LocTite 680 Strength?

[Tozguy]

If the barrel is a big heat sink, how is it going to get too hot for Loctite?
Your original idea should work with something like this, maybe.
http://na.henkel-adhesives.com/adhesives/product-search-1554.htm?nodeid=8797948444673

 

[Glenn Brooks]

Loctite starts loosing strength at 200 degrees, progressively gets weaker until failure at around
450...

 

[brasssmanget]

Well here is the scoop. I did use 680 and pressing in the trunnions a couple of days ago. Tried heating with Mapp gas until they (one) turned blue and still could not budge it loose or turn it in the socket. I'm still going to tack-weld them in, but I'm thinking this is going to be strong enough for now. If there is ever a failure I can get to them easy enough......

Quite a project - and very enlightening for a novice hobby machinist.

 

[Tozguy]

Loctite provides a lot of technical info. This one pertains to a category apart from thread lockers, i.e. retaining compounds, in case anyone is interested.

http://na.henkel-adhesives.com/industrial/retaining-compound-14963.htm

 

[Groundhog]

Loctite High Temp Retaining compound;
Loctite 234772 Green 620 High Temperature Retaining Compound, 10 mL Bottle

 

[Groundhog]

Well here is the scoop. I did use 680 and pressing in the trunnions a couple of days ago. Tried heating with Mapp gas until they (one) turned blue and still could not budge it loose or turn it in the socket. I'm still going to tack-weld them in, but I'm thinking this is going to be strong enough for now. .

When you tack weld you will likely dissolve the thread locker won't you? If not I think thread locker re-hardens after it has been heated (but I'm not sure).
If I were you I would use a high temp retaining compound (post above) instead of a thread locker. They are designed for different applications.

 

[brasssmanget]

680 is more of a retaining compound is it not??

 

[Tozguy]

Its a bit confusing sometimes when the charts and tables from Loctite don't correspond with each other.
This decision tree lists 620 as the best hi temp retaining compound.
http://catalogs.na.henkel-adhesives...okCode=asb15flx&PageLabel=126&Sgt=11&lang=enu

Elsewhere (link above), 680 is shown as a candidate also.

 

[Groundhog]

680 is more of a retaining compound is it not??

Yes it is. Sorry, I was wrong in thinking that it is a thread locker. However, I did not see it listed as a "high temp" retaining product - for what that is worth.

 

[DAT510]

In the end, I think it comes down to how much heat you think the pintle bolts will see? Loctite 680 loses 50% of it's strength at 125C. ~90% at 200C.

Here's the TDS for Loctite 680. The "Hot Strength" graph is on the lower right of the 2nd page. http://www.loctite.tw/twc/content_data/327273_UPGRADE680EN.pdf

Hope this helps,

Chris