Rivnuts, tooling

[barracuda816]

Hi Guys,

I am after abit of advice. I have been using rivnuts for a while with a teng tools hand tool. I have had mixed results from pulling the threads when inserting allu rivnuts to galling in the stainless (my fault as im abit ham fisted and didnt use antiseize for the ss inserts) but i have found even with the serated galv insertes the torque holding ability is not the greatest.

So after abit of research, the hex options look good, but i cant justify spending between £600 and £900 just on the Hex punch. Im allways inserting into a blind hole and usually m5 to m8. Its not professional use but more often then being worth cutting hexes with a file.

Am i onto a non starter or does anyone know of a cheap way of cutting the correct Hex holes? or even better a cheap battery operated or drill attachment? I have googled but found only the super expensive. i would have thought there would be a Chinese knock of somewhere, but cant see it.

Thanks in advance, Luke

 

[hotponyshoes]

What exact inserts are you using and what material are you fitting them into?

I use plenty of them and don't have any torque holding problems.
Some of them are seeing service in corrosive environments and, yes, I do see fasteners that have stuck into the insert but even on the ones that can't be worked loose the head of the fasteners normally gives out before the rivnut spins up if the right insert has been installed correctly

 

[barracuda816]

What exact inserts are you using and what material are you fitting them into?

I use plenty of them and don't have any torque holding problems.
Some of them are seeing service in corrosive environments and, yes, I do see fasteners that have stuck into the insert but even on the ones that can't be worked loose the head of the fasteners normally gives out before the rivnut spins up if the right insert has been installed correctly

mainly just mild steel, 0.8-1.2mm. I'm using the teng "pistol style" so they don't have the most leverage but i'm no weakling , have to be really careful with the aluminium ones as the threads on a m8 pull easily with the tool, even on the stainless steel ones i have distorted the thread more then a few times, so i guess i'm installing them with enough clamp.

The ones i buy are branded novus. They are sold in my local builders merchant in Germany. They have a light serration on them and the holes are always snug.

 

[hotponyshoes]

I don't know about the teng tool but on all the hand tools I have there is a stop so its not possible to strip the thread.
It might just be that you are overtightening them and distorting the grip area?

 

[barracuda816]

I don't know about the teng tool but on all the hand tools I have there is a stop so its not possible to strip the thread.
It might just be that you are overtightening them and distorting the grip area?

hmm that is a good point, i will have to do some more testing.