# Converted to a QCGB; which change gears should I keep?



## ARC-170 (Feb 1, 2021)

*CHANGE GEARS*
I have converted my 101.07403 from a change gear lathe to one with a QCGB. I know I need to keep certain gears (I was told in another thread, but I can't remember right now what they were) for making metric threads, but *what other gears should I keep? *I think I saw a Tubalcain video where he kept a gear set that reduced the feeds by half. I think as long as it's a set that has a 1:2 ratio and doesn't interfere with the other gears, then it will work. For example a 16/32 of a 12/24.

*NAMEPLATE
Should I change the name plate on the back?* The lathe is a 12x18, so it's not really an "official" 101.27430 (12x24) or 101.27440 (12x36). 

*DONOR LATHE*
The donor lathe is all fixed up and ready to sell. It's a 101.27440, but without the change gear box, it's really a 101.07403. *Should I leave the original tag on this one, or switch them/get a new one? *

I'm leaning toward just leaving everything the way it was originally, but I thought I would ask and see if it mattered or was important.


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## mickri (Feb 1, 2021)

I would keep all of the change gears.  Who knows when you might need them for a project.  You need a 52/44 combo to cut the more common metric threads.  They go in place of the two 48 gears.   The 44 on the inside towards the headstock with the 52 on the outside.


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## wa5cab (Feb 2, 2021)

If you don't want to sell the full set of change gears with the donor, I would leave the nameplates on their original beds.  There is no indication that Atlas furnished a new nameplate with the gear box kits that were sold to convert the earlier machines.  And the gear boxes would also fit the babbit bearing machines, too.

You should report the serial number and original model number of the machine that was upgraded.


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## Shotgun (Feb 4, 2021)

You don't want to keep any of them.  They are terrible for your health.  You should send them all to me, so that I may relieve you of your burden.  ;-)


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## ARC-170 (Feb 4, 2021)

mickri said:


> I would keep all of the change gears.  Who knows when you might need them for a project.  You need a 52/44 combo to cut the more common metric threads.  They go in place of the two 48 gears.   The 44 on the inside towards the headstock with the 52 on the outside.


Chuck, do you have a picture of this? I'm assuming I should keep a 44 and a 52 and put them on the same axle, or are they paired with a smaller gear or are they placed in series (the 44, then the 52 or vice versa)? Thanks!


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## ARC-170 (Feb 4, 2021)

Shotgun said:


> You don't want to keep any of them.  They are terrible for your health.  You should send them all to me, so that I may relieve you of your burden.  ;-)


You can have all of them for $100,000,000,000,000,000, including shipping.

Seriously, do you need a set? I might be willing to part with them. I'll have to inventory them and make sure I have what I need going forward.


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## ARC-170 (Feb 4, 2021)

wa5cab said:


> If you don't want to sell the full set of change gears with the donor, I would leave the nameplates on their original beds.  There is no indication that Atlas furnished a new nameplate with the gear box kits that were sold to convert the earlier machines.  And the gear boxes would also fit the babbit bearing machines, too.
> 
> You should report the serial number and original model number of the machine that was upgraded.



I'll leave the serila number plates alone then.

Where should I report?


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## mickri (Feb 5, 2021)

The 52 and 44 are keyed together on the same shaft so they both turn together.  To cut metric threads the slider gear is moved to the inner position and meshes with the 44.  To cut imperial threads the slider gear is in the outer position and meshes with the 52.  My lathe is currently set up for imperial threads with the slider gear in the outer position meshing with the 52.


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## Bi11Hudson (Feb 5, 2021)

I don't know if this post has any real bearing on the question, just thought I'd throw it out. Some 15 years back, I acquired a 101.27440. A 12X36 with the built on QCGB. A while later I found a complete set of change gears for the earlier model. I don't know if it was a good buy(eBay), but was within what I was willing to pay at the time. So I did. . . 

They have never been used, I built a wooden "peg" stand and wrapped them in plastic. They just take up shelf space which I am sorely short of. My philosophy is that I would rather have and not need than to need and not have. Each person has to make decisions like that regularly. It's individual. . .  Me, I may or may not need them in the undefined future. But, if I do, I got them. Not too handy, but in the same shop building.

.


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## ARC-170 (Feb 5, 2021)

Thanks, Chuck, this is helpful. Is there enough room for the gears to slide over toward the headstock so the 52 engages? Hard to tell in the photo, but I'm assuming it does. I'd check on my lathe, but the QCGB is in pieces. 

BTW, what lube are you using on the gears?


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## ARC-170 (Feb 5, 2021)

Bi11Hudson said:


> I don't know if this post has any real bearing on the question, just thought I'd throw it out. Some 15 years back, I acquired a 101.27440. A 12X36 with the built on QCGB. A while later I found a complete set of change gears for the earlier model. I don't know if it was a good buy(eBay), but was within what I was willing to pay at the time. So I did. . .
> 
> They have never been used, I built a wooden "peg" stand and wrapped them in plastic. They just take up shelf space which I am sorely short of. My philosophy is that I would rather have and not need than to need and not have. Each person has to make decisions like that regularly. It's individual. . .  Me, I may or may not need them in the undefined future. But, if I do, I got them. Not too handy, but in the same shop building.
> 
> .



I figure the same thing. As long as I have an extra 44 and 52, and anything else I might need, I'm good. Going back to my original question: *Does anyone know what other gears I might need?*


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## ARC-170 (Feb 5, 2021)

I did a little reading in the MOLO and I think I've figured out which gears are needed to do metric and the odd, frequently used ones:
20, 24, 32, 36, 40, 44, 46, 48 (2), 50, 52, 54, ,56, 60, 64 (2) and 2 steel spacers.

So, all of them!


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## mickri (Feb 5, 2021)

The 52 gear is always meshed with the gear in the QCGB.  The 52/44 combo does not slide in or out.  Here is how it works.  When cutting imperial threads the 52 gear is an idler and the 44 just spins along for the ride.  The sliding gear is in the outer position and meshes with the 52 which meshes with the gear in the QCGB.  When cutting metric threads the sliding gear is in the inner position and meshes with the 44.  Because the 52 and 44 are on the same shaft and rotate together the 52/44 combo changes the 8 tpi lead screw to rotate at 7.5mm.  This change is how the lathe can cut different metric threads.  I did all of the math as to which metric threads can be cut and Robert did a really nice thread chart that you can download.  I have the chart taped with clear packing tape on the cover of my lathe.  When you get the QCGB installed you will see how the gears fit and mesh together.

I use whatever grease I have handy.  The last grease I used was I believe spray on white lithium grease.  It doesn't take much.  I probably over did it.  Besides grease on the gears you need to oil the shafts that the gears ride on.  Putting a couple of drops from my needle oiler between the washer and the gear seems to be sufficient.  Do you have a needle oiler?  If not you should get one.  Makes it really easy to get oil everywhere it needs to go.


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## mickri (Feb 5, 2021)

Do you have the manual for the QCGB?  If not I believe it is available in the downloads and you can download it from Vintage Machinery. At Vintage it is in the Atlas Press Company section.  Not the Sears Craftsman section.  There are over 60 pages of different threads that can be cut through the QCGB.


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## wa5cab (Feb 7, 2021)

The first part of the name of the .DOC file is A30secondMetricConversion and then the version number I think.  Anyway, it is in Downloads.  A friend of mine wrote it up several years ago.  I also have color TIF scans of the original and adjusted settings plate but can't recall if I put them in Downloads or not.


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## ARC-170 (Feb 9, 2021)

mickri said:


> Do you have the manual for the QCGB?  If not I believe it is available in the downloads and you can download it from Vintage Machinery. At Vintage it is in the Atlas Press Company section.  Not the Sears Craftsman section.  There are over 60 pages of different threads that can be cut through the QCGB.





wa5cab said:


> The first part of the name of the .DOC file is A30secondMetricConversion and then the version number I think.  Anyway, it is in Downloads.  A friend of mine wrote it up several years ago.  I also have color TIF scans of the original and adjusted settings plate but can't recall if I put them in Downloads or not.



I found a manual on the vintage machinery site. It has a dark blue cover and is titled "Atlas Quick Change Attachment Hand Book (big letters) for 10" Atlas Metal Working Lathes (small letters)". It's copyright 1947 so it's around the same vintage as my machine. *Am I correct in assuming it will work for a 12" machine?  *59 pages of every feed you could possibly want! I can't wait to try out 1000 threads per inch (0.001" feed rate)! Ha!

I found the charts as well. I had to use the "advanced Search" option and look in Downloads. Thanks!


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## wa5cab (Feb 9, 2021)

ARC-170 said:


> I found a manual on the vintage machinery site. It has a dark blue cover and is titled "Atlas Quick Change Attachment Hand Book (big letters) for 10" Atlas Metal Working Lathes (small letters)". It's copyright 1947 so it's around the same vintage as my machine. *Am I correct in assuming it will work for a 12" machine?  *59 pages of every feed you could possibly want! I can't wait to try out 1000 threads per inch (0.001" feed rate)! Ha!
> 
> I found the charts as well. I had to use the "advanced Search" option and look in Downloads. Thanks!


By Model Number. Atlas built either 7 or 8 different QCGB's.  However, the differences between 5 or 6 of them are the badges (Atlas or Craftsman).  All of them are the same in the feeds or threads that they will cut.  So any of the settings charts and the charts for how to cut threads or feeds not available with any of the stock boxes will work with any model.  Most of the parts, and specifically the gears, are the same in all of them.  The differences are mainly in the main casting.  So none of the 10" boxes will bolt up to any of the 12" machines and vice versa.

So anyway, the short answer to your question is yes.  But I think that we have the same information for the 12" machines.  We don't have the Atlas versions of the QCGB parts manuals but the boxes are the same as the Craftsman ones.  And we don't have the 2nd version of the Craftsman models but the only difference between the 2nd and 3rd versions is the output shaft and the additional mounting bolt that is physically located inside the headstock.  The 2nd version has a solid output shaft where the 3rd has the slip clutch added.


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## wa5cab (Feb 9, 2021)

BTW, each  time that you do a search in Downloads, you need to specifically tell it only to search Downloads.  The default is to search everywhere, including all threads in the Fora.  So you will probably get a bunch of bogus hits.


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## wa5cab (Feb 10, 2021)

ARC-170 said:


> I'll leave the serial number plates alone then.
> 
> Where should I report?


Jeff,

The circus going on in D.C. reminds me that some people will sue at the drop of a hat.  So if you have one available, it might be safer to sell the donor machine as a 101.07403.  However, unlike back in the 30's and early 40's when Sears was selling three models each year, by the time that the QCGB was introduced on the 12", Sears finally did what Atlas apparently had done from the beginning with the 10", and that is that each serial number assigned after 1950 is unique.  AFAIK you will not find a 101.07403 with the same number as a 101.27430 or 27440.  So ideally what you should do is put a 101.07403 nameplate on the machine that you are going to try to sell but change the serial number to the one that is on the 101.27440 plate.  Somehow...

I haven't actually confirmed it by experiment but my belief is that the 10" charts and the 12" charts (both early and late) are interchangeable.  The gear boxes are not the same but the internal gears are the same in all of the 10: and 12" versions.  And the threads that they will cut are all the same.


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## mickri (Feb 10, 2021)

I wouldn't worry about changing the plates or serial numbers.  I would tell whoever buys the lathe what you did.  Full disclosure.  You are covered.


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## wa5cab (Feb 10, 2021)

I disagree.  The lathe could go through two or three buyers before it actually gets used again.  The serial number is OK but not the model number.

And incidentally, what is the serial number we are discussing?


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