Okay I am trying to tighten up the blade on a Craftsman electric lawnmower my neighbor threw out. It still works, but the blade will not tighten up. I have tried to hold the blade and loosen, held the spinning mechanism the blade sits on, I have jammed screwdriver up into the bottom of the mower to brace it from moving but nothing worked. Is there an internal screw up there or did the neighbor get the nut on there scallywag and now it is jammed on? The nut does look just slightly raised on one side. If so then what? James

There would be more than a center bolt keeping the blade from spinning on the shaft. Either the "hub", (the part that slides on the shaft and the blades sits in or on) is a cradle or it has pins to holt it in place. It could a number of things. These would be my first choice with the info at hand
1-Make sure there is a hub.
2-if there is make sure it is not spinning on the shaft (should be keyed).
3-make sure the blade is secured to the hub with either pins or shoulders built into the hub.

If all of the above is good go to to the Craftsman web site for parts and get a schematic of your mower to see what could be missing or not right.

Hope I explained it well
Regards,
Don

I think I figured it out. I think the center bolt was screwed in wrong. It looks a little off. The nut holding the blade is crooked. I will check the site you gave just in case. Thanks.

Jm

Most craftsman mowers used a cradle that had a pin to to fit a notch in the crank, If you do not have the cradle or the pin in the cradle is sheared it will not tighten up.

Like you said if the nut is cross threaded it won't tighten either.. .

Thank you for the rare response
Regards, Don

Thanks for the help. I will check the pin and cradle tomorrow.

Thanks again.