Metric sizes in machine screws and bolts. M7 seems very rare.

[David]

I'm getting ready to fix a TV bracket to a vertical wood panel in the
caravan.

My (fairly) trusty electronic callipers give an internal diameter of 6.93
for the 6 fixing holes in the metal plate which fixes to the wall. This
should make them M7.

What I need is 6 countersunk machine screws 25mm (or possibly 30mm) long,
with suitable nuts and washers. Stainless if at all possible.

I thought a domed nut would probably be the smartest.

For some reason the online stores I have looked at so far don't seem to
stock M7. After M6 they seem to go up in even numbers only.

Is this because once you get to a certain size the machine screws are man
enough that you just go down a size, or do I have the usual case where I
have assumed that fixings will be available but they aren't?

M7, where are you?

Cheers



Dave R

--
AMD FX-6300 in GA-990X-Gaming SLI-CF running Windows 7 Pro x64

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

[Lee]

On 18/03/2017 14:28, David wrote:

> M7, where are you?
>

A few on Ebay, though whether the pitch of the Thread is the same...

Seems M7 is used in split rim wheels, didn't know that ;)

[Lee]

Sorry, scratch that, not in countersunk style there isn't :(

Bolts though :)

[Judith]

On Sat, 18 Mar 2017 14:28:48 +0000, David wrote:

> I'm getting ready to fix a TV bracket to a vertical wood panel in the
> caravan.
>
> My (fairly) trusty electronic callipers give an internal diameter of
> 6.93 for the 6 fixing holes in the metal plate which fixes to the wall.
> This should make them M7.
>

If they are holes, it doesn't really matter what screw you put through
them. 1/4" is 6.35, they should work.


If they are threaded, then the internal diameter of 6.93 suggests (a
loose but tolerable fit for) 8mmx1.

[Dave Plowman (News)]

In article <ej4ugv...@mid.individual.net>,

David <wib...@btinternet.com> wrote:
> I'm getting ready to fix a TV bracket to a vertical wood panel in the
> caravan.

> My (fairly) trusty electronic callipers give an internal diameter of 6.93
> for the 6 fixing holes in the metal plate which fixes to the wall. This
> should make them M7.

> What I need is 6 countersunk machine screws 25mm (or possibly 30mm) long,
> with suitable nuts and washers. Stainless if at all possible.

> I thought a domed nut would probably be the smartest.

> For some reason the online stores I have looked at so far don't seem to
> stock M7. After M6 they seem to go up in even numbers only.

> Is this because once you get to a certain size the machine screws are man
> enough that you just go down a size, or do I have the usual case where I
> have assumed that fixings will be available but they aren't?

> M7, where are you?

> Cheers

M7 is going to be difficult to find. But M6 will be more than up to the
job. CSK SS with an allen socket may look the best.

--
*Dance like nobody's watching.

Dave Plowman da...@davenoise.co.uk London SW
To e-mail, change noise into sound.

[tabb...@gmail.com]

On Saturday, 18 March 2017 15:12:04 UTC, Judith wrote:
> On Sat, 18 Mar 2017 14:28:48 +0000, David wrote:

> > I'm getting ready to fix a TV bracket to a vertical wood panel in the
> > caravan.
> >
> > My (fairly) trusty electronic callipers give an internal diameter of
> > 6.93 for the 6 fixing holes in the metal plate which fixes to the wall.
> > This should make them M7.
> >
>
> If they are holes, it doesn't really matter what screw you put through
> them. 1/4" is 6.35, they should work.

For once she's right. Any woodscrew upto 6.9mm dia should fit.

7mm threaded holes does not mean M7, it means M8. 8mm is the outer diameter of an M8 bolt, not the inner, which is what your calipers are measuring.


NT

[David]

Thanks - not threaded just a metal plate with counter sunk holes for bolts
or screws.

[David]

On Sat, 18 Mar 2017 15:19:19 +0000, Dave Plowman (News) wrote:

> In article <ej4ugv...@mid.individual.net>,
> David <wib...@btinternet.com> wrote:
>> I'm getting ready to fix a TV bracket to a vertical wood panel in the
>> caravan.
>
>> My (fairly) trusty electronic callipers give an internal diameter of
>> 6.93 for the 6 fixing holes in the metal plate which fixes to the wall.
>> This should make them M7.
>
>> What I need is 6 countersunk machine screws 25mm (or possibly 30mm)
>> long,
>> with suitable nuts and washers. Stainless if at all possible.
>
>> I thought a domed nut would probably be the smartest.
>
>> For some reason the online stores I have looked at so far don't seem to
>> stock M7. After M6 they seem to go up in even numbers only.
>
>> Is this because once you get to a certain size the machine screws are
>> man enough that you just go down a size, or do I have the usual case
>> where I have assumed that fixings will be available but they aren't?
>
>> M7, where are you?
>
>> Cheers
>
> M7 is going to be difficult to find. But M6 will be more than up to the
> job. CSK SS with an allen socket may look the best.

Ta.

There seem to be plenty of M6 so I will go for some of those.

Still not sure why nobody seems to use M7.

[tabb...@gmail.com]

On Saturday, 18 March 2017 17:39:33 UTC, David WE Roberts (Google) wrote:
> On Sat, 18 Mar 2017 15:12:01 +0000, Judith wrote:
> > On Sat, 18 Mar 2017 14:28:48 +0000, David wrote:
> >
> >> I'm getting ready to fix a TV bracket to a vertical wood panel in the
> >> caravan.
> >>
> >> My (fairly) trusty electronic callipers give an internal diameter of
> >> 6.93 for the 6 fixing holes in the metal plate which fixes to the wall.
> >> This should make them M7.
> >>
> >>
> > If they are holes, it doesn't really matter what screw you put through
> > them. 1/4" is 6.35, they should work.
> >
> >
> > If they are threaded, then the internal diameter of 6.93 suggests (a
> > loose but tolerable fit for) 8mmx1.
>
> Thanks - not threaded just a metal plate with counter sunk holes for bolts
> or screws.

then I don't understand why you'd want M7. Something's not right with this picture.


NT

[Bill Wright]

On 18/03/2017 14:28, David wrote:

> I'm getting ready to fix a TV bracket to a vertical wood panel in the
> caravan.
>
> My (fairly) trusty electronic callipers give an internal diameter of 6.93
> for the 6 fixing holes in the metal plate which fixes to the wall. This
> should make them M7.
>
> What I need is 6 countersunk machine screws 25mm (or possibly 30mm) long,
> with suitable nuts and washers. Stainless if at all possible.

Use M6. It's a telly not the QE2.

Bill

[Bill Wright]

On 18/03/2017 17:41, David wrote:

> Still not sure why nobody seems to use M7.

There's no demand for it because it isn't available.
It isn't available because there's no demand for it.

Bill

[Bob Minchin]

It is quite popular in the motor trade M7 x 1.0 (same pitch as M6)
I got asked to make quite few car bits over the years and so bought a
set of taps and a split die for M7 (Iso-coarse).

[Bob Minchin]

Hex head is normally M11 for these.

[Dave Plowman (News)]

In article <ej59pg...@mid.individual.net>,

David <wib...@btinternet.com> wrote:
> > M7 is going to be difficult to find. But M6 will be more than up to the
> > job. CSK SS with an allen socket may look the best.

> Ta.

> There seem to be plenty of M6 so I will go for some of those.

The important thing is how they sit in the countersink.

> Still not sure why nobody seems to use M7.

Use two M3.5 electrical screws? ;-)

--
*I went to school to become a wit, only got halfway through.

[bm]

"Dave Plowman (News)" <da...@davenoise.co.uk> wrote in message
news:561eff5...@davenoise.co.uk...

> In article <ej59pg...@mid.individual.net>,
> David <wib...@btinternet.com> wrote:
>> > M7 is going to be difficult to find. But M6 will be more than up to the
>> > job. CSK SS with an allen socket may look the best.
>
>> Ta.
>
>> There seem to be plenty of M6 so I will go for some of those.
>
> The important thing is how they sit in the countersink.
>
>> Still not sure why nobody seems to use M7.
>
> Use two M3.5 electrical screws? ;-)

Blimey Dave, you are up late. Fresh out of Brexit comments?

[F Murtz]

David wrote:
> I'm getting ready to fix a TV bracket to a vertical wood panel in the
> caravan.
>
> My (fairly) trusty electronic callipers give an internal diameter of 6.93
> for the 6 fixing holes in the metal plate which fixes to the wall. This
> should make them M7.
>
> What I need is 6 countersunk machine screws 25mm (or possibly 30mm) long,
> with suitable nuts and washers. Stainless if at all possible.
>
> I thought a domed nut would probably be the smartest.
>
> For some reason the online stores I have looked at so far don't seem to
> stock M7. After M6 they seem to go up in even numbers only.
>
> Is this because once you get to a certain size the machine screws are man
> enough that you just go down a size, or do I have the usual case where I
> have assumed that fixings will be available but they aren't?
>
> M7, where are you?
>
> Cheers
>
>
>
> Dave R
>

They are clearance holes for m6 screws or 1/4 screws

[David]

I measured the hole to see what the size of bolt would be to match.

The dimensions suggest that you can fit an M7 bolt through the hole.

Biggest is usually best, especially when fixing heavy stuff with leverage
(bracket folds out from wall).

So I was opting for the chunkiest bolts I could fit through the hole.

[David]

The bracket is built like the QE2.

My main concern is the leverage when the bracket is fully extended with a
TV on the end. It folds out quite a long way.

[newshound]

Yes but these brackets are usually fixed to a masonry wall. This implies
wall plugs of some sort, and you can't fit these with perfect accuracy.
So having holes in the bracket which are slightly oversize to the screws
you use makes life very much easier. In any case, if fitted correctly
what stops the bracket moving around is not the lack of diametral
clearance between the bracket and the screws, but the friction between
the back of the bracket and the wall. You get the friction from the
tension in the screws. The bracket may be "resting" on one or two of the
screws, it's not likely to be resting on all of them (unless they are
countersunk).

ICBA to do the sums at the moment, but the shear strength of a single M6
bolt is something like a ton.

[Dave Plowman (News)]

In article <ej7as7...@mid.individual.net>,

David <wib...@btinternet.com> wrote:
> > Use M6. It's a telly not the QE2.
> >
> > Bill

> The bracket is built like the QE2.

> My main concern is the leverage when the bracket is fully extended with a
> TV on the end. It folds out quite a long way.

It is almost certainly designed for wall mounting using screws and wall
plugs. With these, the larger the better. So the plug doesn't pull out of
the bricks. But the chances of shearing an M6 nut and bolt, remote. The
fixing of the bracket to the 24" TV back here is 4 x M4.

I'd say your main problem in a caravan is finding something strong enough
to fix the bracket to - rather than the strength of the bolts.

--
*No word in the English language rhymes with month, orange, silver,purple

[newshound]

It's also a 7 mm af Allen key, isn't it? I recall having to buy one for
some VW brake callipers, iirc.

[rick]

On 18/03/2017 14:28, David wrote:

> I'm getting ready to fix a TV bracket to a vertical wood panel in the
> caravan.
>
> My (fairly) trusty electronic callipers give an internal diameter of 6.93
> for the 6 fixing holes in the metal plate which fixes to the wall. This
> should make them M7.
>
> What I need is 6 countersunk machine screws 25mm (or possibly 30mm) long,
> with suitable nuts and washers. Stainless if at all possible.
>
> I thought a domed nut would probably be the smartest.
>
> For some reason the online stores I have looked at so far don't seem to
> stock M7. After M6 they seem to go up in even numbers only.
>
> Is this because once you get to a certain size the machine screws are man
> enough that you just go down a size, or do I have the usual case where I
> have assumed that fixings will be available but they aren't?
>
> M7, where are you?
>
> Cheers
>
>
>
> Dave R
>

You sure it is M7 .. and not another thread form
This is not far off 17/64 ... could it be an imperial thread, many items
made in Japan or US still use imperial sizes.

[Bill Wright]

On 19/03/2017 12:11, David wrote:

>> Use M6. It's a telly not the QE2.
>>
>> Bill
>
> The bracket is built like the QE2.
>
> My main concern is the leverage when the bracket is fully extended
with a
> TV on the end. It folds out quite a long way.

You'd pull the wall down before you snapped two M6 bolts.

Bill

[Bill Wright]

On 19/03/2017 12:11, David wrote:

>> Use M6. It's a telly not the QE2.
>>
>> Bill
>
> The bracket is built like the QE2.
>
> My main concern is the leverage when the bracket is fully extended
with a
> TV on the end. It folds out quite a long way.

[David]

Hole isn't threaded.

Just trying to get a bolt/set screw with a snug fit.

[David]

On Sun, 19 Mar 2017 13:01:12 +0000, Dave Plowman (News) wrote:

> In article <ej7as7...@mid.individual.net>,
> David <wib...@btinternet.com> wrote:
>> > Use M6. It's a telly not the QE2.
>> >
>> > Bill
>
>> The bracket is built like the QE2.
>
>> My main concern is the leverage when the bracket is fully extended with
>> a TV on the end. It folds out quite a long way.
>
> It is almost certainly designed for wall mounting using screws and wall
> plugs. With these, the larger the better. So the plug doesn't pull out
> of the bricks. But the chances of shearing an M6 nut and bolt, remote.
> The fixing of the bracket to the 24" TV back here is 4 x M4.
>
> I'd say your main problem in a caravan is finding something strong
> enough to fix the bracket to - rather than the strength of the bolts.

I did think that larger diameter bolts backed up by washers would spread
the load over a larger surface area and be more difficult to pull through
the wood panel.

For example an M1 bolt would probably pull straight out, M2 less so etc.

So going for the largest possible diameter of bolt seems sensible where
possible.

[David]

Just to add to other responses, the holes in the bracket are counter sunk.

It isn't about the shear strength but about spreading the load around the
area of the nut on the back of the wood panel.

M6 looks O.K., but M7 would be nicer.
Just not a lot of it about.

[Dave Plowman (News)]

In article <ej9j1c...@mid.individual.net>,

David <wib...@btinternet.com> wrote:
> > I'd say your main problem in a caravan is finding something strong
> > enough to fix the bracket to - rather than the strength of the bolts.

> I did think that larger diameter bolts backed up by washers would spread
> the load over a larger surface area and be more difficult to pull
> through the wood panel.

> For example an M1 bolt would probably pull straight out, M2 less so etc.

> So going for the largest possible diameter of bolt seems sensible where
> possible.

Would probably best to use something larger than washers to spread the
load. But at the end of the day the strength of the panel is the limiting
factor. Same as with a plasterboard wall, it would make more sense to fix
to the uprights etc that the panel is fixed to.

--
*There are 3 kinds of people: those who can count & those who can't.

[The Other Mike]

On 18 Mar 2017 17:41:04 GMT, David <wib...@btinternet.com> wrote:

>Still not sure why nobody seems to use M7.

While M7 is standardised at three different pitches it's not a preferred size,
M3 M4 M5 M6 M8 M10 M12 etc are preferred sizes under ISO 262

The only place I've seen an M7 in widespread use is on the first motion shaft
extraction thread on a GM 1980's gearbox where you could remove the end cover
from the gearbox, remove a sheet metal cover plate underneath the clutch, press
the clutch pedal, clamp the clutch and cover plate to the flywheel with u-clips,
withdraw the first motion shaft, and unbolt the flywheel and clutch as one, drop
it through the hole in the bellhousing and thus change the clutch without
removing the gearbox / driveshafts etc. An easy 30 mins for a complete clutch
change vs three or four times that after they changed the design to a solid
bellhousing.

--

[Bob Minchin]

I had one of those. Brilliant idea! no wonder it did not catch on.
I even made a 36mm x 1/2 square socket to remove the cover.
In order to get an M7 bolt for the job, there was one of several nearby
on the engine(bell housing?) that could be borrowed.

[The Other Mike]

Never owned one myself but I worked on them on a few occasions and loved the
design. I knew a mechanic on a works rally team that could do the change in
less than 15 mins.

The only thing that came remotely close and as a plus could be done completely
from the comfort of the inside of the car was the longitudinal FWD Triumph 1300
& 1500 where the clutch was at the rear of the engine, the main body of the
gearbox was below the clutch and the final drive ahead and under the sump
(separate from the engine oil) I wonder if this is where GM got the idea
from?

http://2.bp.blogspot.com/_i2e7HKldO9A/SQrjonPbyHI/AAAAAAAAAe0/DiRypwZf5Qc/s1600/crosssection.jpg

--

[newshound]

Penny washer!

[Dave Plowman (News)]

In article <oaolob$7u1$1...@dont-email.me>,

It certainly sounds a good idea - and I've never heard of it before. But
do wonder how much effect having a hole in the bell housing large enough
to remove the clutch would have on engine/box rigidity?

--
*Letting a cat out of the bag is easier than putting it back in *

[Clive George]

On 20/03/2017 08:47, David wrote:

> Just to add to other responses, the holes in the bracket are counter sunk.
>
> It isn't about the shear strength but about spreading the load around the
> area of the nut on the back of the wood panel.
>
> M6 looks O.K., but M7 would be nicer.
> Just not a lot of it about.

Drill it out to 8mm?

[charles]

In article <58ce236f$0$17455$c3e8da3$dd96...@news.astraweb.com>, F Murtz

or for something American

--
from KT24 in Surrey, England