SBL 9a configuration question

[Walther1522]

Hello all,

Quick question on the south bend lathe 9a vs 9b.
Recently I was gifted a 9b and am in process of cleaning, repairing, modifying and restoring (if i can say that) this 9b into a 9a.
I have acquired a QCGB and new lead screw for this 3 1/2’ bed to accommodate the QCGB.
From what I understand this is the only modification needed apart from drilling the extra counter sunk screw hole in the bed to put the QCGB onto a 9b.
I had two questions. Concerning this mod.
The first, what are the two gears that are standard at the gear train on the head stock end when in the 9a configuration?
I know that the 9b has several configurations but the 9a only has two that consist of swapping only the 20t and 40t gear. From my understanding the QCGB eliminates having the need for change gears in the gear train.

Secondly, I have a gear banjo that does not have a guard plate like the 9a does. Ill post pictures of what I mean.
Is this a problem or will it function fine?

Thank you all for any help

 

[SteveM]

Greg Halligan converted his 9b to a 9a.
Check and see if he did a video on it.

https://www.youtube.com/@Halligan142

Steve

 

[M.B. Naegle]

The QC gearbox doesn't eliminate the need to change gears, it just covers 99% of the most common threads. Most of the combinations on the gearbox chart are with one set-up, with a few that require a different gear. A "properly outfitted" 9A has all the gears assembled in the gear train, you'll just have to rearrange them. If you even need to cut metric threads or some odd 17 3/4 TPI thread, you'll still need to change gears. If you look in a 9A parts list for the gearbox and gear train (mines not at arms reach ATM), it will show you which gears are needed and what order to have them in.

The guard is just to keep chips and fingers out. It'll work without it. They pop up for sale though and would be easy to add. It's the same banjo, but with two 10-32 holes tapped into the side.