Power Tools Explained
Oscillating Multi-Tools Explained: The Renovator's Swiss Army Knife
What an oscillating multi-tool can do, which blades and accessories to use, the specs that matter and how to make plunge cuts, flush cuts and remove grout.
The oscillating multi-tool (also called a renovator or multi-cutter) is the tool renovators love for awkward jobs. Its blade does not spin; it swings back and forth a few degrees at very high speed. That lets it cut flush against floors, plunge into walls, scrape, sand and remove grout in places no other tool can reach.
Quick answer
- Best for flush cuts (door frames, skirting), plunge cuts (outlet boxes in plasterboard), grout removal, scraping and detail sanding.
- Look for a universal or StarlockPlus-type tool-free accessory mount, variable speed and low vibration.
- It is slow for long cuts; use a jigsaw or circular saw for those.
What a multi-tool can do
- Undercut door frames and architraves so flooring slides underneath
- Trim skirting boards and floorboards in place
- Cut openings for outlets and switches in plasterboard
- Cut nails, screws and pipes flush in tight spaces
- Remove old grout and silicone
- Scrape off old tile adhesive, vinyl, glue and paint
- Sand corners and profiles
Key specifications
- Accessory system: Starlock, StarlockPlus and StarlockMax are widely adopted across brands; older universal (open) mounts accept many blades too. Tool-free change saves time.
- Variable speed: slow for scraping and sanding, fast for cutting.
- Vibration control reduces fatigue.
Blades and accessories
| Accessory | Use |
|---|---|
| Bi-metal plunge blade | Wood with nails, plasterboard, plastic |
| Japanese-tooth wood blade | Fast, clean cuts in wood |
| Carbide blade | Hardened screws, fibreglass, cement board |
| Segment (round) saw blade | Longer straight cuts, flooring |
| Carbide / diamond grout blade | Removing grout |
| Rigid and flexible scrapers | Adhesive, vinyl, sealant, paint |
| Delta sanding pad | Detail sanding |
Blades are consumables and wear quickly, especially on metal and grout. Carbide and diamond blades cost more but last much longer.
How to make a plunge cut in plasterboard
- Mark the outline of the box. Check for cables and pipes first.
- Fit a bi-metal plunge blade. Set medium speed.
- Start the tool, then slowly press the blade into the board on the line, rocking gently.
- Cut each side. Keep the blade perpendicular.
How to undercut a door frame
- Place a piece of your flooring (plus underlay) against the frame as a height guide.
- Rest a flush-cut blade flat on the offcut.
- Cut into the frame at that height. Remove the cut piece so the new floor slides under.
How to remove grout
- Use a grout blade the same thickness as the joint or slightly thinner.
- Work at medium speed, guiding the blade along the joint without levering against tile edges.
- Wear eye protection and a dust mask; grout dust contains silica.
Safety tips
- The blade cuts skin easily; keep fingers well away.
- Remove the battery before changing blades; blades get hot.
- Wear hearing protection; multi-tools are loud and high-pitched.
Frequently asked questions
Can a multi-tool replace a jigsaw?
No. It excels at short, awkward and flush cuts, but it is slow for long cuts and curves.
Are blades interchangeable between brands?
Many are, thanks to shared systems such as Starlock and universal mounts, but check the mount type on both the tool and the blade.
This guide is general information, not professional advice. Always read your tool's manual, use the right protective equipment and follow local building and electrical codes. See our disclaimer.