Need Help!- Drilling problem....

[REVCAM_Bob]

I am having trouble with a particular drilling situation.
We put what we call "Jack screws" in die details..... That is: a thread, lets say 3/8 about 1/2" deep into a block, and then a 3/8 clearance hole on the other side to allow insertion of a long 3/8 bolt or threaded rod...

The problem is the tap drill hole from the opposite side is sometimes drilled first i.e. and then the clearance drill i.e. 1/32 over 3/8 is drillled on top of that
hole, and when doing so the drill chatters and gets torn up very quickly...

Any suggestion on how to stop the tool damage?

Thanks!

[davereagan]

What material are you drilling? Are you enlarging the tap hole (~5/16") to 13/32" ? If so, the feed needs to be nearly twice what you would run that drill at if drilling from the solid, with pecking every .200" because you will get long stringers unless it's really high carbon like D2.

[REVCAM_Bob]

We are drilling A2 and D2, the tap drill is 5/16 and we are opening it up to 0.406


I will check out what feeds and speeds we have and try faster...

Thanks, Bob.