JB Weld Technique....

C

croag

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Hi Guys - I'm refurbing a 12' tinny and, after removing the transom today, found 2 cracks along the weld where each gunwale meets the back aluminum plate.

So - since I'm not handy welding aluminum, I'm opting for JB weld (dumb idea?) I'm also using it to repair a hole or two here and there as well.

My question is, how to you stop this crap from running - its a bit soupy! I've tried letting it sit for a little bit then applying but the end result it still pretty close to when i apply it right after mixing.

I've settled on this procedure, mix, wait a few, apply, then 'holding' in the area i've applied it with lightly w/ masking tape. Is this the way to do this? Is there a better technique? What am I missing?

Thanks in advance!
 
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fishrdan

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Re: JB Weld Technique....

croag said:
Hi Guys - I'm refurbing a 12' tinny and, after removing the transom today, found 2 cracks along the weld where each gunwale meets the back aluminum plate..............

I've settled on this procedure, mix, wait a few, apply, then 'holding' in the area i've applied it with lightly w/ masking tape. Is this the way to do this? Is there a better technique? What am I missing?
Click to expand...

If a weld cracked, JB weld is going to crack too. You wither need to weld it back again, or reinforce the area being JBwelded with an aluminum patch. I would take it somewhere and have it welded.

You are close on your procedure for applying a JB weld patch. Take 2 strips of duct tape and stick them together so you have a 4"x4" tape patch, puddle your JBweld in the middle of the tape patch and then stick it to the boat, working quickly to stick the tape down so you make a nice "bubble" of JBweld under the tape.
 
Bob_VT

Bob_VT

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Re: JB Weld Technique....

If they are cracks then the area is under stress. JB weld has an extremely limited holding strength on aluminum......

You might be better served if you obtained a piece of aluminum and made a patch that was sealed and riveted in place along with some 3m5200
 
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JAFO1

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Re: JB Weld Technique....

To stop the crack from spreading, you may think about drilling a small hole at each end of the crack. And then proceed with your patch.
 
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fishrdan

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Re: JB Weld Technique....

tmcalavy said:
Mix it thicker
Click to expand...

Yeah, I'm not clear on that either, how do you mix it thicker? I have popped it in the microwave for a couple seconds to kick it off and get it over the hump of being really runny (goes to runny when heated and thickens more when cooled back down), but I think this makes for a weaker bond and not advisable.

I'll agree with bob that there are better products to seal up a couple holes. JBweld is brittle when cured and won't flex at the same rate as the aluminum hull, could pop off. If these are just screw holes you are filling, use a panhead SS screw and nut, sealed with 3m 5200.
 
109jb

109jb

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Re: JB Weld Technique....

With epoxt you should never change the mix ratio. JB weld is supposed to be mixed 1:1 resin to hardener and should not be altered.

Having said that, JB weld does make a putty product if you need thick and non-running.
http://jbweld.net/products/jbstik.php
 
Huron Angler

Huron Angler

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Re: JB Weld Technique....

I agree wth Bob_VT, if it's a stressed area riveted aluminum will hold where welds, JB or otherwise may fail.

If you are working on aluminum boats you will want to get real familiar with a rivet gun. It's very easy and long-lasting:)
 
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croag

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C

croag

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Aug 10, 2010
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Re: JB Weld Technique....

109jb said:
totally different. That stuff is melts into the hull with a propane torch. The JB weld is an epoxy that you knead to mix and then apply. It is just like the regular JB weld but manufactured to be a thicker consistency..
Click to expand...

Ok Awesome. I'm thinking then that I should probably go to cabela's and grab some of that stuff and also plan on re-enforcing that 90 degree w/ and aluminum 90 riveted in.

Think that'll do the trick?!
 
109jb

109jb

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Re: JB Weld Technique....

Can you post a picture of the crack. As some have said, it may be in an area where taking it to a welding shop for repair might be the better choice.
 
Huron Angler

Huron Angler

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Re: JB Weld Technique....

croag said:
Ok Awesome. I'm thinking then that I should probably go to cabela's and grab some of that stuff and also plan on re-enforcing that 90 degree w/ and aluminum 90 riveted in.

Think that'll do the trick?!
Click to expand...

I've used both the Cabela's patch stuff and 3M 5200...and to seal rivets nothing is better than 3M 5200. It will hold strong and the aluminum rivets will not rust, so you've got a long-term fix.
 
T

tmcalavy

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Re: JB Weld Technique....

If you mix it 50:50 or 1:1, however you want to express it, it shouldn't be runny...should be about the consistency of toothpaste...maybe you're mixing/patching a boat in Hades?
 
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