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Unread 04-13-2013, 02:05 PM
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ByTheLake ByTheLake is offline
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Default Hilti DEG 500-D Angle Grinder

My son builds aircraft parts for a living. Knowing that I like to repair and rebuild just about anything, about a year ago he gave me a dead power tool. It's a Hilti DEG 500-D Angle Grinder, made in Germany. With the northern Michigan winter refusing to leave, I decided to do a quick project to repair this tool.

My power tools tend to be "household" grade - Ryobi cordless tools from Home Depot, for example. That could be why this angle grinder seemed so heavy - like a rock. This tool retails for $200 on Home Depotís web page, so itís a better quality tool than Iíd normally buy for myself. I plugged it in, pulled the trigger Ė and nothing happened. The grinder came apart quickly, held together with Torx-head screws.

I found a parts manual on-line, which was helpful. The toolís trigger switch tested good, and the motorís armature was also good. The motor had a pair of carbon brushes, one of which was highly worn. Brushes are cheap, so I decided to replace those. The sealed roller bearings were smooth and solid, so I left those alone. The bevel gears were in good condition and only required cleaning and lubrication.

I drove to a local hardware store to browse their selection of carbon brushes. There were 4 boxes of brushes of various sizes to pick from. Not a single brush was an exact fit, so I decided to buy a pair that were slightly larger than what I needed. These carbon brushes can be filed or ground down re-size them very easily. The new brushes were $5.50 each, so my total investment in this tool repair was $11. When I got home, I spent a few minutes at the grinding wheel to reduce the carbon brushes to the size needed, then reassembled the tool.

The Hilti Angle Grinder went together much faster than I expected, but there really werenít many parts. When it was finished, I plugged it in and pulled the trigger. The tool spun quickly, starting right up with a solid kick. I put on a new cutting wheel and tried it again. It really sounded good, and had a lot of power. This tool will only see occasional use Ė how many times do you need an angle grinder?

The pictures below show the tool from start to finish.

















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