# Reverse Tumbler Bearings



## blockmanjohn (Jul 22, 2020)

Hi,

I was looking at the replacement ball bearing, reverse tumbler gears that they sell on E-Bay. They claim to make the gear train a lot quieter. My South Bend 10L is pretty noisy, and I was wondering if any one has installed these and if they work as claimed?

Thanks, John.


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## SmithDoor (Jul 22, 2020)

Most of the 10L only had thrust ball bearing. Some had thrust ball bearing in cluch and or cross slide screw.
The rest are used pain bearings.

Dave



blockmanjohn said:


> Hi,
> 
> I was looking at the replacement ball bearing, reverse tumbler gears that they sell on E-Bay. They claim to make the gear train a lot quieter. My South Bend 10L is pretty noisy, and I was wondering if any one has installed these and if they work as claimed?
> 
> Thanks, John.


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## blockmanjohn (Jul 23, 2020)

Dave, 

I was not very clear. I'm talking about the twin gears on the the feed reverse mechanism. They normally have plain bearings. A vendor on E-Bay is selling replacement gears with ball bearings instead of plain as an upgrade to make the gear train quieter. I was thinking of replacing mine, but I was hoping to find some one who has done it to see if they work as claimed.


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## goldstar31 (Jul 23, 2020)

blockmanjohn said:


> Dave,
> 
> I was not very clear. I'm talking about the twin gears on the the feed reverse mechanism. They normally have plain bearings. A vendor on E-Bay is selling replacement gears with ball bearings instead of plain as an upgrade to make the gear train quieter. I was thinking of replacing mine, but I was hoping to find some one who has done it to see if they work as claimed.



FWIW, the Myford owners have been using a pair of Tufnol 20DP gears on their machines as standard- from-----I was going to say from the 1940's and the n I realised that the older machines had them as well.

So let's say- from the building of the Ark or very nearly. There a re no inserted bearings of any kind. I pres ume  that that case hardened spindles are used.  Lubrication is supposed to be twice daily-- but then
Hope this helps


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## oldengineguy (Jul 23, 2020)

John:  If you do get those gears please post to let us know how they turn out. I have a very noisy Heavy 10 that might benefit from a new set of gears.


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## SmithDoor (Jul 23, 2020)

If you are planning on changing the type of bear use Neel bearing.
The ball bearing your seeing on eBay cost about $1.00 the rest is profit.

I typically replace with same bearing as they it came from the manufacturer. Just look how long the first bearing lasted.
I you can replace with larger shaft and ream the gear for new shaft size or If you need to build the shaft up use hard nickel Plating this done at home. 

Dave



blockmanjohn said:


> Dave,
> 
> I was not very clear. I'm talking about the twin gears on the the feed reverse mechanism. They normally have plain bearings. A vendor on E-Bay is selling replacement gears with ball bearings instead of plain as an upgrade to make the gear train quieter. I was thinking of replacing mine, but I was hoping to find some one who has done it to see if they work as claimed.


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## SmithDoor (Jul 23, 2020)

Please post photos .
You find the ones on eBay is trying to sell.
I have needle bearing sleave or even made sleave's to go over the shaft and bored out the gear to fit the sleave.

Dave



blockmanjohn said:


> Hi,
> 
> I was looking at the replacement ball bearing, reverse tumbler gears that they sell on E-Bay. They claim to make the gear train a lot quieter. My South Bend 10L is pretty noisy, and I was wondering if any one has installed these and if they work as claimed?
> 
> Thanks, John.


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## BaronJ (Jul 23, 2020)

blockmanjohn said:


> Dave,
> 
> I was not very clear. I'm talking about the twin gears on the the feed reverse mechanism. They normally have plain bearings. A vendor on E-Bay is selling replacement gears with ball bearings instead of plain as an upgrade to make the gear train quieter. I was thinking of replacing mine, but I was hoping to find some one who has done it to see if they work as claimed.



I doubt whether it would make much difference if any !  The noise comes from the meshing of the gears.  I wouldn't waste my money.

You can check how closely the gears mesh by passing a sheet of paper between them and looking to see if any holes get cut in the paper.  A rub with a fine file or stone will take off any high spots.

Mark the gear with a marker so you know that the gear has done a full rotation.


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## SmithDoor (Jul 23, 2020)

If the gears are to close they make a loud noise.
The odd part of reverse tumbler  gears they pull to get her and make noise.

Dave



BaronJ said:


> I doubt whether it would make much difference if any !  The noise comes from the meshing of the gears.  I wouldn't waste my money.
> 
> You can check how closely the gears mesh by passing a sheet of paper between them and looking to see if any holes get cut in the paper.  A rub with a fine file or stone will take off any high spots.
> 
> Mark the gear with a marker so you know that the gear has done a full rotation.


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## chrsbrbnk (Jul 24, 2020)

could be possible that the ball bearings on a proper fit shaft could put the gears at a more correct center to center distance   just out of curiosity how many rpm are these spinning at ?


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## BaronJ (Jul 24, 2020)

chrsbrbnk said:


> could be possible that the ball bearings on a proper fit shaft could put the gears at a more correct center to center distance   just out of curiosity how many rpm are these spinning at ?



Dave might be in a better position to answer that second question!

As far as C2C distance the lathe manufacturer will have determined that.

The design of lathe tumbler gears is an interesting exercise.


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## SmithDoor (Jul 24, 2020)

Older equipment will lossing up over time on any gear shift.
Some South Bend Lathes gears can be adjusted too.

Dave



BaronJ said:


> Dave might be in a better position to answer that second question!
> 
> As far as C2C distance the lathe manufacturer will have determined that.
> 
> The design of lathe tumbler gears is an interesting exercise.


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## goldstar31 (Jul 24, 2020)

BaronJ said:


> The design of lathe tumbler gears is an interesting exercise.



Considering that the Myford Super7 with and without a gearbox Does require a careful counting up of the 'cogs'.
I also have no doubt that something similar is required on-- is it aa Soth Bend.

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'Idle Thoughts of an Idle Fellon's I guess that my Sieg C4 cannot get the lead screw to go forward and reverse- and the operation of a lever with three locating pegs.
Well, it serves me right for buying cheap lathe.  It was only £350


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## blockmanjohn (Jul 24, 2020)

I was thinking that it might be possible the new gears may have been machined to a higher standard than the originals. Just a thought, but if it's true it might make a difference.


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## SmithDoor (Jul 24, 2020)

blockmanjohn said:


> I was thinking that it might be possible the new gears may have been machined to a higher standard than the originals. Just a thought, but if it's true it might make a difference.


The gears from South Bend Lathe are hob. The gears from eBay may be cut on a CNC mill which is not high quality.

Dave


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## justintime (Jul 25, 2020)

blockmanjohn said:


> I was thinking that it might be possible the new gears may have been machined to a higher standard than the originals. Just a thought, but if it's true it might make a difference.


If anything expect the ball bearing gears to be louder !  Do not for a second believe "Marketing Jargon / Claims"  !


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## Richard Carlstedt (Jul 25, 2020)

John
Forget about gears for a moment
think about a Lathe without gears and only the headstock spindle
Lathes with spindles in plain Bearings (bronze ie) are always quieter than spindles running in either ball or roller bearings . The bronze absorbs vibration where as steel may amplify the vibrations. the spindle turns easier with balls , but not quieter
In plain words its a gimmic 

Your noise is from the gear train and is either wear related or spacing on the Banjo
Some lathes use  "Anti-backlash"  gears in the gear train. These are special gears that are split and spring loaded .
Think of a gear with a 1/2" face ( thickness)- so they make the gear 3/8" thick to do the work , and mounted on that same  gear (radially) is a 1/8 thick gear with springs that force it to be off half a tooth so when engaged with another gear, that tooth slips into position , but keeps all backlash under spring pressure. You might consider it to be a continuous  variable tooth form and that reduces noise substantially 
Rich


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## Richard Carlstedt (Jul 25, 2020)

Edit
I should add that "IF" your bronze bushings are worn, then you do get increased gear noise, but that is fixed by rebushing the gear. Put a indicator on the gear tooth and see if you have more than .001" movement, if so, then it needs rebushing . Any gear on the gear train should have no more than .001" IMHO.
Some people put grease on their gear train to quiet it down, and it works   BUT
That has two problems. It takes more power to turn the gears and on a low powered hobby lathe, it may be more than you want. It also can become a lapping/grinding compound over time as metal dust/chips become mixed with the grease


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