Topic: Which is stronger, two part epoxy, properly mixed, or the UV hardened glues/fill

[DaleReid]

I have a small piece of potted white metal which has broken in of course the worst place to try to repair.  Attempts at getting a replacement for something made in the 1960 is zero.  Unfortunately it cannot be easily disassembled with any hope of getting it back together again, so my only option is to attempt to prep the surface (about the size of a popcicle stick broken across the narrow way, and use the toughest glue I can find. This isn't going to the moon, and while I want it to look reasonably good, there is very little clearance all around so I can't build it up much, but think I can rig it up to stay in play while a good two part epoxy cures. 

Then while researching this, a friend mentioned that some of the  incredibly strong glue that dentists use an cure with a UV light exposure is now (expensively) available.

There is a slight gap in my repair, as the underlying potted metal gave slightly when breaking (sort of normal and not a sudden snap), so there will have to be some degree of fill (maybe a couple tenths of a millimeter at most.)

Has anyone read, or had experience with, both of these in sort of head to head strength?   

Dale

[BoDuke]

Unfortunately I don't have any experience with UV hardened glues but I typically like to reinforce epoxy with paperclips, pieces of plastic, etc.

I understand if you don't want to post pictures of the broken item but if you did, it may help come up with ideas on how best to make the repair.  Of course, describing all of the constraints would be needed, too.

[DaleReid]

Pictures, worth a 1000 words.  But I'm a poor picture taker and getting the angle to show the problem lead me to just trying to post the question.

Oh, and I know about trying to put some string or pieces along side, to 'splint' the break and give the glue more purchase.

Well, here are a few feeble attempts at pictures for helping.  The green glow is from the chrome surface reflecting a piece of green plastic under it to be a clean work surface.  The whole break area is about a half inch tall and maybe 1/8" thick, and of course in the worst place possible so no way to get something around it like a piece of shrink wrap to hold a fill of epoxy before it hardened.  I had tried to mate the two halves of the break together, but for the picture separated them a wee bit to show where the break was and what the surfaces looked like.  And I have read it is worth trying to scuff with sanddpaper, dremel drill or file the chrome remaining on the part near the break to give the glue of whatever sort a place to hang on to.

Dale

[Garth Bock]

Is it under any type of load ? Glue might not last long. I didn't think glueing pot metal would end up with a strong enough bond. Can't you get it tack welded ? (No experience welding so I am sure there is a better term and welding procedure). One other possibility is drill a small hole through one piece into the other and use a sheet metal screw with a compression washer to hold it together with some glue between the two pieces. Here is a video that might help..

https://youtu.be/jwLuV00Psu0

[miraculon]

I have had good luck with both Devcon (the Plastic Steel kind) or JB Weld, mostly the JB Weld at home.

I had a nick in the mating surface of the oil filter mount on my old Camaro and the Devcon worked for as long as I kept that vehicle. JB Weld worked well on a number of metal items over the years. It was the idea of a ME that I worked with at the time.

Greg H.

[DaleReid]

Thanks for the replies.  I am fascinated by the flux/rod plus brazing heat video that  was offered.  Unfortunately the main piece is so well mounted in a tiny space that there is no chance to try that method.

This won't be under much of a load.  The heavy thing the bracket is attached to shifted due to poor packing before shipping and would have been equivalent to dropping something that should never have dropped.  Sad, but sometimes eBay sellers have no experience nor guidelines to point out the obvious.

I'll check the kinds of high quality epoxies, the JB Weld I've heard of, but not the Devcon.  They may be pretty similar.  In production and high end repair work there are no doubt a lot of formulations with, for the users, critical things like easy of breaking, tensile strength variations, slight pliability and so on.

As an aside, I'd never heard of self vulcanizing or bonding tape until a friend who worked for a power company gave me a little left over roll end of the stuff, sort of a grey 3M product.  I was blown away on how it worked and solved a couple problems I was facing.  Just knowing what's out there is part of the solution.

Again, thanks for the discussion and sharing of information, which makes this part of the forum like a big coffee meeting where a wide range of information and experiences can she shared.

Dale

[DaleReid]

Thanks for the replies.  I am fascinated by the flux/rod plus brazing heat video that  was offered.  Unfortunately the main piece is so well mounted in a tiny space that there is no chance to try that method.

This won't be under much of a load.  The heavy thing the bracket is attached to shifted due to poor packing before shipping and would have been equivalent to dropping something that should never have dropped.  Sad, but sometimes eBay sellers have no experience nor guidelines to point out the obvious.

I'll check the kinds of high quality epoxies, the JB Weld I've heard of, but not the Devcon.  They may be pretty similar.  In production and high end repair work there are no doubt a lot of formulations with, for the users, critical things like easy of breaking, tensile strength variations, slight pliability and so on.

As an aside, I'd never heard of self vulcanizing or bonding tape until a friend who worked for a power company gave me a little left over roll end of the stuff, sort of a grey 3M product.  I was blown away on how it worked and solved a couple problems I was facing.  Just knowing what's out there is part of the solution.

Again, thanks for the discussion and sharing of information, which makes this part of the forum like a big coffee meeting where a wide range of information and experiences can she shared.

Dale