Hole dialog discussion

[uwestoehr]

I took some more time. The result is this PR: https://github.com/FreeCAD/FreeCAD/pull/4039

You are right, there are no fine thread screws around according to ISO 14583. However for ISO 4762 there are. The vendors obviously often mix the DIN and ISO around. Some even state DIN 912 is equal to ISO 4762. However, it does not harm to have a ISO 4762 fine because the cut dimensions are independent on the thread anyway.

I found the original ISO 4762: http://www.rosmetiz.ru/upload/files/gos ... o_4762.pdf
Since it defines no M27 size, I removed it from the JSON. However it defines two more larger sizes that I added to the JSON.
I was wondering why the cut diameter should be equal for M3.5 and M3 and according to some "Bohrtabelle" I could find (e.g. this one: https://schraube-mutter.de/bohrtabelle- ... schrauben/), they are different. I fixed the file accordingly.

I also changed the name of the profile from "metric coarse" to "metric regular", since the Norm says regular and also the vast majority of vendor websites and shops.

Sine I use them at work, I added definition files for IS0 2009, 7046 and 12474.

The M3 screw I found and thought it has a fine thread, is simply not a metric screw . Nevertheless I cross-checked that the threaded screws have the same head dimensions than their regular thread counterparts.

Just as reference, here is a list of the DIN norms compared to their successor ISO norms:
https://www.schraubenhandel24.de/din_wird_iso_schrauben

[chrisb]

The M3 screw I found and thought it has a fine thread, is simply not a metric screw

AFAIK there are different series for fine threads. “ISO fine thread I” seems to be the same as DIN 13-1 and has a rather fine gradation including M3. See e.g. https://www.gewinde-normen.de/iso-feingewinde.html.

[rynn]

Why must this be unique?

Implementation-detail.
This should be fixed.

[uwestoehr]

as DIN 13-1 and has a rather fine gradation including M3.

Yes, the thread itself is defined for different sizes. But we need here the screw head dimensions. In one of our products we use for example M1.0 fine thread screws ("watch maker" screws) but I could not find a norm in which the head of these screws is normed. I will have a look again tomorrow because maybe there are special norms around for watch maker screws.

[uwestoehr]

Implementation-detail. This should be fixed.

What exactly? I cannot see a problem so far.

[rynn]

Implementation-detail. This should be fixed.

What exactly? I cannot see a problem so far.

The problem is, that it’s not possible to have cut-profiles with the same name for different thread-types. (p.e. “DIN 912” for metric and “DIN 912” for metric fine.)
This is the result of an implementation-detail and should be fixed.

[rynn]

The problem is, that it’s not possible to have cut-profiles with the same name for different thread-types. (p.e. “DIN 912” for metric and “DIN 912” for metric fine.)
This is the result of an implementation-detail and should be fixed.

Fixed in PR #4041 (hopefully)

[uwestoehr]

Fixed in PR #4041 (hopefully)

Many thanks. it was already merged.

I tested again and only encounter this issue: when changing the depth for a countersink, nothing happens. Sure, one can set the depth by increasing the diameter but in practice you don't perform a calculation what diameter increase leads to the e.g. desired 0.2 more depth, you just cut 0.2 mm deeper.

I'll have a look the next days.

[uwestoehr]

but in practice you don't perform a calculation what diameter increase leads to the e.g. desired 0.2 more depth, you just cut 0.2 mm deeper.

Since the angle is fixed to 90° (at least for the ISO norms), it is an easy task since then 2 mm wider = 1 mm deeper. But for the UTS norms we have 82°. Then you need trigonometry.

There is another issue: when creating a new hole with an ITS profile, nothing is proposed for the diameter and depth.

[uwestoehr]

There is another issue: when creating a new hole with an ITS profile, nothing is proposed for the diameter and depth.

This will be fixed with this PR: https://github.com/FreeCAD/FreeCAD/pull/4046