Drill to exact depth?

[bruleront]

Here's a stupid question I haven't seen addressed elsewhere:

How do you drill to an exact depth? For instance, the counterbored hole for a pivot (in titanium, using a drill bit to start and an endmill to finish). The drill stop on my press is wildly imprecise. The best thing I can think of is a drill stop collar for the bits themselves. But will that cause a problem with heat and chip removal? In other words, are they meant for heavy duty machining?

 

[Tinker Simpleton]

1) Lower your table out of the way.
2) Remove your depth stop and run the drill bit down as far as it will go. Hold it there.
3) With your workpiece on the table, raise the table until it is just touching the workpiece.
4) Raise the drill bit.
5) Place a spacer under the workpiece equal in height to how deeply you'd like to drill

Pain in the rear, but it will work.

 

[inuumarue]

Ive used a little bit of masking tape to mark depths on bits before.

 

[P.Brewster]

The collars will impede the chip evacuation, but it is manageable.

 

[SaguaroKid]

I used to operate a tool room Jig Bore for many many years. When I wanted to hold a precise depth I would place the tool so it would just touch the part then use gauge blocks on the spindle stop.

 

[bruleront]

Thanks for the replies, all. It's great to hear a variety of techniques and creative solutions. I'd certainly like to hear more.

I'm going to order a couple of drill stop collars and give it a shot. Seems like it will be simple and precise. And, hopefully, manageable.

 

[galadduin]

I lower the platen that the drill bit just touches to the object, and I mark that level at the column and the ring's bottom, then I raise the platen and I measure the collar position at the column with a caliper. The distance to your mark is your drill depth (exactly).

Emre