fori e prefori per bulloni

[il secco]

hi guys don't know if I'm in the right part of the site to ask this question but anyway I try if someone can help me. I would like to know if it is possible to find tables that indicate the size of the hole when I already know the size of the bolt. thanks to all

 

[stefanobruno]

But what do you want, the hole measures to be done and then file?

ps. : you're not in the right place but I can't move you.

 

[il secco]

If it is possible I would be comfortable having them both you know in what section should I ask the question?thanks

 

[maxopus]

I moved the discussion to a more suitable area and renamed it.
try to specify what you need better.
for screws at a metric step?
or do you need to know if a hole diameter 18 is needed on a m16 screw?

 

[il secco]

I try to explain myself better, I have to do workshop executives, from the engineer I get the size of the screws I have to put in the various knots. I have to give the size of the hole in which the screw will go. Since it is the first time I mention this, I would need to know if there are tables that according to the screw give me the size of the hole I need. I know that something is written about the norm cnr10011 but sincerely I did not get very clear.thanks

 

[il secco]

Let's say that it's easier I need to know that if I have a m16 I need a hole from 18, that's why they asked if there were tables

 

[maxopus]

I read on the nunziata manual:
for bolts with a nominal diameter <= to 24 holes with a diameter greater than 1.5 mm than the diameter of the bolt (m24, hole 25,5) are allowed.
for bolts with a nominal diameter >= to 24 holes with a diameter greater than 2.0 mm than the diameter of the bolt (m30, hole 32).

in practice it tends to always use a + 2 mm.

in case there is no movement under load or in the presence of inversion of effort, the limits will be more restrictive and the coupling is said of precision.

 

[il secco]

Thank you very much I presume that for particular provisions I will give indications to you in. thanks

 

[Fulvio Romano]

depends on the type of piece. . .
Imagine having an object of a couple of tons to hit on a flange that brings six bolts. If you want to avoid the blasphemy of the chariot, perhaps it is better to abound with the size of the holes and then put multiple washers. . .

 

[michele81]

from cnr-uni 10011-1988:
the holes must have a diameter equal to that of the bolt increased by 1 mm up to d=20mm and 1.5mm beyond d=20mm when a siege under load of the joint is allowed. You may derogate from these limits, respectively up to 1,5mm and 2mm if you check under the service loads. . .
check the d.m. of 14 January 2008 for confirmation.
greetings

 

[maxopus]

I consider what is reported by michele81.
a 17 hole for a bolt m16 I allow myself to say that it is a half caxxata.
keep in mind that typically the carpenters are hot galvanized (and this already takes you away 1 mm near the holes, because the 200 microns of thickness of the galvanization are theoretical for the flat parts, in correspondence of the edges you have an accumulation of material even 5 times higher).
to this we add the manufacturing tolerances of plates and profiles.
in the end if I make a 17 hole for a m16, 90% of the holes I have to go back to drill in the yard (when it is okay, otherwise they use the cannello, with all the consequences they derive).
Some parts of some rules should be revised to bring them back to reality...

 

[michele81]

I consider what is reported by michele81.
a 17 hole for a bolt m16 I allow myself to say that it is a half caxxata.
keep in mind that typically the carpenters are hot galvanized (and this already takes you away 1 mm near the holes, because the 200 microns of thickness of the galvanization are theoretical for the flat parts, in correspondence of the edges you have an accumulation of material even 5 times higher).
to this we add the manufacturing tolerances of plates and profiles.
in the end if I make a 17 hole for a m16, 90% of the holes I have to go back to drill in the yard (when it is okay, otherwise they use the cannello, with all the consequences they derive).
Some parts of some rules should be revised to bring them back to reality...

I was just allowed to bring back a passage of the norm quoted in the post... I personally think that 1 mm more than the nominal is good until the maximum m8/10 after definitely 2 mm at least until the m20/24 then 3 mm more than the nominal. then as already said it is necessary to evaluate the individual situations and tolerances in play.
greetings

 

[Meccbell]

apart from that there should be all in the eurocode relative to steel constructions, for the rest I feel to quote to the cube max.

1 mm of play or even less is good for everything that needs to be mounted at the counter, perhaps by mating worked surfaces, with masked holes or on automatic machines.

for the rest, structures in the first place, and even more 'if it is about sheds, chariots or other things like that, and taking into account that in these cases we usually use bolts from m16 up, I would say that 2 mm are just the least indispensable.
also because the coupling, if well calculated, holds for friction between the 2 parts, generated by the screws, and therefore that the bolt "sweet" in the hole of 1 ,2 or 4 mm little changes.
In case of particularly laschi holes or even oval hollows for the adjustment of the parts, be careful to choose diameter washers and thickness suitable to best distribute the clamping force on a surface as wide as possible.

 

[Fulvio Romano]

depends on the type of piece. . .
Imagine having an object of a couple of tons to hit on a flange that brings six bolts. If you want to avoid the blasphemy of the chariot, perhaps it is better to abound with the size of the holes and then put multiple washers. . .

a 17 hole for a bolt m16 I allow myself to say that it is a half caxxata.

That's right.
Moreover, what does it mean that the pin must stop the slip? Are we talking about a threaded pin that's cutting? : eek:: eek:: eek:

 

[michele81]

for completeness I quote also the eurocode (now I am in the vein of quotes...:smile:
7.5.2 tolerances in holes for joint devices
(1) except for calibrated bolts where reduced tolerances or increased holes are specified, the tolerance for niminal holes must be:
- 1 mm for bolts m12 and m14
- 2 mm for m16 to m24 bolts
- 3 mm for m27 bolts and morethen mention all the exceptions including this:(6) the nominal tolerance in the increased holes for friction links must be:
- 3 mm for bolts m12
- 4 mm for bolts from m14 to m22
- 6 mm for m24 bolts
- 8 mm for m27 bolts and beyondthis in support of the speeches so far made, also about the updating of the legislation.:wink:

 

[Meccbell]

Right... It seemed to me to remember that the Eurocode ruled the thing.