Spotting drills advice?

[Recoil Rob]

After spending way too much time drilling out some rusted bolts from the underside of my Toyota I decided there has t be a better way. Seems I should have used a "spotting drill" first to start a centered hole on the bolt head.

Recommendations for a set of spotting drill bits, commonly used diameters and also what tip angle? What type steel?


thanks,

Rob

 

[Dave455]

I only use spotting drills in my mill or jig borer where I'm positioning a hole centre a certain dimension from a fixed reference - i.e. find an edge with an edge finder, dial in the dimension, then spot drill, then pilot drill!

If you are not using a machine you are far better off using a centre punch, and giving it a good hard bash if needed!

 

[rsanter]

I have used center drills where I center punch the broken bolt and drill a small hole an 1/8th deep to get things started then used a center drill to start a nice big drill spot on the bolt to be sure my drill stays on center. This is mostly useful when the broken bolt is very uneven and could cause the drill to push off center

Bob

 

[crewchief888]

you could also choose a drill bit that "fits the hole"

drill until you get a spot marked, then go back with your pilot drill bit...

it's time consuming, and does take practice....