@MrAI
Working with ferrite cores reminded me mostly of the days when I did glassblowing. I suspect a small score would help direct the fracture, and maybe forcing a tapered rod into the hole with the score on the outer perimeter would help more. A little spit on the score also helps, at least with glass. I just used a thin abrasive cut-off wheel (not the fiber reinforced one) in my Dremal. I put a wet sponge next to it and cut through the sponge and ferrite at the same time. That gave adequate cooling.
As for high-temperature adhesives, there are of course purpose made ones available. For a cheap substitute, you might consider water glass (sodium metasilicate and other names).
John
Working with ferrite cores reminded me mostly of the days when I did glassblowing. I suspect a small score would help direct the fracture, and maybe forcing a tapered rod into the hole with the score on the outer perimeter would help more. A little spit on the score also helps, at least with glass. I just used a thin abrasive cut-off wheel (not the fiber reinforced one) in my Dremal. I put a wet sponge next to it and cut through the sponge and ferrite at the same time. That gave adequate cooling.
As for high-temperature adhesives, there are of course purpose made ones available. For a cheap substitute, you might consider water glass (sodium metasilicate and other names).
John