The Problem with "Complete" Sets
Walk into any machinist supply store and you can buy a complete 115-piece fractional, letter, and number drill index for under a hundred dollars. It comes in a nice case with every size labeled. It feels like you have everything covered.
Here is what actually happens: you use 15 of those drills constantly, another 20 occasionally, and the remaining 80 sit in the case until you forget they exist. The 15 drills you use constantly wear out. You go to replace them, but they are buried in a crowded case with other drills of similar size that are still sharp. You end up using dull drills because finding the right ones is a hassle, or you buy replacements for drills that are technically still in the case but mixed in with the rest.
Low-volume job shops — the ones running a few dozen jobs a month rather than a few hundred — almost universally get better results from a smaller, curated inventory than from a complete set. Fewer drills, all in known condition, clearly organized, beats a comprehensive set where half the drills are of unknown sharpness.
The 80/20 Drill Sizes: What Actually Gets Used
Across general fabrication, repair, and light manufacturing work, a large fraction of holes fall into a predictable size range. These are the drills that earn their keep in a small shop:
Fractional — The Core Set
1/16, 3/32, 1/8, 5/32, 3/16, 7/32, 1/4, 9/32, 5/16, 11/32, 3/8, 7/16, 1/2. That is 13 sizes covering the range from small clearance holes to anchor bolts. Add 9/16, 5/8, and 3/4 if your work regularly involves larger fasteners or pipe work. Stop there unless a specific job demands otherwise.
Letter Sizes — The Tap Drill Group
If you tap threads, you need tap drill sizes. The ones that see the most action in general shop work: #7 (for 1/4-20), #21 (for 10-32), #29 (for 8-32), F (for 5/16-18), Q (for 3/8-16), W (for 7/16-14), 27/64 (for 1/2-13). Keep dedicated tap drills separate from your general-purpose drills — they wear differently and you want to know they are sharp before you commit to threading a hole.
Number Sizes
For most general shops, number size drills outside of tap drill applications are rarely needed. If you do electronics work or precision instrument work, #60 through #40 are useful. Otherwise, skip the full number set and buy specific sizes as jobs require them.
A Sticky Note Tracking System That Actually Works
Software is not the answer for a one- or two-person shop. The overhead of entering data into an inventory system is not worth it at this scale. What works is simpler: a sticky note on the inside of each drill case or drawer section, updated every time you touch the drills.
The sticky note has two columns: Size and Status. Status has three options: Sharp, Needs Sharpen, and Order. When you use a drill and it is still cutting well at the end of the job, no change. When you notice it starting to require more pressure, squeak instead of cut, or produce rough holes — write Needs Sharpen. When you have no drill in that size or the one you have is beyond resharpening — write Order.
Review the sticky note at the end of each week. Collect all Needs Sharpen drills and set them aside for the resharpen batch. Order anything in the Order column. This takes five minutes per week and keeps you from ever starting a job and discovering your drill is dull halfway through.
The key is honest status updates. The temptation is to keep using a drill that is 80% sharp because it technically still cuts. Resist this. A dull drill costs you in time, surface quality, and in some cases a ruined workpiece. The resharpen cost is less than the cost of one scrapped part.
Organizing Physical Storage
Drill indexes — the hinged cases with labeled slots — work well if you use them correctly. The rule is simple: a slot is either empty or has a sharp drill in it. Dull drills do not go back into the index. They go into a separate container labeled for resharpening.
A small plastic bin or a labeled section of your tool tray works for the resharpen-holding area. When it fills up with enough drills to make a mail-in batch worth sending — typically ten to twenty drills or more — it gets packaged and shipped. This naturally creates a batch cadence without requiring you to track anything beyond the physical bin filling up.
Separate storage for specialty drills is worth doing once your shop grows beyond the basics. Left-hand drills, cobalt drills for stainless work, step drills for sheet metal, and spot drills all benefit from dedicated spots where they are easily found and not mixed with general-purpose inventory.
Buy vs Resharpen: The Economics for Small Shops
The break-even point where resharpening becomes economically better than replacement sits at roughly 3/16 to 1/4 inch diameter for HSS drills, and lower for cobalt. Below that, the replacement cost of the drill is often close enough to the resharpen cost that convenience tips toward replacement. Above that, resharpening consistently beats buying new.
Worked example: A 1/2 inch M2 HSS jobber drill costs roughly $4 to $8 depending on brand and supplier. A quality resharpen through a mail-in service like MachinistPost costs less than half that and returns a drill with the same geometry as new. Over the life of a frequently used 1/2 inch drill, resharpening it three or four times before retirement costs less than buying two replacements. The savings compound across your whole inventory.
Cobalt HSS makes the math even more favorable. A 1/2 inch M42 cobalt drill costs $10 to $20 at retail. Resharpening it costs the same as resharpening standard HSS. The per-resharpen savings are larger, and cobalt drills can typically be resharpened more times before the flute geometry becomes a limiting factor because the material wears more slowly.
The drills that do not make sense to resharpen: anything below 3/16 inch diameter (the economics favor replacement), drills with chipped or broken flutes (material cost to remove the damage exceeds the drill's value), and drills so far past their wear limit that the flute geometry is compromised beyond what a normal resharpen can restore.
Building the Inventory Without Breaking the Bank
If you are starting from scratch or rebuilding after inheriting a drawer of mystery drills, a phased approach is more practical than buying everything at once.
Phase one: buy the 13-size fractional core set in a quality brand — Norseman, Triumph, or equivalent US-made HSS. Do not buy the cheapest option. Cheap drills are soft and cannot be resharpened because the geometry deteriorates faster than they can be maintained. A mid-tier US-made drill will outlast three budget import sets and resharpen cleanly when the time comes.
Phase two: add tap drills for the thread sizes you cut most often. Buy these individually, not in a set, so you can buy the quality you actually need in the sizes you actually use.
Phase three: add specialty drills as specific jobs demand them. Left-hand set, cobalt set for stainless, step drills for sheet metal work. Buy these when you have a job that needs them, not speculatively.
Phase four: establish the resharpen rotation. Once your core fractional drills have been through a few jobs, start cycling them through MachinistPost when they need attention. The rotation runs itself from there — dull drills go in the bin, bin fills up, send the batch, get them back sharp.
A focused inventory of 25 to 30 drill sizes, all in known good condition, is more valuable to a working shop than a 115-piece set where half the drills are of unknown sharpness. Know what you have, keep it sharp, and you will spend less time fighting tooling problems and more time making chips.