power trowel blades buying guide
Disc size, blade material, mounting and wear — the four decisions behind every smooth, flat concrete pour. Here's how to pick the right troweling disc and when to replace it.
by peter zhang · aug 16, 2026 · updated sep 16, 2026
380mm for the slab, 280mm for the edges
Hardened steel for everyday commercial pours, magnesium alloy for decorative finish. One disc SKU covers CIR-01L through CIR-41L.
1. size — 380mm for the floor, 280mm for the edges
380mm discs finish the main slab on the full CIR-series power trowel line — the CIR-01L and CIR-02L straight-handle and steering-wheel machines, the CIR-05 and CIR-06 corded models, and the CIR-38L, CIR-39L, CIR-40L and CIR-41L lithium machines. 280mm discs handle edges, columns and tight pours. A 380mm disc will leave corners it can't reach — every crew should own 280s for the trim-out.
2. material — steel is durable, alloy is lighter
Hardened steel discs are the economical default: tough, long-wearing, right for everyday commercial slabs. Magnesium alloy discs are lighter and ride flatter, which gives a cleaner finish on soft, high-slump concrete — the choice for decorative and polished work. If you finish both kinds of jobs, keep a set of each rather than forcing one material to do both.
3. mounting — make sure it matches the machine
The same 380mm and 280mm discs mount across the CIR-01L through CIR-41L troweling range, so one disc SKU covers your whole fleet. If you run a non-CIR machine, send us a photo of the disc mount and we'll confirm fit before you order.
4. wear — know when to flip, know when to replace
Rounded edges cause chatter and a wavy finish long before the disc looks worn out. If your machine vibrates or leaves a non-uniform float, check the blade edges first. Reversible/double-sided designs let you flip the disc and get a second life from each one — then replace when both sides are spent.
faq
280mm or 380mm troweling disc?
380mm discs are the standard for main-floor finishing on power trowels like the CIR-01L, CIR-02L and CIR-38L-41L lithium models. 280mm discs are for tight areas, edges and smaller pours where a larger disc can't maneuver. Stock both if your jobs mix open floors and corners.
Hardened steel or magnesium alloy trowel blade?
Hardened steel discs are durable and the economical default for most finishing. Magnesium alloy discs are lighter and ride flatter for a higher-quality finish on softer, creamier concrete, but cost more. Alloy suits decorative and high-polish work; steel suits everyday commercial slabs.
When should I replace troweling discs?
Replace discs when the blade edges round over, when you see uneven wear that causes chatter, or when the disc no longer produces a flat float. Reversible or double-sided designs extend life by letting you flip the disc before replacement.
stock the right mix
Most crews run 380mm for the slab plus 280mm for edges. Tell us your machine model and monthly pour size and we'll recommend quantities.