Removing blade from a Honda mower.

[PeterC]

A friend 'obtained' for me a self-propelled Honda petrol mower. It probably has never been serviced and is, at a guess, 5 years old at least). The blade (rather annoyingly an inch longer than the spare I have) needs sharpening, to be polite about it. I couldn't move either bolt, even with about 18" leverage using steel handlebars. My neighbour tried whilst I held the blade with my size 13. He moved one but the other wouldn't budge. I might get a better quality 14mm socket, file the end of it so that there's no lead-in and it sits right down.

Any suggestions for moving it, please. I'm worried that it might shear off, although I hope it's 8.8 steel. I wondered about using a torch but there's a lot of plastic under there.

[Brian]

Chances are you need to use an impact tool. If you don’t have one, a good fitting socket with a T bar and a firm ‘tap’ with a hammer.

[alan_m]

Lump hammer and shock it off. Spanner/socket on the nut then hit other end of the spanner or ratchet bar with the lump hammer.

Stop the blade from turning with a lump of wood wedged in the deck.

If it's a petrol mower first remove the spark plug lead

[Peter Able]

Agreed. I've had two big Hondas over the years. The first had a thick slasher, rather than a blade. The second was a blade that could be sharpened whilst on the mower.

Can't say more as the OP didn't identify the model. Helpful.

PA

[The Natural Philosopher]

Just lock the blades up using anything that comes to hand - wood blocks, mole grips, etc. and use serious long bar torque. I mean a 3ft long bar

- hire but or borrow Also get it red hot with a blowtorch and douse in penetrating oil overnight

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[Andrew]

Take it to a tyre fitting place and ask them to undo it with their air-impact gun.

[Tim Lamb]

Two retainers were mentioned. Single bolts can be reverse threaded for self tightening depending on cutter blade rotation.

[Tim+]

Are you certain it isn’t a reverse thread? I cheap electric impact driver is great for jobs like these.

Tim

[Thomas Prufer]

Penetrating oil and let it sit for while. May not help, but certainly will not harm...

Thomas Prufer

[The Natural Philosopher]

There is no point in reverse thread on these. Its juts massively gunged up. My ride on got like that once

I just added even more torque till it gave up

[Fredxx]

I was thinking the same. I've been caught out before. Many rotary mowers are intended to spin in a specific direction that deposits clippings to one side. I'm pretty sure the couple I have dealt with have been ordinary RH threads.

Only the OP will know if the bolt moved in the attempt to undo the bolt. If it did and then wouldn't move any more I'd be tempted to 'tighten' the bolt to see if it moves and undoes.

[Davey]

Note his final sentence: " I wondered about using a torch but there's a lot of plastic under there."

Not a pretty sight if that catches fire.

[Tim Lamb]

If the blade is retained by an anti slip *slot* or two bolts, there is no benefit in using a reverse threaded bolt. If the blade relies on bolt tightness only, an eyeball check for direction of rotation will indicate the possibility.

Takes a bit of head juggling but starting at the drive shaft... the cutter will try to *slip* in the opposite direction. The retaining bolt thread needs to tighten in the direction of slip.

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[PeterC]

Right, sorry about no model but it's very similar to my still broken one (coil poss. but getting help to check for spark is difficult as it needs strength and some skill, which most seem to lack!). I always remove the cap from the plug - I don't want to 'bump start' it! The bolts are RH thread. Hammer, with as much preload as I can manage, tried with sharp blows. One undid; the other didn't move at all. I can try a torch (got 2 'asbestos' mats) but not too hot, then put oil on to cool it and, hopefully, the oil will be 'sucked' in. Tyre place - getting something that size on the bus...

Now, impact driver. Seems best but I don't have the fittings to get from 6mm hex to 3/8" square - the hex stem sockets stop 1mm short. Been looking but can't see anything.

[David]

Is this the kind of thing?

It should certainly work in a cordless drill with an SDS setting.

Not sure where my set is at the moment so I can't immediately check with my impact driver.

[PeterC]

Thanks - ordered adaptors and an impact socket

[Paul]

On this one, the two bolts seem conventional and CCW removal.

| | | | | | | xxxH (engine) | | | | | | xxxH | | | | Plate Blade Blade

I still can't see how you'd distort that enough, to jam the thread. If there was a blade strike, the one bolt you did get out should also have caused grief.

Paul

[Harry Bloomfield Esq]

Heat up a sacrificial socket to red heat, then put it on the bolt head to transfer it heat to the bolt.

[Jeff Layman]

Heating up the bolt will cause it to expand and grip whatever it's in even tighter. You need to heat up the bolt then pour ice-cold water on it in the hope that it'll contract away from whatever it's in faster than whatever it's in contracts to grip the bolt again!

[Paul]

I would look at the bolt that was removable, for hints about what it would take to stop the removal of the other one.

The thing is probably cross-threaded or stripped by overtorque or there is Red Loktite. If it had been to a shop, maybe someone used a power tool on it, when they should have been using a torque wrench like the service manual said to do.

The thread length on the plate, may be too short for a simple rust job to hold it that securely. Applying a "rust busting" recipe, might be a waste of time.

I don't know if heat is enough to degrade Red (permanent) Loktite or not.

Even examining the back of the plate, where the bolt comes through, may give a hint how it's been abused. A dental inspection mirror might work.

Paul