I've access to both. Ping me if I can be of any help.rynn wrote: ↑Sat Nov 14, 2020 11:04 amThe problem is, these cost a fortune: DIN 74 (42,88 €) and DIN EN 20273 (30,23 €)
That’s why most developers here do not have access.
Hole dialog discussion
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Re: Hole dialog discussion
Regards / Viele Grüße
Max
Max
Re: Hole dialog discussion
Probably. But many websites are rather interpretations of the norm, and it is usually impossible to see where they deviate from the real document itself.
Hopefully M4x can shed some light on this. I am, of course, against spending money for something that can be found for free. But I am even more against investing time following the wrong path, albeit only a slight deviation.
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Re: Hole dialog discussion
They want to sell their screws. The norms for sure follow the norms - no one will setup a product line which nobody will buy or send back. So when they write according to " ISO 4762" and then specify a table we can be sure these are the dimensions of screws defined in this norm. Moreover, I of course checked several screw seller pages.
Re: Hole dialog discussion
I'll have a look and compare the tables to the norms later today.
Regards / Viele Grüße
Max
Max
Re: Hole dialog discussion
DIN EN 20 273 : 1991 Durchgangslöcher für Schrauben = german translation of the ISO 273 : 1979 Fasteners; Clearance holes for bolts and screwsuwestoehr wrote: ↑Sat Nov 14, 2020 12:08 pm This defines hole diameter sizes:
https://cad-markt.de/index.php/cad-tutu ... bmessungen
or
http://www.iim.maschinenbau.tu-darmstad ... 20273.html
[...]
The links uwestoehr provided earlier are correct but some values the norm defines are missing. I assume because those are uncommon in practice. I've asked duckduckgo.com and found this photo from a (I guess) Mechanical and Metal Trades Handbook or something like that: Link photo ISO 273 / DIN EN 20 273 values. I've checked all values, the table in the linked photo is complete and correct according to the norm mentioned above.
DIN 74 : 2020-01 Senkungen für Senkschrauben, ausgenommen Senkschrauben mit Köpfen nach DIN EN 27721 = Countersink for countersunk head screws, except countersunk head screws with heads according to DIN EN 27721
This norm defines four different countersunk types (A, E, F and G), gives information about what countersunk type should be used with which screw type (described by a norm of course) and includes tables with the relevant dimensions.
Further more, the norm tells us something about how, in special cases, other countersunk depth should be handled.
example
countersunk type A for an M4 screw should've a depth of 2,1 mm. If you'd need a depth (t [the norm uses t_1]) of 3 mm, the diameter d_2 would change accordingly. And you'd write something like "countersink DIN 74 - A4 x 3" to make that clear.
Does this help already? I probably have access to all screw related norms and could read up on specific questions / check if found tables are correct and so on. I must confess that I didn't read the whole thread so I'm not entirely sure "where" the discussion is at the moment
edit: typo
Last edited by M4x on Sun Nov 15, 2020 6:41 pm, edited 1 time in total.
Regards / Viele Grüße
Max
Max
Re: Hole dialog discussion
And this saved FreeCAD another 73,11€. Thanks for looking it up.
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
Re: Hole dialog discussion
You're welcome. I'm glad that I could help. I'd even do it again
Regards / Viele Grüße
Max
Max
Re: Hole dialog discussion
Yes. Thank you. Note however, the ISO screw definitions differ in the height if the screw heads from the ISO norms. Thanks to @rynn we have the new feature to select a screw definition norm to get a proper proposal for the cut depth.
Here is the PR: https://github.com/FreeCAD/FreeCAD/pull/4058uwestoehr wrote: ↑Sat Nov 14, 2020 12:08 pm So we have 2 issues:
- some of our "close fit" diameters for metric holes are incorrect (we use e.g. values like 3.15 despite the norms define a precision of max 0.1 mm)
- we don't support the defined "coarse fit"
I'll correct/add this after the pending PR is merged.
- It adds the coarse fit
- it takes whenever possible the hole diameters of the ISO norm
- While implementing this, I found out that we did not support the sizes M4.5, M7 and M39, They are normed and you can buy screws in that size, e.g. here M39: https://schraube-mutter.de/schrauben/m39/ I added these sizes with the PR.
Re: Hole dialog discussion
In the PR on Github I commented on the name used for the largest of the clearance hole sizes: @uwestoehr went with "Wide," but that doesn't match either the ISO standard or the reference I normally use for these (Glover's Pocket Ref). uwestoehr suggested we discuss the name here.
I agree that the ISO's naming of "Fine," "Medium," and "Coarse" for the clearance hole fit is confusing, and that "Wide" is a better choice. However, I've never seen clearance holes described using that term before. I don't know if there is precedent for it, so I suggest that maybe using "Close Clearance," "Normal Clearance," and "Loose Clearance" is even more clear/descriptive, and has at least one other source (Glover). That said, there's no reason to treat Pocket Ref as an absolute authority on the manner: it might be a good idea to use someone else's terms instead of making up our own, though. Is there another reference for what terms to use in this menu?
I agree that the ISO's naming of "Fine," "Medium," and "Coarse" for the clearance hole fit is confusing, and that "Wide" is a better choice. However, I've never seen clearance holes described using that term before. I don't know if there is precedent for it, so I suggest that maybe using "Close Clearance," "Normal Clearance," and "Loose Clearance" is even more clear/descriptive, and has at least one other source (Glover). That said, there's no reason to treat Pocket Ref as an absolute authority on the manner: it might be a good idea to use someone else's terms instead of making up our own, though. Is there another reference for what terms to use in this menu?