Hole saw arbor size chart: threads, shanks, and brand fit
A hole saw does not clamp into the drill. The chuck holds an arbor (also called a mandrel), the arbor's center post threads into the saw cup, and a pilot drill through the middle keeps the cut centered [1] [2]. That makes two separate compatibility questions: does the arbor's shank fit your chuck, and does its thread fit the cup. This page is the chart for both, with the thread standards, the diameter ranges each thread covers, the shank-to-chuck mapping, and brand-by-brand part numbers, every row sourced. For which cup diameter a given job needs, see our hole saw size chart; for the wood side of big holes, wood boring bits compared.
The two compatibility rules
Rule one: the arbor shank diameter must be no larger than the chuck size. Rule two: the arbor's collar screw thread must match the cup's center thread exactly [1]. Everything else, brand names, quick-change systems, pilot bit styles, is convenience layered on top of those two constraints. The good news is that the industry has quietly standardized: there are only two major cup threads and three common shank diameters [1] [3].
The thread chart: which arbor runs which saws
Cups thread onto the arbor at their center hole, in one of two sizes: 1/2 inch-20 (small thread) and 5/8 inch-18 (large thread, Unified Fine) [1] [3]. The large thread is the de facto industry standard above roughly 1-1/4 inches: Milwaukee, DeWalt, Bosch, and Lenox cups all share it, so cups and arbors cross brands freely at the thread level [3] [5]. The diameter ranges below are the honest ones published by manufacturers and industrial retailers, and they differ slightly by brand; note that brands set their own cutoffs, which is why the small-thread ceiling is 1-3/16 inch in most catalogs but some arbor lines (Milwaukee's own large-thread arbor, Ruko) start the large thread at 1-1/4 inch [2] [7].
| Arbor thread | Cup diameter range | Notes | Sources |
|---|---|---|---|
| 1/2 in-20 (small thread) | 9/16 to 1-3/16 in (14 to 30 mm) | Only thread available on 1/4 in shank arbors | [1] [2] [6] [9] |
| 5/8 in-18 UNF (large thread) | 1-1/4 to 6 in (32 to 152 mm) | Shared by Milwaukee, DeWalt, Bosch, Lenox; extended arbors reach 6-5/8 or 8-5/8 in | [1] [2] [3] [8] |
The 18 and 20 are threads per inch, so a 5/8-18 arbor post physically cannot enter a 1/2-20 cup: different diameter, different pitch, no partial fit [5] [9]. Measure across the cup's center hole threads with calipers if the stamp is worn off: about 0.500 in means small thread, about 0.625 in means large [1] [5].
The shank chart: which arbor fits your chuck
On the drill side, arbor shanks come in three diameters: 1/4, 11/32, and 7/16 inch [1]. A chuck can hold any shank at or below its capacity, so the mapping runs one way [1]. Hex shanks are the default for grip; round-shank arbors exist for drill presses and slippage matters more in a hand drill [1] [2].
| Arbor shank diameter | Threads available | Fits chucks | Sources |
|---|---|---|---|
| 1/4 in hex | 1/2-20 only | 1/4, 3/8, and 1/2 in | [1] [2] |
| 11/32 in hex (sold as 3/8 in) | 1/2-20 and 5/8-18 | 3/8 and 1/2 in | [1] [2] |
| 7/16 in hex | 1/2-20 and 5/8-18 | 1/2 in only | [1] [2] |
Two footnotes to that table. First, the 11/32 inch shank is commonly rounded to 3/8 inch in catalog listings because the diameters are so close [1]; Empire Abrasives and Milwaukee sell their 3/8-class arbors as literal 3/8 in hex shanks [2] [4]. Second, shank diameter limits thread choice only at the bottom: a 1/4 in shank arbor exists solely in 1/2-20, so a drill with a 1/4 in chuck is locked out of large-thread cups entirely [1] [2]. For impact drivers, use the 7/16 in shank version: a 3/8 shank fits but is not rated for impact torque and can break [3] [2].
Brand by brand: what each maker calls it
Every brand wraps the two-thread reality in its own naming and part numbers. The table below cross-references the major lines; the pattern is the same everywhere, small-thread arbors for cups to 1-3/16 inch, large-thread arbors above that, with quick-change mechanisms as the brand-specific layer [3].
| Brand and part | Thread | Shank | Covers cups | Sources |
|---|---|---|---|---|
| Milwaukee 49-56-7010 (small thread arbor) | 1/2-20 | 3/8 in hex | 9/16 to 1-3/16 in | [4] [6] |
| Milwaukee 49-56-7240 (large thread quick-change universal) | 5/8-18 | 7/16 in hex | 1-1/4 in and larger | [8] [3] |
| Lenox standard small arbor (1779803 class) | 1/2-20 | 3/8 in hex | 9/16 to 1-3/16 in | [7] [5] |
| Lenox standard large arbor (1779801 class) | 5/8-18 | hex | 1-1/4 to 6 in | [7] [3] |
| Spyder 600066/600067 (Rapid Core Eject) | 5/8-18 | 1/2 in hex | 1-3/8 to 6-5/8 in (35 to 168 mm) | [9] [10] |
| Diablo Snap-Lock Plus mandrels (DHSAR500 class) | adapter nuts: 1/2 and 5/8 | 3/8, 7/16, SDS | 9/16 to 1-3/16 in (1/2 nut); 1-1/4 to 6 in (5/8 nut) | [11] [12] |
The brand-specific layer deserves one paragraph of honesty. Milwaukee's large-thread quick-change arbors add a notch-lock that drops notched Hole Dozer cups on without threading; Lenox, Bosch, and DeWalt cups still thread onto the same arbor normally, they just do not quick-change [3]. Milwaukee also sells QUIK-LOK 2-in-1 adapters covering both threads on one shank, which DeWalt does not match [3] [4]. Spyder's Rapid Core Eject arbors push the cut plug out at a button and extend the large thread's range to 6-5/8 in [9] [10]. Diablo's Snap-Lock system uses swappable adapter nuts, one per thread size, so one mandrel body serves both cup families [11] [12].
Arbored versus non-arbored cups
One more fork in the catalog: arbored hole saws have the arbor permanently attached, swapping fast but locking you to one pilot bit and shank; non-arbored cups are threaded blanks that take any matching arbor, so you pick the pilot and the shank for the drill in hand [2] [1]. Most professional kits ship non-arbored cups plus one arbor of each thread, which is the cheapest way to cover the full diameter range on one drill [2] [3].
The pilot drill
Nearly every arbor carries a replaceable pilot drill through the center, and the standard diameter is 1/4 in (6.35 mm) across brands: Milwaukee prints it in the arbor spec, Ruko grounds its pilots to 6.35 mm DIN 1412 C, and McMaster-Carr ships 1/4 in pilots in theirs [4] [13] [8]. The pilot leads the cut and takes the most abuse of anything in the assembly; when the saw starts wandering at hole start, the pilot tip is dull or bent, and replacement is a standard 1/4 in bit rather than a new arbor [3] [13].
Buying decision, compressed
Own the cup already: read its thread off the center hole (or measure, 0.500 versus 0.625 in) and buy the arbor with the matching thread and a shank at or under your chuck [1] [5]. Buying from scratch: one small-thread and one large-thread arbor on a 3/8 or 7/16 hex shank covers every cup made [1] [3], or a single 2-in-1 adapter arbor (Milwaukee QUIK-LOK, Diablo Snap-Lock nuts) does it in one shank [3] [11]. Impact driver: 7/16 shank, impact-rated, no exceptions [3] [2].
Related
For which cup diameter a job needs, conduit, plumbing, door locks: the hole saw size chart. For the chuck side of the shank question: drill chuck sizes explained. For when a spade bit or Forstner beats the saw in wood: wood boring bits compared. For thin-sheet holes where a cone beats a saw entirely: step drill bit sizes.
Sources
- eReplacementParts, Hole Saw Mandrel Buying Guide: arbor shaft diameters 1/4, 11/32, 7/16 in; shank-to-chuck compatibility matrix; thread sizes 1/2-20 and 5/8-18; 1/2-20 diameter range 9/16 to 1-3/16 in, 5/8-18 range 1-1/4 to 8-9/16 in; shank styles round, flats, hex, SDS (ereplacementparts.com/repair/hole-saw-mandrel-buying-guide)
- Empire Abrasives, Hole Saw Arbors: 1/4 hex 1/2-thread arbor fits 9/16 to 1-3/16 in (14 to 30 mm); 3/8 and 7/16 hex 5/8-thread arbors fit 1-1/4 to 6 in (32 to 152 mm); arbored vs non-arbored definition; pilot drill benefits (empireabrasives.com/hole-saw-arbors)
- Tool Army, Hole Saw Arbor Compatibility: 5/8-18 UNF shared by Milwaukee, DeWalt, Bosch, Lenox above about 1-3/4 in; 1/2-20 below 1-3/16 in; Milwaukee notch-lock quick-change only engages notched Hole Dozer cups; QUIK-LOK 2-in-1 adapters; 3/8 hex for drills, 7/16 impact-rated for impact drivers; 1/4 in pilot standard (toolarmycompany.com/blogs/universal/hole-saw-arbor-compatibility)
- Platt Electric Supply, Milwaukee 49-56-7010 listing: 3/8 in hex shank, 1/2-20 thread, hole saws 9/16 to 1-3/16 in, 3/8 in and larger chucks, includes 49-56-8010 pilot bit (platt.com/p/0179795)
- ToolsAdvisers, Are Hole Saw Arbors Interchangeable: thread diameter and pitch mismatch means 5/8-18 arbor will not fit 1/2-20 cup regardless of brand; Will Lenox Hole Saw Fit Milwaukee Arbor: compatibility follows shared thread size and pitch (toolsadvisers.com)
- Ohio Power Tool, Milwaukee 49-56-7010 listing: same 9/16 to 1-3/16 in range, minimum chuck 3/8 in, hardened steel, 5.7 in length (ohiopowertool.com/milwaukee-tools-49-56-7010)
- MSC Direct, Lenox hole-cutting arbors: small arbor 9/16 to 1-3/16 in hole saws (0.5625 to 1.1875 in), large arbors 1-1/4 to 6 in, hex shanks, quick-change attachment (mscdirect.com, items 91985416 and 91985408)
- Werner Supply, Milwaukee 49-56-7240 listing: Large Thread Quick-Change Universal arbor, 5/8-18, 7/16 in shank, for all hole saws 1-1/4 in and larger, 1/2 in and larger chucks (onewerner.com/product/Milwaukee-49-56-7240)
- SIM Supply, Spyder 600635P/600634P Rapid Core Eject arbor listing: 5/8 in-18 thread, hex shank, fits hole saws 1-3/8 to 6-5/8 in (35 to 168 mm), pilot bit included (simsupply.com)
- Spyder Products, Hole Saws collection: Rapid Core Eject arbor system drops cores at a button, drills at angles, enlarges existing holes; 5/8 in thread (spyderproducts.com/collections/hole-saws)
- Amazon, Diablo 1/2 and 5/8 Hole Saw Adapter Nuts (Snap-Lock): 1/2 thread nut for 9/16 to 1-3/16 in cups, 5/8 thread nut for 1-1/4 to 6 in cups (amazon.com/dp/B00Q8UXCW4)
- MSC Direct, Diablo DHSARSDS mandrel listing: Snap-Lock Plus mandrel system, fits all Diablo hole saws 5/8 to 6 in diameter, SDS-Plus shank, quick-change, HSS pilot (mscdirect.com/item/55906283)
- AutomationDirect, Ruko Arbor Holders spec sheet: 7/16 and 3/8 hex holders, 1/2-20 UNF and 5/8-18 UNF threads, HSS pilot drill 6.35 mm (1/4 in) x 82 mm ground DIN 1412 C with split point (cdn.automationdirect.com, rukoarborspilots PDF)