I'm doing a job which requires me to tap a hole in prep for a schrader valve
core.
The thread, according to Schrader's website, is 0.206"-36tpi

This tap is not commonly available from stock.
I know that I can special order this tap, but seems to be an unnecessary
expense for a short run job

If anyone has any of these that they would like to sell, or knows of a
source, please contact me

thanks

Jon

Jon wrote:

I'm doing a job which requires me to tap a hole in prep for a schrader valve
core.
The thread, according to Schrader's website, is 0.206"-36tpi

This tap is not commonly available from stock.
I know that I can special order this tap, but seems to be an unnecessary
expense for a short run job

If anyone has any of these that they would like to sell, or knows of a
source, please contact me

Maybe a slightly different approach? What if the original part were redesigned
to accept a brazed-in tire valve? You can get a set of 4 all-metal tire valves
from Pep Boys for under $10, or could about 3 years ago anyway. Those of course
have the threads already in them.

Alternatively, you could try making a one-off tap.

Grant

--
Posted via a free Usenet account from http://www.teranews.com

"Jon" wrote: (clip) a hole (clip) a short run job (clip)
^^^^^^^^^^^^^^^^^^
One or several? If it's only one or two, have you thought of inserting the
end of a valve stem (silver solder or epoxy)?

No options here, I need the tap, but thanks for the suggestion.


"Leo Lichtman" wrote in message
...

"Jon" wrote: (clip) a hole (clip) a short run job (clip)
^^^^^^^^^^^^^^^^^^
One or several? If it's only one or two, have you thought of inserting
the end of a valve stem (silver solder or epoxy)?

On Mon, 14 Jan 2008 18:30:26 GMT, Jon wrote:

No options here, I need the tap, but thanks for the suggestion.


"Leo Lichtman" wrote in message
...

"Jon" wrote: (clip) a hole (clip) a short run job (clip)
^^^^^^^^^^^^^^^^^^
One or several? If it's only one or two, have you thought of inserting
the end of a valve stem (silver solder or epoxy)?


Are you sure there are no options?

Schrader valve stems are sometime threaded *outside* as well - don't know
the thread, but it may be a more common one.

Drill & thread that hole, insert & loctite a valve stem.

I have a customer supplied design to follow. No options.

Thanks!

"_" wrote in message
...
On Mon, 14 Jan 2008 18:30:26 GMT, Jon wrote:

No options here, I need the tap, but thanks for the suggestion.


"Leo Lichtman" wrote in message
...

"Jon" wrote: (clip) a hole (clip) a short run job (clip)
^^^^^^^^^^^^^^^^^^
One or several? If it's only one or two, have you thought of inserting
the end of a valve stem (silver solder or epoxy)?


Are you sure there are no options?

Schrader valve stems are sometime threaded *outside* as well - don't know
the thread, but it may be a more common one.

Drill & thread that hole, insert & loctite a valve stem.

"Jon" fired this volley in
news:tPLij.8816$W73.3610@trnddc04:

I'm doing a job which requires me to tap a hole in prep for a schrader
valve core.
The thread, according to Schrader's website, is 0.206"-36tpi

This tap is not commonly available from stock.
I know that I can special order this tap, but seems to be an
unnecessary expense for a short run job

If anyone has any of these that they would like to sell, or knows of a
source, please contact me

Jon,

I went through the same folly-worn path on a project in my shop.
Schrader wanted something like $80 for the tap, with a five week waiting
perior.

I ended up finding the best quality "tire valve tool" I could find, and
hardened the internal thread chaser. With that, and a bit of care, I was
able to tap the six holes I had to make for Schrader inserts.

If I were to do it again, I'd just fabricate the tap from some good air-
hardening stock, and be done with it for the foreseeable future.

LLoyd

On Mon, 14 Jan 2008 10:10:01 -0600, Jon wrote:

I'm doing a job which requires me to tap a hole in prep for a schrader
valve
core.
The thread, according to Schrader's website, is 0.206"-36tpi

This tap is not commonly available from stock.
I know that I can special order this tap, but seems to be an unnecessary
expense for a short run job

If anyone has any of these that they would like to sell, or knows of a
source, please contact me

thanks

Jon



Doing some Google searching, I found this link.
http://www.ctatools.com/tireair.html
Open the PDF catalog and look for 4-Way Tire Valve Repair Tool.

Or in looking up the price $1.25
http://www.autopart.com/TOOLS/TOOLSMAIN/tool/T_1925.htm

Would that qualify as a tap for you?

Wayne D.

"Jon" wrote:

I'm doing a job which requires me to tap a hole in prep for a schrader valve
core.
The thread, according to Schrader's website, is 0.206"-36tpi

This tap is not commonly available from stock.
I know that I can special order this tap, but seems to be an unnecessary
expense for a short run job

If anyone has any of these that they would like to sell, or knows of a
source, please contact me

thanks

Jon


I don't know if this site is selling a tap:
http://www.maico.com.mx/product_info...oducts_id/315T

I wonder if 13/64-36 is what you are looking for?

http://www.myisuzuparts.com/2004/1/9...showparts.html
CORE - A/C REFRIG SERV VLV(INCLS SPRING)(EXC O-RING)(13/64-36 THD)(PART OF
33)

I didn't do very well looking for you but I did try.

It looks like threading a piece of A2, grinding flutes and hardening is the
way to go atm.

And I thought the 7/32-40 irrc, tap for rear sight aperature inserts was an
oddball!

Wes

"Wes" wrote in message
...
"Jon" wrote:

I'm doing a job which requires me to tap a hole in prep for a schrader
valve
core.
The thread, according to Schrader's website, is 0.206"-36tpi

This tap is not commonly available from stock.
I know that I can special order this tap, but seems to be an unnecessary
expense for a short run job

If anyone has any of these that they would like to sell, or knows of a
source, please contact me

thanks

Jon


I don't know if this site is selling a tap:
http://www.maico.com.mx/product_info...oducts_id/315T

I wonder if 13/64-36 is what you are looking for?

http://www.myisuzuparts.com/2004/1/9...showparts.html
CORE - A/C REFRIG SERV VLV(INCLS SPRING)(EXC O-RING)(13/64-36 THD)(PART
OF
33)

I didn't do very well looking for you but I did try.

It looks like threading a piece of A2, grinding flutes and hardening is
the
way to go atm.

And I thought the 7/32-40 irrc, tap for rear sight aperature inserts was
an
oddball!

Wes

gun threads have always been a joy, from what I hear.

The Engineering manager at schrader didn't offer me the option of buying one
from them.
He basically said I had no business cutting a thread to fit THEIR (gasp)
core.

I can get them custom made, around 3/$100

I need one, a spare would be a good idea.

I won't make one for that price, but it just seems to me that since schrader
valve cores are in half the tires in the world, SOMEBODY would have these on
the shelf.

I think the relief valve in Bernz-o-matic cyinders is the same construction
and thread. You might try approaching it from that direction.

On Mon, 14 Jan 2008 23:12:28 GMT, Jon wrote:

"Wes" wrote in message
...
"Jon" wrote:

I'm doing a job which requires me to tap a hole in prep for a schrader
valve
core.
The thread, according to Schrader's website, is 0.206"-36tpi

This tap is not commonly available from stock.
I know that I can special order this tap, but seems to be an unnecessary
expense for a short run job

If anyone has any of these that they would like to sell, or knows of a
source, please contact me

thanks

Jon


I don't know if this site is selling a tap:
http://www.maico.com.mx/product_info...oducts_id/315T

I wonder if 13/64-36 is what you are looking for?

http://www.myisuzuparts.com/2004/1/9...showparts.html
CORE - A/C REFRIG SERV VLV(INCLS SPRING)(EXC O-RING)(13/64-36 THD)(PART
OF
33)

I didn't do very well looking for you but I did try.

It looks like threading a piece of A2, grinding flutes and hardening is
the
way to go atm.

And I thought the 7/32-40 irrc, tap for rear sight aperature inserts was
an
oddball!

Wes

gun threads have always been a joy, from what I hear.

The Engineering manager at schrader didn't offer me the option of buying one
from them.
He basically said I had no business cutting a thread to fit THEIR (gasp)
core.

I can get them custom made, around 3/$100

I need one, a spare would be a good idea.

I won't make one for that price, but it just seems to me that since schrader
valve cores are in half the tires in the world, SOMEBODY would have these on
the shelf.

Did a bit of googling and found this response in a similar thread:

"We carry these as specials. Normal delivery is just one day. They are not
on our website, but if you go to http://www.Discount-Tools.com you can send
an email or call 714-751-3844."

url is http://v2.pneumaticsonline.com/webfo...sages/736.html

Let us know if you find something; no doubt you are neither the first nor
the last to be in this pickle.

Suggest you make the special. Take a split die of -36tpi that is close
and compress or expand and see if the .206 will fit - might be able.

Martin
Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Charter Founder
IHMSA and NRA Metallic Silhouette maker & member.
http://lufkinced.com/


Jon wrote:
I'm doing a job which requires me to tap a hole in prep for a schrader valve
core.
The thread, according to Schrader's website, is 0.206"-36tpi

This tap is not commonly available from stock.
I know that I can special order this tap, but seems to be an unnecessary
expense for a short run job

If anyone has any of these that they would like to sell, or knows of a
source, please contact me

thanks

Jon

Grant Erwin wrote:
Jon wrote:

I'm doing a job which requires me to tap a hole in prep for a schrader
valve core.
The thread, according to Schrader's website, is 0.206"-36tpi

This tap is not commonly available from stock.
I know that I can special order this tap, but seems to be an
unnecessary expense for a short run job

If anyone has any of these that they would like to sell, or knows of a
source, please contact me

Maybe a slightly different approach? What if the original part were
redesigned
to accept a brazed-in tire valve? You can get a set of 4 all-metal tire
valves
from Pep Boys for under $10, or could about 3 years ago anyway. Those of
course
have the threads already in them.

Alternatively, you could try making a one-off tap.

Grant

Even if you get the hole tapped, there's the gently tapered seat for the
bottom of the schrader valve to be reamed out. Jerry

On Wed, 16 Jan 2008 16:04:14 GMT, Jerry Wass
wrote:

Grant Erwin wrote:
Jon wrote:

I'm doing a job which requires me to tap a hole in prep for a schrader
valve core.
The thread, according to Schrader's website, is 0.206"-36tpi

This tap is not commonly available from stock.
I know that I can special order this tap, but seems to be an
unnecessary expense for a short run job

If anyone has any of these that they would like to sell, or knows of a
source, please contact me

Maybe a slightly different approach? What if the original part were
redesigned
to accept a brazed-in tire valve? You can get a set of 4 all-metal tire
valves
from Pep Boys for under $10, or could about 3 years ago anyway. Those of
course
have the threads already in them.

Alternatively, you could try making a one-off tap.

Grant

Even if you get the hole tapped, there's the gently tapered seat for the
bottom of the schrader valve to be reamed out. Jerry

Get a threaded tire valve stem and thread the hole to take the stem.

--
Posted via a free Usenet account from http://www.teranews.com

Grant Erwin wrote:
Jon wrote:

I'm doing a job which requires me to tap a hole in prep for a schrader
valve core.
The thread, according to Schrader's website, is 0.206"-36tpi

This tap is not commonly available from stock.
I know that I can special order this tap, but seems to be an
unnecessary expense for a short run job

If anyone has any of these that they would like to sell, or knows of a
source, please contact me


Maybe a slightly different approach? What if the original part were
redesigned
to accept a brazed-in tire valve? You can get a set of 4 all-metal tire
valves
from Pep Boys for under $10, or could about 3 years ago anyway. Those of
course
have the threads already in them.

Alternatively, you could try making a one-off tap.

That sounds cool. How do you make a tap in the home shop?

Chris

On Mon, 14 Jan 2008 08:54:57 -0800, Grant Erwin
wrote:

Jon wrote:

I'm doing a job which requires me to tap a hole in prep for a schrader valve
core.
The thread, according to Schrader's website, is 0.206"-36tpi

This tap is not commonly available from stock.
I know that I can special order this tap, but seems to be an unnecessary
expense for a short run job

If anyone has any of these that they would like to sell, or knows of a
source, please contact me

Maybe a slightly different approach? What if the original part were redesigned
to accept a brazed-in tire valve? You can get a set of 4 all-metal tire valves
from Pep Boys for under $10, or could about 3 years ago anyway. Those of course
have the threads already in them.

Any time I need an adapter with a tire valve connection, I take an old
valve stem that the tire shop replaces every time they mount a tire,
cut the rubber off, wire brush it clean and silver solder it into a
quarter inch hole in whatever fitting I am adapting to. No cost except
for heat and a bit of silver solder.

Alternatively, you could try making a one-off tap.

Grant
Gerry :-)}
London, Canada

On Wed, 16 Jan 2008 23:50:10 +0000, Christopher Tidy wrote:

That sounds cool. How do you make a tap in the home shop?

I may be doing it the wrong and/or hard way but, I've done it a couple
of times. Once when I had a die of the right size but not a tap - used
it to thread some rod, then just ground out some relief cuts on the rod
to make a tap-shaped object. Very freehand and very much not optimal
angles for anything but, it made the cut I needed for exactly one hole.
Second one was a bit more ambitious, single-pointed a threaded rod on
the lathe and again hand-cut 2 relief cuts. Made the hole I needed.
Probably not the right way but, for this job, was fine. (metric
left-hand thread for one-time use, don't ask).

Dave Hinz wrote:
On Wed, 16 Jan 2008 23:50:10 +0000, Christopher Tidy wrote:


That sounds cool. How do you make a tap in the home shop?


I may be doing it the wrong and/or hard way but, I've done it a couple
of times. Once when I had a die of the right size but not a tap - used
it to thread some rod, then just ground out some relief cuts on the rod
to make a tap-shaped object. Very freehand and very much not optimal
angles for anything but, it made the cut I needed for exactly one hole.
Second one was a bit more ambitious, single-pointed a threaded rod on
the lathe and again hand-cut 2 relief cuts. Made the hole I needed.
Probably not the right way but, for this job, was fine. (metric
left-hand thread for one-time use, don't ask).

Did you have to heat treat or case harden it? Or were you only tapping
brass?

Best wishes,

Chris

On Thu, 17 Jan 2008 02:28:08 +0000, Christopher Tidy wrote:
Dave Hinz wrote:

I may be doing it the wrong and/or hard way but, I've done it a couple
of times.
(snip)

Did you have to heat treat or case harden it? Or were you only tapping
brass?

Once aluminum, once mystery-steel for a nut that was expected to have
about 3 uses ever. Lots of lube and it came out OK but I wouldn't
suggest it for a "real" project. This was for a water-pump tool for
Triumph/Saab inline-4 engines, and several hand-turned uses per year are
to be expected, kind of a gear puller with a threaded end rather than a
point. If it was anything that'd deal with any number of cuts, I
probably would have just bought the oddball tap. But for a one-off of
not-rocket-science dirty hack spec, it was good enough. (I never
claimed to be a machinist, I'm just a guy with machine tools in the
basement).

Dave Hinz wrote:
On Thu, 17 Jan 2008 02:28:08 +0000, Christopher Tidy wrote:

Dave Hinz wrote:

I may be doing it the wrong and/or hard way but, I've done it a couple
of times.

(snip)


Did you have to heat treat or case harden it? Or were you only tapping
brass?


Once aluminum, once mystery-steel for a nut that was expected to have
about 3 uses ever. Lots of lube and it came out OK but I wouldn't
suggest it for a "real" project. This was for a water-pump tool for
Triumph/Saab inline-4 engines, and several hand-turned uses per year are
to be expected, kind of a gear puller with a threaded end rather than a
point. If it was anything that'd deal with any number of cuts, I
probably would have just bought the oddball tap. But for a one-off of
not-rocket-science dirty hack spec, it was good enough. (I never
claimed to be a machinist, I'm just a guy with machine tools in the
basement).

Interesting. Did you use ordinary mild steel for the tap or drill rod?

Best wishes,

Chris

On Thu, 17 Jan 2008 04:53:09 +0000, Christopher Tidy wrote:
Dave Hinz wrote:

Once aluminum, once mystery-steel for a nut that was expected to have
about 3 uses ever. Lots of lube and it came out OK but I wouldn't
suggest it for a "real" project.

Interesting. Did you use ordinary mild steel for the tap or drill rod?

It sparked like it had some carbon in it but, I inherited a large amount
of "mystery metal". Sorry to not be a lot of help.

On that topic, anyone have a rundown of paint color codes for steel? I
don't know the vendor and last time I looked, I found about 4 different
standards referenced by various sites I found on google. So it's racks
of mystery metal, I'm afraid. For stuff with a spec, I buy to that
spec, of course.

On 2008-01-18, Dave Hinz wrote:

[ ... ]

On that topic, anyone have a rundown of paint color codes for steel? I
don't know the vendor and last time I looked, I found about 4 different
standards referenced by various sites I found on google. So it's racks
of mystery metal, I'm afraid. For stuff with a spec, I buy to that
spec, of course.

As you've already discovered -- each vendor has its own color
code standards. I could look up the standards for Jorgensen Steel
(because I have one of their older catalogs), but that would be useless
for any other vendor's steel, let alone those from an unknown vendor.

And there is a *lot* of codes to type in, so I won't do it while
I know that it would not do any good.

If you can find out who the original vendor likely was, you want
to get a copy of *their* steel catalog.

And -- if you get steel from another source, but know what the
steel is, *paint it yourself* to match the catalog you have, so you will
know later what it is.

If you can't find out -- just get a catalog from your own
vendor, and keep all newly-bought steel in a separated area.

Good Luck,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On 18 Jan 2008 05:15:56 GMT, DoN. Nichols wrote:
On 2008-01-18, Dave Hinz wrote:

[ ... ]

On that topic, anyone have a rundown of paint color codes for steel? I
don't know the vendor and last time I looked, I found about 4 different
standards referenced by various sites I found on google. So it's racks
of mystery metal, I'm afraid. For stuff with a spec, I buy to that
spec, of course.

As you've already discovered -- each vendor has its own color
code standards. I could look up the standards for Jorgensen Steel
(because I have one of their older catalogs), but that would be useless
for any other vendor's steel, let alone those from an unknown vendor.

It's a damn same too, I've got a ton or more of nicely marked mystery
metal.

And there is a *lot* of codes to type in, so I won't do it while
I know that it would not do any good.
If you can find out who the original vendor likely was, you want
to get a copy of *their* steel catalog.

TO go with the ton of mystery metal, is a ton of paperwork, some of
which might be a catalog. If they're all from the same vendor (a
reasonable assumption for starters), I'm wondering if spark-testing by
someone who can read sparks would be able to narrow down which vendor's
"red with a brown stripe" this stuff is.

And -- if you get steel from another source, but know what the
steel is, *paint it yourself* to match the catalog you have, so you will
know later what it is.

Seems like a sharpie and actual numbers wouldn't be a bad approach?

If you can't find out -- just get a catalog from your own
vendor, and keep all newly-bought steel in a separated area.

That's what I've been doing for important projects. Mystery-metal is
fine for some things, though, and I can't bear to just toss it...

On 19 Jan 2008 01:43:32 GMT, Dave Hinz wrote:
On 18 Jan 2008 05:15:56 GMT, DoN. Nichols wrote:
On 2008-01-18, Dave Hinz wrote:

On that topic, anyone have a rundown of paint color codes for steel? I
don't know the vendor and last time I looked, I found about 4 different
standards referenced by various sites I found on google. So it's racks
of mystery metal, I'm afraid. For stuff with a spec, I buy to that
spec, of course.

As you've already discovered -- each vendor has its own color
code standards. I could look up the standards for Jorgensen Steel
(because I have one of their older catalogs), but that would be useless
for any other vendor's steel, let alone those from an unknown vendor.

It's a damn same too, I've got a ton or more of nicely marked mystery
metal.

And there is a *lot* of codes to type in, so I won't do it while
I know that it would not do any good.
If you can find out who the original vendor likely was, you want
to get a copy of *their* steel catalog.

TO go with the ton of mystery metal, is a ton of paperwork, some of
which might be a catalog. If they're all from the same vendor (a
reasonable assumption for starters), I'm wondering if spark-testing by
someone who can read sparks would be able to narrow down which vendor's
"red with a brown stripe" this stuff is.

If you keep the lot all together, and find something that you
/really/ want to ID (I.E. the assay costs are far less than going out
and buying the metal new) find a junkyard with one of those nifty
X-ray Spectrometer (IIRC) metal ID guns.

You just put a 12-pack of chilled (or a fifth at room temp) potent
potables in the back seat of the gun owner's car as "payment", place a
small sample in the jaws, and press the button. You might not be able
to ID it to a precise compound if it was true mystery metal, but you
DO have a clue what it most likely is.

The gun gives you the component mix of carbon, manganese, lead, etc.
A hardness tester tells whether it's tool steel or spaghetti. Spark
testing would be another confirmation of carbon content. That, and
the old paperwork and vendor color chart would confirm what you have.

And -- if you get steel from another source, but know what the
steel is, *paint it yourself* to match the catalog you have, so you will
know later what it is.

Seems like a sharpie and actual numbers wouldn't be a bad approach?

Hell NO!!! Die stamps and a ball-peen hammer would be best, as long
as you don't plan to use every mm of it... Or paint marker. And if
it's hardened metal that would ding your die stamps, you can use paint
marker and a vibratory etcher as backup.

Sharpie fades and weathers off way too easily - when I want to mark
a power panel "permanently" I use a LaCo-Markal paint marker like the
junkyards use - the LaCo looks like a regular marker with a valve tip,
the junkyards buy the little squeeze bottle with a big ball-point tip.

Real paint that will hold up outdoors in the sun for 20 years and
still be readable (like the address a roof air conditioner belongs to,
or the unit number in large installs) - and if some bozo paints over
it you can still read the bump in the paint and reapply on top.

-- Bruce --

On Fri, 18 Jan 2008 22:20:41 -0800, Bruce L Bergman wrote:

If you keep the lot all together, and find something that you
/really/ want to ID (I.E. the assay costs are far less than going out
and buying the metal new) find a junkyard with one of those nifty
X-ray Spectrometer (IIRC) metal ID guns.

Ahhh...I have a cousin who runs a scrapyard. I should see what toys he
has.

You just put a 12-pack of chilled (or a fifth at room temp) potent
potables in the back seat of the gun owner's car as "payment", place a
small sample in the jaws, and press the button. You might not be able
to ID it to a precise compound if it was true mystery metal, but you
DO have a clue what it most likely is.

I use liquid barter regularly. Every couple of weeks I drop off sodas
for the computer site support guys in the building where I work, because
they've helped me out more than a couple of times, and because I used to
do that and nobody appreciated our group until they needed us.

The gun gives you the component mix of carbon, manganese, lead, etc.
A hardness tester tells whether it's tool steel or spaghetti. Spark
testing would be another confirmation of carbon content. That, and
the old paperwork and vendor color chart would confirm what you have.

And once I've got a couple of them ID'd, I'll know which vendor's code
it is. Again this relies on it all being from the same vendor, but
knowing where they came from, (cutoffs from a hydraulic controls
manufacturer), it's likely that they stuck with one vendor.

Seems like a sharpie and actual numbers wouldn't be a bad approach?

Hell NO!!! Die stamps and a ball-peen hammer would be best, as long
as you don't plan to use every mm of it... Or paint marker. And if
it's hardened metal that would ding your die stamps, you can use paint
marker and a vibratory etcher as backup.

Makes sense. Woudn't have thought of the die stamps.

Sharpie fades and weathers off way too easily - when I want to mark
a power panel "permanently" I use a LaCo-Markal paint marker like the
junkyards use - the LaCo looks like a regular marker with a valve tip,
the junkyards buy the little squeeze bottle with a big ball-point tip.

Yup, got a yellow and a white. Learned that one from an old-fart I used
to work for (no disrespect involved, that was his title as he told me).

Real paint that will hold up outdoors in the sun for 20 years and
still be readable (like the address a roof air conditioner belongs to,
or the unit number in large installs) - and if some bozo paints over
it you can still read the bump in the paint and reapply on top.

Ah, my racks are inside but, never know when they'll get wet I suppose.
Paint pen it is then.

replying to _, fyiman wrote:
According to this page:
http://www.sheldonbrown.com/gloss_sa-o.html

The external threaded part of a Schrader valve is 0.302" x 32
Threads-per-inch.

19/64" is about 0.297" (0.296875") which is a little smaller than 0.302".
5/16" is 0.3125" which is a little bigger than 0.302".
0.302 inch is about: 7.67mm (7.6708mm).
7.7mm is about: 0.303 inch (0.30314 inch)

For a tap, 5/16-32 (if that is standard) would probably fit close enough.

--
for full context, visit https://www.polytechforum.com/metalw...tap-98941-.htm