Complicating vise jaw replacement

[Ranchermech]

I acquired a Record vise needing one jaw insert bolts were sheared off. I ordered the replacements and received them the problem is the vise is tapped 5/16 NC and replacements are supplied 1/4 NC. Question is should I drill out the insert as it's hardened steel and regular bit don't touch it or machine a 5/16 bolt with a 1/4 thread in it? I was thinking start a pilot hole in the end of the bolt on the lathe screw it in with thread locker and then drill and tap 1/4". Seems more fun than trying to find the proper insert!

 

[Kevin54]

Are you absolutely sure they are hardened or are they just tough? If you have a drill press where you can clamp then down, you can use a carbide drill to drill them out. If you have a mill, use a carbide end mill to mill them out. Or if you want, send them to me and I'll knock them out and send them back for the cost of shipping only.

 

[bad_idea]

Ship em to Kevin. Problem solved.

 

[sharkytm]

Why are you trying to swap sizes? You should probably replace the bolt with something in the original thread size, and either modify the head or the jaw to accept the different bolts.

 

[Ranchermech]

My thanks to Kevin54. I will try the carbide cutters. The replacements are the right size just holes are to small. Yes they must be hardened as a standard drill bit won't touch them. I've tried 2 times after resharpening drill bits.