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Old 03-04-2017, 04:32 PM   #1
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Default Anyone ever use JB weld to repair pulled screw ears in CF?

Basically the part I broke (2 actually) won't be around for a few weeks and nobody stocks it. There is about 1mm of material around the screw hold of the counter sunk holes so there isn't a ton of material around it so they pull out on occasion. I have used JB weld for other applications in the past and it does the business I've made a bit of a mold, sanded/cleaned the surfaces, applied a coat, sanded it back and put another coat on. I'm using JB quick which I rarely use but it's all I have currently and it seems a tad soft after sanding back the first coat. Not instilling much confidence but I've applied my second coat and I'll let it cure for a few days to hope it hardens more. It's said to cure in 4 minutes but I'm sure that's not a full cure so I'm hoping after a day or so it'll be a bit harder. Fortunately the pull through was just the size of the ID of the screw so there was a bit of a ridge so filling the hole as well and redrilling will give me a bit more surface to bite to.

Anyone ever done this with any level of success?
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Old 03-04-2017, 09:15 PM   #2
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I've done a bit of carbon fiber work with laminating epoxy and JB Weld, and both need some heat to complete the cure. It will help the cure if you can heat it up to 80F or so for a couple of hours. I have used a cardboard both with a 60W light bulb as a hot box, but electric blankets work or even putting the parts into a car parked in the sun for awhile.

Hard to say how your repair will hold up but I'd say your chances are good, JB Weld is pretty tuff.
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Old 03-05-2017, 12:13 AM   #3
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Are you having to heat it to fully cure it or just to expedite the curing process?

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Old 03-05-2017, 02:14 PM   #4
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Are you having to heat it to fully cure it or just to expedite the curing process?

Dave
In the case of JB Weld, probably just to expedite the cure process. I don't have the data for Quick Weld, but the plain JB Weld states to apply above 50F and cure can be accelerated by applying heat after 6 hours. Unfortunately, their web site doesn't give a lot of information about cure cycles.

Most laminating epoxy resins can be cured at room temperature, but will be even stronger with a "post - cure" at elevated temperatures.
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Old 03-05-2017, 03:35 PM   #5
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Yeah I gave one of them a day to dry and while sanding it didn't bond well even after sanding the CF quite well. It would have bit if it was going to bite. Looks like I may need something that can penetrate the CF.

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Old 03-05-2017, 03:57 PM   #6
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CA works better than anything
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Old 03-05-2017, 04:00 PM   #7
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it's very hard to rebuild a pulled ear w/ thin CA.

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Old 03-05-2017, 04:05 PM   #8
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Fill the delaminated layers and put a clamp on it
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Old 03-05-2017, 04:13 PM   #9
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these are not delaminated layers, these are pull throughs completely. There is no longer a screw hole.

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Old 03-06-2017, 10:45 AM   #10
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Reflex Racing could probably cut you a new one and have it on the way. You should contact them.
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Old 03-06-2017, 10:53 AM   #11
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I wasn't aware third party companies did this type of thing? If so I wonder if they had a waterjet and could cut one out of alum. for me. I'd love the cad drawing for this to just do it myself. I started to create a cad drawing for this just haven't finished it.

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Old 03-06-2017, 12:19 PM   #12
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Reflex can cut carbon and aluminum. Shoot Cristian Tabush on here an email contact@reflexracing.net
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Old 03-06-2017, 01:11 PM   #13
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Quote:
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Basically the part I broke (2 actually) won't be around for a few weeks and nobody stocks it. There is about 1mm of material around the screw hold of the counter sunk holes so there isn't a ton of material around it so they pull out on occasion. I have used JB weld for other applications in the past and it does the business I've made a bit of a mold, sanded/cleaned the surfaces, applied a coat, sanded it back and put another coat on. I'm using JB quick which I rarely use but it's all I have currently and it seems a tad soft after sanding back the first coat. Not instilling much confidence but I've applied my second coat and I'll let it cure for a few days to hope it hardens more. It's said to cure in 4 minutes but I'm sure that's not a full cure so I'm hoping after a day or so it'll be a bit harder. Fortunately the pull through was just the size of the ID of the screw so there was a bit of a ridge so filling the hole as well and redrilling will give me a bit more surface to bite to.

Anyone ever done this with any level of success?
What kind of car are you repairing? Odds are good someone on this site may have what you're looking for.
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Old 03-06-2017, 02:06 PM   #14
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Thanks guys, i've contacted Cristian. I had asked on my local forum and didn't even get a reply so I'm guessing not. Hopefully Cristian can make one or I'll just wait it out. I've repaired both of mine so maybe they'll hold up, probably not though. I had JB quick and I don't think it's as strong as the slow curing stuff I normally use. Maybe if these fail I'll get some of that but I've also been reading 3M has some good stuff also. 3M usually = $$$ though so the adhesive is probably double the part.

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Old 03-06-2017, 08:03 PM   #15
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Use CA, and build up the area with baking soda. Do it in small amounts as it will set up and be hard as rock, you'll have to grind it to get your taper back but it will be very strong. Ive built up missing parts of cf chassis this way and they last forever. The baking soda is very fine powder and fills the area very effectively.
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