One reason that drives me to keep the 109 lathe as my project is that it has building setups to for thread cutting. I have got many gears with my original acquisition of the lathe. However, the set is not complete. I have asked the seller about it, but he said that he has never used it.
I looked through the gears that I have. It looks like that I am missing the gears that are on the tumbler assembly. Those gears are available on eBay, but are generally going for $15 to $20 a piece. I have been contemplating about cutting them myself, but I would need to build a milling attachment as well as an indexer. Thread cutting seems to be a rather important part of the projects I have in mind. So I decided to get those gears complete first.
On Dean's webpage (from the same gear cutting link above), it was stated that the 109 lathe uses the same gear as the 618 lathe. So I have been scouting eBay for some time, and found a tumbler assembly. I got it for about $40 (including shipping). But when it arrives, I found to my surprise that they don't fit the tumbler I have. Didn't Dean said so? I went back to read his comments, and it turns out that what he says are that the gears fits (I think he means the change sets).
Fortunately, I think the gears pretty much looked in place, except with a bigger hub size. That should be easy on the lathe. I quickly machined some bushing, and now it goes on like they are made for it.
After some work and additional money out of pocket, my lathe is finally up cutting threads. I have heard that people complaining that the motor is too fast for cutting threads, but mine works just fine for me. I will be using that in my coming projects.