cool_hardware52
Contributor
Much good info here already.
If I need to drill 300 seires SS I use:
135 degree spilt point drill, cobalt if available. When your buying drills consider a counter sink to champher the holes after you drill them.
Cutting oil, not lubricating oil. (Hardware stores usually have small cans of "Tapping fluid")
Center punch the center of the hole
Use a slow speed, 3/8 hole ~700-800 rpm (this may be hard to achieve with a hand drill motor)
Feed the bit without dwelling, i.e. with out stopping. If you need to withdraw the drill for more cutting oil do so quickly without dwell. SS will "work harden" if you stop. If you work harden you are in trouble.
Use a drill press if at all possible, easier to feed without stopping.
If you have no drill press start with a smaller pilot drill, ~3/16.
Don't use too large a pilot drill or your finish drill will just cut "threads"
A word of caution: anytime your drilling thin materials, i.e. where the thickness is less than about 1/2 the drill diameter, there is a very good chance that the drill will "catch" as it breaks thru the back. The material can then spin. If your using a drill press think about where you hand is and where the spinning material will go. Best to clamp if you can.
If your using a a hand drill, clamp down the material.
Good luck, be careful
Tobin
If I need to drill 300 seires SS I use:
135 degree spilt point drill, cobalt if available. When your buying drills consider a counter sink to champher the holes after you drill them.
Cutting oil, not lubricating oil. (Hardware stores usually have small cans of "Tapping fluid")
Center punch the center of the hole
Use a slow speed, 3/8 hole ~700-800 rpm (this may be hard to achieve with a hand drill motor)
Feed the bit without dwelling, i.e. with out stopping. If you need to withdraw the drill for more cutting oil do so quickly without dwell. SS will "work harden" if you stop. If you work harden you are in trouble.
Use a drill press if at all possible, easier to feed without stopping.
If you have no drill press start with a smaller pilot drill, ~3/16.
Don't use too large a pilot drill or your finish drill will just cut "threads"
A word of caution: anytime your drilling thin materials, i.e. where the thickness is less than about 1/2 the drill diameter, there is a very good chance that the drill will "catch" as it breaks thru the back. The material can then spin. If your using a drill press think about where you hand is and where the spinning material will go. Best to clamp if you can.
If your using a a hand drill, clamp down the material.
Good luck, be careful
Tobin