On Thursday, May 28, 2020 at 10:26:19 AM UTC-5, Bob La Londe wrote:
On 5/27/2020 8:56 AM, pyotr filipivich wrote:
Gerry on Tue, 26 May 2020 23:28:49 -0400
typed in rec.crafts.metalworking the following:
Last time I was in HF I picked up a couple packs of TiN coated small
bits.

For some reason, this reminded me of a Learning Experience. Was
drilling very small holes with very small tolerances. Discovered that
at this size, the TiN coating made the resulting holes "too big". One
more thing to keep in mind.



Its pretty much accepted that drills make over size holes. To remove
material I drill. To make straight holes I bore. To make accurately
sized holes I ream. However I've found even reamers do not make perfect
holes. Material, temperature, and runout all have an affect. If I need
a tight hole I'll use an under size reamer with the metal still hot from
previous operations (if applicable), and then measure after it cools.
Then I'll ream again if necessary.

I have slowly been replacing my bits with ones from DrillHog. The Ebay store is less expensive than on Amazon. They are claimed to be made in the US and have a lifetime warranty.

Paul