# Building a small gear reducer (model sized)



## Brian Rupnow (Dec 16, 2008)

Why???---Just because I can!!! Now that I have a lifetime supply of little gears---FREE little gears---Stay tuned.


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## defarijf (Dec 16, 2008)

Ive seen all the little gears you picked up, now to see a project born from them will be interesting..

Joe


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## Kludge (Dec 17, 2008)

See? I told y'all!


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## BrianS (Dec 17, 2008)

Hi,

Did you make those gears yourself? How did you do the internal ones? Thanks


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## Bernd (Dec 17, 2008)

Brian,

Your answer is right here http://www.homemodelenginemachinist.com/index.php?topic=3607.0

Bernd


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## BrianS (Dec 17, 2008)

Berd,

Thanks, Yes I just saw that thread, but only after I posted. I just saw internal threads and thought WOW I wanna know how to make those and just had to post without searching around first. Sorry 'bout that...


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## Brian Rupnow (Dec 17, 2008)

And for any who didn't like my hen scratch design, here it is in Cad.


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## rleete (Dec 17, 2008)

3/4"? Planning to drive a tractor with it? Find some miniature ball bearings (printers are a great source), and cut those plates down to 1/4"


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## Brian Rupnow (Dec 17, 2008)

rleete  said:
			
		

> 3/4"? Planning to drive a tractor with it? Find some miniature ball bearings (printers are a great source), and cut those plates down to 1/4"


Yeah, your right. I have reduced the plate thickness to 1/2". No ball bearings though. I have aluminum and brass, and this is not going to be a high speed unit anyways.


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## BrianS (Dec 17, 2008)

Hi,

Nice gearbox ya got there. What ratio would you have gotten if you just left the planetary arrangement together? I mean like you drove the sun gear and the output shaft was off the planets or spider with the ring gear locked? I need to make a visit to my local tool repair place. I hope they are as nice as the one near you.


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## rleete (Dec 17, 2008)

Brian,

Here at work my boss is a self sufficient type, and lives out in the boonies. He does a lot of DIY projects, and he always overbuilds everything. We call it "farmer engineering". i.e. build it heavy duty enough, and it will never break. Me, having a background in automotive (where weight savings is King), I tend to go the other way. Together, we reach a pretty good balance.

You're just guilty of a bit of farmer engineering.  :big:


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## Brian Rupnow (Dec 17, 2008)

BrianS  said:
			
		

> Hi,
> 
> Nice gearbox ya got there. What ratio would you have gotten if you just left the planetary arrangement together? I mean like you drove the sun gear and the output shaft was off the planets or spider with the ring gear locked? I need to make a visit to my local tool repair place. I hope they are as nice as the one near you.



I didn't know how to make it work, leaving the planetary cluster intact, but I expect the ratio would have been HUGE!!!


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## Brian Rupnow (Dec 17, 2008)

Rleete ---Farmer engineering ---Perhaps. However--Have you ever had the totally horrible experience of designing something for an industrial application, engineering it right to the very edge of acceptable strength and weight.--Then, after your customer has spent thousands of dollars, and weeks or months of time, stood there and watched the machine self destruct in the first 45 minutes of operation, because some of the engineering parameters are impossible to predetermine. I can assure you, it will definitly spoil your day. When you consider all of the associated costs that go into any prototype machine (which covers pretty well everything that I design), the cheapest thing in there is material. I don't get two kicks at the can. I do not have the option of creating half a dozen prototypes and testing them to destruction so that I can shave off a few more pounds here, or a fraction of an inch there. Everything I design is expected to work, first time, every time, and last for the next hundred years---(No built in obsolescense here). so--farmer engineering perhaps, but the life expectancy of my machinery has to be far, far, greater than lasting untill next years model.---Brian


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## rleete (Dec 17, 2008)

It wasn't meant as a criticism, just a friendly tease.


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## Brian Rupnow (Dec 17, 2008)

First one done.


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## Brian Rupnow (Dec 17, 2008)

So---All things considered, that went very well. Tomorrow I'll make the sideplates.


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## kustomkb (Dec 17, 2008)

Brian, you are a machine!

Very nice work, you have the imagination, passion, skill, time and perserverance to complete any task you challenge yourself with.

Thanks for all you have shared.

Kevin.


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## Brian Rupnow (Dec 18, 2008)

This may well be the fastest build that I have ever been involved in, but due to no engineering work, I was able to spend the entire day yesterday and today building this reducer. Of course, my plan is to use this reducer on the varying load machine I will build to run with the steam engine, but that is down the road a ways yet. So, without further adue, here is the gear reducer.


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## dsquire (Dec 18, 2008)

Brian :bow:  :bow:

Way to go. Either your going to have to slow down or we are going to have to give you harder projects. LOL

I am glad to see that you are enjoying yourself so much. By the time you are finished building all the little pieces to go with your engine, you are going to have quite the setup. I would think that you will be building pieces for it that you haven't even thought of yet.

Cheers 

Don


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## rleete (Dec 18, 2008)

Holy cow. Do you ever sleep or eat?


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## Kludge (Dec 20, 2008)

rleete  said:
			
		

> Holy cow. Do you ever sleep or eat?



There is evidence to suggest that feeding is interveinous and sleep is accomplished by shutting down parts of his brain while the rest remains operational. The areas swap around so that in any given 24 hour period, they all get adequate rest. 

Brian, that is beautiful work. Again. As usual. But now that you have a nice low speed, high torque output, I know that you'll find something to drive with it. 

Best regards,

Kludge


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## Art K (May 1, 2013)

Brian,
You never cease to amaze me with the projects you come up with, some of which I'd like to try out sometime.
A few posts back you were talking of engineering the project right the first time. That reminded me of a story my boss told of how Colin Chapman of Lotus fame built his car frames as light as possible. Started by over designing it then removed parts till it failed, oops guess we need that piece and put it back in. He was fanatical about weight savings. He also wasn't designing it perfect the first time and could afford to perfect it where you have to be perfect the first time. I found the story amusing at least.
Art


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