Gears ... or how to save $78

Warning .... this may turn into a rant , and it really doesn't have anything to do with bullet casting .

So lets start with why ... I have a spindle failing on my lawnmower deck . I've rigged it up just to get by for awhile but it isn't going to last and a new spindle is pretty near $400
So I am going to make a new one . But .... isn't there always a but ?
To make it I need to be able to cut left hand threads , something my Chinese lathe won't do .
But ( there it is again ) if I add a gear to my drive train I can make it happen . If I use two gears I can make a nice fancy idler set up and make things even fancier and be able to go from forward to reverse without having to set up the gear each time .

But. ( yet again ) two store bought gears are going to be $78 after shipping .

So I tell myself ... screw that I didn't buy machine tools to spend money on store bought junk ! I'll make my own gosh darn gears and really stick it to the man ! .... yea ;)

After two hours with machinery's handbook and eating twelve Advil
From the math headache
I've sort of slussed out how to make a cutter .
Four hours later I've got a cutter 75% finished . I made it from 01 tool steel . It still needs hardened and then finished ground to sharpen it.

So now I have a cutter , danged if I don't need someway to hold it on the mill . An hour and a half later I have a mostly finished arbor .
It still needs a key way cut ... I'll do that when I set up the dividing head again .

Speaking of dividing heads .... I also needed an arbor to hold the the gear blank when I cut the gear . The arbor I used for the cutter is to big for the blank fyi.
So about an hour and a half later I had another arbor almost done .
It still needs the clamping nut turned into a hex or a square for a wrench !

Oh yea ... I also need a blank for a gear . So bored and turned a blank from acetal plastic for a test before I put two more hours in the cutter .

Let's review ... so far I am about 10 hours into an effort to save $78
And will easily have another 4-5 hours just in making two gears .
Makes a lot of sense doesn't it .

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Just curious as to why your lathe won’t cut left hand threads. Can you feed the cutting tool from the tool head towards the tail stock? You should also be able to cut the left hand threads on the back side of the workpiece with the feed towards the headstock. The tool will need to be upside down.

Oh that's a simple answer , if I reverse the spindle it also reverses
The lead screw , so if you just hit reverse you get right handed threads cut from left to right .
To cut left hand threads you need to be able to reverse the lead screw while the spindle go forward .
Yea ... about as clear as mud . But that's what has to happen .
Or the exact opposite , reverse the spindle and not the lead screw of course .

If you think that's hard to grasp .... try to understand the quantum physics on why you can't use the same cutter on a 52 tooth gear as you would a 27 tooth gear .

What is the thread you are trying to cut?

Not a rant at all.

Not sure why you need left hand threads on a mower spindle but if you say you do, then I guess you do need it.

I understand having the machine tools and wanting to put them to use, however......(don't get mad at me).....at some point the value of your time exceeds the value of someone else's time.

To me a spindle is a housing that contains a shaft and some bearings. The shaft has a blade fitted on one end and a pulley or gear on the other end. The housing that holds all that stuff provides the means to mount the spindle to something else (usually a mower deck).

You're 10 hours into making the TOOLS to make the spindle and you haven't even started making the spindle !

I understand the path you're on, I've been down that path. Typically when I go down that path it is due to necessity (read that as lack of money) and not really by choice.

Never complain about the time spent making tools. The next time you need them they are ready to go. Gramps use to say no time lost in the whetting. I have tools I have used only twice in 30 years but they were there the second time and saved me money and time. I am currently making a set of reamers to make paper patch bullet moulds, I may never use them again but who knows.

The Home Shop Machinist mag had a story about making gear cutters many years back. Single tooth cutter using a 1/4" lathe bit. The radius was ground in the mill with the tool bit held in the vice. A simple fixture to hold the tool bit in the collet. No heat treat needed and it will work, a little slower than a regular cutter.

I won't say I am complaining , more questioning my sanity .
For the most part I enjoy the time spent making and fixing things .
But when one project snowballs into twelve I sometimes wonder exactly how much sense the effort takes .
For instance I mention the cost of the gears , but I didn't mention that I could have bought a Chinese gear cutter for about $12 .. or the whole set needed to cut from 12 - 160 teeth for about $100

But ( yet again ) as mentioned the experience does make it worthwhile when your learning new skills .
Plus little costs do add up over time and it does take time to earn money , time that you are giving someone else in exchange for that money .

So back to gears , there are a whole lot of ways to make them without a hobbing machine .
I have looked at ways to make them with single point cutters in both the mill and shaper . There is a lot of peril involved with a single point cutter ... mostly the risk if breaking the cutter if you screw up and do something wrong or dumb and then having to make a new exact duplicate tool .
There are ways to do it on a shaper ( which I have ) that don't need
The perfect form ground in the tool but I'd have to build the fixture and still put the time in .

With all that said , I went this way ( and to all the effort )for a couple reasons .
First and for most I was comfortable getting the cutter made correctly so I have nice gears that won't ruin the surface finish I get from my lathe or be overly noisy from not being quite right .
I'll also have the benefit of being able to cut left hand threads of course .
Plus I'll now be able to cut from the left to the right without having to turn tools upside down . Improving my lathe for future projects .
And lastly , I might want to make some oddball change gears in the future and now I'll be able to .

Whew .... the effort we go to to justify things to ourselves .
I think I've convinced myself it's all worth it .

No gear cutting tonight . I am going to get the dividing head set up indicated in and call it good . I hear some blt's calling my name for dinner .

Must be a heck of a mower. I got two spindles for my Husqvarna for about $60 on eBay. Can't see any spindle worth $400.

Share your mower make so we can STAY AWAY FROM the manufacturer.

You can get left handed taps and dies on eBay for cheap. Ever thought of going that way?

He seems to be focused on gears vs what left hand threads he needs to cut.

Taps and dies cost money , only the briefest thought towards a die entered my mind . I haven't measured to know the exact size
But it's metric , left handed and about 35 mm .. add that up and expensive comes to mind .
Besides that , I need to cut left hand threads now so there's a good chance I'll need to again in the future so a die only delays the inevitable

And yes I am focused on gears , I need the gears to cut the threads when I make the spindle . I didn't measure the thread pitch when I had it apart because at the moment it was and still is a bit of a moot point .
When I am ready to make the spindle I'll worry about it .

I say lawnmower , but it's a Ford tractor , Kubota bx series size
It's close to 30 years old and they was pretty darn expensive when new so they only sold my tractor a few years in the state's .
Shibuhara who made the tractor for Ford still sells parts , and most of the parts for the tractor itself are over the counter still at the Ford dealer ... plus a lot of parts cross reference to Kubota .
But the deck spindle I need is the one the pto gear box goes on
And it's a complete assembly or nothing , add in shipping from Japan
And it's expensive .
But it's a nice heavy fabricated deck that's very much worth the effort to fix . Actually if it hadn't been so well built I might have caught the bad bearing that trashed the spindle soon enough to need nothing more then a $12 bearing .

Any Mower with a $400 dollar spindle needs to be replaced with a new mower.

Dollars vs. cost to mow. Time is money mowing

I'm still wondering about the need for left hand threads.

Geezer ... easy math again , a new comparable size tractor with a mower deck $14,000 or more .
I'd be very happy to take cash or a check for a new tractor ;)
The left hand threads is easy as well ... the gear box attaches to the spindle ( which drives the rest of the deck ) with a left hand thread , short of throwing the gear box away and starting from scratch it's left hand or nothing .

I'd take a pic and show you , but the deck is on the tractor still and the guard's don't come off without taking the deck off .... @400lbs I don't remove it any more often then I need to

Almost set up for gear cutting ,... I tell myself every time I should make a sub plate and save some time aligning things up .
But it went quickly this time .
I'll put the dividing plates and the sector arms on once I get the clamping nut cut for a wrench ... tomarows project . Two blt's telling me to relax and do nothing tonight .


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Originally Posted by Petrol & Powder

I'm still wondering about the need for left hand threads.

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Im assuming the rotation of the spindle would cause a right handed nut back off.

To be simple that's it .... if it had been the case of simply a nut I would have just went to a right hand thread and either used safety wire or drilled it for a lock pin .

In this case the output shaft of the gear box goes directly on the spindle and is left hand for just that reason .

Sounds like a fun project! Some times its nice to just make stuff yourself. I've got several 16T gears and a pinion gear that I should make for my Sheldon Lathe.

I do enjoy making things myself , but sometimes I go overboard and fall down a rabbit hole .

I also tend to work slowly and methodically so projects take more time then they should . I also have issues with math .
A whole heck of a lot of the math needed in machining is beyond me .
So I spend a lot of extra time with it , either learning what I need to
Or learning how to do things without the math ... and yes more often then not it can be done .

Case in point ... I'll probably spend an hour or more just figuring out what plate I need and holes for just the dividing .

Quote:

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Taps and dies cost money , only the briefest thought towards a die entered my mind . I haven't measured to know the exact size
But it's metric , left handed and about 35 mm .. add that up and expensive comes to mind .

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They do, I’ll be the first to admit the fact. That said if you don’t know what you even need to end up with, you not only know at what price point you can achieve the desired result but even if it can be done for less than what you are already looking at.

I am all for expanding knowledge and such but with a “how to save $78” title, I need more information.

Just to put another spin on things, I have at times asked folks about “how to” and they have solved the problem with a single tool loaned to me..and a nice dinner for their significant other and them.

I have at times dumped a lot into “one time” soultions but that is after all other options proved to be less ideal.

why not right hand thread and safety wire nut

The universal dividing head I have has one plate with holes on both sides and a cheater plate with 36. Usually At 40:1 ratio plus whatever # hole pattern you're using makes it seem like a monster, but the sector makes it easy to index without having to count individual holes every time. I keep saying I'm going to make more cheater plates....someday

What's the part number? This isn't it is it? https://www.ebay.com/i/173903323272?...SABEgKDtvD_BwE

Couldn't just re do the spindle by building up metal and new bearings? I'm confused on how it was damaged?

The boss where I worked dabbled in rideon mowers,he got a MF mower that had been mowing either rocks or logs........the splines on the spindles ,and the bearing housings were chopped out.......no replacement parts,new spindles were all one piece welded ,and bearings too......anyway ,there was just enough spline left to turn the spindles upside down,and the bearings were ag bearings cost a few bucks for a tube of 10......I fixed it good enough to sell for the boss's favorite price...under $10

What kind of lathe? I have a HF 9X20 and it did not cut left hand threads. I made a tumbler plate for it.
Also it does not cut true SAE threads, close but no cigar. Found that out when I tried cutting a long thread for a loading die.

Weld it and remachine it!

Ok to answer , no that's not the spindle , it's close to the two outboard spindles but not the one I need .
And to answer the welding question , that was the first fix .
It also warped the spindle and it now vibrates . A good welder might not have warped it ... but a good welder I never claimed to be and it is what it is now .
So before it shakes itself to death a new spindle I shall make .

But that's not really what this threads about ,it's about the quest to make the parts that make the parts .
Once that's done the spindle is the easy part ... it'll be two hours and done even at my slow pace .

My lathe is a grizzly 10x22 and a new tumbler plate is exactly what I'm making . It does have imperial lead screw so threads are correct .
Metric threads are like .003 % off but that's so minor to not even be noticeable . You just can't disengage the lead screw when metric threading because the thread dial is off

I like it , the making it yourself to make what you need , makes sense to me , buy tooling when you need it , make what you can make to do jobs now and in the future . Something to be said for the doing it yourself also as that is what a lot of this site is , making our own .

Error Error error will not compute .

So I got time to do a bit of gear cutting and made a boo boo
I accidentally disengaged the worm about a third the way threw .
No big deal , tomarow when I cut the steel gear I'll not do that again .
The mistake shows up when it happened , and again of course at the last tooth .

Otherwise , I have everything dialed in and ready to go so ... woo hooo

Attachment 248039

Success .. finally ;)

Went out after dinner and made a few more gears , one more out of acetal plastic just because .
And the one I need from a piece of stress proof I found laying around

The blank I cut the gear in was long enough to saw out 5 gears , leaving three extras to play with .
So I tried doing a case harden with some cherry red on the off chance I'll ever need a hardened gear .
It went ok , warped the gear just a tiny bit , but if it had been a gear I was going to use I'd have left enough meat to true it back up after .
I feel no need to harden the gears I'll be using .

A few lessons learned .
Everything has to be spot on to make a good gear . From the cutter to the blank if one dimension is wrong your gear is going to wrong .

Same goes with your set up , if your cutter isn't centered perfect to blank .... your gear won't be right . Cut depth has to be perfect as well

Of course how perfect you want your gears to be is really dependant on the application. In my case I wanted them to be as perfect as I could make them so as not to ruin surface finish on my lathe .

Would I do this again ? Well for the most part yes .
The only thing I probably wouldn't do is make my own cutter unless the one I needed was very expensive or it was something I needed to make asap.
Otherwise I'd just buy a cutter ( or the whole set )

So now I can make a new tumbler and be able to make the spindle that started this , it's gonna feel a bit anti-climatic. I spent more time just making the cutter then the rest of the work is going to take :)

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Nice looking gear!