Is loctite alone strong enough for a crankshaft?

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Odyknuck
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Re: Is loctite alone strong enough for a crankshaft?

Post by Odyknuck »

IMHO, the best way is to have parts with an interference fit. Then heat the ID part and freeze the OD part. They will slip fit and then hold parts together while they normalize.
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Bill Shields
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Re: Is loctite alone strong enough for a crankshaft?

Post by Bill Shields »

knurling is not the best of options with Loctite...
Too many things going on to bother listing them.
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cbrew
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Re: Is loctite alone strong enough for a crankshaft?

Post by cbrew »

knurling is not the best of option for anything outside of making handles
If it is not live steam. its not worth it.
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Harold_V
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Re: Is loctite alone strong enough for a crankshaft?

Post by Harold_V »

If anyone has any doubts about knurling being a poor choice for anything but creating a good grip, check the concentricity of the related diameters after knurling. It's highly likely that you'll find that concentricity is lost. It's also not easy to get a dead parallel diameter, which would be troublesome in assembly, creating a false sense of true perpendicularity.

If you must knurl and assemble with Loctite (a choice I wouldn't make) do so only after taking a skim cut on the knurl to establish a proper relationship between the shaft and hole (for alignment purposes). Then hope like hell that there's enough Loctite of proper thickness to permanently bond the two pieces.

I like proper fits.

There is no right or wrong. Just personal preferences.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
Odyknuck
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Re: Is loctite alone strong enough for a crankshaft?

Post by Odyknuck »

Knurling takes away too much metal surface to surface contact IMHO.
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Fender
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Re: Is loctite alone strong enough for a crankshaft?

Post by Fender »

I don’t think my explanation was understood. I said to lightly knurl and then FINISH the part. The finishing cuts down the tops of the knurls and restores the accuracy of the slip fit between the parts, so the alignment is preserved, but provides space between them for the loctite to work.
Dan Watson
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Harold_V
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Re: Is loctite alone strong enough for a crankshaft?

Post by Harold_V »

Fender wrote: Fri Feb 17, 2023 7:42 pm I don’t think my explanation was understood.
I tend to agree. What you had posted (which I just re-read) is what I suggested. It's not a bad idea, although I'd still choose proper fits over LocTite.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
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cbrew
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Re: Is loctite alone strong enough for a crankshaft?

Post by cbrew »

Fender wrote: Fri Feb 17, 2023 7:42 pm I don’t think my explanation was understood. I said to lightly knurl and then FINISH the part. The finishing cuts down the tops of the knurls and restores the accuracy of the slip fit between the parts, so the alignment is preserved, but provides space between them for the loctite to work.
look into how the retaining compound cure, you will change your approach,
I have used 680 on all of my car wheel sets and never had an issue with concentricity of the fit.
the compound self centers as it cures
If it is not live steam. its not worth it.
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Greg_Lewis
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Re: Is loctite alone strong enough for a crankshaft?

Post by Greg_Lewis »

I, too, have used Loctite with success on wheel-axle assemblies. If you follow the directions and keep the use within the specifications, it works as advertised.
Greg Lewis, Prop.
Eyeball Engineering — Home of the dull toolbit.
Our motto: "That looks about right."
Celebrating 35 years of turning perfectly good metal into bits of useless scrap.
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Fender
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Re: Is loctite alone strong enough for a crankshaft?

Post by Fender »

I think people are missing the point. The discussion was about a crankshaft, not wheels on axles. It was stated that loctite requires more space than a thousandth of an inch between the parts to work properly. At the same time, it is important to keep the parts in proper alignment for a crankshaft. The knurling followed by finishing (a light cut in the lathe over the knurls) is a way to preserve the alignment while also providing space between the parts for the loctite to function properly.
Dan Watson
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Bill Shields
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Re: Is loctite alone strong enough for a crankshaft?

Post by Bill Shields »

:mrgreen: Now I get it
Too many things going on to bother listing them.
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Greg_Lewis
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Re: Is loctite alone strong enough for a crankshaft?

Post by Greg_Lewis »

What Chris and I meant was that we have used Loctite successfully and the parts centered up fine without knurling. I think David wanted to know if he should pin the assemblies in addition to the Loctite, and I vote yes. It's not all that much more work for the insurance. If the clearances are within the specs for the Loctite, I don't see why knurling would be necessary. The spec sheet shows bond gaps between .002 and .010:
(https://tds.henkel.com/tds5/Studio/Show ... rization=2)
Greg Lewis, Prop.
Eyeball Engineering — Home of the dull toolbit.
Our motto: "That looks about right."
Celebrating 35 years of turning perfectly good metal into bits of useless scrap.
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