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mark61
12-16-2008, 04:03 PM
On another forum there arose the question of how to disolve JB weld to seperate the halves of an alumnium engine cases for an old pan head? What do you all got for doing it other than cold chisling with a BFH?

mark61

SGW
12-16-2008, 05:04 PM
Heating to around 400 degrees F might do it, with minimal risk.

As far as a solvent: I don't think epoxies, in general, dissolve in anything that one would be likely to want to use, but my knowledge on that score is limited.

torker
12-16-2008, 05:26 PM
Isopropanol will soften it over time. You'd need a lot to soak an engine in tho.

Peter.
12-16-2008, 05:29 PM
I don't think you'll have much luck with petroleum products. Perhaps neat Toluene might have a chance. Petrol won't touch cured JB Weld.

Dawai
12-16-2008, 05:30 PM
Mark.. you can't.. just send it to Gawgia and I'll send you back a set of evo/twin cam fatso cases..

Fasttrack
12-16-2008, 05:33 PM
Formic acid and (supposedly) concentrated sulfuric acid will disolve JB Weld. Formic acid is sometimes used to desolve epoxies in industry, but is extremely nasty stuff.

Also, methylene chloride is used in paint strippers for epoxy based paints. No idea whether this would work on JB Weld. According to their website, the best way to remove cured JB weld is to heat it to 600*F

jacampb2
12-16-2008, 05:36 PM
From the manufacturers web site:


Q: How can I remove J-B Weld after it is fully cured?

A: When fully cured, J-B Weld can only be removed by grinding or filing it off, or by directly heating the product above the 600 degree maximum temperature threshold.

I seem to remember the instruction on the package also saying something about the cured product being soluble in acetone if exposed for extended times.

Good luck,
Jason

Fasttrack
12-16-2008, 05:38 PM
From the manufacturers web site:



I seem to remember the instruction on the package also saying something about the cured product being soluble in acetone if exposed for extended times.

Good luck,
Jason

Yep - I just read an account of a blade smith trying to remove a hilt that someone had jb welded in place. He soaked it in a container of acetone for 4 days and was able to remove it. It didn't "dissolve" the JB weld, but it softened it to a consistency that he called "old bubble-gum"

Benta
12-16-2008, 05:50 PM
Acetic acid will "loosen up" epoxy, but how the aluminium will react is a different question...:eek:
Probably not worth the risk, as it needs to soak for some hours.
Acetone you can forget, it won't even bite on non-cured epoxy (for that use normal alcohol to clean hands etc.)

Benta

davidwdyer
12-16-2008, 06:54 PM
I have a vague memory that we used some product called "Attack" to dissolve epoxy. I'm not sure where to get it, but it might work.

davidwdyer
12-16-2008, 07:03 PM
I just did a quick search for "Attack" "solvent" and came up with a number of suppliers. It seems to be made just for dissolving epoxy and polyester resin glues.

torker
12-16-2008, 07:03 PM
I don't know about JB weld but I used to build RC airplane chassis parts from epoxy and glass. Isopropanol would soften the epoxy if left to soak long enough.

lunkenheimer
12-16-2008, 08:08 PM
I have some Attack and it works ok for straight epoxy. No info on metal filled, though.

But, I have an item that is glass 'crystal' bonded together with some transparent adhesive (think of a glass trophy) that Attack won't attack. Does anyone have any guesses what this might be, and how to dissolve it (preferably selectively)? I'm thinking some kind of UV activated adhesive but I don't know what their underlying chemistry is. Apparently not epoxy chemistry....

ulav8r
12-16-2008, 08:52 PM
In my experience, hot coolant in a radiater will eat through JB Weld on a seam. Took a bit of cleaning ( couple of hours ) before I could make my first attempt at soldering a seam on a radiator.

The JB weld held for about 3 days, the low temp silver bearing solder held for at least 4 years.

ckelloug
12-16-2008, 10:26 PM
According to the Huntsman Araldite GY6010 technical datasheet, Pure Acetone, Pure Butanol, and 96% ethyl alcohol have a good chance of destroying the stuff in about a week. Nothing else will touch it. I just happened to have the datasheet open as part of my research when the question came up.

http://www.huntsmanservice.com/Product_Finder/ui/logPDF.do;jsessionid=c0a8010230d9b484daca94cf495f9 c69f7e6872a6cfa.e38Max0ObhqTaO0Ma3qQah4Qa3qSe6fznA 5Pp7ftolbGmkTy?pLink=https%3A%2F%2Fwww.huntsmanser vice.com%2FWebFolder%2Fui%2Fbrowse.do%3FpFileName% 3D%2Fopt%2FTDS%2FHuntsman+Advanced+Materials%2FEng lish+US%2FLong%2FGY6010_us_e.pdf

This is the basic epoxy constituent used is most common epoxy products.

Of course, the hotter the solvent, the faster it will dissolve the epoxy. Don't however burn the shop down heating the solvents as they are all flammable. Acetone, smells acetony, flammable. Butanol, reeks; flammable. Moonshine- probably good but pricy. Anhydrous denatured ethyl alcohol would be perfect.

By the chart, most other things either don't do anything or they do it on geologic time.

Regards,
Person who has spent way too much time reading epoxy data sheets.

Dawai
12-16-2008, 11:05 PM
Dang.. you guys could mess up a wet dream..

I thought I almost had him swapped for them old panhead cases.. if he ain't got em apart yet.. that means the wheels are still there too..

Acetone.. my vote.. I normally use hardening permatex, slightly thinned with a solvent brush it around the case.. as you press out the timken it makes a POPPing sound.. the right hand case sits off.. Anyone pressing HD cases with a hydraulic press is mad. THE jims bearing press is the ticket. A press can break the motor mounts off the front.. Using wood under the sealing surface is not a good idea in case it shifts and busts the case..

davidwdyer
12-17-2008, 06:49 AM
Lunkenheimer,

I have often bonded glass with clear silicone. Could it be that?

Circlip
12-17-2008, 07:33 AM
Spensive Austrian Crystal? Isn't it bonded with a UV activated Cyano??

Regards Ian.

torker
12-17-2008, 07:50 AM
According to the Huntsman Araldite GY6010 technical datasheet, Pure Acetone, Pure Butanol, and 96% ethyl alcohol have a good chance of destroying the stuff in about a week. Nothing else will touch it. I just happened to have the datasheet open as part of my research when the question came up.

http://www.huntsmanservice.com/Product_Finder/ui/logPDF.do;jsessionid=c0a8010230d9b484daca94cf495f9 c69f7e6872a6cfa.e38Max0ObhqTaO0Ma3qQah4Qa3qSe6fznA 5Pp7ftolbGmkTy?pLink=https%3A%2F%2Fwww.huntsmanser vice.com%2FWebFolder%2Fui%2Fbrowse.do%3FpFileName% 3D%2Fopt%2FTDS%2FHuntsman+Advanced+Materials%2FEng lish+US%2FLong%2FGY6010_us_e.pdf

This is the basic epoxy constituent used is most common epoxy products.

Of course, the hotter the solvent, the faster it will dissolve the epoxy. Don't however burn the shop down heating the solvents as they are all flammable. Acetone, smells acetony, flammable. Butanol, reeks; flammable. Moonshine- probably good but pricy. Anhydrous denatured ethyl alcohol would be perfect.

By the chart, most other things either don't do anything or they do it on geologic time.

Regards,
Person who has spent way too much time reading epoxy data sheets.
Not really the "only" things that work...this guy tells of some real nasty stuff that works as well....
http://yarchive.net/chem/epoxy_solvent.html

gnm109
12-17-2008, 08:30 AM
Dang.. you guys could mess up a wet dream..

I thought I almost had him swapped for them old panhead cases.. if he ain't got em apart yet.. that means the wheels are still there too..

Acetone.. my vote.. I normally use hardening permatex, slightly thinned with a solvent brush it around the case.. as you press out the timken it makes a POPPing sound.. the right hand case sits off.. Anyone pressing HD cases with a hydraulic press is mad. THE jims bearing press is the ticket. A press can break the motor mounts off the front.. Using wood under the sealing surface is not a good idea in case it shifts and busts the case..


The only madness here was using JB Weld for gasket cement on a Harley motorcycle engine although I have seen Harley engines with aluminum weld passes across the rear motor mounts to hold the oil in. Nice.