# 1957 Logan gear question



## moorepower (Sep 10, 2013)

Can some one tell me what screw gear is used for threading using the chart on the gearbox. Is it the 56T or 60T?
Thanks  Pat


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## Chuck K (Sep 10, 2013)

Pat, I can look in a manual in the morning, but I think it tells you right on the threading chart which stud gear to use for the tpi your doing.

Chuck


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## Terrywerm (Sep 10, 2013)

Pat,

Chuck has it right. Nearly any gear can be used as the screw gear, which one you need to use depends on what thread you wish to cut.  For example: for 10 TPI on a Logan 200, you would use a stud gear of 32T, an idler gear of 72T, and a screw gear of 40T.  12 TPI would be the same setup except that the screw gear would be 48T. 

In order to properly answer your question, we need to know what thread you wish to cut.


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## yugami (Sep 10, 2013)

moorepower said:


> Can some one tell me what screw gear is used for threading using the chart on the gearbox. Is it the 56T or 60T?
> Thanks  Pat



My manual calls out a 72T gear as the screw gear on the quadrant


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## moorepower (Sep 11, 2013)

A real stupid question, other than metric threads, why would you use any other screw gears? On the gearbox it shows using the 24 and 48 tooth gears for different thread pitch but the operators manual I got off of ebay does not mention ever changing the screw gear that drives the gearbox. Is their another chart somewhere that lists what the other screw gears cut?


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## yugami (Sep 11, 2013)

You don't change them - they probably changed the pairing at some point in the serial number series.  I would have to read ab it deeper into my manual. 

You should have bought the manual from Logan vs the internet, the Logan one calls out changes and which serial numbers they affect.


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## yugami (Sep 11, 2013)

Page 8 of the Logan purchased manual (under the picture of the lathe bed/tailstock)  48/24 stud gear through serial number 67838 and 72/36 after 67839


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## moorepower (Sep 11, 2013)

yugami said:


> You don't change them - they probably changed the pairing at some point in the serial number series.  I would have to read ab it deeper into my manual.
> 
> You should have bought the manual from Logan vs the internet, the Logan one calls out changes and which serial numbers they affect.



 I am finding that out! On the Logan site I found the info that I need. The ebay manual is nice, but lacking alot. I will just print off some pages from the Logan site. I am really getting excited as it is starting to get close to making chips fly.


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## yugami (Sep 11, 2013)

Great machine.  I just got a die head for my turret that I need to get setup and play with once I finish the job thats sitting in the chuck.

I highly recommend buying the Logan manual if you get a few free dollars.  You get a nice bound copy that calls out all the changes between various serial numbers and  a PDF version (well I bought that I can't remember if I payed extra for that)  PDF prints out copies to get your dirty fingers on without messing up the nice physical copy.


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## Terrywerm (Sep 11, 2013)

My apologies, Pat. For some reason I was thinking that your lathe was a change gear machine, but instead yours has the quick change gearbox.  Enjoy!


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## moorepower (Sep 12, 2013)

I bought the machine cheap and crashed. $850 shipped from Cali to Nebraska. After watching eBay I have picked up all the gears in the gearbox and another compound gear for $150, a brand new carriage for $125 shipped. It has a brand new 1 1/2h.p. motor on it, and after installing the cross slide, less than .002 backlash on the cross slide. The ways look and feel very good. I have got an Axa tool post, a 3 jaw set true and a Bison 4 jaw for it. Through patients and lots of watching I will have right around $2k in it after I get a steady rest. I really want to see how straight it cuts!


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