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T-mount (T2): M42 × 0.75 thread, 55 mm flange, thread rings

Name: T-mount (T2): M42 × 0.75 thread, 55 mm flange, thread rings dimension sheet
Creator: Xem Studio
License: https://creativecommons.org/licenses/by/4.0/

What is the T-mount (T2) flange focal distance? · Standard part · basis: Published numbers only (sources per row); thread drawn at the ISO 68-1 basic profile

Also called: t2 thread, t-mount thread pitch, m42x0.75, t ring, t2 adapter stl, t-mount flange distance 55mm

Exact dimensions. True size, with no printing tolerance added.

sizes: 8 in table

Notes

Flange focal distance is the distance from the mount's reference face to the image plane; adapters and extension tubes must add exactly the difference between two mounts' flange distances to keep infinity focus.
Telescopes, mirror lenses and microscope adapters end in a male M42 × 0.75 thread; a camera-specific T-ring carries the female thread and sets the 55 mm to the image plane.
Not interchangeable with M42 × 1 (M42 screw mount).

T-mount (T2): M42 × 0.75 thread, 55 mm flange, thread rings size chart

parameter	value	from
flange focal distance	55 mm	T-mount (Wikipedia); Flange focal distance table
throat / inner diameter	not published in a source I could verify (left out)	—
thread	M42 × 0.75	standard
major Ø D	42.000 mm	standard
pitch P	0.75 mm	standard
pitch Ø D2 (basic)	41.513 mm	ISO 68-1 basic profile
minor Ø D1 (basic)	41.188 mm	ISO 68-1 basic profile
files	male and female ring sections, 8 turns, basic profile	—

Where the files are

Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.

Wikipedia	T-mount: M42 x 0.75 thread, 55 mm flange focal distance	web	CC BY-SA 4.0 (text); dimensions are facts
Wikipedia	Flange focal distance (table of mounts)	web	CC BY-SA 4.0 (text); dimensions are facts
Bureau of Indian Standards (via Public.Resource.Org)	IS 4218 (Part 1):2001 ISO general purpose metric screw threads, basic profile (identical with ISO 68-1:1998): H = 0.866025404 P, 5H/8 = 0.541265877 P, 3H/8 = 0.324759526 P	web	Public.Resource.Org (public law); dimensions are facts
ISO	ISO 68-1:1998 ISO general purpose screw threads — Basic profile — Part 1: Metric screw threads	web	Publisher's page; dimensions are facts

Free files

★ Free files 2 parts. Generated by Xem Studio from the standard; threads are plain cylinders at major diameter. CC BY 4.0. index.json

m42x0-75-male-ring	M42 × 0.75 (T2) external thread ring section: ISO 68-1 basic profile, major Ø42, pitch Ø41.513, minor Ø41.188, pitch 0.75; 6 long (8 turns), bore Ø37.188 (wall is a design choice); exact nominal, no tolerance	STEP · STL
m42x0-75-female-ring	M42 × 0.75 (T2) internal thread ring section: ISO 68-1 basic profile, minor Ø41.188, pitch Ø41.513, major Ø42, pitch 0.75; 6 long (8 turns), outside Ø46 (design choice); exact nominal, no tolerance	STEP · STL

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Plain text: sheet.txt · JSON: /api/geometry?object=t-mount-t2