Loctite on shafts

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Loctite on shafts

This topic has 9 replies, 5 voices, and was last updated 8 December 2009 at 21:00 by mike robinson 2.

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7 December 2009 at 12:25 #45961
mike robinson 2
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@mikerobinson2
I am making a fabricated mill engine crankshaft using silver steel for the crankshaft and big end with mild steel for the crank webs. The Loctite I have used is very strong and sets very quickly. Too strong and too quickly!!! It bonded before I could get the webs in the correct position.

Before I really mess it up whats the best way to destroy the bond so I can disassemble and try again. Need to make sure I dont heat treat the silver steel,,,,, is a domestic oven ok ? Whats the minimum heat? I dont want to use a blowtorch if I can help it. Is there another way ?

Thansk for the help

Mike
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7 December 2009 at 12:25 #4876
mike robinson 2
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@mikerobinson2
How to break the bond
7 December 2009 at 13:08 #45963
keithmart
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@keithmart
Hi heat is the answer, or you might try acetone (nail varnish remover).

The amount of heat required should not worry the silver steel.

You could also email the locktite site, as they are normally very helpfull
7 December 2009 at 13:15 #45964
mike robinson 2
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@mikerobinson2
Hi thanks for the confidence boosting comments – will try it tonight
7 December 2009 at 13:27 #45966
D.C.Clark
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@d-c-clark
What flavor Loctite? They make many different types of adhesives. Some will release at fairly low temps: < 450F ( 230C ) others will not.

Does it say “Threadlocker” on the label? Loctite red or green Threadlocker will release with heat. Blue should break pretty easily with a wrench.

All the info is available at http://www.loctiteproducts.com/  They are also very helpful and responsive to inquiries, in my experience.

A counter-top toaster oven is a handy thing to have in the shop. I use one to release adhesives, melt machinable wax and cerro alloys. Coat mild steel parts with motor oil and bake, for a nice rust resistant patina. Dry things.

Give your wife a new one for Christmas, and take the old one. ( Nota Bene: It is important to perform these steps in the given order. )

One of those little palm-sized refillable butane torches is also useful for releasing adhesives when you just want a quick, point application of heat.

It is vital to have excellent ventilation. Heating cyano-acrylates, especially, is risky business how ever you do it. I take it outdoors and stay upwind of the work.

David Clark in Southern Maryland, USA
7 December 2009 at 14:26 #45970
mike robinson 2
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@mikerobinson2
Its 648 retaining compound. The clearence on my parts are minimal (transition fit) and the lower clearance speeds the cure time. Great if your fast enough. Lesson learned. I will try some a la carte cooking tonight with the windows open. Appreciate the advice
7 December 2009 at 18:38 #45983
Martin W
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@martinw
Hi Mike

Just been on the Loctite site re 648 retaining compound. The data sheet says heat parts to about 250C then dissemble when hot. Then if required clean by soaking in Loctite solvent and use a wire brush to remove any residue, presumably a brass brush would do and it shouldn’t mark the steel.

This compound is not a cyanoacrylate based material but a Urethane Methacrylate based product. Even so its probably best not to take a chance by breathing the fumes giving of during heating.

Hope this helps and good luck.

Martin
7 December 2009 at 22:56 #45992
Martin W
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@martinw
Mike

Looked at the data sheet again and should you decide to give it a second try with Loctite 648 you can delay the setting time by cooling the parts to be joined. The graph indicates that at 22C the bond reaches 5% of full strength in 5 minutes whereas at 5C the bond reaches 5% of full strength after 1 hour, these figures are for steel/steel joints and the time taken to reach 100% bond strength of other metals/finishes vary. These figures are based on a 0.05mm gap.

Looks like the way to go would be cool, assemble, adjust and then warm.

Cheers

Martin
8 December 2009 at 09:26 #46003
Tony Martyr
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@tonymartyr14488
Mike

I agree with Martin – when I built a camshaft where each lobe was loctited with 648 onto the shaft I always put the shaft in the freezer overnight. Not only does it give you greater adjustment time but it gives you a greater initial clearance, so long as the male part has been left at ambient temperature of course!

Tony
8 December 2009 at 21:00 #46043
mike robinson 2
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@mikerobinson2
Success, the crankshaft components are now apart without damage and cleaning up was quite easy. After some chef style work in the kitchen it soon became blowlamp time. I am really impressed with this 648 stuff, its so strong. Appreciate the idea about cooling down in the freezer, time to get my jigs sorted and practice a few dry runs agaist the clock. Thanks to all for the welcome suggestions. Mike
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