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adamp2006

Suddenly higher temperature needed before PLA will flow

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New to 3D printing so bear with me , so i've had my Ultimaker for a couple of weeks now, sorted out the teething problems (leaking hot end etc) and all was going fine , prints were coming out great at 215 and 100%fr on the supplied PLA , a couple of days ago though things changed over night, to get a good print i've had to bump the temp up to 230 and have 100 - 110 % fr, now no adjustments were made between it being good at 215 and now

Anyone ideas what can make such a difference ? maybe because its reaching the end of the spool of PLA and the thickness is different or something ?

Thanks for any advice given :)

 

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Hi! Welcome! Are you printing the same models, or something different? Really it would be useful to see some pictures to get a sense of what the problems are that you're trying to overcome. It really all depends on the problems: Changing the temp and or speed may just be masking problems that have developed for other reasons, rather than directly solving the problems.

Its possible that the PLA is behaving differently later on the spool. Certainly if the thickness changed, that might affect things, or even the chemical composition might have changed slightly across the spool.

Another possibility is that as your printer has bedded in, something has changed about the material feeder, and it's not feeding quite as well as it was.

Or perhaps your belts have loosened a little, leading to backlash, which can affect the finish quality and even the apparent extrusion rate.

When you talk about %fr - are you referring to the speed adjustment on the Ulticontroller? That's just affecting how fast the head moves. A 10% change in that is unlikely to make much difference there, and in general, slower is going to give better results than faster.

 

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Sounds to me like you have a partial blockage in the nozzle, hence it is creating back pressure and you have to get the PLA hotter to push it through. Try clearing it with a pin or if that fails you can burn the plastic out by holding the brass nozzle in a gas flame. Don't overdo it though, a gas flame can melt brass. This ties in with you having to up the feed rate, as the back pressure is causing slight extruder slip.

An alternative possiblity is the filament is thicker toward the end of the reel (more than about 3.05mm dia) and is binding in the bowden tube. Can you feed it through by hand OK?

 

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Judging by what I've read in the 'fora' I've had more hot end issues than the average owner during the fairly short time I've had my Ultimaker.

Eventually I bought some 0.4mm drills (http://www.ebay.com.au/itm/261116222911?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

).

A grand total of approx AUD10!

Now if I think that there may be a problem with the nozzle - while the hot end is up to temperature - I carefully insert the drill into the nozzle, largely by trial and error 'cos it's difficult to see the nozzle exit hole without some disassembly, and it's easy to feel whether or not the hole is fully clear or partially blocked. If it's partially blocked then a bit of twirling and to-ing and fro-ing with the drill should clear it.

BTW this is done just holding the chuck in my fingers. The reason for the chuck is that I found it too difficult to hold and manoeuvre the drill on its own.

Note, also, I have used the chuck and drill with a Dremel type unit to clean out a cold nozzle.

 

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I had blockage issues a week ago causing all sorts of under extrusion mysteries and I cranked it up temperature too to no avail. I even partially disassembled the hot end and tried to clean it out some.

What eventually fixed it although crude and possibly temporary is heating up the hotend to 230, and then retracting manually a bit after it starts oozing and then took a piece of PLA that I cut off earlier and jammed it up into the nozzle until half the piece melted. Then cleaned it off again and extruded some through. Crude, but worked.. and still going right now...

It's like it couldn't squeeze it through the .4mm hole, but you can dislodge it upwards instead. Worth a shot until you order those drill bits.

 

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