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Caster stem types and sizes: threaded stem (3/8-16, 1/2-13, M10, M12), grip ring 7/16 in, expanding adapter, bolt-hole fitting

What stem sizes do stem casters come in: 3/8-16, 1/2-13, M10, M12, grip ring 7/16 in? · Standard part · basis: One retailer's stem-caster sizing guide (text and spec sheet) and a Blickle bolt-hole datasheet, read in this session; numbers only

Also called: stem caster sizes, threaded stem caster 1/2-13, 3/8-16 stem caster, m12 stem caster, grip ring stem caster 7/16, friction ring stem, expanding stem caster tube size, caster stem length, castor stem types, m10 threaded stem castor

Exact dimensions. Every file is drawn at true size with no tolerance added. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your process's clearance before making the part. Mating features

sizes: 5 in table

Notes

A stem caster is held to the equipment by a stem instead of a top plate: a threaded stem screws into a tapped hole or nut, a grip-ring stem presses into a socket, an expanding adapter wedges in a tube. Thread sizes the guide lists: UNC 3/8-16, 1/2-13, 5/8-11, 3/4-10, 1-8; UNF 3/8-24, 1/2-20, 5/8-18; metric M8, M10, M12, M16 (BSF / BSW are mentioned without sizes). Stem lengths are measured from the caster plate or shoulder to the tip.
Stem diameters printed: 1/4 (.250), 5/16 (.313), 3/8 (.375), 7/16 (.437, grip ring), 1/2 (.500), 5/8 (.625), 3/4 (.750), 7/8 (.875), 1 (1.000) in. The guide says the stem diameter must match the host hole or tube within 1/64 in. It prints no tap-drill, host-hole or socket diameters, so none is given here.
Grip ring: the guide's table lists 7/16 × 7/8 and 7/16 × 1-7/16 in; its introduction says 7/16 and 1/2 in diameters exist, but 1/2 in is not in its size table. A commonly quoted '7/16 × 1-3/8' size is not on this guide and is not used.
No file: the shape of a stem fitting (collar, shoulder, grip ring, kingpin) is not defined by published numbers in the sources read. Plate casters are on caster-top-plate-patterns.

Caster stem types and sizes: threaded stem (3/8-16, 1/2-13, M10… size chart

stem type	thread / diameter (inch)	UNF (fine)	metric	length	host
threaded stem	UNC 3/8-16, 1/2-13, 5/8-11, 3/4-10, 1-8	UNF 3/8-24, 1/2-20, 5/8-18	M8, M10, M12, M16	1, 1-1/2, 1-3/4, 2 in (from the plate to the tip)	tapped hole in the host; no tap drill printed
grip ring (friction ring) stem	7/16 in diameter (the guide's table; its text also mentions 1/2 in)	—	—	7/8 in or 1-7/16 in; sizes printed 7/16 × 7/8 and 7/16 × 1-7/16	precision-fit socket; no socket size printed
expanding adapter stem	—	—	—	1-1/2 to 2 in compressed	tube ID between the compressed and expanded OD; tube sizes 7/8, 1, 1-1/8, 1-1/4 in (and metric)
plain round stem and square stem	—	—	—	varies by OEM	—
bolt-hole fitting (not a stem)	—	—	Blickle LMDA-TPA 50 and 75: hole Ø10.2 mm, plate Ø41 / Ø55 mm	—	single central bolt

Mating features

Drawn at the exact size. Open press, slide, run and socket features by your process's clearance (tolerances by process); leave designed gaps and clamp fits as drawn.

feature	exact	mates with	fit	files
threaded stem	UNC 3/8-16, 1/2-13, 5/8-11, 3/4-10, 1-8; UNF 3/8-24, 1/2-20, 5/8-18; M8, M10, M12, M16	tapped hole or nut of the same thread in the equipment	designed	all
grip ring stem	Ø7/16 in (11.1 mm) × 7/8 or 1-7/16 in long	socket within 1/64 in of the stem diameter (guide's rule; socket size not printed)	press	all

Where the files are

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

CasterHQ	Stem casters sizing guide: stem types, thread sizes, stem lengths, grip ring 7/16 in, expanding adapter tube sizes	web	Retailer guide; numbers only
CasterHQ	Stem casters sizing guide spec sheet (PDF)	web	Publisher's page; dimensions are facts
Blickle (via Raptor Supplies datasheet)	LMDA-TPA 50 / 75 castors with central bolt-hole fitting: wheel diameter, total height, plate diameter, bolt hole diameter, offset	web	Maker datasheet; numbers only
McMaster-Carr	Casters (plate, stem, bolt-hole) (free STEP/IGES per part, for your own design use; no redistribution)	STEP, IGES, PDF	McMaster-Carr site terms: personal design use, no redistribution verify

Xem scan

File coming

No downloadable true-size file yet: the published figures do not fix the whole shape, and Xem never guesses a number. A measured scan is planned; request it and it moves up.

Let your AI pull this. Add https://xemstudio.com/mcp to Claude, ChatGPT, Cursor or any MCP client (free, no account, one minute) and it can look up exact sizes, mating fits and free STEP/STL from every chat.

Set it up →

Plain text: sheet.txt · JSON: /api/geometry?object=caster-stems-threaded-grip-ring

Schematic, not to scale.