Question about Black & Decker 7750 4 1/2'' Small Angle Grinder

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I can't get the wheel to my grinder loose. The locking nut barely locks. Is there any tricks to loosening it up and getting the wheel off so I can put a new and better one on. I don't know if I shouold put some WD-40 on it or what? Please help me Drew

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You should have a pin spanner wrench that fits into the holes on the lock down nut. Hold the shaft with a open end wrench that fits the flats on the shaft.
If you dont have the spanner wrench, use a drift punch to tap the lock down nut to loosen.

Posted on Jun 03, 2009

  • George Fleming Jun 03, 2009

    You should have a pin spanner wrench that fits into the holes on the lock down nut. Hold the shaft with a open end wrench that fits the flats on the shaft.

    If you dont have the spanner wrench, use a drift punch to tap the lock down nut to loosen.

    You can put so WD on it if you think it will help.


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I have a Delta 6 bench grinder model #23-680. How do I hold the shaft from turning as I loosen the nut hold the grinding wheel in place?

Hold (or lock) the grinding wheel on the other side if loose or lock because the locking direction is the same direction and don,t forget to ringing (sound-check -like a tuning fork) the stone if you replace it with a new one The risk is small but safety first

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Hi, I'm trying to change the fiber disc on a DeWalt DW402 but after pushing the locking button on top I'm not able to unscrew the wheel. If I turn counterclockwise the wheel turns, but it seems I...

  • 1 Check the grinder before you begin. The newer discs on rotary grinders have patented buttons that allow you to remove the disc without any tools. You may have one like that. In models like this, there's usually a spot to depress and then remove the disc.

  • 2 Turn off the grinder before you attempt to remove and change the disc on your rotary grinder. If it's battery powered, put the grinder in lock position so you can't accidentally turn it on. If it's electric, unplug the grinder from the wall.
  • 3 Look for a nut in the center of the disc. This is a give away that you need to use your special wrench. Sometimes the grinder comes with a tool necessary to loosen and remove the nut. Other times you need to use a wrench.
  • 4 Lock the wheel into place before you begin. You can find a button or switch at the side or back that allows you to do that. When you lock the wheel in place, the disc remains still as you loosen the nut in the center.
  • 5 Remove the nut in the center with either the tool provided with the grinder or a shop tool and lift the disc off your rotary grinder.
  • 6Lift the disc off the rotary grinder. If you have different discs, remember to check for the best fit. Put the nut back on a different way for different discs. Check for a rim and indentation on one side of the nut and a flat side on the other. A visual inspection of the disc for the rotary grinder gives you information about the side to use.

  • Here is a diagram of your grinder and the tool you are looking for is number 50...

    Jun 11, 2011 | Dewalt 4 1/2" Small Angle Grinder D28402

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    I dont know how to change the wheel/blade on this DeWalt cut off tool/grinder! Help!

    If its a hand held grinder, on the back or the side of the grinder itself there is a button in which you must depress. While depressing it you must turn the wheel at the same time until it locks in place. You have to keep the button pressing to get it to lock.

    Once it locks into place, you need a spanner wrench to loosen up the nut (counterclock wise). If you have a grinding wheel on it, some just screw on without a nut. And if this is the case, then just grab a hold of the wheel by hand and turn it counterclock wise and it should come off.

    Make sure you unplug the tool before doing any of the above.

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    I cannot remove the cutting wheel from my bosh angle grinder. Please advise as jammed very tight.

    I had the same problem and it cost me new gears in the end but I found a solution.
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    Below I included a link to the manual for your grinder.
    However it will tell you the same thing I'm going to tell you.
    Most bench top grinders do not come with a shaft lock. In order to loosen or tighten the retaining nut you need to place a small wooden wedge between the wheel and the metal wheel shroud. This will prevent the shaft from turning. This may seem archaic but it serves a good purpose by preventing the over-tightening of the retaining nut.
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    I don't know how to change the grinding blade on my makita angle grinder.

    There is a nut that you release from the middle of the grinder wheel, (grinder blade)
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    You will see you are providing a spanner wrench to remove this nut. The wrenches' actual name is Lock Nut Wrench. It has a U shaped end with two pins sticking out. On on each side of the U shape.

    The pins are inserted into the holes in the flat lock nut, located in the middle of the grinding wheel. The wrench is laid flat against the grinding wheel, with the two pins of the wrench going into any two holes of the nut.

    At the top of the Makita grinder you will see a Black button. The button is pushed down to keep the grinding wheel from spinning. Holds the grinding wheel in place, as you turn the lock nut loose. When you release the button, a spring inside pushes the button back up out of the way.

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    1 Answer

    I can't get the wheel to my grinder loose.

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    Lock nut on Makita 9069 is stuck & I can't loosen it. Using the lock nut wrench, but it won't budge. Any suggestions?

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