I’ve been doing a couple of prints using PAHT-CF and I’m rather disappointed by the finish. I’m using a 0.6 nozzle and the BBL “strength” settings. I’m finding the surface very rough. This is a new spool and I don’t have a dryer yet, but I’m in a pretty dry area (<30% RH), and I put the spool straight into the AMS.
So I’m wondering whether what I’m seeing is wet filament or just what this stuff ends up looking like… (I’m using the 0.6 nozzle 'cause that’s what is recommended and to get a bit more strength over the 0.4).
When I compare with the PAHT-CF parts in the announcement post it’s like night and day (dunno which nozzle/settings they used and whether they post-processed the parts):
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Nylon is terrible for soaking up moisture, and that looks like yours has tons of moisture in it. Just because it came straight out of the bag and into the AMS doesn’t guarantee it was free of moisture. I was lucky with my roll and it was exceptionally low in moisture, but I’m sure they all aren’t that way. Which is why they emphasize drying it when you buy it.
If you have a X1 or X1C, try the printer drying function until you can get a dedicated dryer.
Mine was showing 15% RH in my dryer before printing and came out like this.
Reporting back after ~20hrs of drying time in the X1C. The ~470g spool lost just about 2g. I didn’t reprint the same pieces but did a test print and some flat bars instead and they come out with good surfaces. A bit rough, but I suppose that’s the CF. There are still some issues with a bit of stringing and poor bridge undersides but that may be the limit of PAHT-CF or it may be that some time in a real dryer is required. But at least it’s usable now.
The photo has the PAHT-CF test print on the left together with a bar in front (top side is the top of the print). The test print on the right is PLA-CF for comparison (and that is probably with an 0.4 nozzle instead of the 0.6 for PAHT-CF).
The most important thing with PAHT-CF is drying. Dry, dry and dry again. I have also had to dry the last two days: Sunlu S4, 70°C, 24h. I have a test card that I print and see if the last drying was worth it. After the filament is dry, so that I no longer achieve a significant print improvement, I calibrate the filament manually and save the value together with the filament. I then no longer carry out an automatic calibration before printing (there are too many deviations that can mess up the result). I then print with the standard settings on the X1C with a 0.4 mm nozzle and get the best results.
Warping:
I print PAHT-CF exclusively on glass (because it does not yield to material warping), and I use a covering spray of 3D-lac as an adhesion promoter (but the glue stick applied well also works excellently). The heating plate temperature should be as high as possible. The default setting is 100°C, 120°C would be the maximum that is possible on the X1C.
Surface:
PAHT-CF is rough to very rough when the filament is wet, the finished print has no glossy. In addition, the print is not dimensionally accurate, so that parts that belong together do not fit together. If PAHT-CF is sufficiently dry, the surface becomes glossy, but it feels rough, the accuracy of fit / dimensional accuracy is correct.
I didn’t notice it at the time you posted this, But I would have also suggested you change the print orientation so that it prints on its side and added 5+ walls for reasonable strength. Still would need supports, but only for the small fillets around the mounting holes and the holes themselves. Granted this project is likely long done and dusted, I think its a good idea to add the suggestion to the pool for the benefit of others.
I would have suggest something like this, if the looks were important as well as a little bit of strength.
I’ve tried to print PAHT-CF several times and none of them were usable. The first time I dried it in a dehydrator, 2 days ago in the X1C. The corners are rough and the bed side faces are convex. In the past everything warped at the corners. As far as I’m concerned this is a completely useless filament.
That still does not look great. I would expect a smoother surface. It shouldn’t be as perfect as PLA-CF (The matte nature of that filament hides all sins), but it should only be a little rougher.
Now, the bar you printed is very close to what I would expect, which tells me that the test print with the small features and overhangs might not have enough cooling. The BBL profile for this filament has very little cooling (See attached image).
Now, I know that cooling is blasphemous with Nylons. Cooling can negatively affect layer adhesion and potentially cause more warping with Nylons…but I have always found that to get clean prints with objects that have lots of small features, and overhangs, more cooling is needed. It is a tradeoff. I would try the following and then reprint:
Go into the filament/cooling settings…then…
Click the box that says “Keep fan always on.” but leave the minimum at 10%. We want some fan, but not too much!
Set the layer time for “Min fan speed threshold” to 10 seconds
Set the fan speed for “Max fan speed threshold” to 60
Set the “Cooling overhang threshold” to 25% (we already have 10% all the time which is likely good up to a 25% overhang).
Set “Fan speed for overhangs” to 70-90%
Now…to take care of possible warping due to increased fan, we need to heat the chamber. This can be done with gcode modifications, or done manually.
To do it manually, close the door, set the chamber fan to 0. Set the aux fan to 100%
Set the bed temp to the max (in the US it is 120c)
Let the printer sit this way for 12-15 minutes, or until the chamber temperature is over 40c…Ideally 45c
So, the part will be cooled so that small features and overhangs improve…but the chamber will be warm, so that warping is less likely.
Yes, the cooling may reduce interlayer adhesion some - but the large layers, whee this adhesion is needed for strength will only have 10% fan in an already warm chamber.
Last thing - you might try printing 5c cooler if you are near the upper end of the filament temp range.
Hard to say with that picture, but it could be still very moist. Nylon (PA and PAHT) is really difficult to dry if you let it get moisture logged. If you left it out for a week, it can suck up enough moisture to take a ridiculous amount of time to dry out if you live in a humid environment. At least considering the average dryer, which max out around 55-60C. Dryers that can see 70C-100C can speed things up, but still may take a reasonable amount of time.
There’s a professor that has a YouTube channel who ran a test and found heavily saturated roll of Nylon would take about a week in the 60C dryer. That’s insane. So, don’t leave that stuff out.
Yours looks still saturated from the picture, but its tough to say. Do you have a picture of the layers and how they laid down? I’m assuming the pic you posted are of the bottom of the print.
Here are a couple other parts of the project. These parts print well with PLA or PETG, I can’t see the point in struggling with nylon. I just wanted to see what it could do. But my parts have never looked close to the Bambu samples.
I actually love the PAHT CF, but it needs to be really dry to print clean. I’ve only needed to use it once and it printed like a dream on the first try. Looked just like the BBL example models. But what I’ve found, if you don’t need the extreme heat resistance, use something else like the ABS GF, or ASA CF. Most Nylons gets downright weak when its in humid areas, even after printing. The PAHT is pretty good with that, and it stays reasonably strong as long as it isn’t crazy humid or used in water.
From the pic, that still looks saturated with more moisture than I’d want. The sides should look satin like, and should be very clean lines. Texture to the touch, but not in sight. Honestly, if the texture doesn’t look like the lines on BBL’s product page, you can almost bet you need to dry it more.
I love Siraya Tech ASA-GF. Much cheaper than nylon, and prints like butter. Still has a lot of heat resistance, and tons of UV resistance. Very stiff and strong. If you get some, I am happy to share my profiles.
