Saving Old Seagulls

fitting a second hand bilge pump to my boat----needed to remove stainless nut and bolt going through aluminium body of pump----nut was easy but bolt had corroded solid----i don t think the aluminium body is threaded------tried soaking in diesel for a week ----gave it a gentle tap with a hammer daily----no luck----finally lost patience threaded two nuts on easier to acess end and gave it some brute force---- result ----bolt snapped off level with the pump body -----i now have a 6 mm x 25mm stainless bolt to drill out-----enough of preamble----question----what drill bits will handle stainless steel??-----thanks blue

A carbide drill bit or HSS with plenty of lubrication to keep it cool and drill as slow as you can Stainless heats up fast.

thanks keith----tried the hss before-even with plenty of oil blunted very quickly----will try carbide regards blue

Blue

Avoid drilling if possible. It's near impossible to drill it perfectly concentric. Also, it's near impossible to synchronise the thread when you run your tap thru

Suggest you use the mig to weld a blank directly to the broken stud. This can be done even if the stud is broken below flush

This technique is extremely effective on both steel & stainless bolts in alloy, as the heat imparted in the alloy expands & relieves it. Also, the thread is often salvaged undamaged.

to give you an idea of the success of this technique, it would be less than 1% of broken studs that don't yield.

Rex