South bend 117C restoration

[TRC]

I'm doing a restoration of what I presume is a 117C 16x36 lathe (I sent the serial code to Grizzly, maybe they will clarify that). Every part is there, except the original motor. One of the way is slightly worn, so I guess the previous owner hasn't oiled it in a while. Other than that, everything seem fine. However I need to get it running asap, and I was planning to immediately fix the spindle, the underneath motor assembly and the carriage.

I wanted to know three things related to the restoration and a few thing related to possible modifications:

-If I was to neglect the underneath motor, could it lead to permanent damage of the parts, should the bearing be worn? I do not have the mean to take the upper half of the lathe off and I would prefer not have to crawl onto the floor to disassemble, only to spend hour crawling on the floor to reassemble it, if I can even remove them since there is very little space for that.

-What grease does it take for the spindle cone assembly? The lubrification chart recommend to check the manual, but these weren't built as sturdy as these lathe, so I don't have one.

-Can the compound rest screw be replaced with an homemade one, or is it too precise of a piece for an old lathe? There isn't any dials on the saddle wheel. That probably lead the previous owner to use the compound rest to to the heavy work. That lead to a situation where there is a huge backslash onto the compound, but very little backslash while moving the entire carriage. I'm planning to get a DRO on this thing, but I'd rather not install one for this movement.

As for the modifications:

-I'm planning on getting the spindle spin around 3000 rpm, about the triple of what the lathe was built for. Would the current frictionless bearing allow such as speed without damaging the original or hard to replace parts? I don't want to be the morron putting this machine in the grave after a stupid mistake, so I will figure out if it's not safe.

 

[texasgeartrain]

You can't do 3000 rpm on this lathe. That'd be super dangerous. Probably grenade and throw hunks of cast iron everywhere.

South Bends are generally rated in the vicinity of 1000 rpm top speed. You might be able to push that slightly higher for some finish work, but you could never run that all the time. I'd probably only ever do 1200 max, and i wouldn't want it there all the time.

 

[TRC]

You can't do 3000 rpm on this lathe. That'd be super dangerous. Probably grenade and throw hunks of cast iron everywhere.

South Bends are generally rated in the vicinity of 1000 rpm top speed. You might be able to push that slightly higher for some finish work, but you could never run that all the time. I'd probably only ever do 1200 max, and i wouldn't want it there all the time.

That what I feared. I guess I'll have to try turning somme small diameter at low speed and see what the finish look like.

Just to know know, what component are limiting this speed?

 

[animal12]

The headstock with the plain bearings is the elephant in the room
animal

 

[TRC]

The headstock with the plain bearings is the elephant in the room
animal

Are these plain bearings? They used oil, are they not frictionless bearings?

 

[texasgeartrain]

The spindle with the cone pulley are quite heavy, verse just the the two bearing caps of headstock.

There is oil, but it is wiped along the journal, not oil pressure. Running at top speed of about a 1000 rpm, the temp will rise slightly on chuck side bearing cap. Pushing 2000-3000 rpm I'd expect it to lock up and throw pieces.

High speed lathes are going to have roller or ball bearings.

Pushing those speeds you need to be aware of chuck's rated speed too, or use collets.

You can do very nice work on this lathe, but you'll need a variety of lathe tools for certain finishes, use emery clothe, etc for better finishes.

 

[TRC]

The spindle with the cone pulley are quite heavy, verse just the the two bearing caps of headstock.

There is oil, but it is wiped along the journal, not oil pressure. Running at top speed of about a 1000 rpm, the temp will rise slightly on chuck side bearing cap. Pushing 2000-3000 rpm I'd expect it to lock up and throw pieces.

High speed lathes are going to have roller or ball bearings.

Pushing those speeds you need to be aware of chuck's rated speed too, or use collets.

You can do very nice work on this lathe, but you'll need a variety of lathe tools for certain finishes, use emery clothe, etc for better finishes.

I'll see what result I end up at 1000 rpm. I don't wanna damage it badly or have it seize.

As for the underneath, I'll make a new thread, I have some issue.

 

[wood2steel]

TRC, take a breather on the urgency to get the SB flying again. It appears a number of things have been neglected on your lathe and more issues will show up. Forget the high speed operation; your tooling will give you the finish you want; not the speed. Sleeve and thrust bearings on your headstock will build up heat quick past a certain point. You definitely need to pull the spindle shaft and cone pull apart to clean out the old gunk( then add silicone grease) and check for wear which will cause issues soon after you get her running. I have rebuilt several 1940's era SB 16's ---bored and bushed those step pulleys as well as the lower drive unit( line bored and bushed) and have rebuilt gear box units due to gear shaft wear. You will see all these areas come to light if not addressed now. PM if you need to see any photos of those rehabs.

 

[TRC]

TRC, take a breather on the urgency to get the SB flying again. It appears a number of things have been neglected on your lathe and more issues will show up. Forget the high speed operation; your tooling will give you the finish you want; not the speed. Sleeve and thrust bearings on your headstock will build up heat quick past a certain point. You definitely need to pull the spindle shaft and cone pull apart to clean out the old gunk( then add silicone grease) and check for wear which will cause issues soon after you get her running. I have rebuilt several 1940's era SB 16's ---bored and bushed those step pulleys as well as the lower drive unit( line bored and bushed) and have rebuilt gear box units due to gear shaft wear. You will see all these areas come to light if not addressed now. PM if you need to see any photos of those rehabs.

I sent you a PM (or a conversation).

Don't worry, I gave up on the speed aspect the moment I was told these bearing where plain bearings.

I thought they where fluid bearing, and that the only thing I had to do to maintain precision at higher RPM was to use a more thicker oil. Maybe I will do the engineering work to check if it would be possible to convert later on. It would be nice to have these lathe from the 40's catch up with the more recent ones. There definitely is enough place in there to fit the required gearings, only issue is the bearings and the chucks that are no longer standardized.

 

[texasgeartrain]

Don't worry, I gave up on the speed aspect the moment I was told these bearing where plain bearings.

Some food for thought: The South Bend 16" is my favorite of the South Bends, not just because I own one .

Across most of the South Bend spectrum of sizes, most are rated in that 1000 rpm range. The 16" is heavier, and with the weight, more rigid. Also, the wingspan of saddle is longer, and heavier, which contribute to greater rigidity. You also have a slightly better HP at an original spec of 1.5 to 2 hp. Another additional plus to the 16", the way surfaces, and contact surfaces are wider than its brethren.

At a weight of 2600 to 2800 lbs, it's heavy, but manageable in a home shop. And the electrical power requirements to run are also manageable. Also the simplistic nature of design make it easy to operate, repair and understand. All the while doing very very nice work !

I can also tell you I do very nice work below 1000 rpm. Most work I do on my SB 16", I operate between 300-500rpm. One trick is to use material that has a high machinablity rating. Material that is hard to machine, is always going to be tough, no matter the speed. The other trick is the right tools with the right cutting edge.

Part 1 of 2. . .

 

[texasgeartrain]

Part 2 of 2:

All that being said, keep in mind that South Bend was the economical lathe of the time period. Where lathes from Monarch, American Tool Works, Pratt & Whitney and such were the high end, big dollar lathes. Of those, really only the Monarch 10ee was pulling high speeds at 3000 to 4000 rpm. And its bed size is somewhere between a Heavy 10 and a South Bend 13", though weighing about 3000 lbs due to its heavy base.

If you look at those manufactures 16" lathes, the weight was typically doubled over the South Bend 16", usually between 5500 and 9000 lbs. Gear head lathes, and with roller bearings for spindle. . .yet most spindle speeds still below 2000 rpm into the late 1950's. And we are talking real precision high end lathes. Some examples:

Pratt and Whitney model C 16", 1000 rpm:

Pratt & Whitney Co. - Publication Reprints - Pratt & Whitney Model "C" Lathe Brochure | VintageMachinery.org

Monarch's 16" Series 60/61 of the mid 1950's was 1000 rpm.
Late 1950's into the 60's, Monarch 612, model 1610 16", 1500 rpm:

Monarch Machine Tool Co. - Publication Reprints - Monarch Turning Machines | VintageMachinery.org

An American "Pacemaker" 16" late '50's 2000 rpm, prior to that 1800 rpm:

American Tool Works Co. - Publication Reprints - American Tool Works Precision Tool Room Lathe Bulletin #110 | VintageMachinery.org

All in a time period, where here in the US we were doing very high quality work, and skilled craftsmanship. Point being, the fact that South Bend kept right on making the same lathe deep into the 1970's is telling.

 

[TRC]

Part 2 of 2:

All that being said, keep in mind that South Bend was the economical lathe of the time period. Where lathes from Monarch, American Tool Works, Pratt & Whitney and such were the high end, big dollar lathes. Of those, really only the Monarch 10ee was pulling high speeds at 3000 to 4000 rpm. And its bed size is somewhere between a Heavy 10 and a South Bend 13", though weighing about 3000 lbs due to its heavy base.

If you look at those manufactures 16" lathes, the weight was typically doubled over the South Bend 16", usually between 5500 and 9000 lbs. Gear head lathes, and with roller bearings for spindle. . .yet most spindle speeds still below 2000 rpm into the late 1950's. And we are talking real precision high end lathes. Some examples:

Pratt and Whitney model C 16", 1000 rpm:

Pratt & Whitney Co. - Publication Reprints - Pratt & Whitney Model "C" Lathe Brochure | VintageMachinery.org

View attachment 368177

Monarch's 16" Series 60/61 of the mid 1950's was 1000 rpm.
Late 1950's into the 60's, Monarch 612, model 1610 16", 1500 rpm:

Monarch Machine Tool Co. - Publication Reprints - Monarch Turning Machines | VintageMachinery.org

View attachment 368181

An American "Pacemaker" 16" late '50's 2000 rpm, prior to that 1800 rpm:

American Tool Works Co. - Publication Reprints - American Tool Works Precision Tool Room Lathe Bulletin #110 | VintageMachinery.org

View attachment 368182

All in a time period, where here in the US we were doing very high quality work, and skilled craftsmanship. The fact that South Bend kept right on making the same lathe deep into the 1970's is telling.

I didn't knew that. I'll see what I can do at 1000 rpm.

The thing is that I need to turn some 3mm shaft, with groove going all the way down to 2mm. I had to choose between this thing and an import mini lathe. The mini was probably the most adequate machine for what I need, but I went for this because it was about the same price for a more polyvalent machine that seem to be in near operational conditions. I'm pretty sure It's gonna last me a while, unlike the mini lathe.

In the worst case, I can just mount my lathe tools on my mill and get a nicer finish on the important surface if the diameter is too small and rectifying is not an option.

 

[neanderthal mach]

For work that small with a lathe of your size and it's restricted rpm limits, then you need to think outside the box a bit and go looking for information you don't already know about. And your certainly not the first that has issues that the available equipment isn't suitable for whatever your trying to do. That person was probably the one who made the very first tool mostly by accident. Machining is all about and literally a series of problem solving tasks. And the industrial revolution has had at least a few century's ahead of you to do exactly that. There mostly designed for milling tasks, but speed multipliers or in North America, normally called spindle speeders are available. It takes the available rpm and multiplies it through internal gearing between 4-8 times depending on the type and model of speed increaser. Very expensive new or used, and mostly outside of what home shops have the budget for. There's also sub spindles electrically driven and/or air turbine versions that can go 40K - 60K + for rpms.

Sort of useless information for you because of there cost for any of those options, but still important due to the concept of getting a method of speed multiplication. At the more budget level though, there's at least this, http://www.hemingwaykits.com/acatalog/Speed_Increaser.html To make it workable for your lathe? You'd probably need to sleeve the head stock spindle down to whatever male Morse Taper you'd chose for that speed increaser and with possibly some redesign work to accept one of the smaller ER collet sizes for the actual work holding. I haven't seen there drawings, so I'm unsure of exactly how it's set up. At the tail stock end, then a step down MT-MT sleeve would again be required to use smaller drill chucks and live centers. Any direct fit drill chucks and centers you already have will just create interference and tiny tool holding issues for machining parts that small. Then add some part size suitable cutting tools to the unmodified carriage, cross and top slide to use them in there normal functions. Overall there's then nothing all that costly to adapt what you have to what you need without any permanent modifications to the lathe. The only question is just how bad do you want that capability and what amount of effort are you willing to go to and get it? If machining was easy, any lazy idiot could do it. Yes a small lathe designed for small work would obviously be better, your needing what will work not what the most ideal and best solution is.

Even easier, places like Little Machine Shop in California sell ready to go versions of what's known as an X2 mill head and motor. One of those aligned to your lathe ways and bolted to a steel block that's in turn bolted down to the ways with it's spindle C/L at the same elevation as your SB's head stock C/L would do about the same. Add a ER 32 collet chuck and collets and you'd have about the same for a bit less effort but a bit more money. Your speed limitations simply aren't a factor if you understand how to logically think your way around them.

The rest of your questions can't be simply answered because there a lot more complex than they seem depending on just how much you already do or don't know. And I'm a bit too lazy to go into that much detail right now. But I've seen everything already answered multiple times on various forums. Some quality time, a bit of work and Google searches will get everything you asked about answered and more. But as a start, Google bearing codes and what they mean, if your motor bearings are bad you'll need that info. Then Google about how to replace electrical motor bearings. Unless it's about something fairly obscure, I rarely ask questions on any forums now because it's much faster and easier to just do your own research.

 

[TRC]

For work that small with a lathe of your size and it's restricted rpm limits, then you need to think outside the box a bit and go looking for information you don't already know about. And your certainly not the first that has issues that the available equipment isn't suitable for whatever your trying to do. That person was probably the one who made the very first tool mostly by accident. Machining is all about and literally a series of problem solving tasks. And the industrial revolution has had at least a few century's ahead of you to do exactly that. There mostly designed for milling tasks, but speed multipliers or in North America, normally called spindle speeders are available. It takes the available rpm and multiplies it through internal gearing between 4-8 times depending on the type and model of speed increaser. Very expensive new or used, and mostly outside of what home shops have the budget for. There's also sub spindles electrically driven and/or air turbine versions that can go 40K - 60K + for rpms.

Sort of useless information for you because of there cost for any of those options, but still important due to the concept of getting a method of speed multiplication. At the more budget level though, there's at least this, http://www.hemingwaykits.com/acatalog/Speed_Increaser.html To make it workable for your lathe? You'd probably need to sleeve the head stock spindle down to whatever male Morse Taper you'd chose for that speed increaser and with possibly some redesign work to accept one of the smaller ER collet sizes for the actual work holding. I haven't seen there drawings, so I'm unsure of exactly how it's set up. At the tail stock end, then a step down MT-MT sleeve would again be required to use smaller drill chucks and live centers. Any direct fit drill chucks and centers you already have will just create interference and tiny tool holding issues for machining parts that small. Then add some part size suitable cutting tools to the unmodified carriage, cross and top slide to use them in there normal functions. Overall there's then nothing all that costly to adapt what you have to what you need without any permanent modifications to the lathe. The only question is just how bad do you want that capability and what amount of effort are you willing to go to and get it? If machining was easy, any lazy idiot could do it. Yes a small lathe designed for small work would obviously be better, your needing what will work not what the most ideal and best solution is.

That's really educative. Thank you a lot. I'll check on these once I've got the lathe up and running.