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Getting Another South Bend 16x6 Operational

texasgeartrain

Titanium
Joined
Feb 23, 2016
Location
Houston, TX
South Bend Lathe 16x6
Catalog No. 8117C
Serial: 134696
Ship Date: 2/11/1943

I didn't plan on doing a thread for this lathe, as I've already done similar, but I hadn't started a thread in a while and I actually accumulated a bunch of pics, so for your viewing pleasure. . .

I purchased this lathe in 2016, yea time flies I guess. Anyway I had a period where I sort of lost my mind and acquired too many machines. To the point where my shop is the opposite of what I like, which is neat, orderly, and generally pleasant.

To rectify it, figured I better sell some off. As I already have a 16x6 in a South Bend 2H turret lathe, thought I'd run through this one and get it going, and sell it, to clear a little more room.

I was thinking that started almost a year ago. But as I began sorting through pics, turns out I started this in Sept 2018. Memory and time slippage I guess, lol. I work a regular job with a bunch of o/t, so I get to things, when I get to them.

For those interested, the other 16x6 2H turret lathe:
https://www.practicalmachinist.com/...no-2-h-turret-lathe-16-x6-restoration-317814/

As I didn't plan on a thread, some pics may be missing or somewhat out of order. I have some sections complete and will get better pics as I unpack and hang them. For now, I've sorted to the best chronological order as possible.

For the most part, this is a clean, lube, and re-felt. Some repairs and parts replacement. Head and tail stock alignments. No grinding or scraping.

On Defense Plant Corp tag, Note: Good Bay. That stands for the Goodyear tire plant in Baytown, TX. There's also a War Production Tag, but its a little hard to read.

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Not by any coincidence, I started with the quick change gear box. The reason was two fold.

I had a repair in mind for the single tumbler. A repair not only to this tumbler, but to the tumbler in my already operational 2H turret lathe. Though that lathe was complete, I didn't have a way to make this repair during its build.

Now with that lathe operational, I could repair one, swap it to my existing lathe. Then repair that one. Both quick change gear boxes are the same, and both single tumbler.

Here's some pics before I tore it down.

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There's been a bunch of posts over the years about the problems with single tumblers.

In my thinking it falls into two problems. First, outside of the original generation of guys that ran these, I'm not sure other generations knew how or where to lube. Plus failures of tumbler to little internal tube, felts, whatever. It kind of sucks anyway.

Second, was the gear/shaft assembly only being supported on one side. Pretty inevitable, that it's going to wear funny over years of time.

In the first pic, the shaft has a step just below the threads for lock nut. That first step is where gear is pressed on, and its keyed, but key slot must be on other side in pic.

The next step on shaft looks like 1.5" or 2". Its nice and clean looking in pic, now, lol. I had already started the repair as I cut the shaft true again on lathe. I put a nut on threads, and locked nut in the chuck. Then using a drill chuck in tailstock, with pilot drill, I made a pilot hole so I could use a dead center in tailstock to hold it stable.

The shaft portion that rides inside tumbler was wore considerable. I cut it till I had it true the length. Once true, I went back to drill chuck on tailstock. I drilled right up the middle entering the pilot hole with a 7/32" drill bit. My plan being to tap it to 1/4"x28 for a grease fitting.

I then cross-drilled through that new clean cut section with a 1/8" drill bit, to intersect with hole running up middle.

I pulled chuck off lathe, and put a drive plate on. I stuck tumbler up and got it centered best I could, as hole was kind of egg shaped. I then bored it out to true it up, and go a bit oversize. In first pic again, note the piece of brass stock. I cut a piece of that down, pressed it into tumbler. Then bored it out to fit the shaft's new size. I left about .0015" for lube clearance, as well as a center trench in new bushing to hold lube.

One problem I discovered. I can't leave grease fitting in. When shifting tumbler to far right position, fitting is too tall and will hit inside of housing. So I lube, pull fitting out, and put a short bolt in, to keep hole filled.

Once complete, I swapped out with the one on my existing lathe. Did the repair again, and swapped again. Both tumblers done. It works well, and I don't need to lube every lathe use, as the grease stays in pretty well.

I went ahead and finished going through this quick change box. I'll post pics of gear side when I go to mount it.

I'll probably double post this repair to that other thread at some point, for posterity, lol.

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Figured I'd go get a couple pics while it was on my mind.

In the second pic, you can see how close the bolt is to housing. Grease fitting is too tall to leave in all the time.

In my working lathe, the repair made a big difference in gear lash, and noise. It really runs nice. Also the grease stays in pretty well, I only lube it maybe once in every 5 lathe uses.

Thinking of leaving a tag off tumbler as reminder to the next guy, lol.

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That hex head looks wrong in there! Are there no other lubricant choices that would work in this application?
 
That hex head looks wrong in there! Are there no other lubricant choices that would work in this application?

I'm not really in love with the look of bolt head either, but when its mounted on machine you'd have to be on your hands and knees and turn your head up to see it.

As it is, I typically sit on a 5 gallon bucket and reach up to un-screw and insert grease fitting to give it a shot.

Original design was shoot oil in front face hole, seen in post #3, last pic. The hole below tray, sort of to the side of a rivet hole.

Then note post #5, first pic. Oil comes through that bent copper tube, and drops on top of tumbler, if you have tumbler all the way to one side. Tumbler had like 3 to 5 inches of felt wick running through it. So you had to hope oil actually hit exposed wick, and saturated it sufficient.

Also because this particular design, the gear is only supported on one side. It puts unusual stress on bearing and on shaft, and forces push gear at a bit of an angle. So 180 degrees from gear teeth engagement, side of gear actually thrusts into side of tumbler. Because of this, I wanted heavier, lasting lube.

A better upgrade was done by South Bend themselves, it supports gear and shaft on both sides. You can see it in parts pic. But I don't have that upgrade. I was kind of curious to do a repair anyway.

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The bad part about using grease (and the reason why SB didn't use and recommended against it) is that any swarf that comes in contact with grease will be HELD by the grease for all of eternity (almost). This increases the chances that swarf will become jammed between critical parts (such as gear teeth) and cause significant damage. Oil, on the other hand (the recommended oil) will allow the swarf to fall off, significantly decreasing the chance of damage.
 
I was thinking about some smart way to label where to park the handle so I can remember to oil it. Maybe a cool looking plug that sticks out of the fill hole?
 
The bad part about using grease (and the reason why SB didn't use and recommended against it) is that any swarf that comes in contact with grease will be HELD by the grease for all of eternity (almost). This increases the chances that swarf will become jammed between critical parts (such as gear teeth) and cause significant damage. Oil, on the other hand (the recommended oil) will allow the swarf to fall off, significantly decreasing the chance of damage.

Pretty fair point. We don't grease main lead screw to drag a bunch of chips into apron. In a shop where guys might use air blowers to clean machines or shop floors I'd be really concerned. I don't do that though.

In truth, I'm not a big fan of open air gear trains at all. I think I'd prefer a gear head lathe just for those reasons. In the South Bends, besides quick change box, you got the whole gear train off headstock as well. What I've done for both is a mixture of grease and oil. It keeps the gears damp with lube, so I don't end up with rust if I don't work in my shop for a few months, which happens. I kind of hit things hard for a while, then take months off due to job, home, mood, or whatever, lol.

Reduces gear noise as well, and straight oil slings everywhere. No perfect choices really. For house keeping, I use brushes on machine to clean chips, and only broom on floor.

I was thinking about some smart way to label where to park the handle so I can remember to oil it. Maybe a cool looking plug that sticks out of the fill hole?

Newer replacement thread charts for single tumbler gear boxes actually have that note. The originals did not. But also, I think tumbler position number in note, was incorrect for most or needed adjustment, memory is a little fuzy.

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The next sub-assembly I went after was the apron. Besides being filthy and filled with sludge and debris, I knew it had a bunch of worn out parts.

The end play on worm gear was crazy excessive, felt like a solid 1/4".

Just visually I could see half nut threads wore down like razor blades.

And main pinion gear, to drive saddle/apron up and down ways, the gear teeth were heavily wore.

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Before I got apron totally apart, I ran into a problem of a stuck taper pin. Pretty much like jmdriller41 on his cone pulley. For me it was getting taper pin out of gear, which goes through main pinion gear assembly, I mentioned above. Though I didn't crack gear, the hole was wasted.

It was a true SOB. In the end, I drilled taper pin on both sides of gear, and brute force drove shaft out with hammer and a drift pin, through that gear.

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Much like suggested to him, I turned gear in apron 90 degress, drilled a new hole, and ran taper pin reamer through it by hand. I put pinion shaft assembly in apron through gear to drill hole, to get gear position on shaft correct. Once drilled, I removed them and used reamer on the bench. After assembly, you can see old hole 90 degrees out.

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As far as taper pin hole repair goes, I was sort of lucky. I was replacing pinion gear/shaft assembly anyway. The new one would need to be drilled and reamed anyhow.

A better look at old pinion:

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Note the "S" stamped on gear. The S signifies "standard". There are optionally different size pinion gears to mate to rack, which you use to drive saddle/apron up and down ways.

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Over time, as ways, and the saddle's mating surface wear, the saddle/apron assembly drop closer to the floor. Sure probably only by thousandths, but as they drop, gear lash between pinion and rack increase. The extra backlash can make handwheel to move saddle/apron back and forth feel sloppy.

One potential fix are slightly oversized gears. I wanted atleast another standard. I contacted Ted, aka SBLatheman, a-g-a-i-n, lol. He hooked me up. He didn't have any standards left, but he had a new plus 30 (+ .030"). You'll probably see me mention him quite a bit in my posts.

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I have not mounted saddle/apron yet. So whether I need to shim rack down a little, or actually shave something off the back side of it, I don't know yet. But I do try to get my gear lash pretty close on this, but without totally removing all back lash.
 
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I just recently dropped rack off bed to paint the bed. While I had it off, I had a chance to clean it up a bit and do a better inspection.

Real pleased with it. Gear teeth are real even the whole length. Not worn like the pinion that runs on it was.

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Part of my reasoning for buying this lathe originally, was that outside of tail stock and compound rest, it was pretty much identical to my other lathe, and they're only about a year apart in ship date. So that any parts or parts accumulation, troubleshooting, etc. . . that one might help me with the other. During the course of this build I feel like that has started to pay off.

In one of the cases with the apron, was the half nuts. When I did one of my first parts orders with Ted, SBLatheman, on my 2H turret lathe, I found out he had NOS(new old stock)half nuts. That lathes half nuts only had minimum wear, but as I had a chance for new ones, I bought and installed them.

Now, in doing this apron, I had a set in much better condition that I could put in. Just need to clean them up a bit.

In the pics you can see considerable difference in thread thickness.

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Another concern on apron I wanted to address was the excessive play on worm gear.

In normal operations, the grand majority of force on worm gear, and it's associated bushings and circle nuts, is one directional. In that nearly all real work, is pushing saddle and cutting tool toward chuck.

Because of that, one bushing and one circle nut are usually always worn hard. The circle nut, doubles as a lock nut, but also as a thrust washer of sorts against bushing.

On my first lathe I had bought 2 new bushings from Ted, but I didn't use them both. So I still had a new bushing on hand.

Reusing the non-worn bushing and nut. I replaced worn out bushing with new. I also flipped circle nut over, to leave worn side out, and put nice flat side toward new bushing.

I had to drill 2 new holes. One is for locking pin for bushing, so it don't spin in the housing.

The other I drilled is through edge of circle nut and through threads of worm gear. That keeps nut in place. I drilled after tightening nut to allow for about .002" oil clearance on whole worm gear assembly. A great improvement over the 1/4" slop it had.

In one pic you see the worn face of bushing, the slot for felt is nearly gone, lol.

In the other pic, you can see worn side of circle nut facing out now.

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Note* the pics in this one particular post are not the parts for this threads lathe. I am just using these 4 pics as visual representation to help explain my last post, for those who may want to know.

The two housing pics are from my first lathe. The two worm gear pics I stole from ebay, lol.

The apron housing has two eyelets in center to hold worm gear assembly. Worm gear assembly goes in and the two opposing circle nuts are tightened to sandwich together against opposing eyelets and bushings.

A potential quick fix to tighten slop. Knock pin out of worn side circle nut. Tighten nut so that there is just a couple thousandths end play on assembly. Use same hole in nut edge, but drill through it, through worm gear threads to knock pin in new location.

In one housing pic, you can see hole for pin in edge of circle nut.

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The rest of apron was pretty standard stuff. Pulled all the gear assemblies and clutch assembly. Cleaned case and all the parts. Re-felted everything with a kit from ebay, seller stevewb, that i got a couple years back.

The only extra additional I did was, as case was stripped, I drilled 2 holes, and kind of counterbored the top of those 2 holes to accept 2 new gits oilers. I did that to two shafts on front side of case, that are not submerged in oil. Just gives me a chance to oil those two directly before operating. I didn't hammer the cups in yet, I'll wait till after the assembly is hung.

After that I assembled the apron, making the repairs or parts replacement already posted. Got it wrapped up in a trash bag waiting to be installed.

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Before I got apron totally apart, I ran into a problem of a stuck taper pin. Pretty much like jmdriller41 on his cone pulley. For me it was getting taper pin out of gear, which goes through main pinion gear assembly, I mentioned above. Though I didn't crack gear, the hole was wasted.

It was a true SOB. In the end, I drilled taper pin on both sides of gear, and brute force drove shaft out with hammer and a drift pin, through that gear.

View attachment 283170

That's the same one I had to drill out. It really ticked me off too because it's so accessible I thought it would be no problem!

Your apron work is exceptional!
 
The next step for me was the motor base. In my thinking, I've felt absolutely certain I was going to need to align headstock and tail stock to get it all pointed at center. That being the case, I need the rest of lathe complete to run an alignment the way I want to. So I yanked headstock off with the assumption it does not matter how it currently sits, I'm aligning from scratch.

In sorting out my pics for the post, I've realized that some I already posted in Kevin T's thread, and probably others pics as well. During certain points of our respective builds we were working on the same sub assemblies, or in close proximity. Current readers prolly know, but for anyone interested his thread:
South Bend 16 Toolroom Lathe - The Adventure Begins...

For this particular build, I didn't feel a need to separate bed, chip pan and legs from tailstock end. Using a roll around cherry picker/engine hoist, I lifted headstock off lathe. With a 6x6 beam running across the rafters overhead in my garage, I hung a chain fall/chain hoist and raised headstock side of bed just enough to slip motor base out.

I then ran a strap through motor base and used cherry picker to roll motor base upside down. With the base flipped, I yanked the electric motor out. I never checked the motor. It was single phase, and looked rough, plus the vee belt pulley looked way too small at about 2" in diameter. I already have 3 phase outlets run around my shop, so I never planned on re-using that motor.

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