just an idea, I'm sure many have something similar.

I realized just last week that tail stock was 1/4" higher then the head stock on my lathe (pretty stupid I know). Since I fixed it Ive had a problem thru drilling/boring.

I've had a dowel center for some time now to use on the drill press but ever since I started boring I haven't went back. I would just hold the stock leveled (or what I thought to be leveled) and went from there.

After messing up 4 out of 20 pieces of my longer stock I decided I was going to make a jig that fit the same way my HM duplicator jigs fits. works great and I no longer have hold each piece balanced until finished.

what are you guys using?

I usually start the end holes with a 5/32 bit with only about an inch of bit protruding out of the chuck. then advance bit all the way out and drill again, and finish up with the long bit you have pictured if necessary. The initial step of only using an inch of bit to start drilling ensures that the hole will be dead straight and as true as possible, and therefore lines up the hole for the rest of the drilling.

I've been doing the same with a 5/32 bit.
I think with the flex of a longer 3/8 bit that sometimes it could possibly walk.

Although, I'm not sure where I went wrong with a few on my last batch.

P.S.

did you end up finishing the duplicator?

I had a few screw ups using a cheap 5/32 bit, so I ended up buying a dewalt 5/32 bit "fluted for high speed", goes for $4 and change at HD, I think it drills a lot better. Remember to back out every so often to allow for chip clearage, especially with hardwoods (you probably already know this, but just in case).

If you're using a cheap bit, I would recommend upgrading, that could be your issue.

haven't even started the duplicator yet, haha. Its still in the "mental design" phase.