More technical problem - drilling cast iron?

[Omits]

My wood burned baffle plate has M6 thread with stuck in stud. I've got to drill the stud out and redo the thread (assumption but I know the thread will not be all that good after the drilling). The hole is blind but i could drill straight through and seal with past. What sort of tap and drill will do it into cast iron. It's M6 but I might go to M8 is things get a bit messed up. Thanks?

 

[Paul Cumbria]

You could try screw extractors - a set costs a few quid from any decent hardware/DIY store. With luck you may get the stuck screw out without too much damage to the threads; if not, a plug tap should clean up the threads nicely - they are designed to tap blind holes, just make sure to remove the swarf every half turn or so.

 

[Omits]

Thanks. Well I mucked up one hole so filed them both down and solved by using the removable back-plate with a countersunk bolt. Works great and more easily maintainable.

 

[Paul Cumbria]

Oh, good, glad you sorted it. Most stuff these days is built to a price rather than for ease of maintenance but most DIY'ers will find a way round problems like this, and most work better than the original design without detracting from the looks or functionality.