I use a 9/32 bit and polyurethane glue. This works well.
The 9/32 bit was suggested by Dick Sing in a class.
Larry
Don't quote me on this, but IIRC Russ Fairfield also used to use a 9/32" on his 7mm tubes. I suspect with anything thicker than CA this would, in fact, be a non-issue. For me, it is. I've got this handy dandy list in front of me right now that has all the conversions. A 9/32 bit is .0057 bigger than a 7mm, and .0043 bigger than a J bit. That tells me personally I dont want to use anything that's more than .005 bigger than the required bit. Having said this, I could have been experiencing some runout or wobble in my drilling, which changes everything, of course. :befuddled:
Case in point- I dont have a 4-jaw chuck yet, but drill on the lathe. I do this by putting the drill chuck with bit in the headstock, and a live center in the tailstock. I use a punch to put a divot in each end of the blank. I snug up the blank between the points, lock the pin indexer, then rotate the blank by hand, slowly advancing the tailstock, until my hole is GOOD and started, like 3/8" deep. Then I hold he blank with channel lock pliers, remove the index pin, and turn the lathe on. I hold the pliers in my left hand, advance the tailstock wheel with my right. When the squeal starts, I shut off the lathe, retract the headstock, and pull the blank off the bit, clearing the flute and hole. Slide the tailstock back on, starting with the bit already in the hole, and proceed again. Repeat until totally drilled to depth desired.
Last night, I wanted to drill a 1/4" hole to fit my mandrel, for making custom pen mill sleeves for bigger sizes. I drilled a 1/4" hole, and the mandrel was loose in it. I drilled the next size down, and it wouldnt fit. So I drilled that hole again with the 1/4" and it was tight. All this to say that I might be well served to get a drill press and my chuck sooner than later, and in the meantime predrill a smaller hole to start with.
Thoughts? (besides..."dang that guy takes a long time to say what he wants to say") :biggrin: