Internal Threading Inserts Puzzle??

[J BENNETT 1Participant @jbennett1]

[J BENNETT 1Participant @jbennett1]

I have been looking at fullform 60 deg ISO inserts for internal threading. I noticed that in the smallest 11 size they are available in 0.5 mm pitch upwards. However, I cannot see what use they are as 0.5 mm pitch would normally be used for 3.0 mm metric coarse or 5.0 mm metric fine, whereas the very smallest bore you could get a tool with this size insert into is 10mm.

I am sure I am missing something obvious, perhaps someone could enlighten me?

[JasonBModerator @jasonb]

You can use any diameter with a metric pitch, no different to say 40 & 32tpi model engineers threads, typical example M42 x 1 camera thread is a lot larger than a M6 x 1 metric coarse nut.

[EmgeeParticipant @emgee]

You can use 0.5mm pitch on any diameter you want, as you say though if internal then you have to consider the bore size. You will of course have to make the matching male part to suit, useful when you want a fine adjustment on something.

Emgee

[old martParticipant @oldmart]

I used 0.5 pitch inserts for this 40tpi threading as I had no other.

[J BENNETT 1Participant @jbennett1]

Thanks for the replies. Wasn't thinking clearly. In the normal course of things I only ever use metric coarse or Whitworth threads. There are of course many many other variations.

Apart from fine adjustment are there any other uses/ advantages for very fine threads?

Should have posted this in the "beginners section"!! Clearly lock-down is starting to bite!

Many thanks

JWB

[JonParticipant @jon]

In hydraulics, have used 0.5mm pitch for internal and extternal threading Titanium cylinders 2.05mm wall thickness. By going even 0.75mm pitch that reduces strength over the thread and extra 0.25mm.

Just look upon it as a pitch, you can easily create your own, used to do a lot of M29.25 X 0.75mm pitch, o/d 33.04mm will hold 450BAR shear if o ring at the front so thread not exposed.

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