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BBs: steel Ø4.5 mm (.177) and airsoft Ø6.0 mm

What diameter is a BB and an airsoft BB? · Standard part · basis: Steel BB .177 calibre (Ø4.5); airsoft 6 mm BB (5.95 ±0.01); drawn as true spheres

Long Earth Society build part. Frames, crank wire and guides for the no-budget can engine. The engines

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

sizes
2 in table

Notes

  • A steel BB is Ø4.5 mm (.177 calibre); the file is a Ø4.5 sphere.
  • An airsoft BB is nominally Ø6.0 mm, typically 5.95 ±0.01 mm; the file is a Ø6.0 sphere.
  • Airsoft BBs are round enough to act as 6 mm balls in a race with a Ø6.0 groove under light load.
  • On the can engine I use BBs as low-friction guides for the displacer rod.

Sizes

balldia_mmnote
steel BB4.5.177 cal
airsoft BB6.05.95 ±0.01 typical

Where the files are

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

WikipediaCraft stickwebCC BY-SA 4.0 (text)
WikipediaBB gunwebCC BY-SA 4.0 (text)
WikipediaTable tenniswebCC BY-SA 4.0 (text)
Long Earth SocietyEngine builds (videos and write-ups)web, videoLES site

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

steel-bb-4-5mmsteel BB Ø4.5 (.177 cal)STEP · STL
airsoft-bb-6mmairsoft BB Ø6.0 (5.95)STEP · STL

Plain text: sheet.txt · JSON: /api/geometry?object=steel-and-airsoft-bbs

BBs: steel Ø4.5 mm (.177) and airsoft Ø6.0 mm, isometric render of a generated part
Render of airsoft-bb-6mm from the free STEP; not to scale.

How it fits

Goes in or on

Can-engine cap for 53.3, 58, 66 and 76.2 mm cansBBs as guides along the displacer rod

Alternatives

Ball bearings, 683 to 6210 and flanged F6xxa ball bearing where a race of loose balls is not enoughGlass marbles 1/2 in, 5/8 in and Ø16 mmlarger loose balls (Ø16)

You might also need

Ping-pong ball Ø40 mm, 0.4 mm wall, isometric render of a generated part
Ping-pong ball Ø40 mm, 0.4 mm wall1 sizes★ 1 files

Questions

What diameter is a steel BB?

4.5 mm (.177 calibre).

What size is an airsoft BB?

6 mm nominal, typically 5.95 ±0.01 mm.

Can airsoft BBs be used as bearing balls?

For light loads, yes: they are 5.95 ±0.01 mm, so a race groove drawn at Ø6.0 holds them.