Heating hysol

[Dorsal]

How warm do you have to get hysol to get it to release or will it. I want to lower my elevator assist spring bracket which is held on with hysol and hose clamps. I would like to be able to trim the plane for a 60 mph final which I can't quite do now.

[jtpitkin06]

I’ve read you could release Hysol with heat, but I was not able to do it.



I had a rib on the tail that was a bit out of alignment and I wanted to shift it. I tried heating the rib and metal frame with a heat gun. I used enough heat to soften the powder coating and was afraid I would scorch or char the wood rib. The Hysol did not soften nor did the bond release. I gave up on the heat idea and used a Dremel tool to cut and grind the rib free. I now consider a Hysol bond to be as permanent as welding.

The answer is somewhere in excess of “pretty darn hot”. Possibly near the point of combustion.


With two metal parts, you may be able to get sufficient heat to break the bond. With wood to metal, I was unable to do so.



Just be careful of nearby covering material. Fabric melts at 432 and I know I had more heat on the bond than that.


John Pitkin
Greenville, TX

[Dorsal]

Thanks John just the kind of info I was looking for. I may just try an extension bracket off the original.

[DanB]

Dorsal,
I have had very good success with getting the Hysol to release using a heat gun. I had to do it on 3 occasions. A tool I made helped assist during the process. It was a hardwood chisel of sorts...1" wide 1/4" thick and beveled the end to about 45 degrees. This allowed me to apply direct pressure immediately after heating it up to a spot on the Hysol I wanted it to release. The tool didn't scratch the powdercoat yet allowed the pressure needed. It doesn't tend to get very soft, but it does release in chunks.

[akflyer]

I used a heat gun on my project when replacing the rib tails. Also used it to remove the wing tank from a KF II. A good heat gun made quick work of it. I used a chisel with a slightly dulled tip so it would not dig in or gouge the aluminum spar. I never measured the temp, but I know the heat gun will put out air around 1200 degrees and it did not need to be held on the joint very long before the hysol got soft.

[Jerrytex]

I too used a heat gun to remove damaged ribs on my project that were glued with hysol. I then used it to loosen a rib that I installed crooked and the heat gun worked perfect. I put pressure on the hysol joint with a screwdriver and when it got hot enough the joint would start to move. Keep the heat more on the metal if working close to wood.

[Dorsal]

Turns out drilling three holes in a piece of aluminum was pretty easy and I moved the attach point for the spring down ~1/2 inch. Thanks for all the feedback.

[rogerh12]

Hey, I have to remove some Hysol too.
What brand or model heat gun would you guys recommend?

thanks in advance
Roger

[akflyer]

Hey, I have to remove some Hysol too.
What brand or model heat gun would you guys recommend?

thanks in advance
Roger

If you have a heat gun for model covering that is all I used. The industrial heat guns can get it hot enough to burn the wood..

[rogerh12]

ok, I was wondering about that. I ahave seen some pretty serious heat guns !!!
Roger

[Wiley]

We just used a craft heat gun we found laying around the house. Definitely not a very expensive or high tech piece of equipment. Worked like a champ when we needed to move a couple ribs in the tail feathers.

[Dave Holl]

I used a cheap black and decker heat gun and a plastic scraper which I used to prise open the glued joint. I used the minimum of heat possible and peeled the joint apart.

[Esser]

I need to move a rib that is hysoled but not very far, can i heat the hysol move it and let it sit where it was? or do i need to remove all the heated hysol and reapply.

[jimcarriere]

Esser, the short answer is you'll need to reapply new Hysol if you move the rib- it just won't stick the same way it first did. I would also make a reasonable effort to remove as much of the old stuff as I could without damaging the rib or scratching the spar.

The "book answer" is that heating the Hysol enough to soften it will also permanently weaken the Hysol. That's the big difference between a thermoplastic (http://en.wikipedia.org/wiki/Thermoplastic), and a thermosetting plastic (http://en.wikipedia.org/wiki/Thermosetting_plastic). The former (ie. nylon, acrylic, PVC) can repeatedly melt and solidify. The latter (epoxy falls in this category) are formed by curing when they are first made. Once they are cured, melting will normally damage them for good deep down at the molecular level.

The data sheet for Hysol 9460 (should be in your build manual) says that this happens at 68°C/155°F... hotter than that and the stuff gets even easier to remove. As others have noted, a heat gun makes quick work of things any time the need arises to fix one of those little mistakes :)

[Esser]

Thanks Jim, when I put the speed tail ribs in I had the plane on its side and three of them slowly slid down as it cured so I guess I have a big job on my hands.