1930 South Bend Junior Lathe - Back Together

It only took me a couple of months, but it's done.

The South Bend is back together.  Still it's not operational because I am missing a couple of things so far, but the main pieces (headstock, bed, tailstock, and saddle/cross slide) are all refinished and re-assembled.  Back gears put back in, handle on, reverse tumbler checked and re-installed, and the spindle has been re-shimmed.  You should know that the shimming was the toughest part of the rebuild.  Even drilling out the Gits oilers on the apron and bed lead screw were relatively easy in comparison.

I don't know if you've ever made shims, but when you want to really get accuracy, you redo the shims to make sure nothing has any runout.  Installing them is fairly easy.  Making them isn't.

I needed some good accuracy, so I ordered a brass shim kit off of Amazon - this was simply a set of brass sheets, each one of which was a different thickness, e.g. 0.001", 0.0015", 0.002", up to 0.015" .  Considering you have one on each side of the spindle (e.g. "four corners"), the resolution actually comes to about 0.00025" since I knew it would take at least 0.010" since I already had one installed and it wasn't enough.  Different combinations got me to exactly the thickness I needed, and gave me a tight spindle with no play, and the ability to turn the spindle in place.  To me, it had to be exact.

Again, it wasn't the installation of the shims - that's cakewalk.  It's cutting them out.  I took original shims, and essentially placed them onto the brass sheet and outlined them with a fine sharpie, then had to remove the outlined brass from the sheet.

On the smaller thickness sheets, it was fairly easy - I used regular scissors or an exacto knife.  But once the thickness got to 0.004", the exacto knife started to be unable to cut through.  I was worried about scissors being damaged, so I grabbed the tin snips.  Those are hard to manipulate, but they worked.  On the 0.015" thick stuff, making really small and fine cuts puts a strain on your hands.  I cut out 16 of those (both ends of the spindle and both sides), just in case I needed 0.09" of clearance.  I ended up not needing that, but I did it just in case.

Once done, I slapped it all together and had it operating as needed.

Now, all I have left is a motor.  I have an old 1.5HP (continuous duty, 2.5HP momentary duty) treadmill motor, and the speed controller from that (it's an MC2100, not an MC60), so I have to now figure out how to implement that.  Also, I must obtain the proper belts and install them.  At that point, I'll start working on making some change gears out of aluminum, and then it should be fully functional!  Nice to have an old relic back in the land of the living!

Allegory of the Old Lathe

Allegory of the Old Lathe

Courtesy of the Butler 7^th ward LDS Deacons Quorum

I recently acquired an old lathe. I had located the tool through a local classifieds advertisement. I had always wanted a good, solid metal-working lathe, but funds were of the nature that I could not spend thousands of dollars. I was elated to finally have a new tool, so I made the run in order to follow through with the purchase on a lunch break during the work day.

The lathe was in pieces – I was willing to accept it in this state because I thought I could assemble this tool using the many resources available to me, such as books, diagrams, and other materials. As I was under the impression that this was a tool that met the standard measurements, I thought it would be an easy task to locate broken parts. I did not think that there were any missing, and that most parts would be operational. I assumed that I could simply assemble it, and I would have a fully functional tool for the workshop.

Missing Parts

As I began the task of putting some of the parts together, I found some parts were missing. These parts were small, and easily lost. They were integral to the general part known as the tailstock, and would prevent the lathe from being functional without the parts. Their absence immediately stalled my efforts – they were required for the end result. I found a piece of metal similar in size in a pile of scrap, and set to work building that tiny, missing piece. It didn’t take long, and the joy I felt when I was able to fully assemble the tailstock motivated me on to the next task.

Corrosion and Disrepair

There were two general parts of the tool (called the “headstock” and the “saddle”) that had not been disassembled. These two parts were covered in old sawdust. For these precision tools, it is a poor operation to not keep the tools clean and free of debris – and it was clear that the lathe had been abused in this fashion. However, I was very grateful that there was good to be found in the abuse and misuse – the wood had absorbed some oils, and kept parts from corrosion that so often destroys the very parts that make them work.

Full Functionality

At this time, I also realized that there were other missing parts, called “change gears”. These “change gears” serve a very specific purpose – they allow different parts to turn at different speeds. These special gears are used to create bolts, nuts, and screws. I knew they were a big part of this tool, but I also knew that the tool would work without them – there were simply some tasks that I would not be able to do without them.

Back Gears, and Standards

I found one additional part that had been broken as I began to disassemble the headstock. This set of parts was called the “back gears”, and were designed to cause the lathe to turn even slower, allowing someone to work shape metal that was larger in size. On these gears, there were two things that were broken – one of the gears was missing a tooth, and the handle to engage and disengage them had snapped off. Once again, I found myself in a state in which work was stopped.  Through some auctions, I was able to track down an assembly from another lathe that I thought had the same dimensions. I purchased the part, and when I had the part home, I immediately set about trying to replace the broken part.

That part did not fit.

The fact that it did not fit forced me to start looking more closely at the tool I had to work with. I began my research, and found that this lathe for the workshop was purchased on January 24^th, 1930, by the Salt Lake Hardware Company, manufactured by the South Bend Lathe Company in Indiana, U.S.A.

It was manufactured about ten years prior to the standards I had assumed. I was surprised to find that those standards, and this tool, did not meet the same standards. They were simply incompatible. As much as I tried, I could not make parts that didn’t meet the same standards work together well – it would never be fully operational without ensuring all parts met the same standards.

I went to my resources, looking for replacement parts. Finding parts for an 85 year old tool is nearly impossible, and over time, I began to realize that I needed to find a way to repair the original parts. I had some experience welding pieces of steel together – but I also knew that these parts were not steel, they were cast iron, and they cannot be repaired by “welding” them back together. The more research I did, the more I realized that these parts needed special care in the repair. They needed to be pre-heated, then (using a torch) they needed to be heated nearly to a state of melting. In that state, bronze can be used to build the missing teeth on the gear, and to reconnect the handle to the assembly. Once complete, you cannot immerse them directly into water to cool them – they will shatter beyond repair.

I had also found small grooves in the “spindle”, the part of the headstock that rotates. These grooves occur when we fail to properly maintain the tool by using correct oils in the proper places. Worried about these grooves, I took the spindle to a machinist. He stated, “It definitely looks used.” He then performed some checks, and felt that it would not need extra machining – it would be fully operational, even with the scars of misuse. It was at this time that I began the reassembly.

Summary

As I look back on the restoration of this tool, I’ve seen many parallels to life. We are simply “old lathes”.

The machinist who examines are parts is our bishop – he knows the standards we should be living by, and is more than willing to help us examine those parts of our lives that we worry about. He has the tools to measure and ensure we are within the proper tolerances.  Remember, things measured by different standards don't work so well together.

We are the very people performing the restoration on our own lives. This cannot be someone else, for only those of us in position of our lives have access to the missing pieces in our hearts. However, we do not have to do this on our own – we have access to many resources that assist us – our families, our friends, our neighbors, and especially our Savior, Jesus Christ.

As we complete the restoration, our greatest source of repair instructions and replacement parts is our Savior.   He fully understands our capacity. He knows what parts are missing from our lives. For those parts that cannot be found, He, alone, knows how to construct new ones. He knows what is broken, and He knows how to repair those parts that can be repaired. He knows that we can be operational, but not have access to the full capability that we have.  He also knows that we can eventually become fully functional.  As we find missing or broken parts, our best option is to allow the Savior to instruct us, to teach us, and to show us how to make repairs – and the only way to properly repair our parts is to do exactly what He states.

Often, we see the daunting task in front of us, and want to stop – to “throw away” the tool, and just find another. This simply cannot be – we are extremely valuable to our Father in Heaven, so valuable that (even when he knew that every one of us will be broken at some point in our lives) He provided Jesus Christ as the greatest source of repairs.

Another Purchase - Melting Furnace

I know I need change gears.  They are rare.  So, I finally knuckled under and made another purchase for $200 - the Lionel Labs "HobbyMelter Furnace Kit".  I'll have to purchase refractory and install it, but this will allow me to potentially make any gears I need.  Woohoo!

http://www.backyardmetalcasting.com/hmkit.html

Lionel Labs - this guy is a genius for the stuff he has completed.  I've been an avid follower, and I've been fairly sad to not really see an update for a number of years - but his work and examples have been amazing and great!

Gearing for my South Bend Junior Lathe

The Formula
Diametral Pitch Calculator
Calculating Gearing for a Specific Threads-Per-Inch
Calculate Threads-Per-Inch from Two Gears

I finally had an opportunity to look at some measurements for change gears.  I knew I needed to - I had seen multiple types of gears for things labeled "original South Bend".  Some were 18DP (diametral pitch), while rare ones were 16DP.  Some had 9/16" bores, while some had 5/8" bores.  The 16DP 5/8" bore change gear sets are rare on eBay (I've been watching, just in case).  There were some 18DP 5/8" bore gear sets, and 18DP 9/16" bore gear sets, but I have yet to see a set of 16DP 5/8" bore sets since I have had the lathe.

Rumors abound that my lathe was the 5/8" bore 16DP gears.  I believe in the mid 1930's, they started moving to the 18DP gears, and then changed the bore at the end of the 1930's when they introduced the "workshop" and "toolroom" models.

I knew I needed to make sure, just in case I saw them, so that I could buy them the spot.

So, I had to grab some measurements.  I needed to identify the diametral pitch of the gear.  You do this by obtaining the number of teeth on the gear, and the diameter of the outside edge (where the teeth get to, not the bottom of the teeth).  The stud gear that drives the idler gear is 1 and 1/8" across, and there are 16 teeth on it.  The bore is (indeed) 5/8".  The formula is :

Diametral Pitch =	(Number of Teeth + 2)
	Diameter of gear in inches

This gave me :

Diametral Pitch =	(16 + 2)
	1.125

And that resulted in a 16DP gear.  Now, when it comes to gears, there are a whole lot of equations.  However, one other field that is required is called the pressure angle.  Fortunately, I believe South Bend only made 16DP gears in the standard 14.5 degree pressure angle, so that tells me exactly what I need to know :

Diametral Pitch :	16
Teeth :	16
Diameter :	1.125
Bore :	5/8"
Pressure Angle :	14.5

Now I just need to buy the set when the rare show up, or cut my own.  I did find out how to determine the pitch based on the gearing, using an old threading chart :

Here's the formula, spot checked all over that threading chart :

Thread Pitch =	screw gear teeth	* 8
	stud gear teeth

For example :

30 =	60	* 8
	16

As a result, you can create a new pitch not listed (e.g. a metric pitch) by plugging in a few numbers until you get rounded numbers, e.g. a 39 threads-per-inch would be :

39 =	78	* 8
	16

So, if I wanted to cut 39 TPI, I'd slap a 16-tooth gear on the stud, and a 78-tooth gear on the lead screw.  Isn't math, science, and engineering fun?  FYI, I threw it into a fast chunk of perl to find that 39TPI, just for kicks :

my $tpi = 39;
my @try_first = (64, 32, 16, 20, 44, 48, 72, 56, 40, 80, 72, 52);
my $stud_gear = undef;
my $screw_gear = undef;
my @stud_gears = @try_first;
my $gear = 16;
while (!defined($screw_gear) && (!defined($stud_gear))) {
  my $stud = shift(@stud_gears);
  if (!defined($stud)) {
    $stud = $gear;
    $gear++;
    if ($gear > 80) {
      $screw_gear = -1;
      $stud_gear = -1;
    };
  };
  my $screw = ($tpi / 8) * $stud;
  if (int($screw) == $screw) {
    print "screw = $screw, stud = $stud = $tpi TPI\n";
  };
};

I know it's lazy code, and rather poorly done, but for an 8-minute "see if I can make it work", it did pretty good! Not the best, but it worked as well as intended.

I also threw the above code into some javascript to see if I could do this in the blog, and it does work :

Diametral Pitch
Outside Diameter	:
Number of Teeth	:
Diametral Pitch	:
Circular Pitch
Circular Pitch	:
Pressure Angle
Base Pitch	:
Pressure Angle	:

Calculating Gearing for a Specific Threads-Per-Inch
Yes, I am editing this blog post - because I thought, "If my dad asks if I can cut a screw for him on his old car, can I calculate the gears to make it happen?" That blossomed into the desire to add a calculator for what gears would be needed on the web, specific to the South Bend Junior.

Threads-Per-Inch :

*note - this could take a while, and may look like the browser locks up*

 

Calculate Threads-Per-Inch from Two Gears

While I was at it, I thought I'd throw one more calculator onto the post - one to get the threads-per-inch when given two gears.

Screw Gear :
Stud Gear :

And something to take two gears and calculate the TPI.

Test Run - Brazing Lathe Back Gear Handle

When taking apart the headstock, I finally noticed two big issues :

1. The bull back gear had a tooth that was missing
2. The handle had broken off

To "fix", I could simply watch eBay for items to come up that would match an original 9" Junior lathe.  Standard 9" South Bends (models A/B/C) would not fit - trust me, I found one on eBay for $20, ordered it, and (when I received it) found the bore through the handle to be offset, and about 1.5 times the size of the original "Junior".

Here's what this means.  I have to fix it, or wait.  The parts are slow to come by - they are a tad bit rare.  I have a second lathe, and had a welder repair a crack in the bed - he brazed it.  So, I thought, "I might as well try it."

I slapped a 2x4 into the wood lathe, and turned down a brace to hold the "newer" model handle.  I didn't want metal, because to would end up being brazed into the handle.  It fit great.  I grabbed some brazing bronze rods from home depot, took them home, and slapped the part into the oven to pre-heat it.  After a half hour, I pulled it out, pressed it onto the wood brace, and fired up the small torch to get it red hot.

After about 40 minutes, I knew it wasn't going to work.  Turns out, when I fired up the "small torch", it was too small.  By the time the handle got warm enough, the wood I wanted to use as the drill marker for the new hole was burnt.  I've tracked my cutting/welding torch down, but I need regulators, hoses, and (hrmmm) acetylene and oxygen.  I have tanks for them with the MIG welder, but they're empty.

So, I bit the dust on that try.  I happened to find one on eBay after this attempt, so I bought it.  That doesn't mean I won't try this again.  Shoot, I believe I can make a temporary handle out of a bushing and a bolt (drill a hole for the taper pin, and drill a hole half-way through, thread it, and throw a bolt in to use as a handle), so using this handle isn't necessary.  I'd at least like to repair the gears so that I have a back up.  If one tooth can break on the gearing, I expect I can easily break another one.

South Bend - To Be Done

As I've tackled the South Bend 22YB "Junior" lathe, I've found a few things wrong.  Inside the spindle bushings, I found some small grooves in the spindle :

Also, the handle had broken off on the back gear, as well as a missing tooth on the "bull" back gear.  I'll try to braze fill a "tooth", and I picked up a handle for a "workshop" 9 back gear.  The handle doesn't fit (hole too big), but if I'm brazing it, I might as well fill the hole in that handle and use it anyway.  That's my next focus.

Plus, I need to identify a clamp - I'm not sure where this one goes :

We'll see what happens!

New South Bend 9"x19" Lathe

Just picked up a new toy, a South Bend 9"x19" (the 19" is between centers, not the whole bed length).      Someone had already started to rebuild it, and I picked it up for a song, but in pieces :

You will notice that I've already put the tailstock back together, and I've taken apart the cross-slide and compound.  In fact, the compound assembly isn't even in the picture because it's being warmed up in the house in preparation for paint.  The cross-slide went back in after taking the picture.

It is true that there is no associated countershaft - the previous owner to the last owner lost it, along with the change gears.  I do need change gears, but I should be able to work without the countershaft by using a variable-speed DC motor.

I found the serial number in the usual place (tailstock end of the bed) :

The serial number found on the lathe bed is 47049A.  The "A" is supposed to indicate a gear change box, but there isn't one, and never was - the screw holes are not included for the gear change box on the bed itself. This is simply because the lathe is tool old - the "A", "B", and "C" designations came a year or two later.  The gentleman I bought it from stated he got it from his Father-in-Law, and his Father-in-Law picked it up from a Dental company for fairly cheap.  The Father-in-Law also used it to turn wood (actually, to my happiness - the wood kept oil in places it needed to be, keeping it in fairly decent shape).  That is all I knew, so I had to do a little more research.

I started to grab some details.  Grizzly (manufacturer of some small lathes) purchased South Bend Tool Company a few years back, and offers a service where you can obtain the "serial card" for old South Bend Lathes in PDF format (just $25).  This card typically offers more details and specifications for the lathe, including what options and accessories were purchased with it.  However, if yours is as old as mine is, be aware you might not get anything but a "ledger line".  Here's what Grizzly was able to provide for that $25 (and yes, I believe it was worth it as it gave a model, a sales date, and the company it was sold to).

Mine didn't wander terribly far from home.  It was purchased by the Salt Lake Hardware Company on January 24, 1930.  It is actually considered a 9x3 (9" swing, 3' bed), so the original dimensions from South Bend are full bed length, not between centers.  The model is 22YB (which is also called a "Junior").  In 1948, South Bend copied those ledgers onto Serial Cards, but didn't add any information (obviously, 18 years later, they won't be able to add details).  Incidentally, Grizzly was kind enough to not just send the ledger row in PDF, they also sent a slightly more legible serial card in PDF along with it :

Model 22-YB information :

From the catalog, we read "The 9-inch Junior New Model Precision Lathe ... is driven from an overhead countershaft which is bolted to the ceiling and connected by belt to the mineshaft.  We recommend the Countershaft Drive Lathe for the shop that is already equipped with lineshafting from which other machines are being operated.  The Junior lathe in the 3-foot bed length is the most popular size.

"Handles Wide Variety of Work.  The New Model 9-inch Junior Back-Geard, Screw Cutting Precision Lathe machines all kinds of metals and has the power and accuracy required for fine precision work.  It has automatic longitudinal feed and a wide range of spindle speeds.

"Cutting Screw Threads.  An index plate is attached to each 9-inch Junior Lathe and shows the correct change gears to use to cut all standard screw threads from 4 to 40 per inch, right or left, including 11 1/2" pipe thread, as follows : 4, 5, 6, 7, 8, 9, 10, 11, 11 1/2, 12, 13, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 36, and 40.

"FEATURES OF LATHE

• Back-Gears headstock gives six spindle speeds.
• Hollow spindle made of special alloy steel
• Phosphor bronze bearings for spindle.
• Graduated compound rest swivels to any angle.
• Precision lead screw for cutting accurate threads.
• Micrometer collar on cross feed and compound rest screws.
• Tailstock set-over for turning tapers.
• Quick-acting spring latch reverses carriage travel.
• Automatic longitudinal power feed to carriage.
• Graduated tailstock spindle.
• Spindle cone pulley balanced for operation at high speeds.

"The Lathe Equipment included in the price of Lathe consists of: Double Friction Countershaft, Face Plate, Tool Post Complete, two Lathe Centers, Spindle Sleeve, Wrenches, Lag Screws and Washers, and a set of Change Gears for screw thread cutting and for feeds, also Installation Plans and book, "How to Run a Lathe."  The hard maple bench for Lathe is extra."

Original Price	:	$169
Swing	:	9 1/4"
Bed Length	:	36"
Between Centers	:	16 3/8"
Hole Through Spindle	:	3/4"
Swing Over Carriage	:	6 3/8"
Width Cone Pulley Steps	:	1 1/4"
Power Required	:	0.25HP
Weight Crated	:	375 lbs
Countershaft Speed	:	255 RPM
Spindle Speeds	:	39, 64, 110, 208, 348, and 596 RPM
Width of Cone Pulley Belt	:	1 1/4"
Acme Thread Lead Screw	:	3/4" 8 pitch
Size of Lathe Centers	:	No. 2 Morse Taper (MT2)
Screw Cutting Range	:	4 to 40 per inch
Draw-in Collet Chuck Capacity	:	1/64" to 1/2"
Cross Slide Travel	:	7 1/6"
Size of Tool Shank for Tool Post	:	11/32" by 13/16"
Double Friction Countershaft Pulleys	:	6 7/8" x 2 3/16"
Back Gear Ratio	:	5.4 to 1

More About This One :

This was (apparently) a custom build by South Bend around early 1930.  It partially had the original black "japanning" finish on it - the bed did not because the previous owner had removed and repainted the bed - I'll finish the refinish that way to get it to match, though I don't want to.  It came from previous owners with an 8" Cushman chuck (Ref No. 6234A), tailstock, apron (for power feed), cross feed, tool post, and tool holder, but no counter shaft.  The headstock has an opening around the threaded area that is 0.926" wide, which equates to about a morse taper 3 (MT3).  The headstock threading for the chuck is 0.775" long (not even an inch), and I count approximately 5.5 to 6 threads, which is approximately 8 TPI, with a 1 1/2" diameter of the spindle.  The tailstock has an opening about 0.694", which equates to a Morse Taper 2 (MT2).

Here's my shopping list :

• Counter shaft (or a DC, variable motor, since my southbound has a pulley ready for both a v-belt and a flat belt).
• A milling attachment Base (South Bend part number pt825nk2).
• Milling attachment Saddle (South Bend part number as826nk2)
• New tailstock drill chuck
• New tailstock live center
• Tooling
• Reversed jaws for the chuck.

Though it's often considered bad idea to turn wood on a metal lathe, I was actually very happy that the previous owners Father-in-Law turned wood on it.  The lathe parts were coated in a soft wood-oil combination, preventing rust in all of the wrong places.

I have already dismantled the Cushman 8" chuck (not reversible jaws), cleaned the old metal chips out, greased it with a nice Molybdenum grease, and re-assembled it.  Seems nice and smooth.

The tailstock handle was missing the pin that held it to the actual tailstock ram screw, so I shot to HomeDepot and grabbed a 1/8" steel rod, took it home, cut two inches off, and chucked it into the drill.  Using a file, I "turned" it down to the size required.  That let me throw the tailstock together :

Additionally, I've cleaned up the apron, repainted, and rebuilt.  There is one thing left to to with that - replace the oil cup on it for the hand wheel.

Next up is to finish the cross slide, compound, and tool posts, put them back together, and to get them installed.

After that, it's time to check the headstock and rebuild it.  I know they offer kits on eBay for rebuilding this, but it's so old, this one doesn't have any felt seals for the bed.  It's going to be a matter of keeping it clean while working on it.