--- In
Homebrew_PCBs@yahoogroups.com, "designer_craig" <cs6061@...> wrote:
>
> Does any one know when the commercial guys have their carbide PCB drills sharpened do they just dress the tips or do they grind the flutes as well?
>
> Just wondering if resharpened drills will drill a smaller hole after sharpening or are they just a little shorter.
>
> Was thinking of getting some resharpened drills for the shop.
>
> Craig
>
I was in the printed circuit business for many years and drilled several million holes per month. We used new bits for multilayer boards and replaced them after 2500 or so holes depending on the customer and project. After multilayer drilling the bits were sent out for re-pointing then used again for two layer boards up to approximately 3500 holes and re-pointed again. After the second re-point the bits were used only on single layer boards until they were worn out or broken.
I paid around $1.75 USD per bit for middle of the range bits such as .028" to .125" etc. The smaller and larger sizes cost more due to complexity and/or cost of carbide. The cost to re-point any size bit was $0.25 USD each and this included new depth rings. All of this took place over ten years ago so I don't think those prices would be good today. Even though it was inexpensive to re-point I eventually bought a sharpening machine that had diamond wheels, drill bushings and a microscope. From then on I bought new bits and maintained them in house.
We actually broke very few bits but I kept all the carbide shanks and now grind them into engraving bits and other small cutters for the CNC machines I use today. The only way to know how many times a bit has been re-pointed is to measure the flute length and compare it to the original specifications. Many sellers of "resharpened" drill bits are actually selling used bits which are fine for hobby projects even though they aren't very sharp. I hope this answers some of the questions concerning pwb drill bits.
Tom