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To the Raspberry Zero Production line...

Posted: Thu Aug 08, 2019 6:13 am
by rin67630
Would it be possible to drill the fixation holes 0,25mm bigger, so that standard 3mm screws could be used?
Currently I must enlarge every hole to fix the PCB with much more common 3mm screws.

Re: To the Raspberry Production line...

Posted: Thu Aug 08, 2019 6:25 am
by Ernst
rin67630 wrote:
Thu Aug 08, 2019 6:13 am
Would it be possible to drill the fixation holes 0,05mm bigger, so that standard 3mm screws could be used?
Currently I must enlarge every hole to fix the PCB with regular DIN screws.
:(
M2.5 is a regular ISO/DIN metric screw thread.

Re: To the Raspberry Production line...

Posted: Thu Aug 08, 2019 6:32 am
by DougieLawson
rin67630 wrote:
Thu Aug 08, 2019 6:13 am
Would it be possible to drill the fixation holes 0,05mm bigger, so that standard 3mm screws could be used?
Currently I must enlarge every hole to fix the PCB with regular DIN screws.
:(
They won't change a form factor that's been there as part of the factory tooling since the RPi B+ launch in 2014.

Re: To the Raspberry Production line...

Posted: Thu Aug 08, 2019 6:39 am
by rin67630
Ernst wrote:
Thu Aug 08, 2019 6:25 am
rin67630 wrote:
Thu Aug 08, 2019 6:13 am
Would it be possible to drill the fixation holes 0,05mm bigger, so that standard 3mm screws could be used?
Currently I must enlarge every hole to fix the PCB with regular DIN screws.
:(
M2.5 is a regular ISO/DIN metric screw thread.
It won't make such a difference to drill the holes to 3mm backward compatibility is assured. And i am not the only one, who must drill the holes bigger, because 3 mm is much more common.

Re: To the Raspberry Production line...

Posted: Thu Aug 08, 2019 6:41 am
by rin67630
DougieLawson wrote:
Thu Aug 08, 2019 6:32 am
They won't change a form factor that's been there as part of the factory tooling since the RPi B+ launch in 2014.
It won't make such a difference to drill the holes to 3mm backward compatibility is assured.

Re: To the Raspberry Production line...

Posted: Thu Aug 08, 2019 7:08 am
by Gavinmc42
I usually drill my Pi holes to 3mm, because spacers and screws are easier to get.

Re: To the Raspberry Zero Production line...

Posted: Thu Aug 08, 2019 8:52 am
by bensimmo
If they did that, they'd fall out of my cases and I'd need to buy 3mm screws and spacers.

2.5mm is fine by me.

Or go smaller, go to 2mm.
Then anyone with 2.5mm can drill out for backwards compatibility.

I can't make 3mm smaller.

Re: To the Raspberry Zero Production line...

Posted: Thu Aug 08, 2019 9:03 am
by rin67630
bensimmo wrote:
Thu Aug 08, 2019 8:52 am
If they did that, they'd fall out of my cases and I'd need to buy 3mm screws and spacers.
No.

Re: To the Raspberry Zero Production line...

Posted: Thu Aug 08, 2019 9:05 am
by bensimmo
rin67630 wrote:
Thu Aug 08, 2019 9:03 am
bensimmo wrote:
Thu Aug 08, 2019 8:52 am
If they did that, they'd fall out of my cases and I'd need to buy 3mm screws and spacers.
No.
No what?
3mm is greater than 2.5mm, how are the push fit cases like the RPi one and many Zero design suppose to work?

Re: To the Raspberry Zero Production line...

Posted: Thu Aug 08, 2019 9:28 am
by fruitoftheloom
rin67630 wrote:
Thu Aug 08, 2019 6:13 am
Would it be possible to drill the fixation holes 0,25mm bigger, so that standard 3mm screws could be used?
Currently I must enlarge every hole to fix the PCB with much more common 3mm screws.

The holes in RPi boards were not originally designed as "fixation" holes......

Re: To the Raspberry Zero Production line...

Posted: Thu Aug 08, 2019 9:31 am
by Burngate
The very first Pis didn't have holes!

Re: To the Raspberry Zero Production line...

Posted: Thu Aug 08, 2019 10:19 am
by rin67630
bensimmo wrote:
Thu Aug 08, 2019 9:05 am
No what?
3mm is greater than 2.5mm, how are the push fit cases like the RPi one and many Zero design suppose to work?
Exactly like today: the slightly larger holes will fit 2,5mm screws as well.

Re: To the Raspberry Zero Production line...

Posted: Thu Aug 08, 2019 11:11 am
by bensimmo
but they don't use screws, they use push-fit interfaces.

also then the specs would need to to change, so the HATs will work and need to be 3mm and then the B/A specs would need to change to be compatible with these HATs, otherwise you'll still need M2.5 setups.
given you can buy them (2.5mm), maybe they cost a bit more. but it works and is fine for the majority of people.

It seems like a lot of hassle to switch a spec for a few people, to save a small bit of time, who wish to use slightly cheaper screw size, when anyone involved in hats and accessories has to alter all of their methods to suit you.

(and i'm sure you've brought this up a few times?)

Re: To the Raspberry Zero Production line...

Posted: Thu Aug 08, 2019 11:31 am
by epoch1970
I am used to bringing the subject up too.
M2.5 is in the iso table but what it really is, is equivalent to UNC/UNF size 3. M2 is ~ UNF 2. M3 is ~ UNF 5
In metric countries 2.5 is far less used than M2 or M3. Fact.
Which leads to ridiculous situations where adding 4 or 8 standoffs for a Pi costs a good fraction of the Pi itself. Fact.

M2 is flimsy. M3 is a bit on the large side. Perhaps the choice towards UNC 3 was constrained but it is not to the advantage of end users in general and it is to the disadvantage of those living in regions where metric is traditional.

Re: To the Raspberry Zero Production line...

Posted: Thu Aug 08, 2019 12:44 pm
by scruss
epoch1970 wrote:
Thu Aug 08, 2019 11:31 am
In metric countries 2.5 is far less used than M2 or M3. Fact.
I'd disagree strongly. M2.5 is one of the R5 preferred sizes: 2.5, 4, 6, 10, etc.
M2 is flimsy. M3 is a bit on the large side. Perhaps the choice towards UNC 3 was constrained but it is not to the advantage of end users in general and it is to the disadvantage of those living in regions where metric is traditional.
No no no no, please don't bring UNC/UNF/ASME confusables in here! Here in Canada we have a horrible mess of weird customary sizes that crowds out metric sizes — and we are a metric country! Hardware suppliers in both the UK and the US are much more metric than we are here.

Remember, there are two types of countries: those that use metric and those that crashed an $300 MM orbiter into Mars because they didn't understand metric.

Re: To the Raspberry Zero Production line...

Posted: Thu Aug 08, 2019 2:44 pm
by epoch1970
I just went to RS France, asked for female threaded spacers
M2: 8 references
M2.5: 55 references
M3: 197 references

I leave you to guess which ones are the least expensive.

Re: To the Raspberry Zero Production line...

Posted: Thu Aug 08, 2019 3:06 pm
by plugwash
I suspect the issue is the clearances needed to make sure that even with a slightly oversized screwhead/spacer body and a screw/spacer not perfectly aligned on the hole that it can't accidentally short anything out.

Re: To the Raspberry Zero Production line...

Posted: Thu Aug 08, 2019 3:32 pm
by rin67630
scruss wrote:
Thu Aug 08, 2019 12:44 pm
I'd disagree strongly. M2.5 is one of the R5 preferred sizes: 2.5, 4, 6, 10, etc.
LOL that preferred numbers are completely irrelevant in the world of metric screws!

The de facto standard sizes are 3, 4, 5, 6 ,8, 10, 12, 16 mm...
2 and 2,5mm exist too, but do not make it to 2% of the other sales

Re: To the Raspberry Zero Production line...

Posted: Thu Aug 08, 2019 3:40 pm
by rin67630
plugwash wrote:
Thu Aug 08, 2019 3:06 pm
I suspect the issue is the clearances needed to make sure that even with a slightly oversized screwhead/spacer body and a screw/spacer not perfectly aligned on the hole that it can't accidentally short anything out.
That's a valid point !
Specially since some american/asian screws are designed to avoid using washers.
You need plastic washers anyway, else you will get into trouble.
By the way the power LED is too close to the hole and gets regularly torn away by the screwing tools.
I personally don't mind: it's a power consumption less.

Re: To the Raspberry Zero Production line...

Posted: Thu Aug 08, 2019 5:07 pm
by scruss
rin67630 wrote:
Thu Aug 08, 2019 3:32 pm
LOL that preferred numbers are completely irrelevant in the world of metric screws!
Nope: ISO 261 and ISO 262 metric screw sizes are based on the R10 and R5 series.

For very little cost I got a box of M2.5 black nylon machine screws, washers, nuts and headers. Non-conducting, non-marring, worth every penny.

Re: To the Raspberry Zero Production line...

Posted: Thu Aug 08, 2019 6:28 pm
by W. H. Heydt
Both 2.5mm and 3mm are something I have to hunt around to find, so the difference between them is of no consequence. Now if people want to debate the differences between 3-48 and 2-56 (let alone 4-40)...

Re: To the Raspberry Zero Production line...

Posted: Thu Aug 08, 2019 8:55 pm
by scruss
W. H. Heydt wrote:
Thu Aug 08, 2019 6:28 pm
Now if people want to debate the differences between 3-48 and 2-56 (let alone 4-40)...
Does the 2, 3 and 4 refer to the size of hammer you need to drive it in? :D

At least you're lucky in that half of you hardware doesn't come with Robertson square-drive heads. They're a peculiarly Canadian thing, mostly for wood screws, but sometimes you'll find them on machine screws.

Re: To the Raspberry Zero Production line...

Posted: Thu Aug 08, 2019 8:58 pm
by davidcoton
scruss wrote:
Thu Aug 08, 2019 8:55 pm
At least you're lucky in that half of you hardware doesn't come with Robertson square-drive heads. They're a peculiarly Canadian thing, mostly for wood screws, but sometimes you'll find them on machine screws.
That's nothing. We get Torx, Hex, even crosshead clones that are neither Philips nor Pozidrive. And that's before anyone starts on the special security versions.

Re: To the Raspberry Zero Production line...

Posted: Thu Aug 08, 2019 8:59 pm
by rin67630
scruss wrote:
Thu Aug 08, 2019 5:07 pm
Nope: ISO 261 and ISO 262 metric screw sizes are based on the R10 and R5 series.
I am speaking of experience, what you get in every European hardware store, you appear to have got another experience, really?

Dont't try to fool us: You won't find a 3,15mm not a 6,30mm, not a 12,5 mm screw, would you?

Please give me a reference on where I can buy these hypothetical ISO 261 screws, you pretend to exist.

Re: To the Raspberry Zero Production line...

Posted: Thu Aug 08, 2019 9:23 pm
by jbeale
FWIW: 2.5 mm standoffs in black nylon https://www.amazon.com/Female-Standoff- ... 07D5T1TXV/
240 pieces for $10 so that's not a whole lot of expense per Pi board.

AFAIK the original PCB holes were only intended to mate with dowel pins for test fixturing at the factory. On the original Pi they weren't even all near the corners, as they now. They did move them to better places for use as mechanical hold-downs, but with layout constraints weren't able to give enough mechanical clearance to make 3mm hardware safe for use.