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Slow Wheel Revolution (Miscalculated RPM).
Grinder wheel does not spin as fast as it should.
Improper Installation.
Check how the flange nut is attached to the center spindle that holds the wheel. If its too loose or too tight, adjust it with the appropriate wrench until it has a firm hold.
Inner Disc Nut is not locking.
Look and see where the nut is for any wear or damage before replacing. If it doesn’t stick to the flange like it’s supposed to, replacing it is the best choice.
Accumulation of Dust and Debris.
Remove and clean all components leading to spindle gear and then reassemble while also applying a little lubrication oil.
Rubs the Guard Assembly.
Examine the way the guard assembly is attached to the hub. If the guard is loose, tighten it with the appropriate tools until it’s held firmly against the hub. check to see if the wheel is still rubbing or not.
Device overheats.
After using the power tool, it becomes too hot to handle and vibrates too hard while in use.
Grinder shakes excessively during use.
Check the ball bearing in between the gear case assembly and the rotor assembly for any wear before replacing entire bearing.
Fault within the wiring.
Take apart the grinder casing to expose all the wire connections. make sure each wire is connected correctly or for any wire damage.
Long periods of use.
Using a grinder for a long time will produce heat. Simply turn the appliance off and let it rest for while and check later to see if it has cooled down at all.
Produces smoke.
Disassemble the grinder to expose the motor and try to locate a fault within the wiring.
Power output inadequate.
When turning on the power tool, it feels like it was not delivering enough power to the grinder.
No power.
Check to see if the battery pack is fitted properly or low on battery life. There should be a button on the battery that shows the “life” of it. A green color indicates that it’s fully charged. However, a red light will indicate that the battery is either dead or needs to be charged. Also, the battery may have developed an electrical fault between the contacts and the terminals. check for the pieces of conductive metals on the battery for any wear or damage before replacing.
Grinder doesn’t spin.
The motor may be jammed/clogged resulting in its failure to grind. Disassemble the parts and clean every component thoroughly as best as you can while also applying lubrication oil when reassembling.
Not enough power.
Take the outside housing apart and expose the inside of the grinder. Check and/or tighten the belts and make sure adequate horsepower is available to reach the required RPM.
Improper cutting.
As I apply pressure to the object I want to grind, it cuts very dully or not at all, ruining the object.
Disc is dull.
Inspect the disc for any chippings and broken off pieces and consider replacing it. A chipped disc will result in safety violations or misuse of the tool.
Mismatched disc compared to its guard.
Make sure the disc is the recommended size. A bigger or smaller size will result in a malfunction or excessive rubbing.
Wheel and/or material is too hard to cut.
Dress or sharpen the disc for the proper job configuration such as an concrete block or abrasive wheel.
Paddle Switch inoperable.
As I clutch the paddle switch to use the power tool, it misfires and doesn’t allow the start up of the tool.
Switch shorted-out.
Usually this means that a fuse or circuit may have blown. Remove the lower cover and any other parts to disconnect and test the wires using an Ohmmeter. Replace the fuse/circuit if necessary.
Carbon Brushes worn out.
Remove the lower cover to expose the inside of the grinder. Locate the brushes by moving the tension springs and check the carbon brushes for any wear or damage that might have caused a fault.
Dust Cover malfunctions.
While using the power tool, dust and material debris blow everywhere.
Bag Filter detached.
Examine the bag filter for any leakage or misalignment. Take it off and reattach it if necessary.
Collector is damaged (small hole/broken piece).
If the dust collector has small holes in the tube or you see any broken pieces, the best thing to do to is replace the collector. Any damaged pieces may jam up the grinder.
Incorrect installation of Dust Cover.
The dust cover may have not been installed correctly. Simply detach the dust cover and reattach it until you feel that it has a firm hold.
Short Filter life.
This means it’s being corroded by the material. The strength of the bag is greatly reduced after materials pack into the filter and the wall of the filter actually starts to thin out until it bursts. Replacing the part after many uses is a wise decision.
5 Comments
Grinder runs hard removed metal housing from plastic housing everything on metal housing runs free reinstall cannot turn by hand
Terry VanLandschoot - Reply
From what I can tell if the electronic switch wears out or has a problem you cant buy a replacement, only entirely new guts to the machine which cost more than it does. POS designed to be thrown away
Regina Carmel - Reply
I have an M18 Fuel 4.5inch angle grinder (2781-20) A bearing was going so I changed it, cleaned out the dust from the grinder and put everything back together. Now when I turn the grinder on it runs perfect and smoothly but turns off after 1-2 seconds. Any thoughts with trouble shooting would be helpful. Thanks
R. Jadon Payne - Reply
Has anyone had a Milwaukee 2780-20 grinder stop working when they are cutting steel and won't start again? If you have did you get it to start again? Please let me know how you fixed it. Wayne
Weypar - Reply
Had the same problem, shut off and won't run. Can't figure it out. Milwaukee 2780-20 grinder
Jim A - Reply