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JB Weld

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Engine Doctor22/09/2020 10:37:11
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2620 forum posts
40 photos

Cymaz . Why don't you use Gorilla glue to fill the profiles then top and tail the ends with some epoxy ? Mix the Gorilla glue with a tiny drop of water first and it will foam up . Insert it with a syringe, working time before it starts foaming will be about 3 to 4 Mon so get all parts ready first. That will be lighter and easier to use than JB weld and more than strong enough for the job . Abrade the U/C wire first and it will grip really well.

Barrie Lever22/09/2020 10:42:22
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358 forum posts
53 photos

Absolutely the way to thin JB weld is by gentle heating.

OK, so lets think about thinning by the addition of acetone or similar materials, Yes the acetone will chemically dilute/thin the epoxy but where does the acetone go that cannot evaporate?

There is no magic path for the evaporation to take place when the JB weld is in a thick blob, hence the acetone remains in the cured JB weld and has a negative effect upon its mechanical properties, if you like the acetone remains suspended in the cured material.

Some people have advocated thinning epoxy resins for wing skinning, this just about works because the coating is very thin and there is a better opportunity for the solvent to evaporate, I would not recommend this, again gentle heating is much better and it helps kick the reaction of the epoxy constraints into the curing action.

Doc

I am really surprised that you have had poor results with JB weld as I find it a very good product, can we discuss in more detail?

B.

J D 822/09/2020 10:47:59
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1620 forum posts
87 photos

Another fan of JB WELD, and not just for model work. Had good results for fixies around the farm with it.

Doc Marten22/09/2020 10:50:32
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872 forum posts
27 photos
Posted by Barrie Lever on 22/09/2020 10:42:22

Doc

I am really surprised that you have had poor results with JB weld as I find it a very good product, can we discuss in more detail?

B.

Fire away Barrie.

conrad taggart22/09/2020 22:58:01
117 forum posts
5 photos

Very good guide here - with JB weld tested too (the heat extreme and original version)

The Ultimate Epoxy Competition--Which Epoxy is the Best?

**LINK**

 

Edited By conrad taggart on 22/09/2020 22:59:28

Barrie Lever22/09/2020 23:10:00
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358 forum posts
53 photos
Posted by Doc Marten on 22/09/2020 10:50:32:
Posted by Barrie Lever on 22/09/2020 10:42:22

Doc

I am really surprised that you have had poor results with JB weld as I find it a very good product, can we discuss in more detail?

B.

Fire away Barrie.

Doc

You seemed to be getting poor bonds with JB weld and somewhere I think you said that you were degreasing the parts.

As you know I have used many different epoxies over the years and JB weld is one of the best, as a starter what did you use to degrease the parts with?

.

conrad taggart23/09/2020 07:48:37
117 forum posts
5 photos
https://www.youtube.com/watch?v=XObmZIbHOzY
Posted by conrad taggart on 22/09/2020 22:58:01:

Very good guide / set of tests here - with JB weld tested too (the heat extreme and original version)

The Ultimate Epoxy Competition--Which Epoxy is the Best?

**LINK**

Results at 12 mins for the impatient

Edited By conrad taggart on 22/09/2020 22:59:28

Doc Marten23/09/2020 09:25:38
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872 forum posts
27 photos
Posted by Barrie Lever on 22/09/2020 23:10:00:

Doc

You seemed to be getting poor bonds with JB weld and somewhere I think you said that you were degreasing the parts.

As you know I have used many different epoxies over the years and JB weld is one of the best, as a starter what did you use to degrease the parts with?

.

I use either meths or Acetone to degrease, celly if none of those are available but that is rare.

Barrie Lever23/09/2020 10:00:59
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358 forum posts
53 photos

Doc

Have you looked at the video linked above.

In there I saw that there was a 3rd type of JB weld called JB weld Extreme Temp, when the tests were being carried out it was the one on the far right and that looked to have an awful performance, you don't by chance have that one?

JB weld held up well against the Devcon Industrial product, not quite as good but close.

So your problem was that you had very easy break out of small components? is that correct?

Regards

B.

Doc Marten23/09/2020 10:56:41
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872 forum posts
27 photos
Posted by Barrie Lever on 23/09/2020 10:00:59:

Doc

So your problem was that you had very easy break out of small components? is that correct?

Regards

B.

Yep.

In hindsight the nut was being held in place by quite a thin wall of epoxy surrounding it, I had 'coned' the JB from the bearer to the top of the nyloc nut, the idea being to encapsulate it to prevent it from turning as the function of it is to act as a fastener at the front of the panel which holds the wings in place, the rear being held by dowels into the fuselage.

Barrie Lever23/09/2020 11:03:09
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358 forum posts
53 photos

Doc

I think coning in that application probably is not the best way to apply JB weld.

You should try and surround the nut with high shoulders, however there is a surprising amount of torque required to hold a Nyloc in position and I would say that is towards the limit of what can be achieved by bonding.

Was it on engine bolts?

B.

Doc Marten23/09/2020 12:08:16
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872 forum posts
27 photos
Posted by Barrie Lever on 23/09/2020 11:03:09:

Doc

I think coning in that application probably is not the best way to apply JB weld.

You should try and surround the nut with high shoulders, however there is a surprising amount of torque required to hold a Nyloc in position and I would say that is towards the limit of what can be achieved by bonding.

Was it on engine bolts?

B.

No Barrie, it was a fastening to hold down the wing fixing panel. I think you're correct that the cone wasn't the best the best method and a nyloc does indeed need a surprising effort to tighten, that's the nature of their function and was my reason for using JB.

I'll give it another crack of the whip before I decide to turn my nose up at it, the overwhelming majority say it's a good product, the video shows it to be superior to other DIY products and your confirming this sways me to think it's worth trying again.

Barrie Lever23/09/2020 12:21:32
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358 forum posts
53 photos

Doc

As you know |I have access to some pretty good aerospace and F1 type adhesives and JB weld is right in there with those products at a fraction of the price.

B.

Andy Stephenson23/09/2020 15:03:18
245 forum posts
40 photos

Barrie,

Did you ever come across this product, we used it a lot in the mining engineering industry.

Belzona

It's like a superior JB Weld.

Andy.

Barrie Lever23/09/2020 15:54:47
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358 forum posts
53 photos

Andy

Yes I came across Belzona in a former life working in the CEGB, we used it for casting repairs etc.

I think the big plus for JB weld is the price/performance/availability triangle.

I have not seen Belzona since 1989 when I left the CEGB though, will have to check it out again.

B.

PS I just checked the pricing on Belzona, I will have to wait until I can win some of that rather than pay for it, tech spec looks good though.

Edited By Barrie Lever on 23/09/2020 15:58:21

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