Grinding machines in the academy check

Grinding machines in the academy check

As part of the preparations for the academy check on the subject of grinding machines, we asked Günther Blümel, guild master of the Viennese body construction technicians and owner of the Blümel car plumbing shop in Vienna-Floridsdorf, what characteristics a grinding machine should have that is used in everyday paint shop work. “It should be light, have low vibrations and be easy to hold,” says Blümel in a nutshell. In addition, thorough extraction of the grinding dust is a must, as paint and metal dust in the air you breathe pose serious health risks. “When grinding aluminum, there is also an acute risk of explosion as the aluminum dust can easily ignite,” explains Blümel. He and his employees mainly work with small, light devices that are connected to the conventional 230-volt power supply. “Compressed air devices have a larger stroke and are better suited for grinding aluminum, but they are also more complicated to handle due to the bulky air hose,” summarizes Blümel. For the academy check, the guild master kindly provided us with a painting frame and used body parts from his company.

BRAND DEVICES IN THE TEST

The sanding machines tested are so-called eccentric sanders with a round sanding disc. The blade used rotates around its own axis at high speed and, thanks to its eccentric assembly, also completes further circular movements of a few millimeters. The size of these additional circuits is also known as the oscillating circuit or grinding stroke and is between 2.8 and 6 millimeters for the branded devices we tested. Incidentally, eccentric sanders can also be used as polishing machines. Instead of the grinding wheel, a special polishing attachment with a lamb's wool cap is installed. All devices are equipped with a connector for connecting a filter or vacuum cleaner hose. This prevents the majority of the resulting grinding dust from getting into the air we breathe. However, effective protective clothing, including a breathing mask and safety glasses, should not be missed in everyday workshop life.

BOSCH

ORDERAL SANDER GEX 125-150 AVE PROFESSIONAL
Power: 400W
Speed: 5,500 - 12,000 rpm
Grinding stroke: 4 mm
Sanding disc: 125 mm and 150 mm
Weight: 2.4kg

SPECIAL FEATURES
no hand tingling thanks to the highest level of vibration dampening even in continuous use, grinding unit decoupled from the housing for uniform contact pressure, flexibility for every area of ​​application thanks to the choice of using a 150 mm or 125 mm grinding plate diameter.

"Large, heavy, vibrates relatively strongly and is unwieldy in continuous operation. It is definitely recommended for hobby sanders at home, but if used professionally in the workshop you risk sore muscles."

FESTOOL

ETS EC 150/5 EQ
Power: 400W
Idle speed: 6,000 - 10,000 rpm
Grinding stroke: 5 mm
Sanding plate: 150 mm
Weight: 1.2kg

SPECIAL FEATURES
only 116 mm height, brushless EC-TEC motor, ergonomic housing geometry with balanced center of gravity, automatic suction detection, integrated disc brake, vibration control system, infinitely variable speed preselection and constant maintenance under load

"I personally liked the Festool machine the best. It is small, light, quiet and handy, and the power button can be locked. If you want to stop, you simply press it again, which is very convenient."

MAKITA

ELECTRONIC POLISHING GRINDER PO6000C 150 MM
Power: 900W
Speed: 1,600 - 6,800 rpm
Grinding stroke: 5.5 mm
Grinding plate: 150 mm
Weight: 2.8kg

SPECIAL FEATURES
The speed can be preset using the adjusting wheel and adjusted with the switch during operation, sophisticated design prevents scratches when polishing, removable dust protection prevents foreign objects from entering the motor, power cable pointing upwards, thanks to rubberized support points, the machine can be placed on car bodies without damaging the paint.

"Compared to the other devices, the Makita is relatively heavy and unwieldy, and the relatively hard sanding disc is not ideal for finer work. However, it is very well suited for rougher work such as sanding away rust."

MIRKA

DEROS 650CV
Power: 350W
Speed: 4,000 - 10,000 rpm
Grinding stroke: 5 mm
Sanding plate: 150 mm
Weight: 1.05kg

SPECIAL FEATURES
variable speed regulation, separate on/off switch, patented motor chip, brushless motor, constant speed even when pressure is applied to the machine, soft start function, motor temperature monitoring, replaceable electric cable, electric motor brake and disc brake, reduced vibrations and additional settings for rough applications, further developed sanding pad with central air inlet

“Similar to the Rupes, I like the small dimensions, the handiness and the smooth running, but I also find it annoying that you have to constantly press the push button.”

RUPES

RX156A SCORPIO E
Power: 250W
Speed: 4,000 - 10,000 rpm
Grinding stroke: 6 mm
Grinding plate: 150 mm
Weight: 1.2kg

SPECIAL FEATURES
Electronic speed regulation and overload control, speed regulation, throttle lever, self-extraction, anti-spinning protective collar, low height of only 10 cm for work in hard-to-reach places, low-maintenance electric motor, sanding pad with 10 channels for good air flow for dust extraction during sanding

“Very handy and light, the only negative point is that you have to keep pressing the switch for the machine to run.”

WURTH

ECCENTRAL DISC SANDER
ETS 150-E TWIN
Power: 350W
Speed: 4,200 - 9,200 rpm
Grinding stroke: 2.8 or 6.2 mm
Grinding plate: 150 mm
Weight: 2.2kg

SPECIAL FEATURES
Two lifting stages with one machine (coarse grinding with 6.2 mm, fine grinding with 2.8 mm), high removal rate, simultaneous rotary and oscillating movement, integrated dust extraction (if necessary, work can also be carried out without external extraction), adjusting wheel for adjusting the speed and oscillation speed, sensitive materials such as: B. veneer or thin layers of varnish can be processed without any problems.

"Despite its size, the Würth is surprisingly light and easy to hold, and the vibrations are also kept to a minimum. The only negative point: the bulky air filter handling."

"I liked the Festool machine best. It is small, light, quiet and handy, and the power button can be locked. If you want to stop, you press it again, which is pleasant."