Center drill options

[martik777]

Is there a alternative to those fragile center drill bits? I'm drilling for a 7/32 hole in 1018 on the mill and the tip sometimes breaks ruining the part. I'm running about 600rpm with with a drop of oil. Center drill is about 1/4" OD

 

[aliva]

Spotting drill

 

[martik777]

Can I regrind a broken center drill into a spotting drill?

 

[benmychree]

Or use a larger size center drill, just use the point as a spotting drill, no need to go full depth. Another option wuuld be to use a screw machine length drill, they are shorter, stiffer, and able to spot the hole without skateing around.

 

[epanzella]

Just put in a divot. Unless you're using a center you don't have to plunge to the 60 degree taper on the center drill.

 

[ChazzC]

Or use a larger size center drill, just use the point as a spotting drill, no need to go full depth. Another option wuuld be to use a screw machine length drill, they are shorter, stiffer, and able to spot the hole without skateing around.

Spotting drills are stiffer than screw machine/stubby bits: the flutes are shallower since tge don’t need to remove a high volume of chips.

 

[DavidR8]

Centre drills while used all the time for spotting holes are really not designed for this purpose.
I have had excellent luck with only a couple of sizes of spotting drills so not a big investment.

 

[martik777]

Found one in the toolbox - works great! Thanks
Will buy some extras here:

spotting drill - Buy spotting drill with free shipping on AliExpress

Quality spotting drill with free worldwide shipping on AliExpress

www.aliexpress.com

 

[Batmanacw]

You really don't need any more than a small divot the width of the small diameter. That cannot possibly cause a breakage.

 

[sdelivery]

One of two things is happening....either your part is moving or your letting the chips build up.
You can run that center drill a little faster but look for chips build up and a dull tip.
These are easily sharpened.