LH
I have an older steel-cased water cooled Generac with screws on the lid that hold the top on. A few of the holes have rusted and the screws no longer thread in. This causes a problem because rain can run in at those holes, causing further rust, and I'd like to fix them. I am wondering if a helicoil would work in these holes, has anyone tried it or have a better idea?
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78buckshot
If I'm picturing it right - those female threads are a barrel that are swaged into the sides that accept machine thread, am I correct? Pretty tough to repair them. A Heli-Coil needs some meat to bite in to - I would think in your case at least a 1/4 inch of metal. I think I would remove the top, grind the offending nut in order to punch it out, then slip a tinnerman nut on the lip and fit a new screw.
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LH
I think you are right, 78buckshot, there isn't much depth there. Tinnerman looks like a good idea. I haven't used them before, will they stay put when I remove the top, so they are in the right place to be screwed into when I put it back on? Thanks a lot for your suggestion.
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78buckshot
Several types of tinnerman nuts are available, the auto manufacturers use them a lot, should be able to find them at a good hardware store.
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JayH
Cage nuts also work and accept machine threads. Very common in electronic rack applications. There are also inserts that can be swaged with a compression tool to give threads in sheet metal. Not sure what the generic term is but typical brand names are Nutsert, Rivnut, etc.
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ZZZRSC
Harbor Freight has a Threaded Insert Riveter Kit for about $23, it includes ten each of insert nuts 6-32, 8-32, 10-24, and 1/4-20 and the installation tool.  Most Tinnerman (clip on) nuts are made to slide onto a sheet metal edge where the hole is within 5/8" from the edge. Snap-in nuts require a square hole. Heli-coils usually require drilling out the hole and threading it to the next larger size, then they screw in and reduce the hole to the original thread size.  McMaster Carr online has all these items, if you want to compare the different types.  The largest hardware supplier company in the world, and anyone can buy there. Same price for everyone no matter how big your company is.  Catalogs printed in 11 languages but they only give those to really big buyers.
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Cobranut
ZZZRSC wrote:
Harbor Freight has a Threaded Insert Riveter Kit for about $23, it includes ten each of insert nuts 6-32, 8-32, 10-24, and 1/4-20 and the installation tool.  Most Tinnerman (clip on) nuts are made to slide onto a sheet metal edge where the hole is within 5/8" from the edge. Snap-in nuts require a square hole. Heli-coils usually require drilling out the hole and threading it to the next larger size, then they screw in and reduce the hole to the original thread size.  McMaster Carr online has all these items, if you want to compare the different types.  The largest hardware supplier company in the world, and anyone can buy there. Same price for everyone no matter how big your company is.  Catalogs printed in 11 languages but they only give those to really big buyers.


I buy from McMaster only when I can't find it elsewhere. 
They have a huge selection, but they eat you alive on shipping.  
The worst part is, they won't tell you the shipping charge until after you've placed the order. 🤬
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UPS
That is one of the weirdest shipping policies I have seen.  They may wait to the next day to tell you what they have charged to your card.  The number of orders they lose out on must be huge.  But they have so much not found elsewhere.
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Charles G
better than the harbor tool nut-sert  kit which are cheap alum that i found strip very easily, the real ma coy metal nut sert's like found on amazon or in a local hardware/ box store do work better and tend to not strip out, there is a special tool to install them but a simple work around is a bolt flat washer and nut they can be installed  
speed clip/nuts like auto makers use is way simpler as long as there is a lip they can fit over 
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