Made in China, Screw Thread

[nigel jones 5Participant @nigeljones5]

Not a thread about things made in china but about a thread size on an item made in China. Its a fine pitch thread OD 6mm but it doesnt match any gauges I have. Do they have a 'standard' fine thread over in that China?

[nigel jones 5Participant @nigeljones5]

[John Stevenson 1Participant @johnstevenson1]

One thing about 'Standards' is there are so many of them.

Listed are 6 x 0.5

6 x 0.6

6 x 0.7

6 x 0.75

6 x 0.8

6 x 0.9

and 6 x 1.0

There are courser but you asked for fine.

[nigel jones 5Participant @nigeljones5]

thanks – had no idea there were so many, its an internal thread so any idea how to determine it without buying every tap?

[John Stevenson 1Participant @johnstevenson1]

screw a bit of wood or plastic in so it forms a bit of a thread and then measure with a set of pitch gauges.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by fizzy on 18/03/2017 21:31:50:

thanks – had no idea there were so many, its an internal thread so any idea how to determine it without buying every tap?

.

As Bazyle recently mentioned [and we have both suggested before] … a wooden dowel, or a plastic knitting needle [etc. etc.] can be screwed into the hole … when unscrewed, it will bear traces of the thread pitch, sufficient to measure/count.

MichaelG.

.

Predictably … JS beat me to it.

and, for reference:  Bazyle's recent post will be found towards the bottom of

http://www.model-engineer.co.uk/forums/postings.asp?th=125655&p=2

Edited By Michael Gilligan on 18/03/2017 21:41:35

Edited By Michael Gilligan on 18/03/2017 21:48:39

[JonParticipant @jon]

Or measure bore I/d and subtract from stud dia (whole number, may well be undersize) and divide by two should be near.

Above would still need a pitch guage.

[Martin ConnellyParticipant @martinconnelly55370]

I would check 1/4" threads as well. There are many reports of mixed metric and imperial threads on Chinese built machines.

Martin C

[mark costello 1Participant @markcostello1]

Also Imperial OD's with Chimetric thread pitches.

[John FlackParticipant @johnflack59079]

John Stevenson

It's not just the pitch…..the thread angles as well. As I have mentioned else where look up MG TD TF 1500cc which for me is a modern post war car, French metric(not the same as ISO ) with Whitworth sized heads to confuse the spannerman. And they are called "Standards" the evil thing is that with little effort you can force an ISO nut onto the same dia French fine thread stud, probably ONLY once!!!!!!!!!

To suggest testing with a wood or plastic dowel sounds plausible , but will it be accurate to measure the thread angle for the same pitch. My attempt with a cocktail stick and 8 BA……………underwhelmed comes to mind(Using magnifier and scalpel blade)

[Michael GilliganParticipant @michaelgilligan61133]

Posted by John Flack on 19/03/2017 13:52:07:

[…]

To suggest testing with a wood or plastic dowel sounds plausible , but will it be accurate to measure the thread angle for the same pitch. …

.

Clearly, it will not … but what it does do, is give you a starting-point from which to select your [commercial or improvised] Go/NoGo gauge[s].

MichaelG.

[John Stevenson 1Participant @johnstevenson1]

So what thread angle is what you call a "French Metric" ? because all I can find listed is 60 degrees.

I was just answering the asked question of what pitches were available and not what thread he had.

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by John Flack on 19/03/2017 13:52:07:As I have mentioned else where look up MG TD TF 1500cc which for me is a modern post war car, French metric(not the same as ISO ) with Whitworth sized heads to confuse the spannerman.

John,

They are French Automobile thread. See about 2/3 of the way down this page. That is not the same as French Metric thread.

It all started when Morris Motors bought Hodgkiss engines from France to fit into the Bullnose Morris Cowley. Later those engines were made under licence in the UK. The fasteners were made with Whitworth hexagons as garage workshops only tended to have Whitworth spanners and no doubt Whitworth hexagon bar was more easily obtained in the UK.

Russell

[John FlackParticipant @johnflack59079]

Look guys asking a Morgan owner to discuss MGs is a non starter. If you refer to the MG thread discussion site they

talk about mad metric and not using ISO dies to clean FRENCH METRIC studs and suggest shot blasting dies to round up the thread, I'm not making it up this is what TD TF owners are doing😅😅😅😅😅

EUNOIA Please

[Ian S CParticipant @iansc]

20 years ago a nephew of mine was making a folding chair in metal work at school, he decided he could speed things up a bit by taking it home and putting some threads on the end of some rods. He got it home, and found three metric tap and die sets, and none of them were ISO standard, so back to school and wait in line to use the schools one die. He's a diesel mechanic with his own company servicing mining machinery all over the South Island after having spent ten or more years doing the same in Australia , Africa, and Mexico. I think he has the correct threading kit now.

Ian S C

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