rskybiz
TreeHouser
Tag sale found a ms280 found its issue, keyway broken all but the very outside. Curious if I could potentially file out a slot for one on the flywheel? Or any tricks to make one stay? Or what may be compatable?
Stihl flywheel key
- Thread starter rskybiz
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Al Smith
Mac Daddy
Is this one with the key as part of the flywheel ?
woodworkingboy
TreeHouser
You have better luck getting the flywheel to stay in place when it is a tapered flywheel hole over a tapered shaft. Gregg at Bailey's recommended using toothpaste if the key ever broke off, at least on a tapered shaft, then tightening down with the nut that holds the flywheel in place should hold it. Some models are prone to that happening where the key is part of the flywheel, often caused by the chain brake activated while at higher rpms. Without the taper, I can't see how the flywheel will stay in place without a key.
Magnus
TreeHouser
The key is to guide only, it holds no force.
If it is really clean no tooth paste or anything else is needed. It will hold good when properly tightened.
If it is really clean no tooth paste or anything else is needed. It will hold good when properly tightened.
Al Smith
Mac Daddy
Without a built in key one method is to use lapping compound and lap the flywheel taper to the shaft .The aluminum will abraid out to conform to the shaft . If you heat the flywheel just a little bit to expand it you will in essence get a shrink fit type of condition .
Now then if you for some reason are unfortunate to get a flywheel that's out of balance it's only a tempory fix because it will shake loose again .Fact stubborn as I am I went through 4 crankshafts on a vintage Mac 6-10 before I threw the damned thing away which I should have done from the onset .
Now then if you for some reason are unfortunate to get a flywheel that's out of balance it's only a tempory fix because it will shake loose again .Fact stubborn as I am I went through 4 crankshafts on a vintage Mac 6-10 before I threw the damned thing away which I should have done from the onset .
woodworkingboy
TreeHouser
Magnus, you don't think that a key makes any difference to the flywheel possibly turning on the shaft, if the brake is suddenly engaged during high rpms?
O
oscar4883
Guest
Spot on IMO.
MasterBlaster
Administrator Emeritus
Magnus
TreeHouser
If the fly wheel is properly tightened and sit as it should nothing happen.
If not, key can't hold the forces and break, regardless of key as these are guides only not meant to hold forces.
I assembled many without key, it is hard as you have no help getting it in correct position. But once it is there and correctly tightened it will hold just as good with or without provided surface is clean and in correct form/shape.
Often when key break it leave residue on sides or other damages that reduce the friction and contact surface.
Clean surface is the best I tested, much better than locktite, tooth paste or anything else as the material itself hold very well when pressure is applied by nut.
Magnus
TreeHouser
I am a curious idiot by nature and have to test things so I cut a big groove in one that lost its alu key that was casted.
I made sure surfaces was clean and correct, cut and put in a hardened steel key and put it together.
As I am a idiot that is curious I did not check the tension on the nut, just assembled the rest and started it up as a 40 year old virgin running up the steps to brothel.
I learned the hard way this will chip the cranks edge of, ruin this and the flywheel beyond repair and leave me with a bill of parts and work not really needed.
Now a bit wiser, just as the 40 year virgin coming down the stairs, I take it easier and make sure I do it correct.
I made sure surfaces was clean and correct, cut and put in a hardened steel key and put it together.
As I am a idiot that is curious I did not check the tension on the nut, just assembled the rest and started it up as a 40 year old virgin running up the steps to brothel.
I learned the hard way this will chip the cranks edge of, ruin this and the flywheel beyond repair and leave me with a bill of parts and work not really needed.
Now a bit wiser, just as the 40 year virgin coming down the stairs, I take it easier and make sure I do it correct.
woodworkingboy
TreeHouser
Magnus, that does make sense and answers the question about why someone would think up a weak aluminum key. Only a guide for position, as you inform. They do break though, I guess if the flywheel nut is under torqued.
Magnus
TreeHouser
Under or over correct tension give same result.
When tensioning it should be calculated what parts, conditions and materials are combined and how they act.
A simple thing like forgetting the washer under the nut does the trick. With that gone there is nothing to kill vibrations and help heat expansions etc.
Some have better nuts with this combined others have just a nut and washer.
The washer itself is not a regular one that you can get in walmart. It is special for this and often quite thin.
When tensioning it should be calculated what parts, conditions and materials are combined and how they act.
A simple thing like forgetting the washer under the nut does the trick. With that gone there is nothing to kill vibrations and help heat expansions etc.
Some have better nuts with this combined others have just a nut and washer.
The washer itself is not a regular one that you can get in walmart. It is special for this and often quite thin.
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