SB questions and rants...

Hi all,
Was wondering if anyone has the correct explanation as to why the 116 tooth turning gear and a 1 to 8 (ratio) compound gear was put on my SB 9" Model C Workshop lathe (s/n 76475). It does appear to be factory. I cannot find any listings in the SB parts manuals for the gears. Also, does anyone have the correct carriage lock (for sale) for this apron? That Plaza Joe in Vermont bloke sold me the wrong one. He has a lot of stuff (very high on the price scale). One major peeve I have with this guy is that my buddy and I drive almost 2 hours to his place to conduct business with him...we spent more time listening to his long-winded conversations to potential customers, friends, etc. while standing around with want lists and cash in hand. Jerk should invest in a answering machine while the live bait is there on his hook. Don't get me wrong - he has a good personality, but his business practice to on-site walk-ins absolutely sucks. Enough of the gripes already. I have more questions but I will let this post run its course.
Tom

He does, as I recall, state in his ads "by appointment" for on-site visits.

If you are an unannounced "walk-in" with no appointment that might affect it.

The 116 tooth gear would be a custom made gear for unknown purpose. It does not match any of the standard gears available for either SAE, BA or Metric screw cutting.

Someone's choice for feed rate?

I don't know what that works out to for feed. But keep in mind the C model doesn't have carriage drive, except through the leadscrew pitch. I.e. "very fine threading".

smt

Tom:

Joe at Plaza is a true gentlemen and there are not many left these days. There are no "walk-ins" and his phone policy takes some adjustment. Understandably in today's fast pace, this laid back approach takes some getting used to.

Have you heard of Rison's in Plaistow. They have hit or miss hours because they are active riggers. They've had SBs on and off.

Den

we just talked about this on the </i>other</i> site about a month ago: the 116 tooth gear is for feeds finer than 160 tpi or 0.00625"/rev.

depending on the rest of your geartrain you could potentially get feeds as fine as 360 up to 400+ tpi or about 0.0002"/rev. and no, there are not too many 0's in that...

obviously there are a bunch of other threadings/feeds this would apply to depending on the gearing but the low end is easiest to calc.

just a caution, you have a VERY rare gear and it is potentially be desirable to the right person. don't let it go!

sinneD

Thanks to all replies...I will take some pics of the gears and post them tonight. As far as the issue with Joe at Plaza...I did not state that he is a bad person - just his method of business when dealing with 2 guys that CALL ahead to visit (yes he does accept walk-ins) his place to purchase equipment. Listening to him chat on phone (no exaggeration at least 6 calls at about 5-6 mins. each) gets pretty thin real fast, especially when a 3+ hour travel round trip already adds to the long day. So advice to people going there - bring a lawn chair to sit down on. Advice to Joe would be to have a machine or secretary take your phone messages while you are trying to unload some of your iron.
Tom

What can you pratically do with greater than 160 tpi? 360 tpi gets even more interesting.

Tom,
When you figure out what to go thread 360 tpi, let me know. I'm still trying to figure out why my heavy 10 goes to 480 tpi. South Bend wasted their time giving me that option. The Blount I have dosen't give me this kind of confusion. Kind of a no brainer: turn it on and go. Sort of utilitarian as the options go.....
-Tony

"I'm still trying to figure out why my heavy 10 goes to 480 "

Don't forget that each thread pitch has a corresponding feed rate. The finer the pitch, the slower the feed rate.
While you may never thread 480tpi, you may someday need a nice slow feed.

On the model C, the half nuts for threading *are* your powerfeed. When "powerfeeding" with a C-model, you are threading, but you are not using a form tool for threading so you wipe out the thread as you go along and end up with a (sort of) smooth finish. It's better to cut (and subsequently wipe out) a fine pitch thread to get a smooth finish.

Dave