Correcting myself: If you lay a rule along a thread with a crest aligned with one inch mark and count crests until you get to the crest aligned with the next inch mark you will get a

I suspect that we are looking at two possible errors that stirred together produce more confusion than either would produce alone. First, as Ondrej points out, an easy and common error when

Howdy, Either someone cannot determine inch pitch or the gear box is metric. I am betting on the former. Good Luck, OK

if the upper spindle gear is supposed to be 20 instead of 40 ..... the thread pitch would be off by 2 - 1 , not 13 per cent. and a 9-pitch lead screw could only cut a few useful

Michael; It would be helpful to know what model lathe you are using. The gear train on a model 9 inch isn't the same as the gear train on a 13 inch model. P. Rankin

thanks for the info ! animal

Allan, I see the differences now in the headstock design and the bed between the N and O series. According to the SB Bulletins for each: 1. both headstocks were "internally

Thanks Allan. Seems I need to do some research. Dave

AFAIK, the bed and headstock on a series N is the same as a series O. The difference is entirely in the apron.

The leadscrew is 8 too, not 9. The gearbox input gear is 56 tooth, not 40.

Threading isn't rocket science. To me the 9 TPI leadscrew doesn't sound right but I don't know. Maybe South Bends did come with that. I'd put a dial indicator on the ways and then turn the lead

Yep, using the half nuts for threading. The gear configuration is as follows: Top stud gear - 40t (according to my parts manual it should be 20t) Idler gear - 80t Stud gear to lead screw - 40t (this

Hmmm, you can always cut a test thread and measure the actual pitch with a known gauge.

Oh dear! Has whoever sold you the lathe kindly supplied a metric transposing gear (127 teeth) in the train under the cover on the left hand side? Check the tooth counts for all the gears from spindle

Correct end gears in the gear train? Using half nuts and not the feed knob/lever? John

Dennis Turk has been playing over on Facebook John

I'm threading a backplate for the Jacobs collet chuck. The spindle is 8 tpi. I've checked that the gearbox levers are in the correct position and did the obligatory scratch pass. The gage shows it

ive got a 9" Series O (wide bed) that im going to part with. Itll need a compound (a bare one will work), it'll need the gear for the crossfeeds (I used it on another lathe (that lathe was sold)),

Animal, There is some interesting history being posted in this thread. To summarize some of it - It was a short production period for this higher priced model, due to the economic times of the

Good to hear. If you remember, tell him Bill Meyers from the old Yahoo Metal Shapers group said "Hello!" Bill in OKC William R. Meyers, MSgt, USAF(Ret.) A human being should be able to change a