Pratt & Whitney 12C Restoration Pictures

[tailstock4]

The first picture shows the oil reservoir for the cross-slide and cross-screw. The little brass plugs meter this gravity fed system. This is all fed by the two oil ports found next to the handle. After I took these pictures, I later decided to re-scrape and re-grind these parts and make a new cross-feed nut and screw. The next three pictures show those results.

 

[johnoder]

The lads that used to work on New Park Avenue in West Hartford are smiling down

The first picture shows the oil reservoir for the cross-slide and cross-screw. The little brass plugs meter this gravity fed system. This is all fed by the two oil ports found next to the handle. After I took these pictures, I later decided to re-scrape and re-grind these parts and make a new cross-feed nut and screw. The next three pictures show those results.

 

[tailstock4]

The lads that used to work on New Park Avenue in West Hartford are smiling down

Thanks, John.

One other note about the compound, it seems to have been made out of steel or some kind of forging. Anyway, it isn't cast. This makes it a little more difficult to deal with for anyone who is planning to machine the top. Not sure why Pratt & Whitney did this, but I do know that this a 3,400 lb. machine is as ridged as any I have.

 

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These two pictures are of the new bushings I made for the feed rod where it enters the apron ends. New bushings were also made for the end support block which I don’t have pictures of.

 

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The first picture is of the clutch control rod which I made a new one due to some wear in the middle.

I also decided to replace all the keys in the apron clutch handle and feed reverse handle. These are cast iron handles and their weight drags on the keys. The keys are all T-shape with the shank of the T being round. They are slipped through the key in the handle and then bradded over.

 

[tailstock4]

The first picture is of the worm and the feed rod that goes through it. The worm is driven by a key in the middle that is about 2” or so long and has a shank in the middle that goes through the worm and bradded over. I think these may be referred to as feather keys. I decided to replace this key because it had a little bit of wear. It was problematic to replace because the key must be held firm against the worm. The solution to this problem came from johnoder who had a post on replacing these keys. I can’t remember which machine he was replacing them on or where he came up with the design for the jig that he made, but it worked really well. Maybe he can tell us again.

The last pictures are of this jig and its use when I replaced the key. This might not seem like that big a deal, but you must remember that this worm gear is a one-of-a-kind part that it is finely made and somewhat delicate, and which I had to use a ball peen hammer to flatten the little key shank. You only have one shot at this to get it right. It all worked very well, and the results were excellent.

Replacing all these keys is a bit of work, but this is what gives a machine a feeling of being tight and have the feel it would have had originally.

 

[texasgeartrain]

I like that bearing in the carriage for what must be dial, and/or crossfeed screw. That's a bit better than what was original on my Monarch 61, I had to make a bushing as the parts had wear and slop.

What I really love is those oilers in the cross slide for the compound. Hard for me not to compare, as my machine is a 1956 and they are roughly the same class of machine but a different swing, same rpm spindles too.

I've had some distractions, so I've had a little break from my build, but the compound is the part I'm working on, on mine. No oilers, but I have a drain passage coming out the side cross slide, presumably to let coolant out, instead of being trapped under the compound. But even still, years of coolant or condensation has left the cast iron of mine not looking great:



I don't have pics yet, nor posted, but I started machining the top surface of that cross slide. After initial machining, the surfaces covered by compound begin to show surface rust, while the rest does not. Makes me think I might have miniscules amount of water in pores of cast iron. And its in a dry environement. . .

Been thinking of baking it in an oven for a little while, or how to handle it.

 

[tailstock4]

I like that bearing in the carriage for what must be dial, and/or crossfeed screw. That's a bit better than what was original on my Monarch 61, I had to make a bushing as the parts had wear and slop.

What I really love is those oilers in the cross slide for the compound. Hard for me not to compare, as my machine is a 1956 and they are roughly the same class of machine but a different swing, same rpm spindles too.

I've had some distractions, so I've had a little break from my build, but the compound is the part I'm working on, on mine. No oilers, but I have a drain passage coming out the side cross slide, presumably to let coolant out, instead of being trapped under the compound. But even still, years of coolant or condensation has left the cast iron of mine not looking great:

View attachment 348347

I don't have pics yet, nor posted, but I started machining the top surface of that cross slide. After initial machining, the surfaces covered by compound begin to show surface rust, while the rest does not. Makes me think I might have miniscules amount of water in pores of cast iron. And its in a dry environement. . .

Been thinking of baking it in an oven for a little while, or how to handle it.

I think I have seen something like this before when I’ve masked parts or parts sitting together, but usually that was the result of a humid environment. Monarch and Pratt & Whitney castings were close grained enough that you wouldn’t think they would absorb much.

 

[m-lud]

Tailsstock4
Your work is 100%. You see and often improve on what the original builder couldn't foresee 60 years later. You will have an amazing lathe there. You buy the best of the old iron and bring it back to spec. It appears you look for good examples that aren't clapped out. It's worth the wait for the right machine.
I learned that the hard way.

Texasgunsmith
When I am putting heat to cast-iron to start brazing often sweat will bead up on what appears to be dry metal. You may have coolant still down in the pores. Bake it at 250f for an hour and slather it with Fluid Film rust inhibitor.
I know its been inside for quite some time but Texas is humid. It is odd that it just rusts where the compound was.

 

[tailstock4]

Tailsstock4
Your work is 100%. You see and often improve on what the original builder couldn't foresee 60 years later. You will have an amazing lathe there. You buy the best of the old iron and bring it back to spec. It appears you look for good examples that aren't clapped out. It's worth the wait for the right machine.
I learned that the hard way.

Thanks. I have a friend who restores antique John Deere tractors. I asked him once if he had any advice. He told me to always start with the best one you can. He would take any advantage he could get. He also said, never explain why you do it. People that do it will understand, and the rest never will.

 

[Tyrone Shoelaces]

That’s a really, really nice centre lathe. The workmanship is exceptional as is the quality of components used in the manufacture. I haven’t seen a better one in my working life. That’d last a man a lifetime if it was looked after.

Regards Tyrone.

 

[tailstock4]

That’s a really, really nice centre lathe. The workmanship is exceptional as is the quality of components used in the manufacture. I haven’t seen a better one in my working life. That’d last a man a lifetime if it was looked after.

Regards Tyrone.

One of the reasons I wanted to post this was to show just how nice these machines are. One of the things pictures can’t convey is how well the parts fit together. It has been nine years since I worked on this machine, but I still remember that about it.

I’m curious if anyone out there knows what this machine equipped the way it is sold for in 1954, and how it compared to its contemporaries.

I’m curious if you ever saw any model C’s or the earlier model B’s in England during your working career. Did any of these make it to England?

 

[Tyrone Shoelaces]

One of the reasons I wanted to post this was to show just how nice these machines are. One of the things pictures can’t convey is how well the parts fit together. It has been nine years since I worked on this machine, but I still remember that about it.

I’m curious if anyone out there knows what this machine equipped the way it is sold for in 1954, and how it compared to its contemporaries.

I’m curious if you ever saw any model C’s or the earlier model B’s in England during your working career. Did any of these make it to England?

Not in my experience. We had more than enough centre lathe builders of our own to be honest. The only American lathes I saw were ones that had obviously come over as part of the “ Lend-Lease “ packages. Quite a few “ Warner & Swasey “ , “ Gisholt “ , “ Acme “ turret and capstan lathes. Lots of “ War Work “ was done by unskilled or semi skilled labour and these were the type of lathes that were in demand. I did see a couple of “ Monarch “ lathes over the years that probably came over at the same time.

On another point, I started my apprenticeship in 1965 and it was probably in the early 1970’s before I was aware of who made what and where. That’s 30 years after the start of the war and by that time probably lots of war time lathes were worn out and scrapped.

Looking at photos obviously isn’t the same as being hands on but that “ P&W “ looks to be a terrific little lathe. Everything about it looks right. Over here the “ Dean, Smith and Grace “ is generally held to be the gold standard small/medium centre lathe. I’ve worked on plenty of those and they are a real delight. Everything about them is right also. The “ P&W “ seems to be very similar but slightly heavier built. Nothing wrong with that.

If you know anything about WW 2 aircraft it’s like comparing the “ Spitfire “ with the “ Mustang “. Both superlative aircraft.

Regards Tyrone.

 

[Clive603]

Concerning P&W lathes I used to know a man who used a Model C to make feed nuts, slide feed screws and other precision parts for the CVA lathes. Wartime lend lease tuned up by CVA to be super accurate. Johns view was 4 tenths backlash was too much! Which I didn't believe until he demonstrated by effortlessly re-working a solid ACME nut for a Churchill Cub that had been supplied with negative clearance on a new feed screw to give almost imperceptible backlash. Apparently the screw wasn't up to his standards so a bit of backlash couldn't be helped. Done on a Kerry AG lathe, not a super tool but he had re-worked it.

The sort of skill level that makes me wonder why I bother.

My P&W is also ex lend lease.

A model B 12 x 30 with two speed motor. Scrap yard rescue.



I was looking for a Holbrook but I couldn't leave it there once alerted. Looks are similar enough to fool anyone who doesn't know. Worth the effort of dragging home as it is still very accurate. Turns parallel and will leave a finish that polish would spoil when I concentrate. Screw cut a 6-32 thread not so long ago when I couldn't face the hassle of swopping my small lathe, a metric Smart & Brown 1024 VSL, over to do one imperial thread. Even though mine is modified to be much faster than the standard palaver. I will say that setting up a 1 tho per inch taper was a bit more stressful than I cared for so that went on the S&B, mainly 'cos the taper slide locknuts are on top. No qualms about the P&W being up for the job but its a long reach over and under for the nuts.

Electrics are still the wartime originals, just new cabling for safety. Including a splendidly mechanical set of Crabtree oil immersed switchgear. Sort of thing that would have a Steam Punk enthusiast drooling like a vampire in a blood bank.

Apart from the never to be sufficiently cursed direct reading dial on the cross slide about the only thing that I really don't care for is that silly little short topside with the sticky up handle and dial assembly that is better at making the dial hard to read than keeping things out of the way. The baby bevel gears between handle and screw are worn so backlash is getting embarrassing. There is an orphan Holbrook C topside in the cupboard that I keep threatening to swop on as its an appropriate size but the bolt spacing is just dissimilar enough to be a major PIA. Besides I spent a fair bit of quality time re-furbishing the somewhat chewed topside and its severely out of flat top. Turned out OK after some serious weld building up, as the pictures show. Its a pretty major miracle that the single tooth dog clutch survived an operator that ham handed.



Clive

 

[tailstock4]

The first picture is of the back of the apron. Next is of the carriage right-hand strap and carriage lock. The spring you see pushes on a plunger/valve that opens when the half nuts are closed allowing it to be oiled. The plunger closes when the half nuts are open.

The third picture is an end view of the half nut oiler. The next is of the left-hand carriage strap.

 

[tailstock4]

The first picture is of the half nut cam, and the hole next to it is for the thread dial shaft and the gear that goes on the end of that. The next picture is of the half nuts and their cover.

 

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The last two pictures of this set are of the single point dogs and the stop binder screw.

 

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This is a picture of the assembled thread stop. It works by pulling the lever to the right which engages the dogs and provides a positive stop. It allows about 2.5 turns of the cross-slide hand wheel which is about 1” off of diameter or 1/2” actual movement.



Up next will be the breakdown of the taper attachment and then the disassembly of the feedbox. I’ll probably do those separately as it makes organizing this a little easier.

 

[tailstock4]

Clive:

I replaced the screw and the nut on the compound on my model C. Even so I still have about .008 backlash. Almost all of that is in the gears, but the gears aren’t worn. Just kind of the nature of the beast. By contrast, the cross-slide screw has about .0035 backlash at any point in its travel.

On the cross-slide dial, the only thing I find difficult is the small numbering. I have trouble seeing it anymore, but a DRO fixed that problem.

The only other thing that I find irritating is the 36 speeds. It takes time to locate them on the speed chart. This machine has a two-speed motor which contributes to that, but it is nice to have an almost instant reduction to half speed in any gear.

Thanks for posting. I figured a few must have made it through lend lease.

 

[Clive603]

tailstock4

Yep dial numbers are a bit on the small side. Numbers and grads are crisp and clear which is some compensation. Mine will get magnetic scales to go with the DRO box I have in stock when I get time to strip and rebuild the apron, saddle and slides. Been saying that for ages. Can't see a neat way to get glass scales on without some unwanted interference.

I soon got fed up hunting for speeds and made a laminated chart with the list of spindle speeds and lever settings for both motor speeds. The white patch stuck on the headstock looks a bit out of place but at least I can choose the right speeds easily. Putting a tacho on the spindle I was impressed to discover that the spindle speeds are as per book. P&W changed pulley diameters to compensate for the 50 Hz UK motor.

Clive