small cylindrical pins in nylon

[HPW 0]

Hello,

For the future use of an UMS5 I have a question about printing small cylindrical pins in nylon of D2 x 20mm which schould later fits in 2mm holes in a nylon part.

 

Should the pins be printed in vertikal or horizontal orientation in the printer/cura?

For a smooth fitting, how much thinner should be the diameter of the pin? For example 1.95 mm for a 2mm hole? Or less?

The pins should be pused in with medium power and should not fall out on its own.

 

Regards

Hans-Peter

 

 

[HPW 0]

Foud this similar question:

 

[gr5 2,097]

You are just going to have to print samples.  Many things will change the diameter - most importantly how far the pin is above the heated bed as temperature drops as you get farther from the hot glass.

 

Some points.

 

1) In general for pins you should get what you ask for.  Unlike vertical holes.  Because your pins are 100% filled, there's no where for the filament to go.

 

2) If you print a single pin it won't have much ability to cool down so you should always print at least two so that one can cool for a few seconds while it prints the other.

 

3) Unlike PLA, Nylon is likely to have bad layer adhesion so the pin may be quite weak if printed vertically.  This should not stop you from printing vertically.  Instead you should enclose the printer (throw a sheet over it) to try to get the air temp up to maybe 30 or 35C.  Also lower the fan as low as possible but where it is around 1/4 the volume of full speed.  Typically 3% for an S5 (or 6% for Um3 or 30% for UM2 - every model and even different versions of the same model will be different on this).

 

4) Break a few pins.  On purpose.  Print some extras.  If they break along layer lines your adhesion is probably not good enough (need to lower fan some more or raise air temp some more or both).

 

I would not print horizontally but that will certainly give you the strongest possible pin but will require lots of PVA potentially.

 

[geert_2 557]

Try using standard nylon hardware: there do already exist thousands of different things: screws, pins, nuts, clamps,... These will be much stronger, have a stable size, require almost no post-processing, and in the end be much cheaper. Maybe these will fit, or only require minor changes to your models to fit?

 

In Belgium and the Netherlands, Essentra Components (previously Skiffy) has a good range. But also RS Components, Farnell and lots of others do.

 

https://www.essentracomponents.com/en-nl

 

If you want to print it yourself:

 

- If you print it horizontally, it will be by far the strongest, but not cylindrical. Then it will only be half a cylinder, and probably have a flash or elephant feet at the bottom.

 

- If you print it vertically, expect overextrusion, lots of blobs and deformations, and a very weak model that breaks easily, especially for high-temp materials like nylon. And expect it to wobble during the print causing a deformed rod, and likely fall over.

 

I am not saying it is impossible, but for very small objects, you will have a hard time sorting these things out. If you use standard injection moulded nylon parts, you don't have these problems.

 

Typical deformations of small, vertically printed items:

 

Insufficient cooling due to the nozzle staying on top of the tiny area, so it does not solidify. Cones are 20mm high x 20mm diameter. Lowering temp does reduce this effect, but also reduces layer-bonding: not a problem in PLA but for sure a problem in nylon.

 

Insufficient cooling, overextrusion, strings and blobs in vertically printed models (ca. 20mm high, printed at different temps and speeds). Less deformations but some flanges in horizontally printed models.

 

So this is what you should expect.