A question for the BR communty....

I've used tapered thumb inserts for many years now and I'm getting ready
to drill (2) new balls this week. I'm going to try either drilling slugs or just
drill the thumb hole straight into the ball. My driller tells me I don't want to
drill the thumb w/o a slug as he says you shouldn't put any type of radius
on the thumb hole. I don't see how that would be an issue.
Any thoughts on this?

Thanks,
Gill Man

IMHO, the selling point of a thumb slug is that it offers the same feel in any ball. A typical reactive piece consists of a shell and filler, and the material feels different from ball to ball. You sometimes even have air bubbles! The thumb slug is a massive urethane (or vinyl) piece that offers a neat and uniform cover. Personally, I have all my equipment fitted with urethane slugs, I found the uniform feel to be a great benefit when switching balls, and the material is IMHO easier to tune than coverstock material.

My driller tells me I don't want to drill the thumb w/o a slug as he says you shouldn't put any type of radius on the thumb hole. I don't see how that would be an issue.  Any thoughts on this?

The benefits of slugs have already been well discussed.  The main benefit of a drilled hole is the cost of installing the slug, but there is absolutely nothing wrong with beveling a drilled hole.  As a matter of fact, every hole drilled, including balance holes, should be beveled to avoid cracking.  Some drillers don't bevel the hole a slug is being inserted into, but I even run the bevel sander once through them.  --  JohnP