Spotting drill size

[Former MemberParticipant @formermember12892]

[This posting has been removed]

[Former MemberParticipant @formermember12892]

[old martParticipant @oldmart]

Any size you like, it is only for making a spot.

[Swarf, Mostly!Participant @swarfmostly]

Hi there, Bill,

Just my two penneth – I'd say the 'spot' needs to be big enough to at least fully contain the chisel point on the first proper drill you intend to use.

Best5 regards,

Swarf, Mostly!

[SteviegtrParticipant @steviegtr]

I only have 6mm spotting drills but they work for most sizes. I guess a really small hole spotting may be difficult. The spotting drills i have are just from Starret holesaws. They have a very fine point so are ideal & much cheaper.

Steve.

[JasonBModerator @jasonb]

Really depends on how you want to treat the hole.

A spoting drill can also be used to camfer the edge of the hole prior to it being drilled thus saving one operation in which case an 8mm min or preferably a 10mm 90deg spoting drill would be the best option so you don't have to deburr the entry side..

Larger still if you wanted a fully countersunk hole as the spotting drill can also pre countersink rather than going back after drilling with a CSK bit.

I would not really class the holesaw pilot drills as spotting drills, maybe 4-facet or split point but a bit long for spotting so may wander a bit. I mostly use an 1/8" one which does for starting holes upto about 5mm, 5mm one above that or 6mm carbide one in the CNC.

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