# Sick Of Lathe Change Gears, Made A Quick Cange Gear Box



## Ugluk (Dec 20, 2015)

Hello hobby machinists. I just (more or less) finished a project that I´ve tinkered with for well over a year now.

Limited by funds as the kids needs come first I´ve had to make do with learning on and gradually improving a rather antique lathe of unknown make and age. A pretty basic machine in a decent size with flat belt drive and change gears.
While it´s very versatile in that the set of change gears is complete enough to cut pretty much any existing thread it seems that as soon as I set it up for fine feed, I need to cut a thread and vice versa.

So I decided to build a quick change gear box that would cater to my needs of oddball threads as well as extremely fine feeds when needed.
It ended up with seven reductions in the first section and sixteen in the second giving me a range of 4-992 tpi or 5mm to 0,02mm, with a total of 33 gears I milled.

It just feels so good to finally have it finished and working I had to share.


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## Micke S (Dec 20, 2015)

Great achievement !


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## FOMOGO (Dec 20, 2015)

Wow, a thing of beauty, and you should have gear cutting down pat. Mike


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## WDG (Dec 20, 2015)

I wish I had the expertise to cut gears and the tools it takes to do so.  I may sign up at the local tec school.  What you've got there is a piece of art!


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## timvercoe (Dec 20, 2015)

Some people have too much time on their hands.  I hope that at some point in the future I could make something as functional and beautiful.    Tim


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## ScrapMetal (Dec 20, 2015)

I'm seriously impressed.  That is a very cool project and some nicely done work on it.

Thanks for sharing,

-Ron


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## Charles Spencer (Dec 20, 2015)

Whoa!


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## kd4gij (Dec 20, 2015)

Very nice work. That should make life much easer now.


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## RJSakowski (Dec 20, 2015)

Very nice! Please post photos when you have it installed.

Bob


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## brino (Dec 20, 2015)

Welcome to the site!
Wow what an impressive build.

You have certainly lived up to your "Somewhat skilled and inventive hobbyist" statement in your introduction......aaahh, nope you surpassed it.
I hope you continue to contribute here!

Thanks for posting.
-brino


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## A618fan2 (Dec 20, 2015)

That is really nice - well done.  Love to see it installed on your lathe.


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## Hawkeye (Dec 20, 2015)

Congratulations. You should get a lot of satisfaction every time you use it. Beautiful work.


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## 4GSR (Dec 21, 2015)

That is neat! 
It's funny that I drew up one from scratch in high school 40 years ago that looks similar to yours.
I know its not, but is similar.  I designed it to fit my 9" SBL, but never built it.  Wound up buying a junked out one from
old man Sobel back around 1978. 
You did a excellent job!!!

Ken


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## Ugluk (Dec 21, 2015)

Wow, I´m humbled by your praise! Of course you have no idea how many times I messed up along the way, and all the imperfections you are not aware of really stand out to me.

I will of course post more pictures as work progresses with fitting it on the lathe. Right now I think I´m at my upload limit so you will have to wait a bit.


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## Ugluk (Dec 21, 2015)

FOMOGO said:


> Wow, a thing of beauty, and you should have gear cutting down pat. Mike


Thank you! Spur gears I can do, conical and helical I will attempt in the future. 
The reason I got my little shaper was that all these gears have their keyways broached in the lathe by winding the carriage back and forth. For the same money as a good set of keyway broaches I eventually found a sweet little 12" floor model shaper.


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## Ugluk (Dec 21, 2015)

WDG said:


> I wish I had the expertise to cut gears and the tools it takes to do so.  I may sign up at the local tec school.  What you've got there is a piece of art!


It isn´t as hard as it may seem, but it takes a good indexer, the correct cutters, and absolute concentration. There are several good instructional videos on youtube, and most older handbooks really explore the topic.
I found the little free program ShopCalc extremely useful as well.


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## Ugluk (Dec 21, 2015)

4gsr said:


> That is neat!
> It's funny that I drew up one from scratch in high school 40 years ago that looks similar to yours.
> I know its not, but is similar.  I designed it to fit my 9" SBL, but never built it.  Wound up buying a junked out one from
> old man Sobel back around 1978.
> ...


Thanks! 
There´s no scrap qcgb´s available here that would fit my lathe though, and I find most seems not to be able to cut all the threads I might need. I have done som repairwork on old blackpowder guns, and those threads can be pretty much anything it seems. A colt pocket I made some new screws for was 38tpi.
This gearbox will pretty much cut any thread, and it cost little more than my labour. And I work cheap..


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## David VanNorman (Dec 21, 2015)

Beautiful  I am speechless. Great work.


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## chips&more (Dec 22, 2015)

WOOOOOOOW!


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## Ugluk (Dec 22, 2015)

Why is it that it's almost never just a case of doing the job you want to? I need to turn down my lead screw to hold the gear that will mesh with the output cone, so I spent the day working on a really sturdy boring bar holder... that will hold the ridiculously long boring bar I need to open up my spindle bore a hair, in order to fit the leadscrew inside it to machine it...
A well.. It will probably come in handy in other projects in the future.
Merry christmas guys!


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## Smithdoor (Dec 22, 2015)

great job
Dave


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## bpratl (Dec 22, 2015)

Great job in design and fabrication.


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## wrmiller (Dec 22, 2015)

And a merry Christmas to you sir!


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## mattthemuppet2 (Dec 22, 2015)

wow, that is both beautiful AND amazingly functional! I'd love to see it in use. love the comment about the shasper too


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## ScrapMetal (Dec 24, 2015)

Ugluk said:


> Why is it that it's almost never just a case of doing the job you want to? I need to turn down my lead screw to hold the gear that will mesh with the output cone, so I spent the day working on a really sturdy boring bar holder... that will hold the ridiculously long boring bar I need to open up my spindle bore a hair, in order to fit the leadscrew inside it to machine it...
> A well.. It will probably come in handy in other projects in the future.
> Merry christmas guys!



Sounds like every one of my projects!  

Merry Christmas to you and yours,

-Ron


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## great white (Dec 24, 2015)

Well done sir.

I'm in for more info and hopefully a video.


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## Navy Chief (Dec 24, 2015)

Beautiful work, I am looking forward to any more details you care to provide on it, maybe a   video of  it in operation once it is installed?


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## Ugluk (Dec 28, 2015)

I'll think about the video part. I'm not that comfortable in front of a camera, but perhaps I will try to record something.
Pictures and descriptions I can promise.
My spindle bore is now enlarged to accept the leadscrew. It really was horrible before, not remotely concentric in the middle and heavy toolmarks and scoring. I suspect it's been either crudely enlarged by a previous owner or hastily drilled from either end at the factory. I suspect its been messed with as the MT4 taper is rather short.

There was a lot of chatter when I bored it, but surface finish matter little. At least it accepts 30mm stock now, and is concentric and centered.


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## rrjohnso2000 (Dec 28, 2015)

No need to be bashful in front of the camera. I don't think anyone wants to see you, just that beautiful work of art you built!

Really nice I think it's safe for me to say we would love to see it in action, however whatever you are comfortable sharing is appreciated


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## Ugluk (Dec 29, 2015)

Slowly getting there.. The leadscrew machined nicely and came out just as I wanted it to. Now it needs bolting in line with the carriage, and then It's time for a test run.


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## Ugluk (Dec 29, 2015)

I did shoot a few quick videos of the gearbox whon I got it running.
It's potato quality, but it is by request..
It moved surprisingly quick at the coarsest setting, 2mm/rpm. Bit of a quiet panic there for a while.




Next I tried the very slowest setting.




And an in-between-one.





So, it actually works.. There is a bit of tweaking left to do. The mount isn't at all rigid yet and there's a few things to do on the gearbox itself, like drilling and tapping holes for a gear cover on the left side (wich will incidentally keep the tumbler bearing and idler shaft from wriggling out).
Then there's of course paint and labeling the positions of the tumblers, and printing out a sheet of combinations for various threads and feeds.
I had to modify the locating pins in the tumblers as well as the holes they went into. In my first attempt I used a centerdrill for the holes and had cut a 60 degree taper on the point of the pin, thinking that this would be plenty strong enough to hold the gears in mesh. They of course came right out as soon as any load was present so I drill the holes out straight through and turned the points into pegs instead. Much better.


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## Ugluk (Dec 30, 2015)

I'm adding the calculations I've made for the various thread possibilities. It's three sets based on a 25, 35 and 50 teeth gear driving a 127 for metric or 100 for imperial. Leadscrew is 4tpi.
I think I've got pretty much all threads covered.

I'm going to think about how to replace the banjo with a quick change setup as well, but I don't think I'll be changing gears that much anymore. The 35 is pretty much only needed for 1,75mm and 0,7mm.
50 will be noisier but cover coarser threads.

Edit:
I missed the 30 tooth. Thats needed as well.


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## planeflyer21 (Dec 30, 2015)

Uglak, loved the videos!  Thanks.

Amazing job there!


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## wrmiller (Dec 30, 2015)

That is quite an accomplishment! Very well done!


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## A618fan2 (Dec 30, 2015)

That's just awesome!  Thanks for posting the videos.

John


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## Steve Shannon (Dec 30, 2015)

That is so cool that you did that from scratch!


Steve Shannon, P.E.


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## Ugluk (Jan 7, 2016)

Thanks for the praise guys! It's finally in place, but It took me literally a week of patient tinkering to get it fitted _properly_ to the lathe. I had to make a new bearing block for the leadscrew tailstock end with a ball bearing and a thrust bearing just to be able to repeatably shim and align it. I also had to take the apron off and shim the cast part that holds the keyed gear that rides along and transmits power to the crosslide feed since that was crooked and caused lots of binding. Once that was sorted it was a never ending job of measuring, adjusting and sighting to get it all lined up, but now it feels great.
It has surprisingly little backlash, and I've now used it to cut the first thread, a rather unexciting M30*1 for a boring head I'm working on for the mill.
Lubed up with chainsaw oil and with the cover on it's actually kind of quiet now. The reverse gears in the headstock makes most of the noise now.


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## Techie1961 (Jan 7, 2016)

That is a thing of beauty. You have done some really nice detailing on it and the function seems like it will work perfectly. Very impressed!


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## dualquad (May 10, 2016)

WOW! that incredible. Nice work


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## David VanNorman (May 10, 2016)

Darn nice job. Youcan be proud.


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## Ugluk (May 12, 2016)

Thanks guys!
I've used it now for some time and cut various threads in both metric and imperial, and it's worked wonderfully. I love how convenient it is to go from a roughing feed to a fine feed and then switch to turning a thread without changing a single gear.
Marvellous..

Still need to fix that guard for the banjo though..


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