Past 920 mm: the XL / XXL Tier
Application Overview
The 920 mm "standard" mining length is a market convention, not a manufacturing ceiling. Every major brand now retails an extra-long tier above it — DeWalt's DW01065 (32 × 1160 × 1300, sold as "XL") and DW01066 (32 × 1360 × 1500), Makita's 53-inch B18057, Bosch's max-7 line up to 1320 mm — because deeper holes mean more advance per cycle and fewer repositioning moves. Zhonghuan manufactures this tier factory-direct: SDS-Max mining bits in 1300 and 1500 mm total lengths, on the same 42CrMo + controlled-atmosphere brazed virgin carbide platform as our standard mining program, OEM and private label.
The Retail XL / XXL Tier, Mapped
| Brand SKU | Size | Note |
|---|---|---|
| DeWalt DW01065 | 32 × 1160 × 1300 mm | Retailed across Peru as the "XL" mining bit |
| DeWalt DW01066 | 32 × 1360 × 1500 mm | The deep end of the broca francesa line |
| Makita B18057 | 1-1/4" × 53" (≈32 × 1350 mm) | Sold through Mexican mining-supply channels |
| Bosch SDS max-7 | Lengths to 1320 mm | Catalog top of the multi-segmented cutter line |
| Diager Ultimax 168 | Catalog to 3,850 mm | Dealers list the XXL specials as "4000 mm" |
| Zhonghuan XXL program | Ø28–38 × 1300 / 1500 mm | Factory-direct OEM; intermediate and longer lengths by drawing |
Buyers quote this tier by SKU and by working length. Our quotations state both total and working length per SKU, following the LONG. USO convention the trade uses.
Why a 1.5 m Bit Is the Hardest Duty a Hand-Held Bit Sees
- Slenderness. A Ø32 bit at 1500 mm is roughly a 47:1 column. Hand-held drilling is never perfectly axial, and the bending moment a stroke puts into the body grows with length — the fatigue duty at 1500 mm is a different class from 450 mm, which is why body steel and full-length heat treatment decide survival here more than anywhere else in the range.
- Straightness is manufactured, not assumed. Long blanks bow during heat treatment; every long bit goes through straightening, and the scrap risk of that step rises steeply with length. A long bit that is not straight whips, widens the collar, and snaps early — straightness and runout control are the real cost of this tier.
- Evacuation over a metre. Past roughly a metre of hole, packed cuttings — not carbide sharpness — set the advance rate. Wide-spiral deep-hole flutes and disciplined withdrawal cycles are what keep the bit cutting instead of recutting its own dust.
- The braze joint lives at depth. Heat builds over a long continuous hole and cycles the head joint every withdrawal. Controlled-atmosphere brazing's whole-joint wetting is the margin that spot induction joints give up.
How Ours Are Built
| Spec | Range | Notes |
|---|---|---|
| Diameter | Ø28–38 mm | Ø32 mm is the volume size — same cartridge logic as the standard mining program |
| Total length | 1300 / 1500 mm | The market XL / XXL points; intermediate and longer lengths evaluated by drawing |
| Body | 42CrMo alloy steel, full-length heat treatment | Straightened after heat treatment; runout checked per batch |
| Head | 6-cutting-edge or ZHMAX-7 multi-segmented cutter | Same two mining architectures as the standard lengths |
| Carbide | Controlled-atmosphere brazed virgin carbide, YG11C class | Ceratizit tips on request with mill certificate |
QC per lot follows the mining program standard: hardness (HRA carbide / HRC body), dimensional and straightness/runout checks, metallographic cross-section of the braze joint, witness drilling test.
Field Technique for Metre-Plus Holes
- Collar short, finish long. Open the hole with a 450–620 mm bit for a stiff, accurate collar, then run the long bit to depth — the long bit should never do the spot-drilling work.
- Withdraw every 200–300 mm to clear cuttings; over a metre of hole this is the difference between cutting rock and burnishing dust.
- Let the hammer work. Leaning adds bending, and bending is what kills long bits — keep the machine aligned and let impact energy do the advance.
- Machine pairing: the 10 kg / 20 J class drives this tier; see the 20 J rotary hammer pairing page.
OEM & Ordering
Standard mining-program terms apply: MOQ 200 pcs per size, laser-etched private label, custom packaging, samples freight-paid for witness testing, ISO 9001 with material certificates per lot. Send the SKU you buy today (DW01065 / DW01066, B18057, max-7 1320) and we quote the dimensional equivalent — or send hole depth and rock type and we spec it from zero. The standard-length program lives on the SDS-Max mining drill bits manufacturer page; head selection is covered on the multi-segmented cutter page and the 6-edge program page.