I would think that a rockwell hardness of 60 or close to would be pretty hard to thread at the best of times
cheers mooncoon
How to remove a broken tap?
- Thread starter Ol' Flinter
- Start date
I would think that a rockwell hardness of 60 or close to would be pretty hard to thread at the best of times
cheers mooncoon
GOT IT!!
I really wanted to use whatever primitive technology I had readily at hand. I clamped the lock plate in my bench vice so the hole that hosts the tumbler was protected from over-heating then fired up my MAP gas torch and heated the hole area until dull red, held it there a couple of minutes and allowed it to cool slowly so the tap and surrounding metal were (hopefully) annealed. Worked - Then I slowly ran a 3/32" drill bit through the tap, then a 7/64 and 1/8". Then I used s broken drill bit shank sharpened to a point to knock out all remaining bits of metal debris. Then I drilled out the hole until all evidence of the old threads and irregular shape was gone. That took me up to a #3 drill so I then tapped the hole 1/4 - 28, countersunk both ends of the hole slightly, silver-soldered a bolt in place and cut it off about 1/32" long on each end. Peened both ends of the insert, filed off the excess, marked the location for the new hole and drilled it. Will buy a new tap tomorrow and say a little prayer while I generously lube the tap and myself before turning it in oh-so-carefully.
Thanks for all the good advice in case, God forbid, I should ever do it again...
I really wanted to use whatever primitive technology I had readily at hand. I clamped the lock plate in my bench vice so the hole that hosts the tumbler was protected from over-heating then fired up my MAP gas torch and heated the hole area until dull red, held it there a couple of minutes and allowed it to cool slowly so the tap and surrounding metal were (hopefully) annealed. Worked - Then I slowly ran a 3/32" drill bit through the tap, then a 7/64 and 1/8". Then I used s broken drill bit shank sharpened to a point to knock out all remaining bits of metal debris. Then I drilled out the hole until all evidence of the old threads and irregular shape was gone. That took me up to a #3 drill so I then tapped the hole 1/4 - 28, countersunk both ends of the hole slightly, silver-soldered a bolt in place and cut it off about 1/32" long on each end. Peened both ends of the insert, filed off the excess, marked the location for the new hole and drilled it. Will buy a new tap tomorrow and say a little prayer while I generously lube the tap and myself before turning it in oh-so-carefully.
Thanks for all the good advice in case, God forbid, I should ever do it again...
Canadian_Zuk
CGN Ultra frequent flyer
- Location
- Pickering, Ontario
Not a good idea at all if cares about what he's working on.
High temperature silver solder (45 % Ag) would have been more than enough without threading and peening. Anyhow, congratulations on your success.
cheers mooncoon
I had the same thing happen in an engine block a few years back a 10-32 and it broke off flush. A dremel, diamond bits and several hours later I got it out. Only damaged about 25% of the threads. If I spent more time I could have done it without damage. So that is the solution in my eyes, and dont expect it to be fast. Set asside several hours and get ready for your eyes to hurt. If the threads get damaged at all, just drill out and tap to #10
