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Why Would I Need A Quick Change Lathe Gear Box?

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Susan_in_SF

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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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lordbeezer

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Nothing wrong with a Logan But I would keep the south bend..
 

SamI

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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.
 

T Bredehoft

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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.
 

bill stupak

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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.
 

markba633csi

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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
 

yendor

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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.
 

dtsh

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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.
 

savarin

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I work mainly in metric and my lathe is only a generic 9x20 but the qcgb is essential for some thread sizes along with the change gears.
My thoughts are if you dont have it available there will probably come a time when its needed for one simple job and you wish you had it.
I dont know anything about your lathes though.
 

ttabbal

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My delicate fingers can't be allowed to get so dirty with the change gears. Nitrile gloves are very nice to keep my sensitive hands clean. :D
 

Winegrower

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I admit to never having a lathe without a QCGB. Here’s some logic for you: All of my stuff is for me, not for pay, so the easier and quicker the lathe is to use, the more fun it is. I like the quality of finish coming from power feeds, and occasionally I have to try a few different feeds. Changing gears is just work. Ergo, gotta have QCGB. Also applies to QCTP, DRO, tapping heads, collets, spin indexer, rotary table, big... oh, sorry. Me stop now.
 

epanzella

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I can do all SAE threads and feeds on my lathe without swapping gears. I just have to swap gears for metric threads so I avoid them when ever possible. I had an old change gear P & W lathe years ago. It was such a PIA changing gears that I just used the wrong feed most of the time. Of course I had to use the right gears for threading but I just can't imagine going back to that.
 

Robo_Pi

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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.
That can all depend on what you might want to put threads on.

If you wanted to thread the inside of a large metal lid or cap it might be difficult to find a tap that would do the job. It would need to be a very large diameter bottom tap. :grin:
 

Eddyde

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No QCGB, Imagine a bicycle without a derailleur. To change gears you would need to stop, get off the bike and move the chain manually to the desired gear. Now your hands are greasy and you've lost time...
 

Robo_Pi

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By the way, that threading tool looks pretty easy to make.

Apparently all you need to do is make the following parts:

289572

My tapping dies are hexagon anyway, so I wouldn't want round die holders.

I think I'd design the knurled sleeve differently. I'd make it quite a bit larger in diameter.

In fact, you could probably just put the tapping dies right inside the the end of the knurled sleeve instead of having separate die holders.

I can start with just three pieces.

  1. The tailstock arbor
  2. The Knurled Sleeve with built-in die holder.
  3. And a stop handle.

I could even start with just a round piece of stock for the tailstock arbor and hold that in a tailstock chuck

It's getting simpler by the moment. :grin:
 

Robo_Pi

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To make this design truly professional you'd need to design in some type of slip-clutch between the stop handled and the knurled sleeve. That way you could tap right into a shoulder and instead of crashing the knurled sleeve would simply turn with the workpiece and break free from the stop handle.
 

rock_breaker

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Not having to be a weight lifter for the cast iron gear guard on my Clausing 100 MKIII is my best reason
Have a good day
Ray
 

Susan_in_SF

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By the way, that threading tool looks pretty easy to make.

Apparently all you need to do is make the following parts:

View attachment 289572

My tapping dies are hexagon anyway, so I wouldn't want round die holders.

I think I'd design the knurled sleeve differently. I'd make it quite a bit larger in diameter.

In fact, you could probably just put the tapping dies right inside the the end of the knurled sleeve instead of having separate die holders.

I can start with just three pieces.

  1. The tailstock arbor
  2. The Knurled Sleeve with built-in die holder.
  3. And a stop handle.
I could even start with just a round piece of stock for the tailstock arbor and hold that in a tailstock chuck

It's getting simpler by the moment. :grin:
When I visited Neil in Arizona (the machinist selling this lathe tapping/die holder tool) he surprised me when he told me he doesn't make the tools. He designed it and pays someone else online to make it to his specs in bulk. I learned a lot from him from my 1 visit....
 

Robo_Pi

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When I visited Neil in Arizona (the machinist selling this lathe tapping/die holder tool) he surprised me when he told me he doesn't make the tools. He designed it and pays someone else online to make it to his specs in bulk. I learned a lot from him from my 1 visit....
Don't tell anyone, but I am desperately in need of additional income. :grin:

So I'm trying to come up with a product to sell. My criteria is that it needs to be easy to make so that I can make it myself. And small enough so that it's also easy to ship. I have several ideas on the burner.

One is to make wooden garden train bridges. These are the large G-scale or Garden Train scale bridges.
Here is my design. I'm thinking of making them in 2 foot sections and the customer can just order how many sections they want for a bridge the size they need.

The 2 foot basic section:

289638

A 4 foot bridge - two sections:

289639

6-foot

289640

8 foot, etc.

289641

Front view

289642

Perspective view

289643

I really should be out there in the shop building these right now. :grin:

I have done some work toward building them. I've been making up jigs and fixtures to make all the individual trusses mass production. So this is a project under construction.

The above drawings were done in Google Sketchup.

I really need to get some finished and put them up on Etsy or eBay, etc. I won't be making any money until I get off my butt and actually build them. :grin:
 

Susan_in_SF

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Don't tell anyone, but I am desperately in need of additional income. :grin:

So I'm trying to come up with a product to sell. My criteria is that it needs to be easy to make so that I can make it myself. And small enough so that it's also easy to ship. I have several ideas on the burner.

One is to make wooden garden train bridges. These are the large G-scale or Garden Train scale bridges.
Here is my design. I'm thinking of making them in 2 foot sections and the customer can just order how many sections they want for a bridge the size they need.

The 2 foot basic section:

View attachment 289638

A 4 foot bridge - two sections:

View attachment 289639

6-foot

View attachment 289640

8 foot, etc.

View attachment 289641

Front view

View attachment 289642

Perspective view

View attachment 289643

I really should be out there in the shop building these right now. :grin:

I have done some work toward building them. I've been making up jigs and fixtures to make all the individual trusses mass production. So this is a project under construction.

The above drawings were done in Google Sketchup.

I really need to get some finished and put them up on Etsy or eBay, etc. I won't be making any money until I get off my butt and actually build them. :grin:
Call me slow, but your bridges don't look easy to make, lol.
If you have a photo of a similar item made by someone else, i'd love to see it.
Btw, wouldn't this be more of a woodworking project?
Good luck, Robo_Pi. At least you have made some sketches of it.
As for me, easy to make and ship would be an item fitting in a small flat rate USPS box.
Susan
 

hman

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When I visited Neil in Arizona ...
Well, durn, Susan! I live in the Phoenix area myself, and know Neil from the Valley Metal club. Fantastically nice guy, isn't he? I would have really enjoyed meeting you. Give a shout next time you plan a trip out here.
 

Chipper5783

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About the Bridgeport / VFD / motor thing. Here with I share some opinions. You are power constrained - 20A @ 120V. Nominally 2400 watts. The VFD will not achieve the voltage change (120 -> 240). You have a 3000W transformer (single phase - I assume). Confirm the VFD is rated at a 240V input (which it probably is). So you connect the 120V side of the transformer to your supply (via a single pole disconnect) and the high voltage side to your VFD inputs.

Run your existing BP motor (mainly because it has the smaller current draw, it works fine for the machine - and it is ready to go). Keep leads as short as you reasonably can - that will reduce the harmonics (voltage spikes). The duty cycle on a manual mill is generally extremely low (few hours and generally lightly loaded) - in practical terms it is going to last a very long time. It will be up to you to operate the motor such that you keep a reasonable RPM so the cooling fan moves a bit of air (i.e. keep the motor speed up above 45 Hz if you are loading the motor).

I have a drill press with a 3/4 HP, 1200 rpm, 3 phase motor. It has class B insulation. I acquired a nice little VFD (vintage mid '90s) - it probably does not have the features of the newer VFDs - the drive and the motor are quite noisy. The VFD is close to the motor, the leads are short and I'm running the start/stop buttons into the VFD controls. The drill press performs very well.

Of course a higher rated motor would be nice, but the likelihood that the motor with class B insulation will fail because it is on a VFD is extremely small (if the motor insulation is that weak, it was probably close to failure anyway).

Let us know how you make out. David
 
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