Schrader value core _extractor_ thread?

[Adrian R2Participant @adrianr2]

So I have three old style chrome telescopic tyre pessure guages, marked Dunlop etc. They are all missing the screw in valve core extractor so I idly wondered if I could make some replacements (can’t find any for sale online)

Measure thread that screws it into the body of the tool – seems to be ~7/32″ or 5.2 mm OD and 4.5mm internal, and thread gauge says 26tpi – what is this then? I thought perhaps cycle but a very odd size if it is and rummaging througgh drawers I can’t find a die to match.

It’s _not_ the same thread as the valve cores themselves.

Not important but if anyone does know please speak up, or indeed knows if they are available somewhere.

[bernard towersParticipant @bernardtowers37738]

thread chart is available on the net

[David George 1Participant @davidgeorge1]

I have a similar gauge on my work bench. Free if you want it it is still in its original aluminium tube with screwed lid complete. I have just been wondering what to do with it.

David

[John HinkleyParticipant @johnhinkley26699]

Adrian,

Assuming your measurements are accurate – 7/32″ x 26 tpi is BSC (cycle) standard thread.  Tracy Tools sell the taps and dies to produce such an animal, here,

Whether they are value or not is for you to decide.

John

 

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Adrian R2, if you mean the tyre valve key, I have a Dunlop No.2 pressure gauge, and the thread that holds it into the telescoping part, has a pitch of 0.8mm, but it’s not what you would call a full form thread of any sort, but more like a piece of wire, and at best only about 3.5mm long, and an O/D of about 4.6mm.

Click on the photo for a larger view.

Regards Nick.

[bernard towers]

On bernard towers Said:

thread chart is available on the net

Are you that boy who was in the advert set at the beach? When the father asked “where is the car?”, the boy replies “it’s in the sand”.

The ‘net’ is quite large, so a slightly more specific answer would perhaps be of rather more utility.

https://www.gewinde-normen.de/en/valve-thread.html

[noel shelleyParticipant @noelshelley55608]

Not sure whether you need a tool to remove valve cores or a replacement to fit your pressure gauge ? If the former then it’s easy, Take a piece of small steel round, 4.3 OD drill a 2.5 hole down the middle then cut the slot 2mm wide and 2.5 deep. For the latter others have the answer. Noel.

[bernard towersParticipant @bernardtowers37738]

Thats half the fun of ot surely

[old martParticipant @oldmart]

I would screwed in a bit of wood and used it to get an idea of the thread pitch.

[Nick WheelerParticipant @nickwheeler]

Why does the replacement have to be threaded? You could machine a small groove where the thread would have been, and use an O-ring to retain the part.

 

I’ve made a number of valve keys, including one from 1/4″ hex to fit in a ratchet screwdriver and others with a knurled grip for use on small wheels where there wasn’t space for a longer tool.

[Adrian R2Participant @adrianr2]

@David, thanks for the offer but my interest is more in whether it is straightfoward rainy day job to complete the gauges I have rather than acquire more.

@John, yes 7/32 BSC that is the best candidate but when you drill [!] down Tracy don’t actually have the die listed. RDG do one but I was looking to confirm my assumption as it’s not a common size and perhaps something else would do.

@Old Mart indeed, I’m reasonably confident of the 26TPI using various thread gauges in go/no go mode, less of the diameter.

@Nick – good suggestion, I suspect even a small piece of PVC cable insulation might work as it doesn’t have to hold anything other than itself.

 

Thanks folks, I’ll leave it to any passing moderator to decide whether it is worth correcting the valve/value typo.

[Author]

Posts