Thread-forming screws for plastic (EJOT PT type): screw hole diameter by plastic, M2.2–M4, boss hole rule, K sizes — dimension sheet Source: Xem Studio, https://xemstudio.com/objects/plastic-thread-forming-screw-holes/ (sheet CC BY 4.0) Basis: EJOT's PT flyer (nominal diameters, hole rule, lengths) and a maker sheet of PT hole diameters by plastic, M2.2 to M4; numbers only Catalog version: 2026-10-20 Sizes: see table below - The hole table gives the recommended hole diameter in mm by plastic for M2.2, M2.5, M3, M3.5 and M4 PT-type screws, standard materials one row each. The sheet lists the high-strength group (glass-filled PA / PBT, PC, PC-GF30, PMMA, PPO, PEEK, PPS) with one value set; the layout did not show whether each material has its own values, so it is shown as one row (it matches the ABS row). For materials with high filler content or high internal strength the same sheet says the optimum hole diameter can be increased to 0.88 d, where d is the nominal screw diameter. - EJOT's flyer prints the rule hole diameter dh = 0.7 to 0.8 × d1 depending on the material (d1 the nominal screw diameter); the table values equal 0.7 × d for PE-LD / PP, 0.75 × d for PA, POM, PE-HD, PBT, PET and 0.8 × d for ABS, PS, PVC and the glass-filled grades. The flyer also prints other design ratios (for example dT = 2 × d1, 0.3 to 0.5 × d1 and di = 2 × d1 near the drawing), but the text read did not say which dimension each belongs to, so they are not stated here. Boss outside diameter and engagement depth tables by PT size were not in the sources read (EJOT refers to its design recommendation or hotline). - EJOT PT sizes by K designation (nominal diameter, mm): K10 1, K12 1.2, K14 1.4, K16 1.6, K18 1.8, K20 2, K22 2.2, K25 2.5, K30 3, K35 3.5, K40 4, K50 5, K60 6, K70 7, K80 8, K100 10. Screw lengths (mm, with the flyer's tolerance): 3, 3.5, 4, 4.5, 5, 6, 7, 8, 10, 12, 14, 16, 18, 20, 22, 25, 30, 35, 40, 50, 60, 70, 80, 90, 100 (which lengths exist for which diameter is not clear from the text read). EJOT recommends DELTA PT for high-filler or high-strength materials and, to reduce boss shear stress when assembling, first reducing the outside boss diameter and then increasing the hole diameter (a larger hole lowers pull-out load; deeper engagement can offset it). - Not on this page: other makers' screws for plastic (Stanley Plastite, PT-K families by other brands) and ASME Type B / AB plastic hole sizes (the hole tables read were not usable). No file: a PT thread (30° flank, trilobular-like profile) is not drawn from numbers here. - Heat-set inserts for plastic bosses: heat-set-insert-holes; sheet metal pilot holes: sheet-metal-screw-pilot-holes. group plastic M2.2 hole (mm) M2.5 hole (mm) M3 hole (mm) M3.5 hole (mm) M4 hole (mm) standard materials ABS 1.76 2 2.4 2.8 3.2 standard materials ABS/PC blend (incl. regrind) 1.76 2 2.4 2.8 3.2 standard materials ASA 1.716 1.95 2.34 2.73 3.12 standard materials PA 4.6 1.606 1.825 2.19 2.555 2.92 standard materials PA 6 1.65 1.875 2.25 2.625 3 standard materials PA 6.6 1.65 1.875 2.25 2.625 3 standard materials PBT 1.65 1.875 2.25 2.625 3 standard materials PE-LD 1.54 1.75 2.1 2.45 2.8 standard materials PE-HD 1.65 1.875 2.25 2.625 3 standard materials PET 1.65 1.875 2.25 2.625 3 standard materials PET-GF30 1.76 2 2.4 2.8 3.2 standard materials POM 1.65 1.875 2.25 2.625 3 standard materials POM-GF30 1.76 2 2.4 2.8 3.2 standard materials PP 1.54 1.75 2.1 2.45 2.8 standard materials PP-GF30 1.584 1.8 2.16 2.52 2.88 standard materials PP-TV20 (20% reclaimed) 1.584 1.8 2.16 2.52 2.88 standard materials PS 1.76 2 2.4 2.8 3.2 standard materials PVC 1.76 2 2.4 2.8 3.2 standard materials SAN 1.694 1.925 2.31 2.695 3.08 high-strength group (as read: one value set for the whole group) PA 4.6-GF30, PA 6-GF30, PA 6.6-GF30, PBT-GF30, PC, PC-GF30, PMMA, PPO, PEEK, PPS 1.76 2 2.4 2.8 3.2 Files elsewhere (not hosted by Xem Studio; license as stated by the publisher): - EJOT: PT screw for thermoplastics (flyer 08.23): nominal diameters K10 to K100, hole diameter rule dh = 0.7 to 0.8 x d1, lengths 3 to 100 mm — web — Maker flyer; numbers only — https://www.ejot.de/medias/sys_master/Industry_Flyer/Industry_Flyer/h54/h3c/9331729760286/EJOT-PT-Flyer-08.23-en.pdf - Cold-forged fastener maker sheet (hosted on a Shopify CDN; PT hole sizes by plastic): Recommended hole diameter for PT-type screws by material, M2.2 to M4, standard and high-strength groups; note: high filler content up to 0.88 d — web — Maker datasheet; numbers only — https://cdn.shopify.com/s/files/1/0056/7856/3437/files/MetPTholesize.pdf - EJOT: PT screws for thermoplastics (product page; CAD and design recommendations on request) — web — Publisher's page; dimensions are facts — https://www.ejot.se/pt 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=plastic-thread-forming-screw-holes