Southbend metric gears

[longtimeshooter]

I have a Southbend Heavy 10 lathe that I would like to be able to cut metric threads on. How many gears would be in a changeover set and other than E Bay where might I look for them. I would appreciate any information from you knowledgeable folks out there.

 

[spitfire_er]

I recently sold my fully restored SB 10L with a metric set NOS. I never used it, but I believe there were 13 different gears in there to get all the metric pitches a guy would need. I just sold a metric chart on eBay not too long ago, if you could find the chart, you can see which gears you need for whatever pitch you need.

 

[Someoldguy]

I'm curious what threads you're trying to cut? Or do you find you need to cut a variety of metric threads?

I find myself needing to cut some metric threads for a 1-time project with a Southbend Heavy 10 and I'm going to try an experiment first. Depending on the outcome, I may do something some here would consider amateurish at best.

But I'm an amateur, so go figure.

 

[GenePoole]

For the SB13, there are 7 stud gears, the 64 tooth drive gear, the 127/120 transposing gear, and a spacer. I believe the SB10L is similar, just a different DP on the gears (unless it is a pre-1950's single-tumbler model).

 

[Dusty Stevens]

Cutting metric threads on a SB may give you an excuse to buy a grizzly gunsmith lathe just so you can have another lathe since you always need one to make a lil somethin after you get a complicated setup dialed in

 

[GenePoole]

The metric gears for a South Bend are about 3 or 4 hundred dollars. Just bite the bullet. You'll make that back with your first AI barrel (OK, maybe two barrels).

 

[pfiori]

The compound gear for the 10L is a 100/127 as it has an 8tpi lead screw, all the other gears are the same. The 10L and the 13 are the same DP.
The single tumbler machines use a different set than the double tumbler machines, I believe the DP is different.
I have a complete NOS set for a 13 if anyone is interested.

 

[paperpuncher]

PMed you

 

[longtimeshooter]

I'm curious what threads you're trying to cut? Or do you find you need to cut a variety of metric threads?

I find myself needing to cut some metric threads for a 1-time project with a Southbend Heavy 10 and I'm going to try an experiment first. Depending on the outcome, I may do something some here would consider amateurish at best.

But I'm an amateur, so go figure.

I'm curious what threads you're trying to cut? Or do you find you need to cut a variety of metric threads?

I find myself needing to cut some metric threads for a 1-time project with a Southbend Heavy 10 and I'm going to try an experiment first. Depending on the outcome, I may do something some here would consider amateurish at best.

But I'm an amateur, so go figure.

I want to cut Sako 1.5 mm threads.

 

[Dusty Stevens]

I want to cut Sako 1.5 mm threads.

You sure theyre 1.5mm? We just went thru this about 2 weeks ago and most are imp threads that appear metric due to internet searches and foreign mfr. if youve already checked then sorry i was just throwing that out there.

 

[spitfire_er]

For the SB13, there are 7 stud gears, the 64 tooth drive gear, the 127/120 transposing gear, and a spacer. I believe the SB10L is similar, just a different DP on the gears (unless it is a pre-1950's single-tumbler model).

Mine was a single tumbler.

 

[longtimeshooter]

You sure theyre 1.5mm? We just went thru this about 2 weeks ago and most are imp threads that appear metric due to internet searches and foreign mfr. if youve already checked then sorry i was just throwing that out there.

Yep the thread gage says 1.5 mm!

 

[Dusty Stevens]

If it was my personal rifle id rethread it to imp threads. If it was a customers rifle i wouldnt have taken it in. My southbends dont thread metric. Check an imp thread gage on it and see if you can make it work with relief cuts

 

[GenePoole]

If it was my personal rifle id rethread it to imp threads. If it was a customers rifle i wouldnt have taken it in. My southbends dont thread metric. Check an imp thread gage on it and see if you can make it work with relief cuts

"Relief cuts"? What do you mean by that? I'm curious how that relates Imperial<->Metric transposition.

 

[SBLH10]

"Relief cuts"? What do you mean by that? I'm curious how that relates Imperial<->Metric transposition.

 

[SBLH10]

A few years back I wanted to do the something, cut a 1.5mm metric thread and I did so with 1 gear. That I had made, a 26 tooth stud gear made for my South Bend Heavy 10 (10L) Have used a few times since then an has always work great and very simple to use.

The simplest way to make 1.5mm thread on the wide range double tumbler 10L is to switch the 40 tooth stud gear for a 26. This causes the gearbox to rotate slower than its normal speed so that the leadscrew acts like it was 12.3 tpi instead of 8 tpi. This is the same as 2.06 mm. The 11 tpi position on the gearbox will then give you 1.5009 mm, for .06% error.
Here is the link to the complete under standing the use the 26tooth stud gear.

http://www.practicalmachinist.com/vb/archive/index.php/t-278105.html
Coyotechet

 

[Someoldguy]

A few years back I wanted to do the something, cut a 1.5mm metric thread and I did so with 1 gear. That I had made, a 26 tooth stud gear made for my South Bend Heavy 10 (10L) Have used a few times since then an has always work great and very simple to use.

The simplest way to make 1.5mm thread on the wide range double tumbler 10L is to switch the 40 tooth stud gear for a 26. This causes the gearbox to rotate slower than its normal speed so that the leadscrew acts like it was 12.3 tpi instead of 8 tpi. This is the same as 2.06 mm. The 11 tpi position on the gearbox will then give you 1.5009 mm, for .06% error.
Here is the link to the complete under standing the use the 26tooth stud gear.

http://www.practicalmachinist.com/vb/archive/index.php/t-278105.html
Coyotechet

I have a Southbend Heavy 10, but it has the single tumbler gearbox. Is the 26 tooth gear only a viable option for the double tumbler gearbox?

 

[GenePoole]

I have a Southbend Heavy 10, but it has the single tumbler gearbox. Is the 26 tooth gear only a viable option for the double tumbler gearbox?

If you have a 40 tooth gear in your geartrain, then substituting for the 26 tooth gear will give you the same ratio change (I haven't checked these ratios; there is a spreadsheet out there that lets you plug in your toot counts and see what substitutions give what ratios).

There are a lot of online calculators too. Maybe something linked here will help:

http://bbs.homeshopmachinist.net/th...-gearbox-to-cut-thread-not-listed-in-QC-chart

 

[Someoldguy]

If you have a 40 tooth gear in your geartrain, then substituting for the 26 tooth gear will give you the same ratio change (I haven't checked these ratios; there is a spreadsheet out there that lets you plug in your toot counts and see what substitutions give what ratios).

There are a lot of online calculators too. Maybe something linked here will help:

http://bbs.homeshopmachinist.net/th...-gearbox-to-cut-thread-not-listed-in-QC-chart

Thanks for the link. I appreciate it.