GT2 idler pulleys, toothed and smooth: 16T / 20T, 3 and 5 mm bore, OD, width, F623 / F625 bearing sizes — dimension sheet Source: Xem Studio, https://xemstudio.com/objects/gt2-idler-pulleys-toothed-smooth/ (sheet CC BY 4.0) Basis: Seller and maker product pages (Tinytronics, Systeal, Filastruder, Printed Solid); bearing sizes from the existing F-series bearing page (NSK, skdin, kugellager-express) Catalog version: 2026-10-20 Sizes: see table below - A GT2 idler is a pulley (toothed or smooth) on a ball bearing, so it spins on a fixed screw or shaft. Toothed idlers have the same teeth as a pulley (16T and 20T are the common ones) and run on the toothed side of the belt; smooth idlers run on the back of the belt. The table is what sellers and Gates print; every row is one product. 'OD' is the shop's own 'outer diameter': for the 16T and 20T it is larger than the tooth OD (9.68 and 12.22 mm by the GT2 rule, see the GT2 pulley page), so it can only be the flange. Printed Solid's Gates smooth idler is a 12 mm OD with no flange stated. - The bearing behind it: the idler bores 3 and 5 mm are the bores of 623 (3 x 10 x 4) and 625 (5 x 16 x 5) bearings, which the flanged-bearing page lists with their flanges (F623 flange 11.5 x 1, F625 flange 18 x 1). None of the sources read says which bearing a given idler holds or how many (Systeal says 'dual bearing' without a size), so the table does not pair them. - Widths differ: Tinytronics prints 8.5 mm for all six, Filastruder 10 mm outside flange to outside flange for its 6 mm-belt idler. Different makers, so different widths: measure the one you buy. - No files: no source read gives a full outline (tooth OD, flange thickness, bearing pocket, hub) for any idler, so a model would be invented. Use the bearing pages for the pocket and the pulley page for the tooth Ø. type product teeth bore, mm OD as printed, mm width, mm belt width, mm toothed, bearing Tinytronics GT2316T 16 3 13 8.5 6 toothed, bearing Tinytronics GT2320T 20 3 18 8.5 6 toothed, bearing Tinytronics GT2520T 20 5 18 8.5 6 smooth, bearing Tinytronics GT2316S 16 (same Ø as 16T) 3 13 8.5 not fully stated smooth, bearing Tinytronics GT2320S 20 (same Ø as 20T) 3 18 8.5 not fully stated smooth, bearing Tinytronics GT2520S 20 (same Ø as 20T) 5 18 8.5 not fully stated toothed, dual bearing Systeal GT2-ID-PULLEY-D5-6W 20 3 or 5 18 — 6 toothed, bearing Filastruder (Gates 2GT idler), 6 mm belt version 20-tooth equivalent 3 or 5 — 10 (flange to flange) 6 smooth Printed Solid, Gates PowerGrip 2GT smooth idler 20-tooth equivalent 5 12 — — bearing 623 / F623 3 x 10 x 4 F623: flange 11.5 x 1 idler for 16T / 20T on a 3 mm bore bearing 625 / F625 5 x 16 x 5 F625: flange 18 x 1 idler on a 5 mm bore, 16 mm bearing OD Files elsewhere (not hosted by Xem Studio; license as stated by the publisher): - Tinytronics: GT2 idler pulleys: toothed and toothless, bore, outer diameter, height, belt width — web — Publisher's page; dimensions are facts — https://www.tinytronics.nl/en/mechanics-and-actuators/parts/pulleys - Systeal: GT2 dual-bearing idler timing pulley, 20 teeth, bore 3 or 5, 6 mm belt, OD 18 — web — Publisher's page; dimensions are facts — https://www.systeal.com/en/pulleys-and-belts/1893-gt2-dual-bearing-idler-timing-pulley-belt-width-6mm.html - Filastruder: Gates 2GT idler: 6 mm belt idlers are 10 mm wide outside flange to outside flange; bore 5 or 3 — web — Publisher's page; dimensions are facts — https://filastruder.com/products/gates-2gt-idler - Printed Solid: Gates PowerGrip 2GT smooth idler: OD 12 mm, 5 mm bore — web — Publisher's page; dimensions are facts — https://www.printedsolid.com/collections/e3d/products/gates-powergrip-2gt-smooth-idler No true-size file yet: the published figures do not fix the whole shape; a measured scan is planned. API: https://xemstudio.com/api/geometry?object=gt2-idler-pulleys-toothed-smooth