Oscillating multi-tool blade compatibility: Starlock classes, OIS and universal fit

01What is an oscillating tool blade interface?

The interface is the shape by which a multi-tool blade locks onto the tool's spindle, and it is the only thing that decides whether a blade physically fits. Older open designs, Bosch's OIS and the 12-point pattern often sold as universal fit, clamp the blade flat under a bolt or lever. Starlock, which Bosch and Fein developed jointly and launched in 2016, replaces the flat clamp with a three-dimensional mount.

Blade type does not affect fit. A plunge-cut blade, a segmented saw blade, a grout blade, a rasp and a sanding pad from the same family all use the same mount, so once you know your tool's interface, every accessory of that interface is available to it. The confusion comes from the fact that the market now carries two families that look similar at a glance: open-mount blades with a ring of points, and Starlock blades with a raised star-shaped collar.

Tool power is the other part of the picture. Starlock exists in three power classes, and the class coding means only accessories rated for a tool's power can be clamped onto it. That rule is the source of most fit questions, and it works in one direction only.

02Which Starlock blades fit which Starlock tools?

A Starlock blade fits any tool of its own class or a higher class. Bosch names the classes Starlock, StarlockPlus, StarlockMax, intended respectively for everyday use, more demanding work and heavy duty. A StarlockMax tool accepts all three, a StarlockPlus tool accepts Starlock and StarlockPlus, and a base Starlock tool accepts base Starlock only. The Bosch GOP 40-30 Professional, for example, is a StarlockPlus tool, so it takes base Starlock and StarlockPlus blades but not StarlockMax.

A common belief is that any Starlock blade fits any Starlock tool. Only the base class does that. StarlockPlus needs a Plus or Max tool, and StarlockMax needs a Max tool, because the mount on each heavier class is shaped so that it cannot clamp onto a lighter tool. That is a deliberate guard against overloading the smaller machine, not a manufacturing fault.

Bosch also gives its Starlock blades a colour-coded interface and a laser-etched blade body so the right blade can be picked quickly. Bosch's US pages tie those colours to the job rather than to the power class: white, gray, blue, purple, brown, for all-purpose work, wood and laminate, metal, soft materials such as sealant, and grout or sanding respectively. No Bosch or Fein page on file maps colours to the three classes, so read the class name printed on the blade, not its colour, when checking fit.

The matrix below shows every combination. Read across from the accessory you have to the tool you want to use it on.

03Do Starlock blades fit older OIS and universal multi-tools?

Base-class Starlock blades do. Bosch states that its base Starlock accessories fit older Bosch OIS tools and OIS-compatible tools from other makers, naming Fein, Makita, Milwaukee and Ridgid, and Fein says its Starlock accessories fit Fein, Bosch and other makers' tools with 12-point mounts. Makita lists its Starlock blade set for its own XMT03, MT01 and TM3010C multi-tools as well as other brands' tools.

StarlockPlus and StarlockMax blades are a different story, and here the sources disagree. Bosch's launch material says only that smaller classes fit larger machines and that base Starlock is backward compatible, so StarlockPlus and StarlockMax are treated here as needing a Plus or Max tool, and an adaptor on other brands. Axminster, a UK retailer, says StarlockPlus also fits some older Bosch OIS tools and all Fein multi-cutters. Until Bosch confirms that for a specific model, check the tool manual's accessory table before buying StarlockPlus blades for an older tool.

Another myth is that Starlock blades will not work on older tools at all. For base-class Starlock, the manufacturers say the opposite, which makes base Starlock the safest choice for anyone who owns tools of mixed age or mixed brands.

04Do universal-fit blades fit Starlock tools?

No. Universal-fit and OIS-style blades do not fit Starlock-only tools. Makita's manual for its StarlockMax XMT04 marks OIS accessories as not usable on that tool, and Milwaukee states that its universal-fit OPEN-LOK blades are not compatible with Starlock tools.

This corrects one of the most repeated assumptions about multi-tools: that a blade sold as universal fits every multi-tool. Universal in this market means the open 12-point pattern used by non-Starlock tools. Milwaukee, for example, says its OPEN-LOK blades use a reinforced universal-fit anchor that fits all major brands of non-Starlock multi-tools, 100+ multi-tools. It does not reach the newer Starlock-only machines. The DeWalt DWA4216 oscillating general purpose blade kit (5 pc.) and the Diablo DOU9S universal fit general purpose oscillating blade set (9 pc.) are both listed by their makers with a universal mount, so they belong on open-mount tools; the Bosch OSL005C 5 pc. Starlock oscillating multi-tool blade set is listed as Starlock, so it covers Starlock tools of every class plus the OIS-compatible tools named above.

For owners of a Starlock-only tool, the practical rule is to buy Starlock blades of the tool's class or lower. For owners of an open-mount tool, both universal blades and base Starlock blades fit.

05Which mount does each brand's multi-tool use?

Bosch and Makita's current flagship tools use Starlock classes, Fein moved its range to Starlock, DeWalt uses its own quick-change mount with a universal adaptor, and Milwaukee's US M18 FUEL tool uses a bolt-and-flange clamp. The table below lists the mounts published for specific models; later models were not checked, so confirm newer tools in their manuals.

Fein's history matters for anyone with an older Fein tool. Fein moved its MultiMaster, MultiTalent and SuperCut lines to the Starlock mount in 2016, and some SuperCut models with Fein's QuickIN system need Fein's QuickIN adaptor to hold star-mount accessories. Fein's own site could not be reached to confirm details of the older pre-Starlock SuperCut mount, so it is not covered here.

Milwaukee states a mount for its US M18 FUEL multi-tool and an adapter for some arbor types, but those details come from one Milwaukee document and are flagged as unconfirmed in the AccessoryFit fact base. No Milwaukee statement was found on whether that tool takes Starlock blades directly; Bosch's list of OIS-compatible brands includes Milwaukee, but Milwaukee has not confirmed it.

06How does DeWalt's universal adaptor work?

The DeWalt DCS356 takes non-DeWalt accessories through a universal adaptor, a washer plus an adaptor nut tightened with a hex wrench, on top of DeWalt's own quick-change mount for DeWalt blades. DeWalt's manual adds that the adaptor and accessory must be tight before use, and that an accessory should not be used where the adaptor may not hold it.

Sources differ on how Starlock blades behave on DeWalt tools. Axminster says DeWalt multi-tools need an adaptor for Starlock blades, DeWalt says non-DeWalt accessories attach with its universal adaptor, and Bosch's list of OIS-compatible brands does not name DeWalt. The safe reading is that any non-DeWalt blade, Starlock or universal, goes on through the adaptor, and only if the adaptor clamps it firmly.

07Do sanding pads and grout blades follow the same fit rules?

Yes. Every accessory type uses the blade mount of its family, so a sanding pad, scraper, rasp or grout blade fits by the same interface and class rules as a plunge-cut blade. The table below lists the main accessory types and their uses as the makers describe them.

Sanding pads add one extra fit layer, because the paper must match the pad as well as the pad matching the tool. Triangle papers are not one standard size: Milwaukee's OPEN-LOK triangle pad is 3-1/2 in on a universal-fit anchor, while DeWalt's universal-fit triangle paper is listed at 3-1/8 in, a figure that comes from a single DeWalt listing. The guide to detail sander pad shapes covers those sheet sizes in more depth.

08When does a multi-tool blade not fit?

A blade fails to fit when its family or class does not match the tool, or when an adaptor cannot clamp it securely. The cases the manufacturer sources describe are:

• Universal or OIS blade on a Starlock-only tool. Makita and Milwaukee both say this does not work.
• StarlockPlus blade on a base Starlock tool. The heavier class does not clamp onto the lighter tool.
• StarlockMax blade on anything but a Max tool. This includes StarlockPlus tools such as the Bosch GOP 40-30 Professional.
• Plus or Max blade on another brand's open-mount tool. Bosch says other brands need an adaptor.
• Any non-DeWalt blade on a DeWalt tool without the adaptor. DeWalt routes other brands' accessories through its universal adaptor.
• A loose fit on an adaptor. If the adaptor does not hold the accessory firmly, DeWalt says not to use it.

A blade that fits can still be wrong for the cut. Bi-metal and carbide blades exist for nails and metal, and high-carbon steel blades for wood; using a wood blade on hidden fasteners blunts it quickly. The shortlist of oscillating tool blade sets compares sets by their published contents and mounts.

09How do you check which blades fit a multi-tool not listed here?

Four checks identify the right blade family for any oscillating tool, using the tool's manual and a look at its spindle.

1. Find the interface name. The manual or product page names Starlock, StarlockPlus, StarlockMax, OIS, universal fit or a brand-specific system.
2. Read the accessory table in the manual. Makita and DeWalt manuals state which accessory families are usable and which are not.
3. Apply the class rule for Starlock tools. Choose blades of the tool's class or lower. Base Starlock fits every Starlock tool.
4. Check for an adaptor requirement. DeWalt tools and some Fein SuperCut models need the maker's adaptor for other accessories; fit it as the manual describes and confirm it clamps firmly.

10What else should you check before buying blades?

Once the mount is settled, battery platform is the other compatibility question for cordless multi-tools, since a bare tool needs packs from its own system; the cross-brand battery compatibility guide compares the main platforms. To check a specific tool model against blades and pads, use the look up what fits your tool lookup. Related abrasives for multi-tools and sanders are grouped under sanding and grinding accessories, and the other fit rules on the site are collected under what fits which tool.

11Questions readers ask