Hi. I have a QiDi Tech printer and I’m trying to do this dual extrusion with PLA and using HIPS for the support structure. Everything works fine until the PLA comes to a point in the model where it expands. Right when the printer should print the first main surface of the model, it jams up and that’s it. I have tried messing with temperatures up and down, but I keep getting the same problem. I would be very thankful for any help or thoughts!
2 Likes
Garyg
2
Hi
From your photo, it would appear that your filament above the hot end is getting too hot.
It might be something known as Heat Creep.
If the thermal barrier is not doing it’s job for one reason or another, this can and does happen.
If you have a small fan, try blowing on your filament just above the hot end.
I have never experienced heat creep but your photo sure looks like others I’ve seen with that
very same trouble.
I hope this comment invites others to chime in.
2 Likes
PDXDDD
3
looks like heat creap do oyu have fans on this? from the block or your filament is not the right dimensions. also try a cold pull to make sure the hot ends not jammed up
The thing that puzzles me is that it just started doing it after many successful prints. I have been working like crazy to get the PLA to stick to the HIPS tho.
Just when i got it right it started doing this. I read about oiling the PLA when switching back from ABS. I’m giving that a try right now.
I do have fans on it and the filament is very exact in diameter.
cobnut
5
Hi @Lehellie also take a look at your extrusion rate settings. I had this on my FF Pro (same design) and it turned out to be caused by over extrusion (the filament was being pushed into the hot end too fast). Try reducing your extrusion rate to something like 90% (when you should see evidence of under extrusion) then increase it 1% at a time until you get a good print. Doing it this way round should avoid further jams…
What temps and speeds are you using? Check your retraction settings. Aggressive retractions can contribute to this. What slicer?
Generally speaking trying to extrude to fast for the temp can cause an issue. slow the print way down.
1 Like
I’ve been juggling these settings a lot trying to find the sweet spot. For some reason this printer likes the PLA really hot. I’m talking 240º.
I tried to oil the filament and run another print with the same settings that I was using. This worked and the printer didn’t jam at all. The PLA however, will not adhere to the HIPS no matter what I try. So I figured for fun I’d try turning the temp down to 210ºC, like normal people, just to see what happened. Then it jammed again.
I’m trying out FlashPrint, witch seems like a better match for the printer than the Maker Bot software.
The settings I’m using are:
Base speed: 40mm/s
Layer height: 0,1mm
Temperature: 230-240ºC
Retraction: 1mm
Retraction speed: 25mm/s
Any thoughts?
I see that setting and it comes preset to 109% in FlashPrint. I’ve tried setting it down, but the problem remains. Might have to go way down. I’ll try experimenting some more with it.
That temp is just way to high for PLA, it’s going to get cooked. If you have to go that hot then I would look for a problem there. Anything over 240 and you are now running the risk of damaging the PTFE tubes.
Is the insulation on the nozzles intact?
Running that hot tells me a few things.
1. The temp reading is way off. What does the bed and extruders temp read when the printer has sat for a long time unused? They should read approximate room temp and all be about the same.
2. You have a partial clog or restriction in the PTFE tubes or nozzle that doesn’t let the proper amount of filament flow at correct temps. Running that high makes the filament more liquid allowing it to flow.
The printer is set to the wrong model in the software making the extruder run at the wrong speeds.
I would say for a .1mm layer height slow way down first or get it working on a .2 or .3 layer first then work from there… Extrusion multiplier should be at .90 to start for PLA. But first check these other things.
PDXDDD
10
Have you dona a cold pull? It’s a method I have tried with good results. Heat up your hot end and stick some filament in so it barely starts to flow then shut off the hot end, let cool just enough to where the filament starts to harden then pull the filament out. A cold pull when done sucessfully pulls particles from the hot end nozzle that can get trapped. Seasoning the hot end has worked for me when using materials other than ABS, I didn’t have to start doing seasoning until I started mixing materials through my hot end… also make sure your cooling fans are blowing the correct direction. They should be blowing air away from the hot end.
I thought that at first too. So I got out the industrial Fluke 51 thermometer we have at work and it doesn’t lie. The temperature on the nozzle is fairly accurate. At least within 5ºC when taken on the nozzle. The heating block is hotter than that, but it seems the software is compensating for that.
The strange thing is the print comes out very nice with this extreme setting.
Going lower on the temp makes the print worse and the layers don’t adhere properly.
I have had the PTFE tube out and inspected it and it is clean as a whistle. Nozzle also looks unobstructed.
In the software it is set for the FFCP, wich is the comparable model.
What is the brand of material? Are you absolutely sure it is PLA and isn’t miss labeled? Is it truly 1.75mm?
With the PTFE tube out run some filament through it to make sure it moves freely. Make sure the length is correct. Look for deformations. Try another brand or roll of PLA.
On the nozzle it is hard to see any small issue. Make sure the size is correct.
How does ABS print and at what temp?
I’d still like to see what the temps read after sitting for a long period. Bottom line is it is really too hot and I believe that is the root of the problems. I print several types of PLA on my QIDI anywhere from 185 to 215 with no issues.
Nebbian
13
I was going to reply to say the same thing. That big aluminium block shouldn’t be getting hot, but it appears to be getting hot and allowing the PLA to melt before it even gets into the throat.
Another thing to try is to add a guide to the PLA. You have a lot of unsupported length (several mm) between the drive gear and where it goes through the block. This means that you’ll never be able to print flexible filaments. I created a guide for my extruder with a small length of PTFE that is almost touching the extruder. You want less than a mm of unsupported length. This would also help your issue.
So now I have an update.
I’ve changed the extrusion rate down and changed the speed down some more.
The retraction rate is also decreased and now I’m able to print at normal temperatures again without having the extruder jamming.
Thanks for all the helpful tips!
I’m still fighting to get the PLA to adhere to the HIPS, but I’m getting closer.
Does any one have any good tips about that?
