Why Would I Need A Quick Change Lathe Gear Box?

Susan_in_SF

Wood and Metal Goddess
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Hi Guys,
As many of you already know, I have too many lathes (6", 9", 10"). I was happy having a South Bend 9A 9" lathe, then got the free Logan 200 10" lathe. Ideally, I would like to keep both lathes. The Logan does not have a quick change box.

Awhile ago, I bought this tailstock tap/die holder from a machinist online, Neil. On his website, there is a video on how to use his gadget.


Anyways, if I were to use this tool, would it matter if my lathe had a QC box or not?

Forgive me if the answer is obvious.

I am debating which lathe to keep if I were forced to keep only one due to lack of space (the Bridgeport mill literally takes up a thirc of my garage).

The Logan seems to have more mass than the South Bend, but is lacking a QC box.

Thanks,
Susan
 
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Nothing wrong with a Logan But I would keep the south bend..
 
Given that the tap / die holder is mounted in the tailstock and not the tool post then you wouldn't be using any power feed therefore it wouldn't make any difference whether your lathe has a QCGB or not.

That being said, I wouldn't give mine up! Being able to change feed rates without mucking about with change gears is a huge bonus for me. Also being able to change between thread pitches could be useful although, on my lathe at least, you have to use change gears when going from your usual feeds to thread pitches.
 
Should you want to chase threads without the Quick Change, you'll spend considerable time manually changing the gears which regulate the feed rate of the saddle. It took me over an hour yesterday, (caveat) new lathe must made gears fit shafts, etc. After a while you'll wonder if you really want to chase threads.
 
If you need to single point threads on a shaft supported by a center or threads longer than the tail stock die holder can accommodate then a QC Gearbox would be an advantage over having to change gears.
 
Hi Susan, quick change boxes are/were a real advantage for production use where lots of threading and feed speed changes were required, back in the old days, pre-cnc. Not so critical for hobby use in my opinion but they do save time and are less messy than individual gear changes.
mark
 
A QCGB is like any other improvements done to machines over time.

Just like Presliced Bread and adding flip tops to Canned Beer, they just make things a little easier.
 
If you don't mind calculating change gears and you have a set that does what you need, there's no requirement for a QCGB.
I personally prefer change gears, but all of my work are one-offs and the time necessary to change gears is insignificant.

When I was figuring out the gears I would need to cut metric threads on my Seneca Falls lathe, I read "The Calculation of Change-Wheels for Screw Cutting on Lathes" by D. De Vries, 1908 (pdf readily available online) and used what I learned there to write a short ruby script to pick gears based on the threads I needed, both metric and imperial/customary. I've used lathes with a QCGB and it's often an advantage, but I don't find it to be a requirement....for what I do.
 
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