more than 7"threads verification

[moleroal]

Hi,
I need to measure the functional size and pitch of 3 threads by direct measure.
8.250 x 16 UNJS 3A LH (EXTERNAL)
7.000 x 16 UNJS 3A LH (EXTERNAL)
7.125 x 16 UNJS 3BG LH (INTERNAL)
Actually I use Johnson Gage Inspection tools.
But I´d like another alternative method to ensure my process. Is possible?

And I would like a RING or PLUG GAGE (measurement attributes) for each thread to be sure that the part can assemble, but the Standards don´t recommend their use.
Is there any industry who use their?

Thanks.

 

[KENAT]

One way to inspect large thread form is to take an impression of the threads with dental paste (or whatever it's called, the stuff they use to form an impression for crowns etc) and then put it up on an optical comparitor or something. There was a thread not so long ago about acme threads that mentioned this.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[CoryPad]

If you want an alternative to the functional measurement method, then you could use a coordinate measurement machine (CMM).

 

[unclesyd]

If you don't want to use a ring gage you might want to give MTG as call. If you look at the first reference you see the frames for external threads and looking on the second reference you see some of the fingers that are available to you.

http://www.mtggage.com/e_frames.html

http://www.mtggage.com/i_threads.html

 

[TVP]

In addition to the options suggested above, a contour measuring system can be used to measure threads. The Contracer system from Mitutoyo is one such system:

http://www.mitutoyo.com/ProductTypeResultForm.aspx?type=1149

There are a number of optical or vision systems that can be used for direct measurement of parts or on casts/molds taken from parts. Here are two providers of such systems:

OGP

http://www.ogpnet.com/ogpMain.jsp?localeId=1

Brown & Sharpe

http://brownandsharpe.com/