How to Troubleshoot a Lagler Hummel

If it's possible for a floor sanding machine to achieve legendary status, the Lagler Hummel has done so for over 40 years. The German-made belt sander is the acknowledged preference of professionals around the world for finishing surfaces ranging from fine, soft-wood mosaic floors all the way to roller skating rinks.

The Lagler Hummel prepares all kinds of wood floors for refinishing.

Its rubber-coated drive drum has three-stage pressure regulation and the intake system offers efficient dust extraction into a high-capacity bag. A 230-volt AC motor outputs 2.2 KW of power, driving a 7.8-inch wide, 29.5-inch long sanding belt at 2,880 r.p.m. A worn belt can be changed in seconds. The Lagler Hummel is designed for dry sanding only and not approved for sanding of any wet surface.

Sander Does Not Run

Check the connection to the AC power outlet.
Make sure circuit breakers or fuses controlling the AC power outlet have not tripped or blown.

Allow the sander to cool down if it has overheated from heavy use and tripped the thermal protection switch.

Motor Attempts to Start but Falters

Allow the sander to warm to room temperature if it has been stored in a cold environment.
Evaluate the extension cords in use. Extension cords with strands less than 2.5 mm in diameter should not be used. Excessively long extension cords should not be used.
Test the tension of the V-belts driving the drum. Adjust it according to the manufacturer's recommendations.

Motor Produces Insufficient Power

Make sure the drive elements are not binding or sticking.
Verify that the abrasive grit of the sanding belt is not too coarse for the wood surface being sanded. Substitute lighter grit if necessary.
Allow the sander to warm to room temperature if it has been stored in a cold environment.
Evaluate the extension cords in use. Extension cords with strands less than 2.5 mm in diameter should not be used. Excessively long extension cords should not be used.
Test the tension of the V-belts driving the drum. Adjust it according to the manufacturer's recommendations.

Excessive Noise And Vibration

Look for excessive wood dust or dirt deposits on the sanding drum and tensioning rollers.
Inspect the sanding belt for damage.
Make sure the sanding belt is tracking correctly. Adjust if necessary.
Look for blockages or deposits in the motor air intake duct or fan housing.

Excessive Dust

Verify that the dust bag is not over-filled, incorrectly mounted or damaged.
Check the integrity of the bumper sealing felt that seals the drum housing to the floor surface.
Look for blockages anywhere in the suction system and clear them if necessary.
Check the tension of the V-belt that drives the suction system and adjust it if necessary.
Make sure the side cover of the machine is correctly installed.

Streaks, Scratches or Wavy Appearance in the Sanded Floor

Inspect the sanding belt and sanding drum for damage.
Verify that the abrasive grit of the sanding belt is not too coarse for the wood surface being sanded. Substitute lighter grit if necessary.
Make sure the wheels are not damaged, dirty or greasy.
Test the tension of the V-belts driving the drum. Adjust it according to the manufacturer's recommendations.
Check the integrity of the linkage from the lowering lever to the drum-lowering mechanism. Make sure it is not binding or inoperative.
Verify that the sanding drum pressure setting is correct.
Make sure that the operator is not pushing too hard on the machine during sanding or using some other improper work method.