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Aluminum thread repair inserts

Clean is defiantly necessary for welding aluminum. Thinking back to one of the last aluminum weld jobs we attempted, it was a cast pot for holding oil or wax and I think it was permeated with those oils. We were welding a small broken bit (3/4" cube with slot in it) back onto a bracket on the side that even after lots of surface cleaning and pre-heat trying to prep it, we couldn't weld it. We ended up exchanging it for another good used one and the broken one is still on the shelf waiting for us to get adventurous again.

With the pieces I'm dong now, I know they'll need to be clean for the epoxy to take, but I'm hoping after drilling out damage and exposing the inner metal I can soak it in enough acetone to get a good bond.
 
That's my initial plan, but without the welding because we don't have any room to experiment with heat and settings. Maybe it's just our luck that when we've tried welding aluminum castings in the past, they were pretty crummy castings.

Making aluminum plugs is the easy part. Permanently bonding them to the piece is what's in question.
2 thoughts, use an aluminum brtazing rod (thats what we call it in the UK)- slightly lower MP than ''straight alu'' - it's what I used back in the day OA welding Alu irrigation pipes - which were thin drawn tubes welded to cast end pieces.

2nd thought bonding them in- what about rivetting over and peening - I've done that on Alu ICE cylinder heads going in to the water jacket and got away with it
 
2 thoughts, use an aluminum brtazing rod (thats what we call it in the UK)- slightly lower MP than ''straight alu'' - it's what I used back in the day OA welding Alu irrigation pipes - which were thin drawn tubes welded to cast end pieces.

2nd thought bonding them in- what about rivetting over and peening - I've done that on Alu ICE cylinder heads going in to the water jacket and got away with it
I've done lots of iron brazing, but haven't brazed aluminum before, so I'd have to get some practice. Material contamination is a concern in getting the brazing rod to stick. And my normal routine of getting the parent metal red hot to cook out contamination and get a good bond with the rod.... wouldn't work with aluminum, lol.

Peening the inserts on the outside or flat surfaces and staking them on the inside if they're proud of the surface is something I was thinking about earlier. I've done that on thicker parts successfully, to the point you almost can see the seam, but I've also broken thinner pieces when trying to do this which is my only hesitation. Can't be ham-fisted about it.

Peening or epoxying the inserts are my two lead candidates right now. The concerns being with peening is if I try to peen too much I could crack or break a piece, and with epoxy is if it will bond well enough with the aluminum if there's any residual contamination, or if over time the bond could break. That's one reason I was thinking about adding a groove between the insert and the part (chamfers too), so even if it comes loose, It can't rotate unless the epoxy totally breaks apart.
 
Lots of epoxies handle well over 200, but no idea how hot you might get with a control failure. I'd go with the fine thread and epoxy route. Not sure a groove adds much because once you have a failure, the stuff in the groove will probably break down quickly. Another thought is using some kind of fine pipe thread to lock the thing in there. Hate to invent threads, but it might have to be finer than the typical 1/8" or 1/4".
 
Lots of epoxies handle well over 200, but no idea how hot you might get with a control failure. I'd go with the fine thread and epoxy route. Not sure a groove adds much because once you have a failure, the stuff in the groove will probably break down quickly. Another thought is using some kind of fine pipe thread to lock the thing in there. Hate to invent threads, but it might have to be finer than the typical 1/8" or 1/4".
The groove won't help if the epoxy broke down (turned to powder or melted), but if it just came un-stuck from the parent metal it would keep the insert from turning (in theory...).
 
only experience I've had with high temp JB weld was when my landlord used it to glue back together some fire brick log things in a gas fireplace. Turns out it's not that high temp and it burns very happily. So, don't use it for that.
 
Good question, but I am not any kind of expert on this. The idea just came into my mind while typing my post.

I would suggest looking to the epoxy manufacturers, on line and via a phone call or two.



For the High Temp Epoxy, Are they typically made to withstand repeated heated and cooling cycles without cracking, or just survive a maintained temperature without melting?
 
Clean is defiantly necessary for welding aluminum. Thinking back to one of the last aluminum weld jobs we attempted, it was a cast pot for holding oil or wax and I think it was permeated with those oils. We were welding a small broken bit (3/4" cube with slot in it) back onto a bracket on the side that even after lots of surface cleaning and pre-heat trying to prep it, we couldn't weld it. We ended up exchanging it for another good used one and the broken one is still on the shelf waiting for us to get adventurous again.

With the pieces I'm dong now, I know they'll need to be clean for the epoxy to take, but I'm hoping after drilling out damage and exposing the inner metal I can soak it in enough acetone to get a good bond.
some cast has a ton of zinc in it, makes it difficult to weld until you dilute the puddle with enough new aluminum to make it not burn off a bunch of black cmut every time you weld on it.
ive welded the worst aluminum to the dirtiest, like 2 stroke boat handle with a ton of 2 stroke oil and gas all over it. or even an engine housing covered in oil.
 
some cast has a ton of zinc in it, makes it difficult to weld until you dilute the puddle with enough new aluminum to make it not burn off a bunch of black cmut every time you weld on it.
ive welded the worst aluminum to the dirtiest, like 2 stroke boat handle with a ton of 2 stroke oil and gas all over it. or even an engine housing covered in oil.
A few days ago, I was watching a "Tips and Tricks" welding video talking about dirty aluminum. Jody suggested just playing the torch over the aluminum on high EP positive (cleaning mode) without adding metal and just observing crud cooking out of the metal. After a short time, he then made a puddle and added metal. Is that a technique you have found useful on dirty aluminum? That was a new idea for me (your very basic inexperienced welder).

Denis
 
I'm working on a job that has heated aluminum castings that are screwed together. They're like shaped clam-shells with a heater cartridge between, used for smoothing and forming leather. A few threads are damaged and my plan is to drill and thread them oversized, lock a piece of aluminum all-thread in, grind excess flush, then drill and re-tap to the original thread size. The screws are 6-32 and 10-24 steel, and most of them havn't had a problem getting out so I'm not concerned with that part (but will likely use a dab of anti-seize on each). I think the damage is more from repeated servicing's over the years with wrong tools, super gluing loose screws, etc. These pieces can't be replaced so not a lot of room for experimentation.

My question is what method would you use to lock the aluminum insert into the casting? They're thin, around 1/4" of threads or less, so not a lot of room to tap an incomplete thread and bottom out the insert. The unknown casting metallurgy makes me warry of TIG welding or soldering, and since these pieces are going through regular heat cycles (100 to 200 degrees), I don't want to rely on red lock-tite or other stuff that melts. Any other ideas?

I purchased a high temperature "thread locker and pipe sealant" through McMaster Carr to repair cast aluminum valve covers to avoid the cost of replacing them. The product is called Resbond 907TS Blue. The manufacturer's website is listed on the bottle is www.cotronics.com The temperature operating range is -300 F to + 2100 F. The locker was used to hold in ultra low profile machine screws inside a car engine's valve covers to resecure some internal baffles. If the screws back out, they could fall into the engine and potentially destroy it. The vehicle was placed back into service with the thread locker in January of 2021 and is still used today daily.

Once the screws were reinstalled into the valve covers, the valve covers had to be air dried for 2 - 4 hours and then cooked at 250 - 350 degrees for 1 - 2 hours. The instruction are on the bottle. If you choose to install all thread and then drill and tap, this type of product may help. BTW, the all thread method sounds like a good first alternative because your parts will not be permanently altered.

Here's a link: https://www.mcmaster.com/products/t...mum-temperature~300~499~f-3/threadlockers-2~/ to thread lockers at McMaster Carr with temperature ranges, breakaway torques etc......

Good luck
 
A few days ago, I was watching a "Tips and Tricks" welding video talking about dirty aluminum. Jody suggested just playing the torch over the aluminum on high EP positive (cleaning mode) without adding metal and just observing crud cooking out of the metal. After a short time, he then made a puddle and added metal. Is that a technique you have found useful on dirty aluminum? That was a new idea for me (your very basic inexperienced welder).

Denis
it does work, but you need a carbide aluminum burr to cut the black junk off the surface a few times repeated until it cleans up.
cleaning action just brings it all to the surface, still need to physically remove it.
also no abrasive flap discs, it just embeds abrasive into the base metal.

any crud in the puddle prevents it all from wetting out and melting into the base metal and will only let the new aluminum sit on top of the old and not break through the oxide layer.
 
I purchased a high temperature "thread locker and pipe sealant" through McMaster Carr to repair cast aluminum valve covers to avoid the cost of replacing them. The product is called Resbond 907TS Blue. The manufacturer's website is listed on the bottle is www.cotronics.com The temperature operating range is -300 F to + 2100 F. The locker was used to hold in ultra low profile machine screws inside a car engine's valve covers to resecure some internal baffles. If the screws back out, they could fall into the engine and potentially destroy it. The vehicle was placed back into service with the thread locker in January of 2021 and is still used today daily.

Once the screws were reinstalled into the valve covers, the valve covers had to be air dried for 2 - 4 hours and then cooked at 250 - 350 degrees for 1 - 2 hours. The instruction are on the bottle. If you choose to install all thread and then drill and tap, this type of product may help. BTW, the all thread method sounds like a good first alternative because your parts will not be permanently altered.

Here's a link: https://www.mcmaster.com/products/t...mum-temperature~300~499~f-3/threadlockers-2~/ to thread lockers at McMaster Carr with temperature ranges, breakaway torques etc......

Good luck
I am wondering what is the objection to Helicoils here. They are available, easy enough to install, and intended for this kind of situation.
 
I’ve repaired aluminum hydraulic blocks by making my own oversized threaded insert out of solid and shrinking them into the repair part that was tapped std size. Takes a little experimenting but a very permanent repair I've found. Last ones I did were 8-32 sized
 
I went with loc-tite PC 3967 which is more of a thread building epoxy than an insert glue. I figure that should boud well for the epoxy holing up in thin small patches. It's good up to 300 degrees or 350 intermittently, which should be OK for these pieces. It looks and mixes like JB weld with a blue tint.
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Rather than trying to plot out exact dimensions to locate the inserts and screws, I decides it would be easier to do this on a drill press using the old holes to locate the inserts and transferring the screw holes from the mating part for the new threads.
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I am wondering what is the objection to Helicoils here. They are available, easy enough to install, and intended for this kind of situation.
In this case, not all the existing holes were in the correct location to match up with the mating part, due to screws being broken off and cross threaded in, so to use off the shelf inserts I would need to hold onto the piece in a mill and plot out the correct locations. In the middle hole, there was no material around the threaded portion of the hole to hold onto a helicoil. For me it was easier to just plug the old holes with oversized plugs and then drill and tap the new holes where they were supposed to be.
 








 
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