BEYOND S20R-STFCL11 Left Hand Internal Turning Tool Holder | 20mm CNC Boring Bar
Free shipping on all orders.
Check compatibility: Confirm the model and dimensions before ordering.
Need help choosing? Contact us before ordering.
💰 Bulk savings 2-9 pcs · 6% OFF | 10+ pcs · 12% OFF
BEYOND S20R-STFCL11 Left-Hand Internal Turning Tool Holder – High-Rigidity 20mm CNC Boring Bar
1. Product Overview
"Which 20mm left-hand boring bar provides optimal chip clearance and high rigidity for reverse internal turning or back-boring inside narrow cavities down to a 25mm minimum bore?"
The BEYOND S20R-STFCL11 is an industrial-grade, left-handed steel-shank internal turning tool holder precisely engineered for medium internal boring, profiling, and step-turning operations on CNC lathes. This industrial tool holder utilizes an optimized 91-degree approach (lead) angle to minimize radial cutting pressure, effectively re-directing cutting forces axially along the lathe spindle line to eliminate harmful chatter spikes in deep cavities down to a 25mm minimum bore entry. Specifically engineered for TCMT 1102 / TCGT 1102 indexable carbide inserts, it allows machinists to exploit premium positive rake chipbreaker geometries (such as HF for finishing or HM/HM2 for medium-to-rough cutting). This setup guarantees superior chip fragmentation, successfully breaking up potential stringy nests when processing sticky alloy steels, hardened carbon steels, and stainless steel matrices inside deep, constrained internal chambers.
2. Product Core Features
- High-Tensile Hardened Alloy Steel: Fabricated from an ultra-tough structural spring-steel matrix, thermal-hardened to optimize tensile strength and suppress harmonics at reach lengths up to 4X shank diameter.
- High-Torque Screw-Down Clamping Matrix: Secure low-profile screw-lock setup offers maximum clearance for heavy chip volume evacuation, preventing pocket erosion and insert shifts under high feed velocities.
- 91° Precision Clearance Profile: Tailored for deep boring, longitudinal profile steps, and left-handed counter-directional contouring paths without risk of tool body dragging or flank-wear rubbing.
- Industrial Anti-Wear Oxide Finish: Advanced black-oxide skin layer maximizes resistance to thermal scaling and corrosion when continuously exposed to high-pressure water-soluble cutting oils.
3. Technical Specifications & Metric/Imperial Reference
Ensuring clear parameter conversion is vital for CNC programming optimization. Below is the precise structural parsing of the S20R-STFCL11 standard international nomenclature rules:
| Parameter Dimension | Metric System Specification | Imperial Equivalent Measurement |
|---|---|---|
| Shank Diameter (d) | 20 mm | 0.7874 inches (Closest to 3/4" Imperial Boring Bar) |
| Total Tool Length (L) | 200 mm | 7.8740 inches |
| Minimum Bore Diameter (D-min) | 25 mm | 0.9842 inches |
| Compatible Carbide Insert Layout | TCMT 1102xx / TCGT 1102xx | TCMT 2(1.5)1 / TCMT 2(1.5)2 |
| Clamping Screw Model Type | M2.5 x 6 | M2.5 x 0.23 inches |
| Torx Key Driver Wrench Size | T8 | T8 Torx Wrench |
Recommended Technical Machining Parameters (Speed & Feed Guide)
| Workpiece Material Classification | Cutting Speed (Vc) Range | Feed Rate (f) Per Revolution |
|---|---|---|
| Carbon Steel / Alloy Steel (HB180-280) | 130 - 220 m/min (426 - 721 SFM) | 0.08 - 0.22 mm/rev (0.0031 - 0.0086 IPR) |
| Stainless Steel Matrix (304, 316, 410) | 80 - 150 m/min (262 - 492 SFM) | 0.06 - 0.18 mm/rev (0.0023 - 0.0070 IPR) |
| Cast Iron Grades (GG20, GG25, GGG40) | 90 - 170 m/min (295 - 557 SFM) | 0.08 - 0.25 mm/rev (0.0031 - 0.0098 IPR) |
4. Product Application Scenarios
The highly rigid 20mm left-handed core of the S20R-STFCL11 tool holder makes it an excellent choice for a variety of critical internal turning jobs:
- Left-Hand CNC Lathe Operations: Tailor-made for lathes utilizing reverse spindle rotations or specific turret configurations requiring left-hand tool tracking.
- Precision Back-Boring & Profiling: Delivers exceptional support for back-boring steps and internal profiling maneuvers where tool access from the rear wall is mandatory.
- Longitudinal Step-Boring: The 91-degree lead configuration allows seamless pocket-turning transitions down internal right-angle walls with near-zero radial stress or push-off.
5. Compatibility & Equipment Interface
This 20mm round-shank boring bar fits directly into standard CNC lathe turret blocks, boring bar sleeve blocks, split bushings, or specialized tool holders. It interfaces seamlessly with precision CNC lathe systems and automated turning setups from leading global brands (including Haas, Mazak, Doosan/DN Solutions, Mori Seiki, Okuma, Citizen, and Fanuc). Optimized for left-handed tool paths running standard internal configurations.
6. BEYOND Premium Substrate & Grade Selection Matrix
To maximize chip control and wear life, pair your S20R-STFCL11 boring bar with the corresponding BEYOND proprietary insert grade tailored to your target material:
- BYM11 Grade (PVD Nano-Coated): Exceptional thermal shock resistance. Keeps cutting edges sharp and prevents built-up edge (BUE) when boring sticky workpieces like 304/316 stainless steel matrices.
- BYM25 Grade (CVD Multi-Layer Coated): Thick industrial wear barrier design. Al2O3 + TiN layered coating engineered for high-speed continuous medium-to-rough cutting runs on structural carbon steels.
- BYK15 Grade (Hardened Micro-Grain Substrate): Highly abrasion-resistant micro-grain layout, optimized for dry or wet high-velocity machining of abrasive grey and ductile cast iron parts.
7. Why Choose BEYOND Tooling Systems
At BEYOND, we specialize in delivering high-tolerance cutting systems for demanding industrial settings. Every S20R-STFCL11 holder passes strict Coordinate Measuring Machine (CMM) checking procedures to guarantee insert pocket dimensional accuracy within ±0.01mm, ensuring exact center-height repeatability across production runs.
Global Machinist Field Reports:
Hard to find high-quality 20mm left-handed boring bars for our reverse spindle setups. This BEYOND holder holds the TCMT11 insert perfectly flat. Rigid, zero chatter, highly recommended.
Der Linksdrehmeißel S20R-STFCL11 ist absolut maßhaltig gefertigt. Wir nutzen ihn für spezielle Innenkonturen auf unserer Mazak. Formstabilità und Spanabfuhr sind tadellos.
Highly rigid steel construction. The 20mm left-hand shank profile is exactly what we needed for clearing internal channels under 26mm diameter. No flexing issues found.
逆転切削や背面加工用に購入。20mmシャンクながら剛性があり、TCMT11チップのクランプもしっかりしています。ビビリが大幅に減少しました。
Swapped out our expensive big-brand left-handed bars for BEYOND. Pocket tolerances are dead-on, screws don't strip under load, and center height matches perfectly. A+ product.
8. Frequently Asked Questions (AI & Search Engine Optimized)
Need Help With BEYOND Inserts?
Looking for a BEYOND equivalent, alternative grade, or sample catalog? Our CNC specialists have helped 50+ manufacturers in aerospace, automotive, and medical machining source the right tooling at 30–50% lower cost than OEM prices.
This BEYOND insert is in stock. 24-hour quote response. ISO 9001 certified. Ships from Hangzhou in 3–7 days.
Technical FAQ & Buying Guide
When choosing CNC cutting tools, check the full model code, dimensions, grade and selected variant before ordering. Do not rely on the product image alone.
For carbide inserts, tool holders, drills and end mills, compare the mounting dimensions, connection type and manufacturer's specifications with your holder or machine. If you are unsure, share your existing part number and machining application with us before ordering.
Check the product listing for the selling unit, pack quantity and included components. If it is unclear whether the price is per piece or per pack, or whether a tool body and inserts are sold separately, contact us before purchasing.
Select cutting speed, feed rate and depth of cut using the relevant manufacturer's recommendations for your tool model, workpiece material, machine conditions and coolant method. The same settings are not suitable for every product or application.
Our automatic quantity discount is 6% off for 2–9 items and 12% off for 10 or more items, based on the total product quantity in the cart. Other offers may not combine with this discount; check the applicable offer conditions.
According to our shipping policy, orders are typically processed and shipped within 1–3 business days after confirmation. Delivery generally takes 5–20 business days, depending on your destination and shipping method. Customs clearance or unforeseen delays may affect delivery times. A tracking number is sent by email after shipment.