huggy
March 20, 2016, 9:39pm
1
Hi all I’m new to the forum but been browsing as a guest for a while. Ive Had my printer about 4 months and not had any issues with it until about 2 weeks ago. The prints started looking lumpy in places and some infill layers where being skipped but it’s progressively got worse. So I decided it was time to change the nozzle. I could have cleaned it but I had some spare so I just replaced it. Anyway that didn’t solve the problem. So I thought maybe it’s a duff new nozzle, let’s try another. Nope still the same issue. I’ve re leveled the bed millions of times to see if that was the problem, tried replacing the nozzles, messed with both nozzle and bed temeratures but still nothing. It was working flawlessly up until 2 weeks ago and no settings had been messed with so I’m stumped as to what to try next. Any advise would be much appreciated so I can get back to printing. Thanks in advance. I have uploaded a couple images to show what the prints are coming out like
3 Likes
What printer are you using?
huggy
March 21, 2016, 7:24am
3
It’s the ctc dual extruder printer.
Moisture in your filament
Maybe the tension on your drive gear isn’t high enough? I would check that first especially if you have a bowden setup. Is your extruder also making a thumping noise?
Yeah that design is amazing, I have a reprap Prusa I3 and it uses the same design for the bowden setup. I can reach really high speeds with it without thumping.
Suggy
March 21, 2016, 11:01am
8
I had the same problem. Turned out to be c**p filiment. Have you tryed a new/differant roll?
I just got a CTC a last week and had similar problems with PLA initially. I had to raise the temperature by about 5C befornit got better. There was also an audible thumping noise that disappeared when I raised the temp. Since, then, I’ve switched to ABS and had no issues with it, except for that sometimes on the first layer when using a raft and extruding lots of plastic you can hear the thumping noise. Hopefully I’ll print a new extruder soon.
The thumping noise is the extruder driver gear slipping. I’ve upgraded my extruders but even still i have to print PLA at 230 degrees to avoid it.
You could also slow the print speed down a bit so the extruder can keep up.
What plastic are you using?
What technique are you using to get it to stick?
What first layer settings are you using in your software?
Filament skipping was what I suspected it was. Have you had any luck with different extruder designs? What is your print quality like with PLA at 230? That’s hotter than I’ve ever heard, but to each his own.
very good results. i’ve no idea if my nozzle temperature is actually 230 or not of course, the calibration could be way off.
1. Looks like you need better bed adhesion (use hair spray, glue stick, painters tape, etc.)
2. Adjust your nozzle height correctly, might be a bit to close to the surface
after fixing those 2 things I bet you will be fine.
huggy
March 21, 2016, 6:34pm
15
Thanks for all the replies. I can hear a thumping sound and that is generally when you can see the print missing areas. I’ve tried both abs and pla and both have the same issue where as they were both totally fine before. Bed has be re leveled hundreds of time both closer and further away with similar outcomes. How would I go about adjusting the tensioner, is it easy to do.
You cannot adjust tension on the stock CTC extruder. You can print one of the upgrades, or buy an upgrade for fairly cheap. Hardest thing to source is the springs though.
However, if you slow down your print and/or increase your nozzle temp you’ll probably have some better results. How you do that depends on your software, but as an experiment, half your print speeds.
Why? if you are trying to extrude a lot of plastic, it sucks a lot of heat out of the hot end, and the molten plastic is more viscous, and therefore requires a greater force from the extruder drive to push it out.
You’re especially likely to have this problem on a first layer, where you are likely to be (deliberately) over extruding to put a lot of plastic down for a smooth finish and good adhesion. Compensate for that by further slowing the first layer down.
Some of the wispy bits in your photos look a bit like poor adhesion too, hence some of the comments. You say you’ve got your bed nice and level - so assuming you’re right, try reducing the first layer height a bit (that’s a setting, which causes the first layer to be thinner than it ought to be, to really squash the plastic into the bed).
For reference, my working starting points for my CTC (in either ABS or PLA) are:-
Speed: 60mm/s
First layer speed: 50% of that.
Outline/Perimeter speed: 50%
Movement speed: 90mm/s
First layer height: 80%
First layer width: 110%
These settings aren’t that fast, but they are working well for me. I use a brim for ABS (stuck with abs juice on glass) and painters tape with a skirt for PLA.
huggy
March 21, 2016, 8:51pm
17
Thanks for the advise ill give that a try and let you know how I get on. All the help is appreciated. I’ve been enjoying using the printer it’s amazing what they can do. But a nightmare when they go wrong and you don’t know what to do fully.
And after all said and done you still hear thumping your over tensioned or not enough power to the extruder motor and youll need to adjust the power either in the software or coding or the stepper driver itself
huggy
March 23, 2016, 7:33pm
19
Hi again. Thought I would update you all. I played about with the temeratures settings and speeds and the prints came out a lot better but I still wasn’t happy with it because in places it was still skipping layers. So I decided I would take the extruder apart and have a look at what was going on. I noticed that the pulley on the stepper motor was full of dust and inside the little black box was another pulley that had blank gunk on it. I took both pulleys off. Gave them a quick once over put it all back together and the prints are coming out great again. Even on my original settings. I think I might give the pulleys a better clean when I get chance because I only gave it a quick going over to see if it made any improvements
