Q Size Drill Bit: Letter Size Chart
A Q size drill bit is a letter-gauge bit from the A to Z series, and this guide explains how letter, number and fractional sizes fit together and which sets include it.
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A drill that wanders off the mark ruins the hole before the bit even bites, and the fix often starts with picking the right size from the right series. A Q size drill bit is a letter-gauge twist bit from the A to Z letter series, and the letter sets in this guide carry the full A to Z range. This guide explains the sizing systems, how to drill with one, and which sets cover Q size work.
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Below: what a Q size drill bit is, the sizing systems, how to drill with one, and the sets that cover Q size work.
115Pcs Cobalt Jobber Drill Bits Set 135 Degree Tip
A 115-piece M35 cobalt set covering 1/16 inch to 1/2 inch, A to Z and #1 to #60, in an indexed metal case.
Pros
- Fractional, letter and wire sizes in one set, so Q is included
- M35 steel with 5% cobalt for hardened steel, stainless steel and cast iron
- 135-degree split point for self-centering, no-walk starts
- Fully ground twist shank clears chips and cuts friction and heat
Cons
- No warranty term is stated
- No bit lengths or case dimensions are stated
- Large set to store if only a few sizes see regular use
- Size range called 'all common sizes'
HIDOTOL 26PCS Cobalt Letter Drill Bit Set M35 HSS
A 26-piece M35 cobalt letter set covering A to Z, with a 135-degree split point and an indexed metal case.
Pros
- Full A to Z letter range, so Q is included
- M35 cobalt with 5% cobalt for hard materials
- 135-degree split point, self-centering to prevent walking
- Indexed metal case for storage
Cons
- Letter sizes only, no number or fractional sizes
- No warranty term is stated
- No weight is stated
- Bit lengths are not stated
MACXCOIP 60Pcs(#1-60) Cobalt Number Size Drill Bit
A 60-piece M35 cobalt number-size set covering #1 to #60, with a 135-degree point tip and an index storage case.
Pros
- 60 pieces covering #1 to #60, from 0.228 inch to 0.040 inch
- M35 cobalt steel for stainless steel, cast iron, copper, aluminum and soft metals
- 135-degree point tip, self-centering to prevent walk-off
- Index storage case keeps the set organized
Cons
- Number sizes only, so no letter size such as Q is included
- No warranty term is stated on the listing
- Bits can stick in the protective sponge and break
- No case dimensions or shank detail are stated
Century Drill & Tool 11606 Letter Gauge Drill Bit
A single letter-gauge F bit in M2 molybdenum high-speed steel, 0.257 inch in diameter and 4-1/8 inch long, with a 135-degree split point.
Pros
- Single-bit buy for one letter size, with no set to store
- M2 molybdenum high-speed steel, fully ground from billet blanks
- Rockwell hardness stated: point C65, shank C34
- 135-degree split point, fully ground from billet blanks
Cons
- Letter F only, so it does not include Q or any other letter size
- No warranty term with a stated length is given
- No storage case is listed with the bit
- The spec table lists the color as 'color'
What is a Q size drill bit?
A Q size drill bit is a letter-gauge bit, named by a letter rather than a fraction or a wire number. Letter-gauge bits run from A to Z, and Q sits in that series. The HIDOTOL 26-piece set and the Pro Edge 115-piece set each cover A to Z, so a Q bit is in the case. Single letter bits are also sold on their own: the Century listing here is a letter F bit, 0.257 inch in diameter.
Letter, number and fractional sizes
Drill bits come in letter, number and fractional sizes. The guide to types of drill bit explains what each kind is for, and the table below shows the ranges these listings cover.
| System | Sizes here | Example |
|---|---|---|
| Letter | A to Z | F bit, 0.257 inch diameter |
| Number (wire) | #1 to #60 | 0.228 inch to 0.040 inch |
| Fractional | 1/16 inch to 1/2 inch | Part of the 115-piece set |
The number range runs from #1 to #60, at 0.228 inch to 0.040 inch, or 5.79 mm to 1.02 mm. The fractional range in the Pro Edge set runs from 1/16 inch to 1/2 inch.
How to drill with a Q size bit
- Pick the letter set. Check that the case index lists A to Z, so Q is in the set before the job starts.
- Seat bits vertically in the case. Hold a vertical angle when you put a bit back in its slot, per the MACXCOIP listing, so it falls into its hole.
- Let the split point center the bit. The 135-degree split point is self-centering, so the bit does not walk off the mark.
- Clear chips as you go. The fully ground twist clears particles faster and cuts friction and heat, per the HIDOTOL and Pro Edge listings.
- Pull the bit straight out. A bit can stick in the protective sponge and break if pulled at an angle, per the MACXCOIP listing, so pull vertically.
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Letter drill bit sets and bits for Q size work
The gear below covers the step that needs a letter size: picking the Q bit from a letter set.
FAQ: garage tools
What size is a Q drill bit?
Q is a letter-gauge size in the A to Z series, and the HIDOTOL and Pro Edge letter sets cover A to Z, so Q is in the case.
Can a Q size drill bit cut stainless steel?
Yes, when it comes from an M35 cobalt set. The HIDOTOL and Pro Edge listings state M35 cobalt steel for stainless steel, cast iron and other hard metals, and both list wood and plastic as well. See the picks for the best drill bit for steel.
What does a 135-degree split point do?
It centers the bit at the start of the hole. The 135-degree split point is self-centering, so the bit does not walk off the mark, and the fully ground twist clears chips faster with less friction and heat.
Do I need a full letter set for Q size work?
Not always. A single letter bit covers a single size, as the Century F listing shows, while a letter set covers A to Z for later jobs. The 60-piece MACXCOIP covers wire sizes #1 to #60 instead.
How do I keep letter drill bits organized?
Keep them in the indexed case they come in. The HIDOTOL set uses a metal case with a size index holder, and the Pro Edge set gives each bit a dedicated slot. Pull bits vertically, since the MACXCOIP listing warns that a bit can stick and break if pulled at an angle.
Related: best drill bit set, types of drill bit and the best step drill bit.
