I’m trying to replace the blade on my B&D 850 electric lawnmower. I can prevent the blade from moving, but when I attempt to unfasten the nut it just rotates. I think the nut is “frozen” to the threaded shaft. How can i prevent the shaft from rotating?
This is what an impact wrench is for…
Generally, there are pins that key the blade to the shaft, so if the blade doesn’t move, the shaft can’t move either. Is the blade partially loose?
I read the first part of your post and was thinking that an impact wrench wouldn’t make a difference, then I read this part. Assuming that this is the case, the OP just needs to put on a leather/heavy duty glove or wrap a towel around the blade and push it up towards the deck to keep the pin in the little hole on the blade so the shaft can’t rotate.
Also, take the spark plug out. I’m not sure how you’re holding the blade steady. Personally, I just put my foot against it, but if it slips and goes past the compression stroke it’ll come around again on it’s own. In theory, a good way to do it is to clamp a piece of wood to the inside edge of the deck so the blade hits it and can’t go anywhere.
I doubt there is one.
There must be a pin or clamp to hold the shaft, maybe there’s a hex head at the top of the shaft over the motor.
ETA: nm, a liitle looking indicates the blade is probably keyed to the shaft.
does a law mower just go after a few clauses?
it’s an electric mower and there may be a shaft lock mechanism.
Nominated for this years SDMB awards in the category of worst comprehension of the first sentence in an OP.
A block of wood is the standard way of locking the blade in place.
Be sure to carefully note any washers and spacers. They need to go back on exactly like they came off.
When I saw the thread title, my first thought was, “so that’s what Antonin Scalia uses!”
I’m not sure if the following is true of your electric mower but I had the same problem with mine until I discovered that the nut holding the blade to the shaft was reverse threaded to make sure it didn’t loosen with use. Try bracing the blade as best you can and crank it the other direction.
A Ratchet wrench will give you better leverage than a simple box wrench.
It’s recommended that you tighten it with a torque wrench. But most homeowners don’t own one. Tighten it well, but don’t get carried away and strip it.
Say what?
Cite?
I’ve been changing mower blades since I was 12. I’ve always gotten better leverage with a socket and Ratchet. A box wrench’s open end wants to slide off the nut. The closed end works better but it’s still a lot shorter than a Ratchet handle. YMMV Go with whatever works best for you.
That just depends on how long the wrench is. Wrenches for smaller nuts do tend to be shorter, but you can get longer ones if you need them, you just have to look.
I do, however, like ratchets for lawnmower blades because it gets your hand an inch or two further away from the plane of the blade. Helpful if you slip.
He means that a simple spanner will be limitted in length,
while an L shaped spanner (commonly formed by a socket and its ratchet ) can have the leverage arm extended.
You can put a cheater pipe on a wrench as well as a ratchet. There is no inherent superiority to a ratchet over a box wrench.
It’s all about length. I have a 2" long stubby ratchet for tight places. I doubt it would be superior to my 12" long box wrench when it comes to removing a mower blade.
If you do not own an impact wrench, bring the mower to your auto mechanic he will use his. Do not insult your mower mechanic by asking him to do this dificult task (to you) for free. He may, but many of them will not think well of you for “taking food out of his kids mouths” I do not believe in discouraging folks from learning more about their machines, so come on by my place and we will get that off for you.
Folks, remember that a ratchet is not designed to loosen TIGHT fasteners. That is what breaker bars are for, break it loose and then use your ratchet. A ratchet may slip a cog smashing your hand against something sharp, looks at scars on knucles, AMHIK. Please use a six point socket.
Good luck, IHTH.