Taking the Mystery out of the Threading Dial

[TomG]

Here's a video I did a while back but finally got around to posting, on the principle behind the threading dial. If you understand the theory behind the madness it'll be easier to remember what line to engage on for a new thread.

Tom

[f350ca]

Great explanation Tom, makes sense now.
While on the subject, can't recall the tip but on my old Taiwanese 14x40 there was one, something like 17 or such that would never line up again if you opened the half nuts. Terry that ran a machine shop close to work said there were in fact a few combinations on his that were the same. Only way you could cut it was to stop the spindle and reverse the lathe with the half nut still engaged.
Which is the way I still thread on my Summit, the apron is so heavy and the half nuts a little tight that the comination makes it hard to kick it out in a grove but the automatic spindle brake stops it

[TomG]

Greg,

Odd threads, regardless of the number of TPI repeat every inch, so you can engage the half nuts on any numbered or any unnumbered line. The only time you need to actually leave the half nuts engaged is when cutting a metric thread on an imperial lathe. Did the 14X40 Taiwanese lathe gave a metric lead screw by chance?

Tom

[f350ca]

Tom I wish I could remember the pitch maybe it was 11 1/2 but thought it was a whole number. It had an imperial lead screw , every other thread cut fine.

[Mayhem]

Thanks Tom, that is very helpful. I need to make a new dial for my lathe which I'm a little unsure how best to go about, given the leadscrew is 2 tpi I have been told that as long as I'm cutting an even thread that I can engage the leadscrew in any position, given they will always be divisible by 2.

[TomG]

That's correct Darren, and you have a 50:50 chance of getting it right with an odd number of threads. Ya' gotta ask yourself...do you feel lucky?

Tom

[Mayhem]

I'v found that when faced with a 50/50 chance, you make the incorrect choice 80% of the time.

[Highpower]

I found out early on that using the thread dial instructions found in Southbend's "How to Run a a Lathe" book go right out the window when you own an Asian lathe.



One size does not fit all.

[Micktoon]

Hi Tom , another fine video , marking it on the tape like that did make it easier to see what was happening.Thanks for Posting .
Cheers Mick

[Rickabilly]

(09-09-2013, 10:21 AM)Highpower Wrote: I found out early on that using the thread dial instructions found in Southbend's "How to Run a a Lathe" book go right out the window when you own an Asian lathe.



One size does not fit all.

Well, it's not just Asian lathes, For instance, apart from South bends and clones I don't remember ever seeing a friction drive feed mechanism, friction overload clutches yes but never on the apron, the same is true of the 45 degree angled compound slide locking screws.

So while South Bend lathes are considered by some to be some kind of standard. It seems that maybe, they're really not that standard, especially outside the US, having said that, the first lathe I ever used was a Hercus the Australian South bend clone, in metalwork class in High school.

I'd be interested to know how many hobby sized "Proper US and English" Lathes were out there during the "Golden age of model engineering" compared to how many Asian lathes have been produced in say the last twenty years.

regards
Rick