Daft mechanical question

  • Thread starter Gareth Magennis
  • Start date
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Gareth Magennis

Guest
Hi,
just need to clarify:


A car wash snapped off my aeriel. I figure I can re-attach it by drilling
and tapping holes in both parts and screwing them together with a bolt with
the head cut off. (i.e. a stud)

So, I presume I drill a hole in both parts using a 3mm drill bit, tap both
holes with a 3mm Tap which I don't have yet, then saw the head off a 3mm
bolt, and screw the lot together.

(Its the 3mm bit I don't quite get - is this the diameter of the hole or the
diameter of the cut threads)



Cheers,


Gareth.
 
I don't know the full answer, but you can always start by making the holes
too small. Right?

It should also be plain that the tap determines the size of the screw. If
the tap won't fit a (say) 2.5mm plain hole, then you need to enlarge the
hole a bit.
 
On Oct 5, 11:59 am, "Gareth Magennis" <sound.serv...@btconnect.com>
wrote:
Hi,
just need to clarify:

A car wash snapped off my aeriel.   I figure I can re-attach it by drilling
and tapping holes in both parts and screwing them together with a bolt with
the head cut off.  (i.e. a stud)

So, I presume I drill a hole in both parts using a 3mm drill bit, tap both
holes with a 3mm Tap which I don't have yet, then saw the head off a 3mm
bolt, and screw the lot together.

(Its the 3mm bit I don't quite get - is this the diameter of the hole or the
diameter of the cut threads)

Cheers,

Gareth.
Click to expand...
from company
<http://www.coasteltools.com>

for fine
<http://www.coasteltools.com/tech_tap_drill_mf.htm>
for coarse
<http://www.coasteltools.com/tech_tap_drill_mc.htm>
 
spamtrap1888 wrote:
On Oct 5, 2:50 pm, spamtrap1888 <spamtrap1...@gmail.com> wrote:
On Oct 5, 11:59 am, "Gareth Magennis" <sound.serv...@btconnect.com
wrote:

Hi,
just need to clarify:

A car wash snapped off my aeriel. I figure I can re-attach it by drilling
and tapping holes in both parts and screwing them together with a bolt with
the head cut off. (i.e. a stud)

So, I presume I drill a hole in both parts using a 3mm drill bit, tap both
holes with a 3mm Tap which I don't have yet, then saw the head off a 3mm
bolt, and screw the lot together.

(Its the 3mm bit I don't quite get - is this the diameter of the hole or the
diameter of the cut threads)

Per this useful chart, for a 3 mm thread tap, you want to drill a 2.5
mm hole.

http://cdn101.iofferphoto.com/img/item/171/052/950/mlND.jpg

Get a 3mm nut to make sure you didnt mess things up when you cut the
head off the screw. You may need to file it gently to make the thread
work.
Click to expand...
Use a long set screw instead of a cut-off bolt.

Cheers

Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net
 
On Oct 5, 11:59 am, "Gareth Magennis" <sound.serv...@btconnect.com>
wrote:
Hi,
just need to clarify:

A car wash snapped off my aeriel.   I figure I can re-attach it by drilling
and tapping holes in both parts and screwing them together with a bolt with
the head cut off.  (i.e. a stud)

So, I presume I drill a hole in both parts using a 3mm drill bit, tap both
holes with a 3mm Tap which I don't have yet, then saw the head off a 3mm
bolt, and screw the lot together.

(Its the 3mm bit I don't quite get - is this the diameter of the hole or the
diameter of the cut threads)
Click to expand...
Per this useful chart, for a 3 mm thread tap, you want to drill a 2.5
mm hole.

http://cdn101.iofferphoto.com/img/item/171/052/950/mlND.jpg
 
On Oct 5, 2:50 pm, spamtrap1888 <spamtrap1...@gmail.com> wrote:
On Oct 5, 11:59 am, "Gareth Magennis" <sound.serv...@btconnect.com
wrote:

Hi,
just need to clarify:

A car wash snapped off my aeriel.   I figure I can re-attach it by drilling
and tapping holes in both parts and screwing them together with a bolt with
the head cut off.  (i.e. a stud)

So, I presume I drill a hole in both parts using a 3mm drill bit, tap both
holes with a 3mm Tap which I don't have yet, then saw the head off a 3mm
bolt, and screw the lot together.

(Its the 3mm bit I don't quite get - is this the diameter of the hole or the
diameter of the cut threads)

Per this useful chart, for a 3 mm thread tap, you want to drill a 2.5
mm hole.

http://cdn101.iofferphoto.com/img/item/171/052/950/mlND.jpg
Click to expand...
Get a 3mm nut to make sure you didnt mess things up when you cut the
head off the screw. You may need to file it gently to make the thread
work.
 
"spamtrap1888" <spamtrap1888@gmail.com> wrote in message
news:d78ce94a-7de2-4b52-9207-7ab79cee0d83@v19g2000pbt.googlegroups.com...
On Oct 5, 11:59 am, "Gareth Magennis" <sound.serv...@btconnect.com
wrote:
Hi,
just need to clarify:

A car wash snapped off my aeriel. I figure I can re-attach it by
drilling
and tapping holes in both parts and screwing them together with a bolt
with
the head cut off. (i.e. a stud)

So, I presume I drill a hole in both parts using a 3mm drill bit, tap
both
holes with a 3mm Tap which I don't have yet, then saw the head off a 3mm
bolt, and screw the lot together.

(Its the 3mm bit I don't quite get - is this the diameter of the hole or
the
diameter of the cut threads)


Per this useful chart, for a 3 mm thread tap, you want to drill a 2.5
mm hole.

http://cdn101.iofferphoto.com/img/item/171/052/950/mlND.jpg
Click to expand...

Ah, thanks for that.

I think I might have used a tap and die once in Metalwork class at school.



Gareth.
 
Gareth Magennis Inscribed thus:

Hi,
just need to clarify:


A car wash snapped off my aeriel. I figure I can re-attach it by
drilling and tapping holes in both parts and screwing them together
with a bolt with
the head cut off. (i.e. a stud)

So, I presume I drill a hole in both parts using a 3mm drill bit, tap
both holes with a 3mm Tap which I don't have yet, then saw the head
off a 3mm bolt, and screw the lot together.

(Its the 3mm bit I don't quite get - is this the diameter of the hole
or the diameter of the cut threads)



Cheers,


Gareth.
Click to expand...
Look up "Taping & Threading Chart" !

A 3mm dia rod can be threaded M3 and a M3 tap requires a 2.45 mm hole
(2.5mm is close enough)

--
Best Regards:
Baron.
 
On Oct 6, 10:26 am, Baron <ba...@linuxmaniac.net> wrote:
Gareth Magennis Inscribed thus:





Hi,
just need to clarify:

A car wash snapped off my aeriel.   I figure I can re-attach it by
drilling and tapping holes in both parts and screwing them together
with a bolt with
the head cut off.  (i.e. a stud)

So, I presume I drill a hole in both parts using a 3mm drill bit, tap
both holes with a 3mm Tap which I don't have yet, then saw the head
off a 3mm bolt, and screw the lot together.

(Its the 3mm bit I don't quite get - is this the diameter of the hole
or the diameter of the cut threads)

Cheers,

Gareth.

Look up "Taping & Threading Chart" !

A 3mm dia rod can be threaded M3 and a M3 tap requires a 2.45 mm hole
(2.5mm is close enough)

--
Best Regards:
                          Baron.- Hide quoted text -

- Show quoted text -
Click to expand...
Wouldn't it be easier to just get a new/replacement antenna? Or, as
many of us do, are you making it into a fun(sort of) project?
 
"hr(bob) hofmann@att.net" <hrhofmann@att.net> wrote in message
news:7f95dd68-a379-4d50-89e2-0875be85e91b@n16g2000yqi.googlegroups.com...
On Oct 6, 10:26 am, Baron <ba...@linuxmaniac.net> wrote:
Gareth Magennis Inscribed thus:





Hi,
just need to clarify:

A car wash snapped off my aeriel. I figure I can re-attach it by
drilling and tapping holes in both parts and screwing them together
with a bolt with
the head cut off. (i.e. a stud)

So, I presume I drill a hole in both parts using a 3mm drill bit, tap
both holes with a 3mm Tap which I don't have yet, then saw the head
off a 3mm bolt, and screw the lot together.

(Its the 3mm bit I don't quite get - is this the diameter of the hole
or the diameter of the cut threads)

Cheers,

Gareth.

Look up "Taping & Threading Chart" !

A 3mm dia rod can be threaded M3 and a M3 tap requires a 2.45 mm hole
(2.5mm is close enough)

--
Best Regards:
Baron.- Hide quoted text -

- Show quoted text -

Wouldn't it be easier to just get a new/replacement antenna? Or, as
many of us do, are you making it into a fun(sort of) project?
Click to expand...

Not really.
The antenna snapped off at the base - it's one of those roof mounted ones
that sits above the middle of the windscreen and faces backwards. (Ford
Focus)

To replace the entire unit, I would have to remove the base mounting from
the car roof. This might be a simple job, but I suspect it is a complete
nightmare as its mounting bolts are probably inside the car, meaning I
would have to remove the interior roof lining, and I will then probably
then have to go to a Ford Main Dealer to have the ECU reprogrammed to
recognise the "new" antenna.
(that last bit was a joke, by the way)

I suspect that by far the easiest and cheapest solution would be to "glue"
back the snapped off antenna.
It will cost me the price of a 3mm Tap and a few minutes of my time, and I
will now know how to drill a hole and tap it.

And I will not have a detached roof lining that I can't put back, causing me
to crash every time it falls onto my face.



Gareth.
 
Hmm, I might spend a few extra minutes on this problem first.

http://www.amazon.co.uk/s/?ie=UTF8&keywords=ford+focus+aerial+base&tag=googhydr-21&index=aps&hvadid=9671994728&hvpos=1t2&hvexid=&hvnetw=g&hvrand=143860820785821392&hvpone=&hvptwo=&hvqmt=b&ref=pd_sl_38nxc9adjq_b



Could be the stud that has snapped off the roof mounting, or the stud that
has snapped off the aeriel.

Gosh, how exciting.


Gareth.
 
"spamtrap1888" <spamtrap1888@gmail.com> wrote in message
news:c1def8e2-0b7d-47bd-a58d-f75226f33d6b@wm7g2000pbc.googlegroups.com...
On Oct 6, 1:00 pm, "Gareth Magennis" <sound.serv...@btconnect.com
wrote:
Hmm, I might spend a few extra minutes on this problem first.

http://www.amazon.co.uk/s/?ie=UTF8&keywords=ford+focus+aerial+base&ta...

Could be the stud that has snapped off the roof mounting, or the stud
that
has snapped off the aeriel.

Gosh, how exciting.


My car dealer that would wash the car as a gratis extra service would
routinely unscrew the similarly designed antenna to prevent damage. I
didn't realize this till I picked up my antennaless Golf one day, and
they had to retrieve it from some drawer.
Click to expand...

I have never washed my cars on principle, it is wet enough in the UK to do
it for you on a regular basis, I am not "car proud", and consider car
washing a vanity and a complete waste of resources.

However, I had parked it under a tree over the course of a few months, and
it developed a horrid sticky coating of sap, particularly on the roof. Also
the rubber window seals started growing a fine crop of moss.

I took it to a hand car wash, which I considered to be the least objectional
form of car washing rather than doing it myself ( I am lazy, and the illegal
immigrants could probably do with the job if the truth be known).
However, all they did was use a Mickey Mouse pressure washer which did not
shift any of the sap. Or the moss.

I figured an auto car wash would probably do a better job, but actually it
didn't, and it ripped off my aerial out of spite instead.


It wasn't the roller brush that did the damage though. After all that rolly
soapy rinsey stuff, the machine decided to dry the car with an air blowy
thing, that comprised of a square section beam the width of the car that was
passed from the back to the front, directing a blast of air vertically
downwards. Now, these machines have sensors to detect where the various
parts of the car are, so it can avoid any contact, but it didn't detect the
aerial, and the square drying thingy was forced underneath it. I heard a
weird kind of Boing, and saw the aerial flying through the air to land some
20 metres from the car.
Good job it didn't perforate somebody's skull I reckon, these machines are
dangerous.



Gareth.
 
On Oct 6, 1:00 pm, "Gareth Magennis" <sound.serv...@btconnect.com>
wrote:
Hmm, I might spend a few extra minutes on this problem first.

http://www.amazon.co.uk/s/?ie=UTF8&keywords=ford+focus+aerial+base&ta....

Could be the stud that has snapped off the roof mounting, or the stud that
has snapped off the aeriel.

Gosh, how exciting.
Click to expand...
My car dealer that would wash the car as a gratis extra service would
routinely unscrew the similarly designed antenna to prevent damage. I
didn't realize this till I picked up my antennaless Golf one day, and
they had to retrieve it from some drawer.
 
In article <D6Gbs.290008$t45.51852@fx02.am4>,
"Gareth Magennis" <sound.service@btconnect.com> wrote:

Hi,
just need to clarify:


A car wash snapped off my aeriel. I figure I can re-attach it by drilling
and tapping holes in both parts and screwing them together with a bolt with
the head cut off. (i.e. a stud)

So, I presume I drill a hole in both parts using a 3mm drill bit, tap both
holes with a 3mm Tap which I don't have yet, then saw the head off a 3mm
bolt, and screw the lot together.

(Its the 3mm bit I don't quite get - is this the diameter of the hole or the
diameter of the cut threads)



Cheers,


Gareth.
Click to expand...
For any size thread you plan to tap, to find the hole size just subtract
the pitch of the thread from the diameter of the thread. For an M3x.5
that would be 2.5, for a 1/4-20 it would be .25-1/20, .25-.05, or .2 (#7
drill is .201), etc.
 
"Mark Storkamp" <mstorkamp@yahoo.com> wrote in message
news:mstorkamp-638960.10463409102012@news.eternal-september.org...
In article <D6Gbs.290008$t45.51852@fx02.am4>,
"Gareth Magennis" <sound.service@btconnect.com> wrote:

Hi,
just need to clarify:


A car wash snapped off my aeriel. I figure I can re-attach it by
drilling
and tapping holes in both parts and screwing them together with a bolt
with
the head cut off. (i.e. a stud)

So, I presume I drill a hole in both parts using a 3mm drill bit, tap
both
holes with a 3mm Tap which I don't have yet, then saw the head off a 3mm
bolt, and screw the lot together.

(Its the 3mm bit I don't quite get - is this the diameter of the hole or
the
diameter of the cut threads)



Cheers,


Gareth.




For any size thread you plan to tap, to find the hole size just subtract
the pitch of the thread from the diameter of the thread. For an M3x.5
that would be 2.5, for a 1/4-20 it would be .25-1/20, .25-.05, or .2 (#7
drill is .201), etc.
Click to expand...

Blimey, that is such a simple rule, and one I will probably not forget.
Makes all those huge charts look rather silly now.

(I'm glad the UK uses the Metric system though, yours looks a total
nightmare!)



I received my 3mm Bottoming Tap today, and now my aerial is back on the car.


Thanks,


Gareth.
 
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