Concrete ceiling sander: Gazelle, Flex giraffe or Hilti DG 150?
On concrete overhead, three solutions meet: the Sept Tools Gazelle fitted with the Fouine XB165 (brushless giraffe in direct drive, on a rack-mast trolley), the Flex GM 340 trolley with its GDE 10 concrete giraffe (remote brushed motor and flexible drive shaft), and the hand-held Hilti DG 150 with its DPC 20 converter. This comparison places them side by side, criterion by criterion, on manufacturer data.
The three concrete solutions at a glance
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| Criterion | Sept Tools Gazelle + Fouine XB165 | Flex GM 340 + GDE 10 giraffe | Hilti DG 150 + DPC 20 |
|---|---|---|---|
| Primary use | Brushless concrete giraffe on a machine-carrying trolley with rack mast | Diamond concrete giraffe on a GM 340 trolley | Hand-held diamond concrete grinder + converter |
| Target material | Concrete, laitance, coatings (diamond grinding) | Concrete, laitance (diamond grinding) | Concrete, screed, removal of thin coatings (max 3 mm) |
| Motor and drive | Brushless in DIRECT drive on the head: no carbon brushes, no drive shaft | REMOTE brushed motor + flexible drive shaft (Flex own term) | Powered by the mandatory external DPC 20 converter (cable-linked) |
| Rotation speed (rpm) | 500 to 4800, VARIABLE | 5800 to 8700 (diamond head) or 1700 to 2500 (pad head), variable | 4700 or 6600 (2 fixed speeds) |
| Motor power | 1600 W useful, constant torque | 1010 W input / 590 W output | 2100 W input / 1500 W output (system) |
| Pad / disc | Diamond 165 mm | Diamond 150 mm | Diamond cup wheel 150 mm |
| Machine weight | 7.6 kg (Fouine XB165 head) | 3.6 kg (giraffe without grinding head) | 4.1 kg (+ 3.4 kg for the DPC 20 = 7.5 kg system) |
| Weight carried by the operator | Near zero: the Gazelle trolley carries the machine | Giraffe guided at arm length, carried by the GM 340 trolley | 4.1 kg by hand, plus the DPC 20 box to drag on the floor |
| Working-height adjustment (trolley) | RACK mast: a hand crank, one-hand adjustment, precise | MANUAL mast: unscrew, lift the mast by hand, re-tighten to lock | Not applicable (hand-held machine) |
| Hand-arm vibration | 0.35 m/s² (reference machine benchmark) | Less than 2.5 m/s² (EN 60745) | 5.8 m/s² |
| Noise level | 60 dB (operator position) | 73.6 dB(A) pressure / 84.6 dB(A) power | 88 dB(A) pressure / 99 dB(A) power |
| Dust capture | Class H at source (IU33 Longopac extractor) | Ø28 mm connection (extractor class not specified) | Shroud + mandatory industrial extractor |
| External converter | IP65 electronic controller (no large box on the floor) | None: integrated electronics | DPC 20 mandatory, sits on the floor, cable-linked |
| Ingress protection | IP65 (high-pressure cleaning accepted) | Not disclosed | Not disclosed (class II motor) |
| Motor lifespan | Up to 20,000 h (brushless, no carbon brushes) | Brushed motor: brushes to replace (wear part) | Not disclosed |
| Warranty | 24 months | Not disclosed (product page) | Not disclosed (product page) |
| Country of manufacture | Roanne, France | Germany (Flex brand) | Liechtenstein (Hilti brand) |
Competitor data from public manufacturer pages and documentation (sources at the bottom of the page). Sept Tools data from product sheets. "Not published" cells flag a figure the manufacturer does not disclose: it is not invented. The 60 dB and 0.35 m/s² figures are positioning benchmarks measured on reference machines.
Direct drive or remote motor: what decides lifespan
This is the difference you do not see, and the one that decides lifespan. The Flex concrete giraffe (GDE 10, like the GE 5 R and GE 7) houses its motor in the body of the machine and drives the head through a flexible drive shaft, which Flex itself calls its "flexible drive shaft". That motor is a universal brushed motor, whose brushes are wear parts. The Sept Tools Fouine does the opposite: a brushless motor mounted in direct drive on the head, with no carbon brushes and no drive shaft. Two fewer wear points (the flexible shaft and the brushes), exactly where intensive concrete puts a machine to the test. This is also what underpins the brushless lifespan rated up to 20,000 hours.
Concrete or plasterboard: do not compare the GE 5 R to a concrete giraffe
Many prospects compare the Gazelle to the Flex GE 5 R because the trolley silhouette looks alike. That is a mix-up: the GE 5 R (500 W, 1100 to 1650 rpm, 225 mm hook-and-loop paper pad) is a drywall sander for plasterboard, filler and paint, and it does not grind concrete. The real Flex concrete giraffe is the GDE 10, with a 150 mm diamond disc, used here. On concrete, the honest comparison is therefore Gazelle + Fouine against GM 340 + GDE 10, and against the Hilti DG 150.
Height adjustment: crank versus manual mast
On a ceiling, you constantly adjust the working height. The Gazelle trolley has a rack mast: you turn a crank and set exactly the right height, one-handed, even mid-pass. The Flex GM 340 trolley has a manual mast: you unscrew, lift the mast by hand at arm length, then re-tighten to lock it. Over a day, that ergonomics gap counts as much as the specs. The Gazelle also adds an LED light, and its carrier can go electric with a tracked drive (Gazellomur).
Rotation speed: a variable range end to end
The Fouine runs from 500 to 4800 rpm in continuous variation, letting you modulate from finishing to heavy attack on a single machine. The Flex GDE 10 giraffe is variable but by tool range (1700 to 2500 rpm at the pad, 5800 to 8700 rpm at the diamond head). The Hilti DG 150 has only two fixed speeds (4700 and 6600 rpm). At a similar disc diameter (150 to 165 mm), it is the width of the adjustable range that sets the Fouine apart most, not the top speed. Crucially, torque stays constant across the whole range: the Fouine delivers as much torque at 500 rpm as at 4800 rpm. You can work at low speed, on decorative concrete or controlled finishing, without losing power, where a brushed motor weakens at low speed and a fixed-speed machine cannot slow down at all.
Footprint: with or without a converter on the floor
The Hilti DG 150 only works with its DPC 20 converter: the head weighs 4.1 kg, but you also drag along this 3.4 kg box placed on the floor and cable-linked, a 7.5 kg system. The Flex giraffe integrates its electronics. The Fouine uses an IP65 controller with no bulky box at the work position. On a ceiling, fewer cables and boxes on the floor means fewer obstacles.
Silica capture: what protection?
Grinding concrete releases crystalline silica dust, so capture at source is essential. Sept Tools pairs its machines with a class H extractor (IU33 Longopac, HEPA H13 filtration, continuous sealed bagging): a UKAS-accredited laboratory measured 0.02 f/ml on an NHS hospital site. The Hilti DG 150 requires a shroud connected to an industrial extractor, the Flex giraffe a Ø28 mm connection. In all three cases, performance depends on the paired extractor.
What Flex and Hilti do very well
- +The Flex GDE 10 giraffe is light at the head (3.6 kg without the grinding head) and reaches very high speed at the diamond head (up to 8700 rpm), with a well-developed integrated speed control.
- +The Hilti DG 150 is a robust, well-documented diamond concrete grinder, backed by the Hilti service and rental network, effective for spot grinding and touch-ups.
- +For plasterboard and filler finishing, the Flex GE 5 R drywall giraffe stays lighter and perfectly in its element. On that ground, concrete is not the point.
Why concrete professionals choose the Gazelle
- 1.Brushless direct drive: no flexible drive shaft and no carbon brushes to replace, unlike the Flex giraffe. Fewer wear parts, a lifespan up to 20,000 h built for intensive concrete.
- 2.The Gazelle trolley carries the machine and adjusts with a crank (rack mast), where the Flex GM 340 imposes a manual mast to unscrew and re-tighten. An anti-strain design validated by the Distrimo study (-56 percent forearm vibration).
- 3.Class H capture at source, measured at 0.02 f/ml by a UKAS laboratory on an NHS hospital site: silica under control.
- 4.IP65 controller with no bulky converter on the floor (unlike the Hilti DG 150 + DPC 20 pair), 60 dB, designed and assembled in Roanne with national service and parts in stock, 24-month warranty.
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Sources
Competitor manufacturer data consulted on 12 July 2026. Sept Tools data from the catalogue product sheets.
- Flex GDE 10 concrete giraffe (Set Turbo-Jet), specifications and "flexible drive shaft": flex-tools.com (1010 W, 150 mm disc, 5800 to 8700 rpm diamond head, flexible drive shaft).
- Flex GM 340 trolley (manual mast, compatible giraffes) and GE 5 R drywall giraffe (500 W, 1100 to 1650 rpm, 225 mm pad): flex-tools.com.
- Hilti DG 150 + DPC 20 converter, manufacturer manual: hilti.com (2100 W / 1500 W output, 150 mm disc, 4700 and 6600 rpm, vibration 5.8 m/s², 88 dB(A), weight 4.1 kg + DPC 20 3.4 kg).
- Sept Tools Gazelle Premium, Fouine XB165, IU33 Longopac: product sheets on sept-tools.com.