Nylon dimensional accuracy in the Z direction

Bambu Lab P1 Series Troubleshooting
1

Hi all,

In the last few days I have been struggling to print a part for an RC project in nylon on my P1s. I am using Polymide CoPa by Polymaker. Initially one if the issues was roughness on overhangs but I think I managed to mostly solve this:

IMG_7870
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The left-most shaft is the latest print and it is mostly acceptable, but you can see what the previous versions looked like before I slowed down the overhang speeds to 20 mm/s.

However, my main issue is the dimensional accuracy. In particular, the shaft loses shape in the z-axis direction. I printed a copy in PAHT-CF and by comparison it came out perfect:

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IMG_7872
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PAHT-CF is on the left and Polymide CoPa is on the right. Both are printed with the same settings (0.15 layer height, 100% infill, 3 walls, with their respective print profiles). Both filaments are dried.

Notice how the hex shape is skewed and the whole shaft is taller on the z-axis on the CoPa print.

Does anyone have an idea about how to address this?

Obviously if it was bigger in alm directions I would scale it, but it seems it is more complicated than that…

Thanks in advance!

1 Like
2

I’m trying Overture CoPa because it’s 3x cheaper than PAHT-CF but yeah it’s really hard to get accurate prints. I’m printing straight from the dryer at 70°C. Did you succeed at improving the quality?

3

Precise Z-height can be helpful:
image

You might also try using OrcaSlicer, which can adjust the filament preset for Z-axis shrinkage.
image

1 Like
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I did manage to improve it a bit by going even slower - I have to check my exact settings, as I haven’t printed CoPa recently. I also print directly from the dryer, even though I keep the dried spool in a separate drybox that indicates around 11-12% humidity.
I have a spool of Overture Easy Nylon that I bought with the intent to test and see if I get better results, but haven’t had the chance to test it yet.

For me it is not just about the cost against PAHT-CF, but also the parts I print are used in an RC car drivetrain and PAHT will end up too abrasive for axles, gears etc.

5

how is Overture Easy Nylon at the end? easier to print than CoPa ?