Inter-layer adhesion issue

[Jules]

Huh! Learn something new every day.....i wouldn't have guessed it. (That will come in handy down the road.)

[PcS]

This was a year old roll of matterhackers pro pla. I will run a few of these with a couple of other brands to see. I suspect different colors and or brands might behave differently.

[dramsey]

Until you get.your z off set ...layer height ....and bed level spot on ....no amount of advice will help.

I'm not sure if you were addressing this to me, or just in general, but I've got all these dialed in.

[Jules]

That's a 3D printing rule we live by.......(If yours is working for you now DON'T change it until after you finish your fobs!)

[PcS]

Black pla from ebay. Cheap chinese stuff I found that prints great.

[dramsey]

I think I've somehow screwed up my thermistor. I have the factory files I saved for printing 1, 4, and 8 fobs at a time-- and every one of them has the extruder at 205 and the bed temp at 60.

I can print at 205 now, barely (this is with the same roll of filament, now almost gone) but the models produced are fragile-- the layers peel apart kind of like cooked filo dough. You can easily jam a thumbnail in the side of the fob to split the layers. And yet, I have a box full of very solid fobs produced with these settings.

Printing at (an indicated) 215 degrees is MUCH better and produced models with about the same quality as an indicated 205 used to.

I tried measuring the extruder temp with an infrared thermometer-- removed the fiberglass(?) sleeve, brought it up to an indicated 205, but I guess the extruder's too small, since I couldn't get a reading over 170, and it can't be THAT far off, can it?

[jimc]

no you cant read the hotend temp with an ir thermometer. you need far more precision than that. you need a probe and meter to actually contact the hotend at different points. unless you see your temp jumping all around in s3d then 99% your thermistor is fine. sounds to me like you are under-extruding. is the filament dia and nozzle dia set correctly? if thats correct then the multiplier should sit in the neighborhood of around 96-98. also extrusion width should be on auto or atleast set larger then your nozzle dia.

[dramsey]

no you cant read the hotend temp with an ir thermometer. you need far more precision than that. you need a probe and meter to actually contact the hotend at different points. unless you see your temp jumping all around in s3d then 99% your thermistor is fine.

Probably is fine then.

sounds to me like you are under-extruding. is the filament dia and nozzle dia set correctly? if thats correct then the multiplier should sit in the neighborhood of around 96-98. also extrusion width should be on auto or atleast set larger then your nozzle dia.

Extrusion multiplier is set to 0.90, which is what was used before. Extrusion width set to 0.40mm for a 0.35mm nozzle. And, as I noted, this is the same spool of filament.

That's the interesting part: a saved factory file that used to work perfectly no longer provides the same result. What changed? The only thing that could have changed would be the Z gap, which I had to reset when I replaced the nozzle, but I've adjusted that puppy to within an inch of its life.

[PcS]

For fun. Home z and take a picture of the nozzle in relation to the heated build plate. A close up maybe.