Feature request: Thread pitch for screws about freecad_fastenerswb HOT 7 OPEN

Workaround before these fine pitches are implemented. For example to get DIN933 M27 with 1.5mm pitch. Open freecad/common/Mod/fasteners/FsData/din933head.csv file. Then Find M27 bolt

"M27",3.0,0.4,38.0,45.2,17.0,1.0,41.0

Second value it pitch. Modify it

"M27",1.5,0.4,38.0,45.2,17.0,1.0,41.0

Save file. Restart freecad. Now make M27 bolt and it has 1.5mm thread pitch.

from freecad_fastenerswb.

I have looked up the DIN 933 and the ISO 4017, the replacement for DIN 933, and in neither mentions a fine pitch version of the screw. I also wasn't able to find a screw on an online screw shop with such a pitch. One possibility would be to make 4 "new" screws where the pitch is modified, it is named probably, "DIN 933 fine I, none Standard" or similar and a note is given in the description part, with a link to where these pitches come from (source).
One possibility is that there is a norm with screws that have a finer pitch but practically the same head as DIN 933 if that is the case than implementing that would be the best move, I wasn't able to find one, but I do not know all screw norms.
If you have a source for where such screws are coming from (an online shop) maybe give a link.

from freecad_fastenerswb.

You a likely right that those are not standard, since those bolts are hard to find from any stores. But those bolts exist and they are used, for example on a Ural motorcycle fork. It's just a cap keeping water out of fork.

https://www.ural-zentrale.de/en/chassis/telescopic-fork-dnepr/telescopic-forks-top-bolt-27-mm

It would nice to be able to 3D print spares when original bolts are lost.

Same thread pitch is also used in pipe caps but with a different head

https://www.rejko.fi/tuote/putket-osat-ja-liittimet/sinkityt-kierreosat/tulppa-sinkitty-uk/tulppa-sinkitty-1/

from freecad_fastenerswb.

As a simpler workaround you can add any screw and cut away its body (so the head is left), then add a threaded rod which can use any custom thread pitch weld them together:

from freecad_fastenerswb.

I have looked up the DIN 933 and the ISO 4017, the replacement for DIN 933, and in neither mentions a fine pitch version of the screw. I also wasn't able to find a screw on an online screw shop with such a pitch.

That's because fine thread screws have their own standards. In this case:
· DIN 961 (withdrawn and replaced by)
· ISO 8676 / DIN EN ISO 8676

from freecad_fastenerswb.

In #285 I added DIN 961 and ISO 8676.
@OH1KK I hope those are the screws that you needed

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I have just added ISO 262 which is a subset from ISO 261 where the different diameters have associated to them a coarse thread and some fine threads (80615b7)
ISO 262 is for bolts, screws, studs, nuts, these are the recommended ones. Apart from this table I have seen bolts commercially with fine pitches that are not in ISO 262 but are in ISO 261, maybe we need to also add it.

P = FsData["ISO262def"][fa.diameter][1] # fine thread 1

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