Single lever or dual lever heavy 10 gearbox?

Mr_Bill · Sep 6, 2015

I am in a unique position. I have parts from two South Bend Heavy 10 lathes therefore I have the choice of a single lever or a dual lever gear box. I would like some reasons to chose which one to keep. Both are 4 TPI to 224 TPI. I do some metric threading and that may play a part in the decision. As I understand it the gears to make the dual tumbler gearbox do metric are more readily available? I will real and take your responses into consideration when making my decision. lets assume that I have everything necessary to make this conversion.

Thanks

Bill in Cincy

kitno455 · Sep 6, 2015

I had a single tumbler 10L that was missing its end gears, banjo and cover. I swapped to a double tumbler, mostly because I occasionally make a metric thread or DP/module worm.

allan

abarnsley · Sep 9, 2015

Single tumbler QC boxes do metric threads, just as double tumbler.

Friend has a single tumbler 14.5 SB . A search through SB forum should bring up some info.

Different set of metric conversion gears is all that is required. Gears can be bought or made. Might be a bit harder to find, but you only need to find them 1 time..

SB had factory single tumbler metric conversion kits with gears and thread charts.
DP pitches can also be done, it just takes some digging for the old info..

I think the double tumblers are a bit stronger gear wise.. But no hogging going on with a Heavy 10...

Which box is in better shape??, and are modifications/fitting needed? Lathes are not bolt together animals.

They were hand assembled/fitted in small lots, over decades of production.

Mr_Bill · Sep 10, 2015

abarnsley said:
Single tumbler QC boxes do metric threads, just as double tumbler.

Friend has a single tumbler 14.5 SB . A search through SB forum should bring up some info.

Different set of metric conversion gears is all that is required. Gears can be bought or made. Might be a bit harder to find, but you only need to find them 1 time..

SB had factory single tumbler metric conversion kits with gears and thread charts.
DP pitches can also be done, it just takes some digging for the old info..

I think the double tumblers are a bit stronger gear wise.. But no hogging going on with a Heavy 10...

Which box is in better shape??, and are modifications/fitting needed? Lathes are not bolt together animals.

They were hand assembled/fitted in small lots, over decades of production.

well i have one of each complete lathes. the one with a double lever is in better shape and is together at the moment.

swatkins · Sep 10, 2015

I really like my single lever for the ease of use.
The small upper lever lets me have three different feeds ( fast, medium and slow) with just a simple move of the lever using only my left hand.

Ohio Mike · Sep 11, 2015

Mr_Bill said:
well i have one of each complete lathes. the one with a double lever is in better shape and is together at the moment.

There's your answer

BBQ BOB · Jun 11, 2020

I’m looking for a. Single lever for a 10 L heavy the handle broke during shipping I have one complete gearbox a guy sent me but deliver was broken on it also I would be willing to get rid of

texasgeartrain · Jun 11, 2020

I'm not familiar with heavy 10's. But both my 16's use single tumbler. As I am used to using it I like it.

But On 16's, the gears on double tumblers are better supported, where on a single tumbler, the gear on single tumbler is only supported on one side.

How are the gears on tumbler arms supported on heavy 10's ?

hitandmiss · Jun 12, 2020

swatkins said:
I really like my single lever for the ease of use.
The small upper lever lets me have three different feeds ( fast, medium and slow) with just a simple move of the lever using only my left hand.

I use the upper lever a lot.
I work with collets most of the time. There is lots more room for the micrometer carriage stop with the single lever.
The adapter to sort of create the same amount of room on the double tumbler with the "newer" carriage stop, it is very cumbersome, and frequently needs to be taken off for clearance.
The old style carriage stop that was user modified before I got the machine has a wedge shaped cutout on the left side that allows it to snuggle up 1/4" closer to the head stock than normal. It is tucked out of the way for almost everything.
The wide range gearbox covers this critical area of the bed and prevents close to the spindle operation using a carriage stop.

So use both lathes, if you are working with a chuck and never use collets, than either one will fill the bill.
But if extensive collet use is expected, I would mount the single lever box on the better lathe.

Bill

SLK001 · Jun 13, 2020

You don't say which double tumbler gearbox you have. I would use the double tumbler (especially if it is the wide range version), simply because it is easier to use. Both can cut metric threads. The double tumbler can mount the 127/100 combo gear directly on the existing gear studs and it fits under the current end gear cover. The single tumbler requires a special banjo to mount the combo gear (it came with the special banjo in the factory metric conversion set) and requires a different end gear cover to cover all the gears (also included in the factory set).

DISCLOSURE: My H10 has the wide range double tumbler GB. I don't recall ever using a single tumbler GB.

Erich · Jun 15, 2020

My bench mount heavy 10 has the single tumbler gearbox AND it shipped with the metric transposing setup.
Somewhere along the way the metric banjo and combo gears were replaced with standard English stufff.
But the larger cover is still there. There is also a cutout in the drip pan AND a cup mounted under the cutout. This provides a leak proof clearance for the 127T gear.

Vandegraaff · Jun 27, 2020

I have the single tumblr and my gearbox looks new once I cleaned it up. No visible wear. Problem with this design, and I'm guessing its why SB changed over to dual tumblers, is the top lever, for Left-Center-Right, is difficult to get engaged especially to the left position. This is because it uses maybe just 6 detents, 60 deg separation, so you have to move chuck quite a bit sometimes to get it engaged. Little better going to the right. IMO this design needed improvement and that's what it got with dual tumblr.

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Single lever or dual lever heavy 10 gearbox?

Mr_Bill

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kitno455

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abarnsley

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Mr_Bill

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swatkins

Titanium

Ohio Mike

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BBQ BOB

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texasgeartrain

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hitandmiss

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SLK001

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Erich

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Vandegraaff

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