Loctite advice Stuart Triple

[DEREK SPEDDING 1Participant @derekspedding1]

I am getting around to the Stuart Triple crankshaft  build.   After a years diliberation I have decided to go for the built up version.    I intend to use loctite and taper pins but am bewilderd by the choice of various types of Loctite.  Can anyone steer me in the right direction as to which to use.

[JasonBModerator @jasonb]

I use 648 but 638 would also do.

[FulmenParticipant @fulmen]

638 is the classic choice for permanent bonds. 603 and 648 are slightly weaker but should still be good choices. I believe 638 and 648 have better temperature resistance than 603.

[Nigel Graham 2Participant @nigelgraham2]

Don’t the manufacturers publish data-sheets helping users to decide the appropriate grade?

[Charles LamontParticipant @charleslamont71117]

Yes. Have you tried making a decision based on reading them? It is not that easy.

[JasonBModerator @jasonb]

That is assuming you know the load being put on the joint to start with.

[David George 1Participant @davidgeorge1]

locktite and taper pin no problem and 648 has slightly higher temperature resistance.

David

[Clive Brown 1Participant @clivebrown1]

Loctite 638 is high viscosity, 648 is low viscosity, otherwise not a lot of difference. On small, close fitting joints 648 might ensure better penetration, Loctite include use on interference fits in their description for 648, but not for 638.

[Ramon WilsonParticipant @ramonwilson3]

Loctite 638 will be more than strong enough- I have used this on cranks before and on my current build a twin throw for a marine condensing engine. I don’t use taper pins but do pin them with mild steel pins through the ends of the crank drilled just a small amount into the other side of the shaft – no need to go any deeper. By doing the ends there is only one area to clean up

I have mentioned this before – do not deburr the drilled hole before insering and loctiting the pin in but just peen slightly  enough to swell the pin and then file to clean up. If done right this will leave little or no trace of the pin but if deburred there will always be a witness

Here are a few pics to give you an idea of the result done as above – the webs were pinned after the setting of the webs and before turning betweeen centres.

Hope that is of help to you

Tug

PS Forgive the bold italics – we really need the ability to underline a word.  Can that facilty be added Jason?

[JasonBModerator @jasonb]

I think it is as good as we are going to get.

[duncan webster 1Participant @duncanwebster1]

I leave the main shaft continuous until the loctite has set, then saw/file it away. Makes keeping it aligned a lot easier

[JasonB]

On JasonB Said:

I think it is as good as we are going to get.

Reported as a bug back when Jason and I tested the prototype.  It was a difficult time, and those in charge decided “enough is enough”, and haven’t changed their minds.   A bunch of moderator useful edit functions went west at the same time, like being able to inject HTML.

Annoyingly  ctrl-u works in the editor, and is only stripped out when the post is published.   Or was last time I tried it!  Works in the editor is underlined.

Dave

[duncan webster 1]

On duncan webster 1 Said:

I leave the main shaft continuous until the loctite has set, then saw/file it away. Makes keeping it aligned a lot easier

Each to his own Duncan but that means the shaft has to be a slide fit through the webs – not to mention requiring milling/filing flat aftercutting out. Doing them as single units means a tighter tolerance can be held on the joins. Loctite will fill slight gaps of course, indeed actually requires one to work efficiently, but to me it’s a high stress component – especially the smaller it gets – so worth making it as strong as you can get it

Thanks for the info on the (lack of) facilities – understood😉

[Howard LewisParticipant @howardlewis46836]

Loctite needs a small clearance, (No more than 0.002″ or 0.05mm).

Using the right grade with clean, grease/oil free steel should produce a bond which is virtually impossible to nove. So do get the alignment right first time. Allow plenty of time to cure, preferably at about 20’C ambient.

Howard

[duncan webster 1Participant @duncanwebster1]

I once burst (literally) a hydraulic jack trying to get a wheel off the axle of a 5″g driving trolley. Scaffold pole on the handle, the cylinder burst.

[Howard Lewis]

On Howard Lewis Said:

Loctite needs a small clearance, (No more than 0.002″ or 0.05mm). […]

Sorry, Howard … that’s not entirely true

In the right circumstances, most of the ‘Anaerobic’ Loctite products can be used with ‘Press’ or ‘Shrink’ fits. …. the microscopic surface texture on a real-world component is sufficient for it to work its magic.

Obviously, however, it is often more convenient to use it with a ‘Slip’ fit of some sort.

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

Good “middle of the night” Howard

I have been fretting a little, fearing that I may have caused offence with my previous post. … So I’ve done the digging for everyone’s benefit.

The Henkel websites have become so “friendly” that it is getting difficult to navigate through them … but eventually I found two downloadable documents on this page:

https://www.henkel-adhesives.com/uk/en/products/industrial-adhesives/retaining-compounds.html

I would class these as “Essential Reference Documents”

MichaelG.

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