axle) seems to slip and not turn when I have the pressure on ie. turn, slip, turn, slip, etc

is this suppose to happen??? if too much resistance is on the servo (from my fingers OR
the filament not going thru the nozzle smoothly).

roger.

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Prusa 'Explorer' (3dStuffMaker), GEN6, J-head Mk III-B, Bowden Extruder, Marlin 1.0.0 RC2, Repitier-Host V0.84 and Slic3r 0.9.8, PLA. Live at Victoria, Australia.

well seeing the cold end seems a bit rooted I though I would play with the nozzle and try to manually push dome black PLA thru.
was sitting on 205 degree. pushed and it flowed thru really easily hardly and pressure for 5 seconds or so and then blobbed up and could not push thru at all.
too hot?

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Prusa 'Explorer' (3dStuffMaker), GEN6, J-head Mk III-B, Bowden Extruder, Marlin 1.0.0 RC2, Repitier-Host V0.84 and Slic3r 0.9.8, PLA. Live at Victoria, Australia.