Stubby Drill Bit Set: Screw Machine Length Guide

By Drill Hog® | Published: 2026-10-23

Category: How-to Guides

Learn when to use a stubby drill bit set (screw machine length) for metal drilling. Includes steps, trade-offs, and product facts for the Drill Hog 115 pc set.

Quick answer

Use a stubby drill bit set (screw machine length) when you need maximum rigidity for drilling metal in tight spaces or with portable drills, trading off reduced depth capacity for less bit wander and breakage.

Why screw machine length bits differ from jobber bits

Screw machine length bits are shorter and stiffer than standard jobber bits. This design reduces flex during drilling, which improves hole accuracy and extends bit life, especially in harder metals like stainless steel. The trade-off is a shorter flute length, meaning they cannot drill as deep in a single pass. For most metal fabrication tasks where holes are less than 1 inch deep, this is rarely a limitation.

When to choose a stubby set over a standard set

Reach the decision by matching your application to the bit's strengths. Use stubby bits when drilling with a handheld drill to minimize wobble, when working in confined spaces (e.g., inside a frame or cabinet), or when drilling thin metal sheets where a longer bit might cause chatter. Avoid them if you consistently need holes deeper than the bit's flute length, which for a 1/2-inch stubby bit is typically around 1-1/4 inches.

How to use a stubby drill bit set for metal drilling

Choose the correct size: Select a bit that matches your desired hole diameter. Use fractional sizes for standard holes and letter sizes for numbered or custom fits. A common mistake is using a letter bit when a fractional bit would give a tighter tolerance.
Secure the workpiece and mark the spot: Clamp the metal piece firmly to a stable surface. Use a center punch to create a dimple at the drill point. Skipping the punch mark is a common mistake that causes the bit to walk and create an off-center hole. Always center-punch before drilling metal with a stubby bit.
Set drill speed and apply cutting fluid: For mild steel, set your drill to 1000-1200 RPM for a 1/4-inch bit (lower for larger sizes). Apply a few drops of cutting oil to the bit tip. A common mistake is running the drill too fast, which overheats the bit and dulls the M7 steel quickly.
Drill with steady pressure and peck: Start drilling at the marked dimple. Use light, steady pressure. If the hole is deeper than half the bit diameter, lift the bit every few seconds to clear chips (peck drilling). A common mistake is forcing the bit, which can cause it to snap or overheat. If you see blue chips or smoke, you are drilling too fast or with too much pressure.
Deburr and inspect the hole: After drilling, use a deburring tool or countersink to remove sharp edges. Check the hole diameter with a plug gauge or caliper. A common mistake is skipping deburring, which can cause the hole to wear oversized or create safety hazards.

Product facts

115 Pc Letter Number Drill Bit Set Stubby Stub Screw Machine Length Drill Hog: Made from HI-Molybdenum M7 high-speed steel, includes 29 fractional sizes from 1/16" to 1/2", plus 26 letter sizes (A-Z). M7 steel offers better heat and wear resistance than standard M2, making this set suitable for production drilling in steel or stainless steel without frequent resharpening.
115 Pc Letter Number Drill Bit Set Stubby Stub Screw Machine Length Drill Hog