Silver and Deming drill bit sizes: reduced shank chart
A silver and deming (S&D) drill bit is a twist drill whose cutting diameter is bigger than its shank: a 1 in body that steps down to a 1/2 in shank so it fits the 1/2 in (13 mm) chuck on an ordinary drill [1][12][18]. The name survives from a 19th century American maker and now just means this reduced shank pattern [12][18]. Tool owners regularly find one in an inherited kit and have to identify it from the stepped profile [17]; this chart is the reference those searches lack: the full diameter ladder, the part numbers behind it, the point angle rules, and where the shank sizes actually stop.
The size grid at a glance
Three numbers define every silver and deming bit: cutting diameter, shank diameter, and overall length. Across the industrial lines these hold almost perfectly still [1][6][9]:
| Spec | Standard value | Notes |
|---|---|---|
| Cutting diameter | 33/64 to 1-1/2 in | 1/64 in steps to 1 in, 1/32 to 1-1/4 in, 1/16 above; retail lines usually start 9/16 in [1][12] |
| Shank | 1/2 in with 3 flats | fits 1/2 in and 13 mm chucks; flats stop spin-out [1][9] |
| Overall length | 6 in | the whole category standard [1][2][6] |
| Flute length | 3 to 3-1/8 in | sets usable hole depth [7][9] |
| Point angle | 135 or 118 degrees | premium lines: 135 split point to 1 in, 118 above; M2 lines: 118 throughout [1][2] |
The rows below are anchored on Norseman's own size table, pulled live for this chart, and every diameter that an independent dealer also lists carries that second surface. Rows marked manufacturer spec only appeared in no independent catalog surveyed today; they are Norseman-listed sizes with no second print, and they are flagged rather than silently dropped [1][2].
Full chart: 33/64 to 1 in, 1/64 steps, 1/2 in shank
Both Norseman fractional series cover this range size for size: the 130-AG premium line (hi-molybdenum steel, 135 degree split point up to 1 in) and the 130-AGX M2 line (118 degree point). Same 6 in overall length, same 3-flats 1/2 in shank [1][2].
| Diameter (in) | Decimal (in) | Norseman 130-AG part # | Norseman 130-AGX part # | Independent second surface | Sources |
|---|---|---|---|---|---|
| 33/64 | 0.5156 | 29550 | 74001 | manufacturer spec only (disclosed) | [1][2] |
| 17/32 | 0.5312 | 29560 | 74011 | MSC, Precision Twist R56, 1/2 in shank S&D [8] | [1][2][8] |
| 35/64 | 0.5469 | 29570 | 74021 | manufacturer spec only (disclosed) | [1][2] |
| 9/16 | 0.5625 | 29580 | 74031 | Grainger 4UM62, 9/16 in reduced shank HSS [3] | [1][2][3] |
| 37/64 | 0.5781 | 29590 | 74041 | manufacturer spec only (disclosed) | [1][2] |
| 19/32 | 0.5938 | 29600 | 74051 | manufacturer spec only (disclosed) | [1][2] |
| 39/64 | 0.6094 | 29610 | 74061 | manufacturer spec only (disclosed) | [1][2] |
| 5/8 | 0.625 | 29620 | 74071 | MSC, Triumph, 5/8 x 1/2 in shank; Benchmark 5/8 [6] | [1][2][6] |
| 41/64 | 0.6406 | 29630 | 74081 | manufacturer spec only (disclosed) | [1][2] |
| 21/32 | 0.6562 | 29640 | 74091 | manufacturer spec only (disclosed) | [1][2] |
| 43/64 | 0.6719 | 29650 | 74101 | manufacturer spec only (disclosed) | [1][2] |
| 11/16 | 0.6875 | 29660 | 74111 | Forney 20668; Benchmark 11/16 [10] | [1][2][10] |
| 45/64 | 0.7031 | 29670 | 74121 | MSC 00980292, Chicago-Latrobe, 6 in OAL [7] | [1][2][7] |
| 23/32 | 0.7188 | 29680 | 74131 | Benchmark 23/32 [12] | [1][2][12] |
| 47/64 | 0.7344 | 29690 | 74141 | manufacturer spec only (disclosed) | [1][2] |
| 3/4 | 0.75 | 29700 | 74151 | Penn Tool R57 091548; Zoro 4UM74; Benchmark [5] | [1][2][5] |
| 49/64 | 0.7656 | 29710 | 74161 | manufacturer spec only (disclosed) | [1][2] |
| 25/32 | 0.7812 | 29720 | 74171 | Forney 20674 [11] | [1][2][11] |
| 51/64 | 0.7969 | 29730 | 74181 | manufacturer spec only (disclosed) | [1][2] |
| 13/16 | 0.8125 | 29740 | 74191 | manufacturer spec only (disclosed) | [1][2] |
| 53/64 | 0.8281 | 29750 | 74201 | manufacturer spec only (disclosed) | [1][2] |
| 27/32 | 0.8438 | 29760 | 74211 | manufacturer spec only (disclosed) | [1][2] |
| 55/64 | 0.8594 | 29770 | 74221 | manufacturer spec only (disclosed) | [1][2] |
| 7/8 | 0.875 | 29780 | 74231 | Benchmark 7/8 [13] | [1][2][13] |
| 57/64 | 0.8906 | 29790 | 74241 | manufacturer spec only (disclosed) | [1][2] |
| 29/32 | 0.9062 | 29800 | 74251 | Benchmark 29/32 [14] | [1][2][14] |
| 59/64 | 0.9219 | 29810 | 74261 | manufacturer spec only (disclosed) | [1][2] |
| 15/16 | 0.9375 | 29820 | 74271 | manufacturer spec only (disclosed) | [1][2] |
| 61/64 | 0.9531 | 29830 | 74281 | manufacturer spec only (disclosed) | [1][2] |
| 31/32 | 0.9688 | 29840 | 74291 | manufacturer spec only (disclosed) | [1][2] |
| 63/64 | 0.9844 | 29850 | 74301 | manufacturer spec only (disclosed) | [1][2] |
| 1 | 1.0 | 29860 | 74311 | MSC, Hertel 1 x 1/2 in shank; Benchmark 1 in [6] | [1][2][6] |
Two reading notes. First, 33/64 and 17/32 exist in the manufacturer table but almost nobody stocks them retail; if you need a hole between 1/2 and 9/16, the 33/64 size is a special-order reality, not a shelf item. Second, the part numbers are not decoration: Norseman AG numbers step by 10 per size (29550, 29560, 29570...), which makes a mislabeled bin easy to catch [2].
Over 1 in: 1-1/32 to 1-1/2
Above 1 in the AG ladder opens to 1/32 steps as far as 1-1/4 in, then finishes in 1/16 steps to 1-1/2 in; its point switches to 118 degrees (a 135 split point is not produced at these diameters). The AGX line thins out to five sizes between 1 and 1-1/4 in [1][2].
| Diameter (in) | Decimal (in) | Norseman 130-AG part # | Norseman 130-AGX part # | Independent second surface | Sources |
|---|---|---|---|---|---|
| 1-1/32 | 1.0312 | 29870 | not listed | manufacturer spec only (disclosed) | [1][2] |
| 1-1/16 | 1.0625 | 29880 | 74321 | manufacturer spec only (disclosed) | [1][2] |
| 1-3/32 | 1.0938 | 29890 | not listed | manufacturer spec only (disclosed) | [1][2] |
| 1-1/8 | 1.125 | 29900 | 74331 | manufacturer spec only (disclosed) | [1][2] |
| 1-5/32 | 1.1562 | 29910 | 74341 | manufacturer spec only (disclosed) | [1][2] |
| 1-3/16 | 1.1875 | 29920 | 74351 | manufacturer spec only (disclosed) | [1][2] |
| 1-7/32 | 1.2188 | 29930 | not listed | manufacturer spec only (disclosed) | [1][2] |
| 1-1/4 | 1.25 | 29940 | 74361 | manufacturer spec only (disclosed) | [1][2] |
| 1-5/16 | 1.3125 | 29950 | not listed | manufacturer spec only (disclosed) | [1][2] |
| 1-3/8 | 1.375 | 29960 | not listed | Benchmark 1-3/8 in, 1/2 in shank, 6 in OAL [12][15] | [1][2][12][15] |
| 1-7/16 | 1.4375 | 29970 | not listed | manufacturer spec only (disclosed) | [1][2] |
| 1-1/2 | 1.5 | 29980 | not listed | Benchmark 1-1/2 in, 1/2 in shank, 6 in OAL [12] | [1][2][12] |
The 1-1/2 in size is the practical ceiling of the 1/2 in shank pattern, and it is a torque ceiling as much as a shank one: a 1-1/2 in twist drill in steel wants drill-press rigidity and the lowest speed your machine turns, per the RPM-by-diameter rules in our drill speed chart.
Shank variants: 1/2 in 3-flat standard, 3/4 in for production, metric bodies
The 1/2 in shank with three flats is the default: the flats give the chuck jaws a positive grip so the bit cannot spin under load, a spec Penn Tool prints as shank type Weldon Flat, 3 flats on a 6 in overall bit [9]. Two real variants sit beside it in the manufacturer catalogs. Norseman's 131-AG is a 3/4 in reduced shank silver and deming line built for production machines with 3/4 in chucks, precision ground for low runout [1]; MSC stocks silver and deming drills on 3/4 in shanks up to 1-11/16 in diameter (Precision Twist R58) [6]. And Norseman's 130-AGM runs the same reduced shank pattern with metric cutting diameters [1]. A 5/8 in shank gets mentioned in workshop threads [17], but no 5/8 shank S&D SKU appeared in the Norseman, MSC, Grainger, or McMaster catalogs surveyed for this chart; 1/2 and 3/4 are the two shanks with first-party print.
Sets: what the 4-piece and 8-piece boxes contain
Sets skip the odd 64ths and pack the useful sizes. The composition is stable across brands [2][4][16]:
| Set | Contents | Part # | Second surface |
|---|---|---|---|
| Norseman 4 pc, premium 135 | 9/16, 5/8, 3/4, 1 in | S&D-4SP 12250 | Norseman page + PDF [1][2] |
| Norseman 8 pc, premium 135 | 9/16 to 1 in by 16ths | S&D-8SP 92400 | Norseman page + PDF [1][2] |
| Norseman 4 pc, M2 118 | 9/16, 5/8, 3/4, 1 in | S&D-4AGX 74771 | Norseman PDF [2][1] |
| Norseman 8 pc, M2 118 | 9/16 to 1 in by 16ths | S&D-8AGX 74781 | Grainger 4UM96, 8 pc 9/16 to 1 in [4][2] |
| Generic import 8 pc | 9/16 to 1 in by 16ths | varies | Amazon 8 pc 1/2 in shank set [16][4] |
If you drill metal occasionally, the 4-piece covers the sizes a 1/2 in chuck cannot otherwise reach (9/16 and up); the 8-piece adds the 16th steps that keep you from wallowing a clearance hole.
Silver and deming vs hole saw vs step bit
The identification question is real: all three tools drill holes bigger than 1/2 in through the same chuck, and a stepped-silhouette bit found in a drawer gets mislabeled as a step bit or an oddball masonry bit [17]. The division of labor is clean once you see the shank. A silver and deming bit is a full twist drill: it drills solid, deep, and straight, and at 3 in of flute it will out-drill any hole saw's depth, but above about 3/4 in in steel it demands slow speed and real torque [1][9]. A hole saw only cuts a ring, so it is faster for through-holes above 1 in in thin stock, and it mounts on a 1/4 in or 7/16 in arbor shank that any chuck holds. A step bit is for sheet metal: each step is one size, the largest step is the hole, and past about 1-1/4 in the cone gets unwieldy. For enlarging an existing hole rather than drilling new, see enlarging an existing hole; the S&D body handles that job well because its 1/2 in shank runs true in a drill press.
Chuck limits are the other half of the story. A 1/2 in chuck is the gateway: everything on this page fits one. What it does not fit is the full jobber-length 9/16 in and up bits, which come with straight shanks at the cutting diameter; the reduced shank is precisely the trick that makes big holes possible on small chucks, as covered in drill chuck sizes explained. For the diameter ladder below 1/2 in at standard length, the jobber drill bit size chart is the companion table: jobber tops out at 1/2 in for exactly this reason.
Buying notes: steel, coating, and the point angle trade
Within the pattern, price tracks steel and point geometry. The premium hi-molybdenum lines (Norseman 130-AG) carry a 135 degree split point below 1 in: it starts without a center punch and resists walking on curved work, which matters when the hole is 3/4 in and there is no second chance [1]. The M2 lines (130-AGX and most imports) use a 118 degree point, the general purpose angle for metal, wood, and plastic [1][16]. Coatings follow the same logic as any twist drill: black oxide or a black-and-gold nitride finish for lubricity and rust resistance, bright for aluminum and wood; the coating choice is covered in drill bit coatings and the bits by material guide. One S&D-specific caution: because the shank is thinner than the body, a seized 1-1/4 in bit transfers all its torque to the reduced section. Peck-drill, use cutting oil in steel, and keep the speed low.
Quick answers
- What is a silver and deming drill bit? A twist drill with a cutting diameter larger than its shank, almost always a 1/2 in 3-flat shank, 6 in overall, from 33/64 (retail: usually 9/16) to 1-1/2 in.
- Will it fit my drill? Yes if the chuck is 1/2 in or 13 mm: every standard S&D bit presents a 1/2 in shank regardless of body size.
- Why three flats on the shank? So the chuck jaws grip a flat instead of a round surface and the bit cannot spin under the high torque these diameters generate.
- What is the biggest one? 1-1/2 in diameter on the 1/2 in shank (Norseman 29980). Beyond that the shank steps to 3/4 in (131-AG, up to 1-11/16 at MSC) or you move to a hole saw.
Related guides
Also on this site: drill chuck sizes explained for the 1/2 in chuck boundary that defines this category, the jobber drill bit size chart for the 1/16 to 1/2 in ladder below it, hole saw sizes for ring-cutting above 1 in, and step drill bit sizes for sheet-metal cones. For running big diameters without burning the bit: the drill speed chart. For steel grades and coatings: drill bits by material and drill bit coatings.
Sources
- Norseman Drill and Tool, Silver and Deming Drills (product page): 1/2 in and 3/4 in reduced shank lines, 3 flats on shank, 135 split point, 118 above 1 in, 130-AG / 130-AGX / 130-AGM / 131-AG series definitions: norsemandrill.com
- Norseman Drill and Tool, Type 130-AG Silver and Deming size table (PDF, pulled live 2026-09-22): full 33/64 to 1-1/2 ladder, part numbers 29550 to 29980 (AG) and 74001 to 74361 (AGX), 6 in overall length, set contents: norsemandrill.com PDF
- Grainger, Reduced Shank Drill Bit 9/16 in 4UM62: HSS silver and deming, reduced shank to fit standard chucks: grainger.com
- Grainger, 8 Pc 9/16 to 1 in Reduced Shank Drill Bit Set 4UM96: silver and deming set composition: grainger.com
- Zoro, Zoro Select Silver/Deming Drill 3/4 in HSS 118 deg 4UM74: zoro.com
- MSC Industrial, Silver and Deming and Reduced Shank Drill Bits category: Triumph 5/8 x 1/2 in shank, Hertel 1 x 1/2 in shank 118 deg, Precision Twist R58 1-11/16 x 3/4 in shank, six inch overall statement: mscdirect.com
- MSC Direct, Chicago-Latrobe Reduced Shank Drill Bit 45/64 in, 1/2 in shank, 118 deg, HSS, 6 in OAL, 3-1/8 in flute (00980292): mscdirect.com
- MSC Direct, Precision Twist Drill R56 Reduced Shank 17/32 in, 1/2 in shank, 118 deg, HSS (78579794): mscdirect.com
- Penn Tool Co., Precision Twist Drill R57 091548: 3/4 in, 118 deg, 1/2 in shank (0.5000 in), silver and deming, 3 flats (Weldon Flat), 6 in OAL, 3 in flute: penntoolco.com
- Forney Industries, Silver and Deming Drill Bit 11/16 in (20668): 1/2 in shank, nitride treated, 118 deg split point: forneyind.com
- Forney Industries, Silver and Deming Drill Bit 25/32 in (20674): 1/2 in shank, nitride treated, 118 deg split point: forneyind.com
- Benchmark Abrasives, Silver and Deming Drill Bits collection: 5/8, 11/16, 23/32, 3/4, 1, 1-3/8, 1-1/2 in sizes, 1/2 in reduced shank definition, 9/16 to 1-1/2 typical range: benchmarkabrasives.com
- Benchmark Abrasives, 7/8 in Silver and Deming HSS Drill Bit: OD 7/8 in, OAL 6 in, shank 1/2 in with 3 flats: benchmarkabrasives.com
- Benchmark Abrasives, 29/32 in Silver and Deming HSS Drill Bit: OD 29/32 in, OAL 6 in, shank 1/2 in with 3 flats: benchmarkabrasives.com
- Benchmark Abrasives, 1-3/8 in Silver and Deming HSS Drill Bit: OD 1-3/8 in, OAL 6 in, shank 1/2 in with 3 flats: benchmarkabrasives.com
- Amazon, Premium 1/2 in Shank Silver and Deming 8-Piece HSS set (B075FGMSN6): 1/2 in reduced shank, black and gold finish: amazon.com
- r/Tools thread "What type of drill bit is this?": silver and deming identification confusion, reduced shanks over 1/2 in, 1/2 or 5/8 shank report (community-sourced, used for the confusion angle only): reddit.com
- Wikipedia, Drill bit sizes: silver and deming reduced shank definition within the twist drill size system: wikipedia.org