Polymaker CoPA and PA6-CF20 on the MK4, looking for well-tested and fine-tuned PrusaSlicer filament settings  

RE: Polymaker CoPA and PA6-CF20 on the MK4, looking for well-tested and fine-tuned PrusaSlicer filament settings

Very Good question. I recently purchased a spool of PA6-CF20 so I could make some Classic Car Heater Vents. The temperature on the spool says 290 to 300. My Mk4 only go to 290 so I'm at the low end of the filament Temperature range. 

I haven't been able to tweak the print quality to an acceptable look yet, but I'm getting very close. 

These are my current settings:

1. Filament Temp: first and last layer 290°C   (nothing I can do here)
2. Speed: 40mm/s   (I started at 60mm/s and I've reduced it to test print quality. Seem better at slower speeds)
3. Cooling fan: OFF   (it hardens quickly on its own)
4. Heat bed: first layer 50 then drop to 40   (Reduces warping) you may need a thin layer of glue on the bed.
5. Using an enclosure to keep filament dry and warm. (I don't know if that's helping or not)
6. 0.6mm nozzle, ruby tip. (I haven't tried it on a 0.4mm nozzle just because I don't have a hardened steel)
7. Layer heights 0.2-0.3.

The issue I'm having is in the more detailed areas where it jogs and moves a lot, it has stingers and bump outs that go outside the part parameters, as if the filament was sticking to the tip of the nozzle and then being pulled off.

If anyone has some better setting, I'd love to try them.

RE:

Those little bumps and artifacts possibly mean that the filament isn't dry enough. Nylon filaments are VERY sensitive to humidity. Did you dry it before use ?.Even new sealed spools might contain already some moisture and nylon is merciless in this aspect.

You didn't say which printing plate are you using. Nylon has poor adhesion to PEI plates (be it smooth nylon or satin), so you need to use glue to get a decent adhesion but that works OK only for small parts. Huge models are a real PITA to print on a PEI plate. As alternative, some people uses garolite or glass plates with more or less success. If you're gonna print PA filaments on a regular basis, do yourself a favor and get a Prusa PA nylon  powder coated plate. It isn't cheap and you can use it only with PA, because the other filaments won't stick at all to this plate, but it's worth the investment IMHO. 

Regarding your settings, think it twice before disabling totally the print fan. If you do that, overhangs and bridges will suffer and also when the layer takes less than 10-15 seconds to complete you may get unpleasant surprises. I never disable totally the print fan, even with PC, PA or any other high temp. filament. You may have to experiment in order to find out the best fan speeds for each filament. Don't rely blindly on the settings suggested by the filament manufacturer. There're lots of different printers out there and a default setting for all of them isn't gonna work in many cases.

For instance, I never printed Polymaker  PA6-CF20, but bed temperatures of 40-50C for nylon seem very low to me. You won't get good adhesion at these temperatures and you'll have to rely solely on glue to get the part stuck to the plate. I wouldn't be surprised if warping is much worse because of that low adhesion.

RE: Polymaker CoPA and PA6-CF20 on the MK4, looking for well-tested and fine-tuned PrusaSlicer filament settings

Thanks for the information Auther. 

As far as the not being dry enough, I have no idea how dry it is. I'm in Colorado where it's very dry and I keep it in a sealed bag with descant until I'm ready to use it, also prior to use I have it on the printer which is in a 35-40C enclosure cover for about an hour prior to use. I'm using a Prusa Power Coat Steel plate, and it seems to adhere very well, no issues there at all.

Now the fan idea may have some good merit. I originally ran the cooling fan like it was printing with PLA, 100% for bridges and 70-80 All the time, except on the first 3 layers, and my Stright edged after the first three layer started turned-out somewhat wavy.  I figured the fan was cooling the filament too fast, and your right. I will have to play with the settings to figure that out.

I'm going to run my bottle opener print and then take a few pictures of it. I'll play with the Bed temp and rase it up to 60C, also turn on the fan to 40-50% and 80% for bridges.

RE: Polymaker CoPA and PA6-CF20 on the MK4, looking for well-tested and fine-tuned PrusaSlicer filament settings

There’s a big difference between disabling totally the fan and setting the speed at 50% .  For a nylon filament that’s very high. On my MK3S+ and Prusament PA11-CF my fan settings are 12% minimum and 24% maximum, bridges at 30%. Of course you have a MK4, so your ideal settings may be different, but I’d start trying lower speeds than 40-50%.

When you say Prusa power coat sheet, you mean a satin or textured plate ? . Using  adhesive on the plate may work for small parts, but I suspect that on larger models with pointy or square corners, it won’t be so easy. Anyway, filaments with carbon fibers do warp a lot less than pure nylon and this is a very positive feature of these filaments.

I reckon that Arizona in summer seems an ideal scenario for keeping the filament dry, but those bumps and artifacts are typical of moist filament. It has been said often in this forum that a spool fresh from a sealed bag is no guarantee of perfectly dry filament. We don’t know for how long and in what conditions that spool has been stored. If the filament has already some moisture when you get it, keeping it in a sealed bag with desiccant will prevent additional water absorption but it won't remove the existent moisture.  To do that, you have to use a  food dehydrator or a dedicated filament drier.

For instance, I never had any problem with moist PLA in this regard, but I have to dry all the PA or PC spools if I want a trouble free and nice looking print.

RE: Polymaker CoPA and PA6-CF20 on the MK4, looking for well-tested and fine-tuned PrusaSlicer filament settings

Well, I put the filament in the oven at 170°F for 1 hour to dry it out. (I Don't have any type of sophisticated drying equipment) The only difference I felt in the filament was it had a little more flexibility and didn't feel so brittle and stiff.

Ran two prints with slightly different parameters.

• Printing temp 285°C and also a 290°C
• Bed 60°C,  Smooth sheet
• Fan speed 0 first layer, then all layers 25%, Bridge 50%
• Enclosure 35-40°C
• Printer Mk4, Speed 40mm/s, Ruby tip nozzle 0.6mm/ slice thickness 0.2mm

First printed at 290°C                                  Second printed at 285°C

Cooling Fan off                                                              Cooling Fan on     

Is there a test print model for this material.  Seem like the smaller features have trouble. Also wondering if my temperature setting is too low. I can only get to 290°C.

RE: Polymaker CoPA and PA6-CF20 on the MK4, looking for well-tested and fine-tuned PrusaSlicer filament settings

As I haven’t direct experience with this filament, it’s hard to make any recommendation looking at the pictures, but I don’t think that the temperature is a real problem. Most PACF filaments print well in the 270-290C range ( I use 275C for Prusament PA11-CF ).

On the other part, drying the filament at 170F/75C for just one hour won’t fix a possible moisture issue, Manufacturers recommend that nylon filaments need a least 8-10 hours at this temperature to be dried properly.

 Comparing both prints fan speed doesn’t seems to be critical. Possibly 25% is a bit too much ?.  It would be preferable to reach 45-50C inside the enclosure, but I don’t expect that this helped much with the print imperfections.

My bet is still on wet filament.