Agreed.
Cool. It is good stuff but be warned, once cured it is like steel!
I was given an old drill vice than had been drilled itself by clumsy people. I cleaned it down, filled the holes with JB Weld and filed them flat. It took some filing!
You are welcome. Let us know how you get on ... and don't forget to get it all nice and clean (acetone?) and don't get any where you don't want it!
Cheers, T i m
t in 2 spots so you've got space to try something else later. Or weld a ste el plate (giant washer) onto the shaft, then bolts through that into the al i flywheel.
Degradation is not the issue, softening is. I've used it at 70, as I said i t goes all soft and weak. Presumably their definition of suitable is in som e situation where it's clamped down in a thin layer and one can get away wi th it going feeble. It's certainly not what I would judge as suitable for u se on a hot engine.
NT
Are you referring to the same stuff? Frankly something that can be used at over 250 degrees seems hardly likely to soften at 70 degrees.
From the webpage: J-B Weld is The Original Cold Weld two-part epoxy system that provides strong, lasting repairs to multiple surfaces. J-B Weld will form a permanent bond that once cured can be shaped, tapped, filed, sanded and drilled. At room temperature J-B Weld will set in 20-25 minutes to a dark grey color. A full cure is reached in under 24 hours.
J-B Weld can withstand temperatures up to 287ºC (550ºF) once fully cured.
AB
Sorry, had to come back with this. It was niggling a little, but I remember that many moons back I had an Evenrude 2hp that died. Magneto similar to the brushcutter.
I replaced the coil, it still didn't work, it was then I spotted the corroded points on the drive shaft cam.
The attached looks similar to the coil ass'y I have.
I suspect there may be a hall sensor or reed switch?
Regards
AB
If you cure it at 70C it sets rock hard.
Presumably their definition of suitable is in some situation where it's clamped down in a thin layer and one can get away with it going feeble. It's certainly not what I would judge as suitable for use on a hot engine.
Depends entirely on the epoxy and how its used.
Imperfect mixing made harder by room temperature mixing means that there are pockets of 'epoxy' and 'hardener' held together with bits that are properly mixed. The results is a rubbery matrix that degrades at temperaruire. If you heat to 90C or more the two parts bbecme far less visdcous and mix far better.
typically a 24 hour epoxy that is cured at 100C or thereabouts will set in about 5 minutes into a translucent glass hard amber like heatproof resin.
You dont have to believe me. Mix some up and put on to a bit of tinfoil in the oven, and see for yourself.
Having said all that, the best way to loch a flywheel to a trapered shaft is with one of the loctites compounds designed for such use. They really are spectacularly good...
Thanks, As I have ordered the jb weld I'll give it a go. The manufacturer claims it's good to 250 degrees.
There is quite a bit on the web about repairing cylinder heads and engine blocks, but I gather each case has it's own problems. Differential expansion rates are quoted and the tendency for cracks to travel.
I tried Loctite, it was some red stuff I had in the toolbox. Not really a very thorough way of doing things.
Anyway, I'll try the JB Weld and see what happens, it seems very popular so I'm sure the manufacturer couldn't continue to make grossly untrue claims.
AB
:
er than a new brushcutter, though those wouldn't be the best choice.
I have a trials bike, bought as a project. It came with a sheared key. It w as fixed up, started, spun about a bit and died, sheared the key. Thought m aybe I had not tightened the nut properly, another key another shear. Then I "Lapped" it. Flywheel has been fine for two years. No weld, no glue is going to hold it together.
It was thoroughly mixed but not hot cured. The application could not heat it until it had some strength.
NT
A decent taper should grip very well. Think Morse taper and a chuck.
Ok.
Ok. I'm guessing at 2hp it would still have been a 2/?
Ok.
I'm not denying it's existence but not sure what impact you think it might have here (as it was running ok till the flywheel fell off)?
Cheers, T i m
And even if they did, all you have to lose is a bit of time and 10mm of epoxy. ;-)
Cheers, T i m
The lapping idea has been raised and I agree it would be a good first step, especially if the mating surfaces are both steel.
Cheers, T i m
They do, that's why I have various 'pullers' for getting flywheels and magnetos off engine shafts.
Yup, like the tail stock on my Myford lathe ... however, I'm not sure if you lap potentially damaged tapers together again?
The point with a tapered joint is that the taper is uniform and continuous. If both faces are such then in theory you could then lap them closer using some grinding paste etc.
However, if the tapers are already damaged (sheared key way etc) then I'm not sure if you could then lap them back together because there wouldn't be any way to ensure the tapers remain linear and so function as a taper when re-fitting the components together?
The only way I would think you could guarantee to re-fit a damaged taper pair would be to re-profile both and then lap?
Hence why, under the 'nothing to lose' circumstances, bonding the flywheel back on may be the best option?
Cheers, T i m
Just make certain there are no high spots on either taper face before lapping. Then as long as the key aligns the two accurately enough for correct timing and you tighten well it should be fine. As last resort do use some bearing lock but use sparingly and leave plenty of time for it to set. If the mating faces are true and bearing lock added, don't expect to ever get the flywheel off again!
Mike
That was exactly what I was going to suggest. Split pin (or even roll pin) will be no good, will fail quickly through fretting and fatigue.
+1
Agreed but there is a limit to the gap they will fill; in this case, with a 2 mm clearance (in the circumferential direction) I'd want a polymer with a high proportion of strong filler; hence JB Weld or similar.
As you say, careful mixing and, if appropriate, mixing and fitting at a bit above ambient temperature is one of the secrets. Cleaning and degreasing also recommended.
Agreed (but the main thing is to get rid of the high spots: you don't have to lap out all the scores or pits).
Just researching something that came up in the course of the discussion.
It didn't seem likely that the natural Voltage build up and decay would produce an adequate spark.
The sudden break of current is what gives the spike, simlar to the old contact breakers that kept the AA and RAC membership figures so high.
Regards
AB
Carefully noted.
No shortcuts, it'l be a textbook stickup :-)
AB
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.