Jack,
For starters, could you look at the nomenclature off the boring bars? Most will have something akin to "A08M-SCLCR 2". Boring bars are the most common tool to find with small differences in construction that can make a big difference in performance. Should you see (for example) "A08M-SCLPR 2", there's a difference right there. The former will use a CCGT or CCMT 21.5x or 32.5x insert. The second one will use a CPGT or CPMT insert. That's 7º side clearance angle on the CCxx, but 11º on a CPxx. Getting inserts that fit is the first step because any instability in the insert seating results in poor tool life.
The TPGB can usually be swapped for a more common TPGT or TPMT, though you might have to use a screw with a different included angle on the head (usually 60º.) The "TT" inserts are proprietary or at least non-standard designation and you're likely stuck with the OE maker's inserts.
When choosing inserts for boring, look for very high positive chipbreaker designs to counteract that tilt. If the insert is tilted down by 7º and you have a 10º positive chipbreaker, you're effectively down to 3º. In some cases, you just turned a positive rake insert into a negative rake one just by mounting it onto a boring bar. And you wonder why it chatters. ;)
To your main question: The orientation of the flats on the bars would in ideal clamping situations put the tip of the insert on-center, at midway point of the O.D. of the bar. The inserts need tilt for clearance in the minimum bore diameter that they're rated for doing, as the side clearance angle of the inserts may not be quite enough by itself. The smaller in diameter the bar, the more clearance (or tilt angle) needed.
My QCTP bore bar holding blocks are also the same "pinch clamp" style. What I do to align them is get the bar in the holder, the holder in the tool post, and leave the bar loose. A simple but high quality level placed on the top flat of the bar is all I need. This gets the orientation correct. I then use the "gauge bar" I've got that is the correct length to match the distance from the flat way to the centerline of the lathe to adjust center height. I wish I could afford to have one block to dedicate to each boring bar, but I wouldn't have enough room to store them all. So, I have to go through that procedure...a lot.
Any further clarification need fire shoot away.
Ken
For starters, could you look at the nomenclature off the boring bars? Most will have something akin to "A08M-SCLCR 2". Boring bars are the most common tool to find with small differences in construction that can make a big difference in performance. Should you see (for example) "A08M-SCLPR 2", there's a difference right there. The former will use a CCGT or CCMT 21.5x or 32.5x insert. The second one will use a CPGT or CPMT insert. That's 7º side clearance angle on the CCxx, but 11º on a CPxx. Getting inserts that fit is the first step because any instability in the insert seating results in poor tool life.
The TPGB can usually be swapped for a more common TPGT or TPMT, though you might have to use a screw with a different included angle on the head (usually 60º.) The "TT" inserts are proprietary or at least non-standard designation and you're likely stuck with the OE maker's inserts.
When choosing inserts for boring, look for very high positive chipbreaker designs to counteract that tilt. If the insert is tilted down by 7º and you have a 10º positive chipbreaker, you're effectively down to 3º. In some cases, you just turned a positive rake insert into a negative rake one just by mounting it onto a boring bar. And you wonder why it chatters. ;)
To your main question: The orientation of the flats on the bars would in ideal clamping situations put the tip of the insert on-center, at midway point of the O.D. of the bar. The inserts need tilt for clearance in the minimum bore diameter that they're rated for doing, as the side clearance angle of the inserts may not be quite enough by itself. The smaller in diameter the bar, the more clearance (or tilt angle) needed.
My QCTP bore bar holding blocks are also the same "pinch clamp" style. What I do to align them is get the bar in the holder, the holder in the tool post, and leave the bar loose. A simple but high quality level placed on the top flat of the bar is all I need. This gets the orientation correct. I then use the "gauge bar" I've got that is the correct length to match the distance from the flat way to the centerline of the lathe to adjust center height. I wish I could afford to have one block to dedicate to each boring bar, but I wouldn't have enough room to store them all. So, I have to go through that procedure...a lot.
Any further clarification need fire shoot away.
Ken