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Dormer Pramet A125 1/2 Inch x 400 mm HSS ST STRAIGHT SHANK EXTRA LONG SERIES DRILL BS 328
| Type | Extra Long Series |
| Drill Diameter | 1/2 |
| Flute Length | 300 |
| Overall Length | 400 |
| Shank Diameter | 12.7 |
| Substrate | HSS |
Learn more about Klarna
Meet the Dormer Pramet A125 1/2 Inch x 400 mm HSS ST STRAIGHT SHANK EXTRA LONG SERIES DRILL BS 328 — a purpose-built drill bit crafted for serious deep-hole work. With its robust construction and smart engineering, this bit is designed to deliver precise starts, clean holes, and dependable performance in demanding fabrication environments.

- 118-degree conventional point creates a strong, self-centering tip that’s easy to re-sharpen in the field, helping you maintain accurate starts and reduce wandering in tough workpieces.
- Steam oxide finish minimizes material sticking to the cutting edge, promoting smoother chip evacuation and reduced friction during long drilling passes.
- Extra-long 400 mm length is specifically chosen for deep-hole drilling and applications where reach matters, letting you access through-thick sections without compromising rigidity.
- Premium HSS material handles a wide range of metals—from steel and aluminum to stainless steel—making it a versatile choice for mixed-material projects.
- Straight shank provides reliable grip and compatibility with standard drill chucks and collets, ensuring consistent performance on benchtop drills, drill presses, and milling machines.
- BS 328 compliance reflects established standards for quality and compatibility in professional metalworking.");
This drill bit is ideal for engineers, machinists, and hobbyists who regularly drill deep holes in thick workpieces or assemblies. Use it for fabricating chassis components, automotive brackets, machine bases, and other metalwork where depth and straightness are critical. Its 1/2 inch diameter balances aggressive material removal with control, while the 400 mm length provides the reach you need without sacrificing stability.
Practical tips for best results:
- Clamp the workpiece securely and use a pilot location to guide the bit on initial contact.
- Use a steady, moderate feed rate and appropriate cutting fluid to cool the bit and evacuate chips, especially in longer drilling passes.
- For deep holes, consider stepping drilling with a series of progressively larger bits to minimize deflection and heat buildup.
- Inspect the bit after use and re-sharpen the 118-degree point as needed to maintain an accurate starting surface.
| Type | Extra Long Series |
| Drill Diameter | 1/2 |
| Flute Length | 300 |
| Overall Length | 400 |
| Shank Diameter | 12.7 |
| Substrate | HSS |
| Coated | Steam Tempered |
What time are Protool open?
We are open Monday to Friday between 8:30am and 5pm.
Do you offer Free Next Day delivery?
Yes! We offer Free Next Day delivery via Royal Mail Tracked 24 on all orders over £50 ex VAT*. We also offer Free DPD Local Next Day delivery on all orders over £100 ex VAT*.
We also offer the following:
- Royal Mail Tracked 24 — £5.90 (FREE on orders over £50 ex VAT*). Order before 4:30pm for next day delivery. No signature required.
- DPD Local Next Day — £8.00 (FREE on orders over £100 ex VAT*). Standard next day delivery to UK mainland addresses.
- Royal Mail Special Delivery — £12.50. Guaranteed delivery before 1pm the next working day.
- DPD Saturday Delivery — £25.00. Must be ordered on Friday before 4pm. Pre-12pm delivery.
For delivery to Scottish Highlands & Islands, Northern Ireland, Republic of Ireland, or overseas locations, additional charges apply. Please see our delivery page for full details, or call us on 01732 887 334.
*T's & C's and exclusions apply. Please see our delivery page for more information on all our services.
Full Range: Dormer Pramet A125 HSS ST STRAIGHT SHANK EXTRA LONG SERIES DRILLS BS 328
View full collection →You are viewing DOR-A1251/2X400. Click any other SKU to view its full details.
| Product SKU | Drill Diameter | Flute Length | Overall Length | Shank Diameter | Price | Stock | Order |
|---|---|---|---|---|---|---|---|
| DOR-A1251.4X160 | 1.40 | 100 | 160 | 1.4 | £18.83 | 2 days | |
| DOR-A1251.5X125 | 1.50 | 80 | 125 | 1.5 | £10.72 | 2 days | |
| DOR-A1251.5X160 | 1.50 | 100 | 160 | 1.5 | £12.72 | 2 days | |
| DOR-A1251/16X125 | 1/16 | 80 | 125 | 1.59 | £13.07 | 2 days | |
| DOR-A1251/16X160 | 1/16 | 100 | 160 | 1.59 | £15.64 | 2 days | |
| DOR-A1251.8X160 | 1.80 | 100 | 160 | 1.8 | £16.45 | 2 days | |
| DOR-A1255/64X160 | 5/64 | 100 | 160 | 1.98 | £16.14 | 2 days | |
| DOR-A1255/64X125 | 5/64 | 80 | 125 | 1.98 | £15.49 | 2 days | |
| DOR-A1252.0X125 | 2.00 | 80 | 125 | 2 | £8.30 | 2 days | |
| DOR-A1252.0X160 | 2.00 | 100 | 160 | 2 | £9.76 | 2 days | |
| DOR-A1252.2X160 | 2.20 | 100 | 160 | 2.2 | £10.11 | 2 days | |
| DOR-A1253/32X160 | 3/32 | 100 | 160 | 2.38 | £9.79 | 2 days | |
| DOR-A1253/32X125 | 3/32 | 80 | 125 | 2.38 | £8.94 | 2 days | |
| DOR-A1252.5X125 | 2.50 | 80 | 125 | 2.5 | £7.84 | 2 days | |
| DOR-A1252.5X160 | 2.50 | 100 | 160 | 2.5 | £9.65 | 2 days | |
| DOR-A1257/64X125 | 7/64 | 80 | 125 | 2.78 | £9.47 | 2 days | |
| DOR-A1257/64X160 | 7/64 | 100 | 160 | 2.78 | £14.50 | 2 days | |
| DOR-A1253.0X160 | 3.00 | 100 | 160 | 3 | £9.17 | 2 days | |
| DOR-A1253.0X200 | 3.00 | 150 | 200 | 3 | £12.25 | 2 days | |
| DOR-A1253.0X250 | 3.00 | 200 | 250 | 3 | £15.53 | 2 days | |
| DOR-A1251/8X160 | 1/8 | 100 | 160 | 3.18 | £11.26 | 2 days | |
| DOR-A1251/8X200 | 1/8 | 150 | 200 | 3.18 | £11.45 | 2 days | |
| DOR-A1251/8X250 | 1/8 | 200 | 250 | 3.18 | £22.28 | 2 days | |
| DOR-A1251/8X315 | 1/8 | 250 | 310 | 3.18 | £25.63 | 2 days | |
| DOR-A1253.3X160 | 3.30 | 100 | 160 | 3.3 | £13.22 | 2 days | |
| DOR-A1253.5X160 | 3.50 | 100 | 160 | 3.5 | £9.30 | 2 days | |
| DOR-A1253.5X200 | 3.50 | 150 | 200 | 3.5 | £11.48 | 2 days | |
| DOR-A1253.5X250 | 3.50 | 200 | 250 | 3.5 | £16.17 | 2 days | |
| DOR-A1259/64X160 | 9/64 | 100 | 160 | 3.57 | £16.32 | 2 days | |
| DOR-A1259/64X200 | 9/64 | 150 | 200 | 3.57 | £16.42 | 2 days | |
| DOR-A1259/64X315 | 9/64 | 250 | 310 | 3.57 | £23.76 | 2 days | |
| DOR-A1255/32X160 | 5/32 | 100 | 160 | 3.97 | £11.43 | 2 days | |
| DOR-A1255/32X200 | 5/32 | 150 | 200 | 3.97 | £13.53 | 2 days | |
| DOR-A1255/32X250 | 5/32 | 200 | 250 | 3.97 | £26.08 | 2 days | |
| DOR-A1255/32X315 | 5/32 | 250 | 310 | 3.97 | £33.11 | 2 days | |
| DOR-A1254.0X160 | 4.00 | 100 | 160 | 4 | £9.33 | 2 days | |
| DOR-A1254.0X200 | 4.00 | 150 | 200 | 4 | £12.04 | 2 days | |
| DOR-A1254.0X250 | 4.00 | 200 | 250 | 4 | £16.13 | 2 days | |
| DOR-A1254.0X315 | 4.00 | 250 | 310 | 4 | £20.00 | 2 days | |
| DOR-A12511/64X160 | 11/64 | 100 | 160 | 4.37 | £15.03 | 2 days | |
| DOR-A12511/64X200 | 11/64 | 150 | 200 | 4.37 | £18.10 | 2 days | |
| DOR-A12511/64X315 | 11/64 | 250 | 310 | 4.37 | £26.08 | 2 days | |
| DOR-A1254.5X160 | 4.50 | 100 | 160 | 4.5 | £10.84 | 2 days | |
| DOR-A1254.5X200 | 4.50 | 150 | 200 | 4.5 | £14.21 | 2 days | |
| DOR-A1254.5X250 | 4.50 | 200 | 250 | 4.5 | £21.78 | 2 days | |
| DOR-A1254.5X315 | 4.50 | 250 | 310 | 4.5 | £23.80 | 2 days | |
| DOR-A1253/16X160 | 3/16 | 100 | 160 | 4.76 | £10.99 | 2 days | |
| DOR-A1253/16X200 | 3/16 | 150 | 200 | 4.76 | £12.52 | 2 days | |
| DOR-A1253/16X250 | 3/16 | 200 | 250 | 4.76 | £15.94 | 2 days | |
| DOR-A1253/16X315 | 3/16 | 250 | 310 | 4.76 | £23.30 | 2 days | |
| DOR-A1253/16X400 | 3/16 | 300 | 400 | 4.76 | £44.05 | 2 days | |
| DOR-A1255.0X160 | 5.00 | 100 | 160 | 5 | £10.53 | 2 days | |
| DOR-A1255.0X200 | 5.00 | 150 | 200 | 5 | £13.86 | 2 days | |
| DOR-A1255.0X250 | 5.00 | 200 | 250 | 5 | £17.24 | 2 days | |
| DOR-A1255.0X315 | 5.00 | 250 | 310 | 5 | £23.89 | 2 days | |
| DOR-A1255.0X400 | 5.00 | 300 | 400 | 5 | £30.42 | 2 days | |
| DOR-A12513/64X200 | 13/64 | 150 | 200 | 5.16 | £21.57 | 2 days | |
| DOR-A12513/64X250 | 13/64 | 200 | 250 | 5.16 | £27.95 | 2 days | |
| DOR-A12513/64X315 | 13/64 | 250 | 310 | 5.16 | £36.71 | 2 days | |
| DOR-A1255.5X200 | 5.50 | 150 | 200 | 5.5 | £12.84 | 2 days | |
| DOR-A1255.5X250 | 5.50 | 200 | 250 | 5.5 | £20.75 | 2 days | |
| DOR-A1255.5X315 | 5.50 | 250 | 310 | 5.5 | £32.83 | 2 days | |
| DOR-A1257/32X200 | 7/32 | 150 | 200 | 5.56 | £16.69 | 2 days | |
| DOR-A1257/32X250 | 7/32 | 200 | 250 | 5.56 | £21.33 | 2 days | |
| DOR-A12515/64X200 | 15/64 | 150 | 200 | 5.95 | £25.86 | 2 days | |
| DOR-A12515/64X315 | 15/64 | 250 | 310 | 5.95 | £24.81 | 2 days | |
| DOR-A1256.0X200 | 6.00 | 150 | 200 | 6 | £14.91 | 2 days | |
| DOR-A1256.0X250 | 6.00 | 200 | 250 | 6 | £19.96 | 2 days | |
| DOR-A1256.0X315 | 6.00 | 250 | 310 | 6 | £24.85 | 2 days | |
| DOR-A1256.0X400 | 6.00 | 300 | 400 | 6 | £36.16 | 2 days | |
| DOR-A1251/4X200 | 1/4 | 150 | 200 | 6.35 | £16.32 | 2 days | |
| DOR-A1251/4X250 | 1/4 | 200 | 250 | 6.35 | £20.69 | 2 days | |
| DOR-A1251/4X315 | 1/4 | 250 | 310 | 6.35 | £25.63 | 2 days | |
| DOR-A1251/4X400 | 1/4 | 300 | 400 | 6.35 | £52.44 | 2 days | |
| DOR-A1251/4X500 | 1/4 | 400 | 460 | 6.35 | £72.96 | 2 days | |
| DOR-A1256.5X200 | 6.50 | 150 | 200 | 6.5 | £17.10 | 2 days | |
| DOR-A1256.5X250 | 6.50 | 200 | 250 | 6.5 | £21.20 | 2 days | |
| DOR-A1256.5X315 | 6.50 | 250 | 310 | 6.5 | £30.64 | 2 days | |
| DOR-A12517/64X200 | 17/64 | 150 | 200 | 6.75 | £21.11 | 2 days | |
| DOR-A12517/64X250 | 17/64 | 200 | 250 | 6.75 | £28.41 | 2 days | |
| DOR-A12517/64X500 | 17/64 | 400 | 460 | 6.75 | £72.96 | 2 days | |
| DOR-A1257.0X200 | 7.00 | 150 | 200 | 7 | £18.45 | 2 days | |
| DOR-A1257.0X250 | 7.00 | 200 | 250 | 7 | £23.58 | 2 days | |
| DOR-A1257.0X315 | 7.00 | 250 | 310 | 7 | £33.24 | 2 days | |
| DOR-A1257.5X200 | 7.50 | 150 | 200 | 7.5 | £22.12 | 2 days | |
| DOR-A1257.5X250 | 7.50 | 200 | 250 | 7.5 | £26.68 | 2 days | |
| DOR-A1257.5X315 | 7.50 | 250 | 310 | 7.5 | £34.56 | 2 days | |
| DOR-A1255/16X200 | 5/16 | 150 | 200 | 7.94 | £20.93 | 2 days | |
| DOR-A1255/16X250 | 5/16 | 200 | 250 | 7.94 | £26.36 | 2 days | |
| DOR-A1255/16X315 | 5/16 | 250 | 310 | 7.94 | £34.88 | 2 days | |
| DOR-A1255/16X500 | 5/16 | 400 | 460 | 7.94 | £86.18 | 2 days | |
| DOR-A1258.0X250 | 8.00 | 200 | 250 | 8 | £26.04 | 2 days | |
| DOR-A1258.0X315 | 8.00 | 250 | 310 | 8 | £35.07 | 2 days | |
| DOR-A1258.0X400 | 8.00 | 300 | 400 | 8 | £44.23 | 2 days | |
| DOR-A12521/64X315 | 21/64 | 250 | 310 | 8.33 | £64.30 | 2 days | |
| DOR-A1258.5X250 | 8.50 | 200 | 250 | 8.5 | £35.66 | 2 days | |
| DOR-A1258.5X315 | 8.50 | 250 | 310 | 8.5 | £47.88 | 2 days | |
| DOR-A12511/32X250 | 11/32 | 200 | 250 | 8.73 | £34.06 | 2 days | |
| DOR-A12511/32X315 | 11/32 | 250 | 310 | 8.73 | £58.37 | 2 days | |
| DOR-A12511/32X400 | 11/32 | 300 | 400 | 8.73 | £72.05 | 2 days | |
| DOR-A12511/32X500 | 11/32 | 400 | 460 | 8.73 | £86.18 | 2 days | |
| DOR-A1259.0X250 | 9.00 | 200 | 250 | 9 | £30.87 | 2 days | |
| DOR-A1259.0X315 | 9.00 | 250 | 310 | 9 | £39.31 | 2 days | |
| DOR-A1259.0X400 | 9.00 | 300 | 400 | 9 | £56.54 | 2 days | |
| DOR-A1259.5X250 | 9.50 | 200 | 250 | 9.5 | £36.98 | 2 days | |
| DOR-A1259.5X315 | 9.50 | 250 | 310 | 9.5 | £49.70 | 2 days | |
| DOR-A1253/8X250 | 3/8 | 200 | 250 | 9.52 | £33.61 | 2 days | |
| DOR-A1253/8X315 | 3/8 | 250 | 310 | 9.52 | £42.59 | 2 days | |
| DOR-A1253/8X400 | 3/8 | 300 | 400 | 9.52 | £53.81 | 2 days | |
| DOR-A1253/8X500 | 3/8 | 400 | 460 | 9.52 | £74.33 | 2 days | |
| DOR-A12510.0X250 | 10.00 | 200 | 250 | 10 | £35.52 | 2 days | |
| DOR-A12510.0X315 | 10.00 | 250 | 310 | 10 | £44.19 | 2 days | |
| DOR-A12510.0X400 | 10.00 | 300 | 400 | 10 | £65.21 | 2 days | |
| DOR-A12513/32X250 | 13/32 | 200 | 250 | 10.32 | £44.32 | 2 days | |
| DOR-A12513/32X315 | 13/32 | 250 | 310 | 10.32 | £54.72 | 2 days | |
| DOR-A12510.5X250 | 10.50 | 200 | 250 | 10.5 | £44.28 | 2 days | |
| DOR-A12510.5X315 | 10.50 | 250 | 310 | 10.5 | £57.46 | 2 days | |
| DOR-A12510.5X400 | 10.50 | 300 | 400 | 10.5 | £68.86 | 2 days | |
| DOR-A12511.0X250 | 11.00 | 200 | 250 | 11 | £40.04 | 2 days | |
| DOR-A12511.0X315 | 11.00 | 250 | 310 | 11 | £51.07 | 2 days | |
| DOR-A12511.0X400 | 11.00 | 300 | 400 | 11 | £63.38 | 2 days | |
| DOR-A1257/16X250 | 7/16 | 200 | 250 | 11.11 | £49.25 | 2 days | |
| DOR-A1257/16X315 | 7/16 | 250 | 310 | 11.11 | £62.02 | 2 days | |
| DOR-A1257/16X400 | 7/16 | 300 | 400 | 11.11 | £129.05 | 2 days | |
| DOR-A12529/64X315 | 29/64 | 250 | 310 | 11.51 | £57.46 | 2 days | |
| DOR-A12512.0X250 | 12.00 | 200 | 250 | 12 | £46.97 | 2 days | |
| DOR-A12512.0X315 | 12.00 | 250 | 310 | 12 | £54.72 | 2 days | |
| DOR-A12512.0X400 | 12.00 | 300 | 400 | 12 | £73.42 | 2 days | |
| DOR-A12531/64X315 | 31/64 | 250 | 310 | 12.3 | £57.46 | 2 days | |
| DOR-A1251/2X250 | 1/2 | 200 | 250 | 12.7 | £57.00 | 2 days | |
| DOR-A1251/2X315 | 1/2 | 250 | 310 | 12.7 | £72.96 | 2 days | |
| DOR-A1251/2X400 Viewing | 1/2 | 300 | 400 | 12.7 | £95.76 | 2 days | |
| DOR-A12513.0X315 | 13.00 | 250 | 310 | 13 | £58.37 | 2 days | |
| DOR-A12513.0X400 | 13.00 | 300 | 400 | 13 | £74.33 | 2 days | |
| DOR-A12517/32X315 | 17/32 | 250 | 310 | 13.49 | £58.37 | 2 days | |
| DOR-A12514.0X315 | 14.00 | 250 | 310 | 14 | £69.31 | 2 days | |
| DOR-A12514.0X400 | 14.00 | 300 | 400 | 14 | £81.17 | 2 days | |
| DOR-A1259/16X315 | 9/16 | 250 | 310 | 14.29 | £69.31 | 2 days | |
| DOR-A12537/64X315 | 37/64 | 250 | 310 | 14.68 | £69.31 | 2 days | |
| DOR-A12519/32X315 | 19/32 | 250 | 310 | 15.08 | £69.31 | 2 days | |
| DOR-A12519/32X500 | 19/32 | 400 | 460 | 15.08 | £93.02 | 2 days | |
| DOR-A1255/8X315 | 5/8 | 250 | 310 | 15.88 | £69.31 | 2 days | |
| DOR-A1255/8X500 | 5/8 | 400 | 460 | 15.88 | £93.02 | 2 days | |
| DOR-A12511/16X315 | 11/16 | 250 | 310 | 17.46 | £69.31 | 2 days | |
| DOR-A1253/4X315 | 3/4 | 250 | 310 | 19.05 | £70.68 | 2 days | |
| DOR-A1253/4X500 | 3/4 | 400 | 460 | 19.05 | £95.30 | 2 days |
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