Micro-swiss + PETG = failed prints?

Laser8302

First off, here is what I have tried: (slicer is Cura 4.0 beta)
Print speed 1st layer = 20mm/s
Print speed others = 30mm/s, 40mm/s
Retract = tried 2mm, 3mm, 5mm, 8mm at 45mm/s and 30mm/s
Extruder temp = tried 220C, 235C, 245C
Build plate temp = 90C initial layer, 80C after 1st layer
Using Amazon basic PETG
No upgrades yet besides micro-swiss throat

I've tried 10-12 times to print, every time I end up with a wad of plastic around my heat block. (It's a PITA to clean up...)
I've got some fiberglass heat wrap tape, I might try wrapping my heat block in, but I don't know if that will help?
I'm trying to print some parts like a new part cooling tube, a new fan mount for part cooling and a BL touch mount.

I did notice that while printing, there is a lot of tension on the filament. I pressed the button on the extruder to release the tension and felt the filament loosen a bit. Even with the nozzle screwed in tight against the throat, the heat block feels loose too. I might try tonight to see if I can get the nozzle closer to the block, I think it's too far from the block right now.

I did some testing too. With the extruder set to 240C, filament flows nicely. I retract 5mm after I see some flow and I can still see the filament oozing for a good 20-30s after the retraction. Further retraction doesn't really stop the oozing. I tried 230C which is the minimum temp listed to print the Amazon basic PETG, and it still has the same reaction, oozing for 20-30s after 5mm retraction.

I know the filament isn't getting stuck because I can release tension on the extruder and push it through by hand no problem and get it to extrude nicely.

Any recommendations? A better heat block made of copper/brass vs the stock aluminum? Will my fiberglass heat wrap help? Should I get a silicone sock?

Samuel Pinches

You can cut a large length out of the Bowden. It is far too long out of the factory on the A5. That will help a little bit with the oozing.

Der_Muck

The all metal throat? no wonder, the total max retraction of that throat is 3mm!
I had the same problem with some filaments. When you are using that throat, you are in the top ligue and every mistake is bitter but the prints are very nice once you got the best setup.
Only with wood I have 7,6 and TPU with 14mm! But Wood doesnt stick on it and TPU just bends so much.
The effect is because you reach the cold area of the throat with your hot filament and than it sticks to it. Only way to lose it is to push it down than you can print again.

Never ever go over 3mm beginn setting up the retraction with 2mm! Its totaly different to the normal setup! Ah and microswiss has that info on the product page.

Laser8302

Ok I'll start with a 2mm retraction, and cut a bit out of the bowden tube. 235C print temp and 30mm/s print rate. Keeping the bed temp the same. 

Should I insulate the block? Fiberglass heat tape or silicone sock?

Many thanks for your help!

Der_Muck

Cutting of is a way but i didnt do that, I am using a capricon blue bowden tube. +- 50 or 100mm doesnt change a lot.

I have a copper block but its only good when you have the PT100 and the 500°C heater on bord. 

I had a silicone sock, the temperatur is more stable with it. It doesnt effect the quality or retract. You heat up a little quicker than without. But I dont use it any more because the head area deflect much more heat because it makes the hot area much bigger than it is without. Because of that, it effects the fanduct and the airflow to because it adds about 2mm down.

Its just a total different printer setting with the all metal throat, thats normal and its a bit tricky to find the settings but its a good system and you dont need to change a PTFE tube any more. Also you have the high temp. option now with the copper hotend and the PT100 with that you can print every filament on the market.

Laser8302

Thanks for the help. I think my major mistake was trying to print too much on the build plate. I started with a simple BL touch mount this time. So far, so good.

Der_Muck

That is looking good
What PETG are you using? Whats your temp. setup.
I print PETG with 235 on the first layer and than 225°C gives a very nice looking first layer.

Laser8302

I did 235C for the whole print.
I tried the next print at 225C and ended up with a bit of a mess and a clog somewhere. I had to go out of town for work so when I get home I'm going to try another larger print.

Oh and its Amazon Basics PETG. 

compman2

I haven't tried the micro swiss throat yet but would like too. 

I purchased a silicone sock for the heat block (generic for e3d).  I had been having problems with PETG building up on the heat block and then blobbing off on the print and at times causing layer shift and print failure.  After adding the silicone sock all those issues have gone away.

Der_Muck

Yeah I had that to, PETG is always a bit on the ozing side     
I had the silicone sock to but I dont use it anymore. I think the hotend with the sock equals in a massive heat block. And secound, it blocks the air from the fan duct. Without the sock, I think the heat which goes up is reduced and the cooling effect is better.     You can change the aluminium hotend block against the E3D copper block, I did it with the 500°C heater and the PT100 and it is just perfect now. Every filament on the market is printable now. OK the hotbed is limiting the print passibilitys.

compman2

I have made the conversion to micro swiss hot end.  I am having problems getting it dialed in.  I have had several small prints, print reasonably well.  The issue that ultimately happens is that the nozzle gets clogged up and quits extruding.  I have limited my retraction settings to 1.5-2mm at 45mm/sec.  I have tried temps from 240-250c.  I had been using 240 with the old hot end.  I have tried adding zhop in cura but this didn't resolve the issue.  

Once it clogs I can easily get it unclogged again by forcing the extrusion of some more filament or running a cleaning filament through.  I have had a couple of prints fail 2-3 hours into the print which is frustrating on a 4 hour print.

Using Cura 4.1,  Amazon Basics PETG black, white.  Microswiss hot-end and everything else stock.  

I also cut about 100mm out of the bowden tube.  

Any other ideas?  I mainly print PETG with a little PLA.

Laser8302

I had a heck of a time with the microswiss with the bowden setup. I put in a PTFE heat break for PLA printing and I haven't had an issue yet with my printer.

Maybe try 40mm/s and 2mm?
Try a retraction test print. One with your part cooling fan on, and one with it off. I found even with an ABS printed part cooling duct, the nozzle was cooled too much because it warped with a 90ºC bed temp.
(I have since printed a polycarbonate fan duct on my work ultimaker 3 printer... should be able to survive the 110ºC bed)

Laser8302

Ok a couple of tips @compman2

1)the stock extruder is crap. Get a titan aero or BMG clone from triangle labs. You'll have to modify the firmware for micro steps but in the end its 100% worthwhile upgrade. Because of the gearing I limited my max feedrate to 70mm/s which is still more than enough speed.

2) use some anti-sieze or thermal paste on the end of the throat that goes into the heat sink. This will keep the throat cooler and limit the transition zone more. Since I did this, I haven't had a single problem with the microswiss throat.