Overhaul of a 9" SB model "A"

[lathohn]

Hi Dave,

Be careful soaking soft metal parts (bronze, aluminum, brass) in Simple Green or Krud Kutter type degreasers. Weird chemical reactions happen that might damage the part.

I've soaked bronze bearings (that were already mostly clean) in full strength Simple Green that I just poured out of the bottle, and after 20 minutes, the solution turned red. Hehe.

I had an aluminum part soaking in Krud Kutter and it turned black.

I've soaked the end caps from the old motor in Krud Kutter, and the finish on the original bronze/brass bearings does not look they way it should. Looks very very red.

I'm guessing anything with copper in it, starts to break down get dissolved if you leave it in too long.

Steel and cast iron are probably not affected. At least nothing I've noticed yet.

John

 

[steamer]

Hey John,

Thanks for the support and interest! I've avoided putting bronze in, but I've not had any problems with aluminum so far.

I only put the saddle parts in thus far. I'll completely disassemble the apron first ......but duely noted! Watch the bronze parts!

Dave

 

[lazylathe]

Hi Dave!

Looking good!!!!
Wish i could i find some of the bits you have found lately!!!

Always noce to see the pics of what you are up too!
Took me a while to figure out what SG was though.... :big:

Andrew

 

[steamer]

Hi Andrew,

Thanks for the interest and support. There is no secret as to were I'm looking for my components...ebay.

It's out there which is why I decided to make this lathe my "small" lathe. There are parts and accessories a plenty.

If you look at what some of this would cost new...the prices are not at all bad...actually they are quite cheap. In the end....and it will be a while still, it will be the lathe I want to use.

Dave

 

[steamer]

Turned the saddle over in the bucket and the paint and grime are gone on the submerged section. The brass felt holders for the ways are nice and bright and clean, not discolored....I'll investigate further this evening.

I am thinking I'll have to line bore the apron to straighten out the worm gear bearing.....but I'm not sure of the datum....if the hole is worn real out of round....how do I pick up on it?

I'm thinking a location shaft to the nominal diameter held between centers on the lathe to locate, then replace with a between centers boring bar...but I'm up for suggestions!

Dave

 

[steamer]

OK

I got the two gears in question off. I was convinced the gear was bronze....its not! :big:

It's steel. There is some wear on the teeth, but it's alright

The wear in the housing is what concerns me...the inside of the apron is pretty crusty....what I saw was wear debri from what I thought was a bronze component....but the two gears are steel....I'll need to clean more to find out what's going on. The bore in question appears to be part of the cast iron apron. The mating worm gear shaft is also steel and outwardly looks pretty good....can't see any obvious wear marks so it could all be in the housing. I'll post some pictures in a bit.

Like I said, it is still far to crusty to really tell yet....

As to SG.

I pulled the saddle out and I found some rust on the part that was above the surface of the liquid....not deep and it came right off with the brass brush. I then looked at the brass way wipers ....they were Red! OK....I checked them and it was completely superficial....brass underneath a very thin outer layer. It will clean up fine.

I then pulled the rear way gib and pulled it out. It had been in the soup for a day and a half. The outside had a brass hue to it that will not come off. Not on the machined surfaces, but the rough cast surfaces.....No worries as it's painted but it was noticeable.

I would say that the SG is acting as an electrolyte. I would have to agree that SG can do wierd things. I would suggest that you not mix metals in the soup. I think some plating is going on.

The two parts were painted tonight. along with some other parts that have been cleaned already.,,,,again more pictures to come.

Dave

 

[steamer]

OK I cleaned the gears and took some measurements. The worm shaft is a consistent .995" and looks like its still round.

I measured the mating bore of the apron and its about 1.005",,,,doesn't sound like much but it wobbles quite a bit.

There is about .02-.03" of axial shake, which seems excessive.

I'll need to tear it down completely and measure the bore more accurately . there isn't a great deal of meat on the bore....so we will have to see ...

Dave

 

[steamer]

The apron is in the soup. I've finished painting the saddle and gib. I've also painted the faceplate, the catch plate, and the drawbar hanger bracket. I'll need to evaluate the half nuts for wear which looked somewhat significant

Nothing I can do but fix or replace the parts as required.

Dave

 

[steamer]

Half nuts are toast! I got some work to do!

Do I repair them or replace them?

Dave

 

[steamer]

OK

The apron casting is stripped and cleaned

The worm bushing:
I'm going to bore the housing in the inverted position 1/16" over size for a undersize cast iron bushing. The OD of this bushing will have a groove cut to allow for the felt wick. the bore will be 0.760" to match the worm bore. I will set the apron up on my boring table on the Logan lathe at a height that will allow the worm and bull gear to mesh correctly. That should be correct. Additionally I am going to line bore the half nuts to machine away the worn nut section in preperation to the bronze insert replacement.

Once bored oversize, and without moving the apron, I'll bond in the bushing into the housing and then bore to fit the worm with .003" clearance...that will take care of that issue.

The half nuts are shot. I'm going to bore them out and bond in a bronze nut with JB weld and pins. After that I'll remove the nut from the assembly and pin it, and then split it. I'll make an extra nut for future repair.

Here's some picture of the housing. The bore is out of round by .005 and over size by .007. The worm is an even .995", so I will work with that.

This will be a complex repair but I think I can do it.

The last picture is the position that I will bore the bearing on my Logan.

Dave

 

[lathohn]

Hi Dave,

I've also run into the problem of what seemed like parts getting plated by another metal while soaking in Krud Kutter.

If I remember correctly, most were just plain cast iron parts, but there was a drum switch cover in the bath as well. I'm not entirely sure if it was copper, brass, or aluminum. But after a day or two, whatever part I pulled out of it, it was looking reddish. It was at that point that I realized that soft metals are reacting with the solvent. I thought the "plating" was permanent, but I took the drum switch cover out, and left the iron parts in there for few more days. Eventually, the red "plating" deposit that was on them just went away on its own. I think, whatever dissolved out of the softer metal, eventually just settled to the bottom of the container.

---

I've seen new old stock half nuts on ebay. Pricey though. There was a pair that recently went for $137.

http://www.ebay.com/itm/330670953452

There is one dealer selling two NOS sets, but he is charging an arm and a leg ($258/$289):

http://www.ebay.com/itm/300656468317
http://www.ebay.com/itm/300647650246

So I'm looking forward to see how you do the half nut repair. Where are you gonna get the bronze bushing for repair? MSC, McMaster-Carr?

Are you going to tap the ACME thread or single point thread it?

Good luck.
John

 

[chuck foster]

great work as always dave :bow:

i thought this might help you with the half nut repair
http://www.practicalmachinist.com/vb/south-bend-lathes/repairing-half-nut-threads-129446/

i repaired a set of half nuts for the first 9" lathe i had and i just built up a bunch of brazing in the threaded part of the nuts.
i then made a jig to hold them in the lathe at work and bored them out and single point cut the threads. they worked just fine.

keep up the good work and thanks for showing us the step by step process of restoring your lathe. will you do mine next???

chuck

 

[steamer]

John and Chuck, Thankyou for your interest and support!

Chuck that's the reference I was reading and the approach, and John if I can find NOS half nuts for $137 , they'd be bought! ;D

The nuts could be used as is for a little while, but considering I have it all apart, it makes no sense to put them back.

The nut I'm going to single point...and I'm going to make two.
I had an opportunity to buy a nut blank, but that appears to be a false lead. So, I'll single point it on the Logan...two mind you....1 for later.
This one shouldn't be as hard as the last one I made....a .354-10 LH nut for my Waltham. That one was tedious.

http://i164.photobucket.com/albums/u27/mcandrew1894/P1010113.jpg
http://i164.photobucket.com/albums/u27/mcandrew1894/P1010123.jpg

Dave

 

[steamer]

Hey Chuck,

Do you have a picture of that fixture that you used to single point the theads in the half nut?

Would love to see how you did that.

Dave

 

[steamer]

Did a bit of measureing this morning and found that the side of the bore near the worm is barely worn because it aligns with a relief groove in the worm shaft. Just behind that I found the wear, and all in one direction, tending in the direction to take the gears out of mesh obviously. I've developed a plan of action, now I need to get me a piece of stock for an alignment mandrel and make up the bushing and a thrust washer. I'll be making the bronze threaded inserts also. So some lathe time ahead...

Dave

 

[steamer]

Got the bronze bar on order. Bronze isn't cheap these days is it!
:wall:

Dave

 

[coopertje]

Hi Dave,

Nothing valuable to add, just want to say "Great work!!!" :bow: :bow:

This is what a restoration is all about, checking every single bit, repair, renew, etc. Not just clean and paints!

Regards Jeroen

 

[kozzmo999]

Great Thread! Didn't I sell you some parts for this lathe at some point???

I joined this forum just to keep up with this thread...time to explore a bit.

Once again for a rank amateur like myself this is a really fun thread, keep posting!!

David

 

[steamer]

Jeroen and David,

Thankyou for your interest and support! Dave, I believe your handle sounds familiar! ;D......Which bit?....a steady or the turret tailstock?...I think the later.

It's coming....she'll be a nice lathe in the end I think...that's the goal anyway.

I have NO intention of rescraping or regrinding the bed....I don't THINK it's warranted.....but I'll guess we'll see. Mostly just repair what's broken and worn out and bring back to good working order....I think she will be.

She has the large dial option, but it also has the ball thrust bearing option on the cross slide screw....Don't know if that's normal or not,,,,but it is nice!

Dave

 

[bronson]

This is been a very interesting thread. I have learned a lot from the repairs that you have done. I bought a southbend model b 1953 9" 3.5 bed about two years ago and back then cleaned, repainted and replaced wicks and has been a great machine a hundred times better then my old lathe. I am looking forward to the half nut repair as i have two sets but both are worn. Keep up the great work.