Pratt & Whitney Model C 12x30 lathe

[motormech1]

I really appreciate the info and guidance. The lube systems will be the first thing I take care of when I dive into it. Thanks for letting me pick your brain!

 

[tailstock4]

I was wondering about the taper attachment’s connection to the shoe on my machines version of it and wondered if I could find any video or picture of it. I also went back out to study it again and found amongst other things in the pan what looks like a shop made shoe utilizing a bearing instead of a block.
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Not a bad idea but probably not as precise as a block. Digging on you YouTube I turned up a guys videos of his model C 1694 and he had the original taper attachment so I grabbed some screen shots.
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Thanks for the pictures. First time I've actually seen the earlier version up close. I think you are right. The large bearing was probably a shop modification. I would think you could adapt to my version. It looks like the earlier version didn't release the block but rather just allows it to slide off the end if the taper attachment was set at zero angle. Is that correct? Pratt & Whitney's attachment on either version was a stationary type. I have to keep in mind when I respond to you that there are difference between our versions. Let me know if I'm helping or not.

 

[motormech1]

The shoes are usually missing from these earlier lathes and I wonder if it’s because there’s no quick disconnect that leaves the shoe in the guide like yours rather, you have to unbolt and remove it from the guide altogether which results in them being lost.
Here’s the parts diagram:

 

[hustlebird]

Wow! What an absolute wealth of information, thank you both so much for sharing.

I managed to grab 1 picture of the backside of my lathe here with the taper attachment, it looks a bit different than both of yours even. If I crack that square nut loose, and crank the slide all the way back I start moving the hole underneath, which I'm guessing would allow for alignment into the taper attachment? It doesn't seem to pinch that area any, which I had initially thought it would hold the taper in. Would make sense for it to be gone with no attachment mechanism, the setup on @tailstock4 is pretty slick!



I'm relatively green to all this, so I'm hesitant to take apart the saddle, though I'm sure it needs the love. Also all my oil sights are cloudy and covered. Either of you have any insight on replacing those?

Also how do you drain the gearbox sump? I found a bolt all the way back, almost touching the head-stock, but its a hex cap, and all the other plugs have been square head, so I left it be.

Thanks again for sharing, the power of the internet is unbelievable sometimes...

 

[motormech1]

@hustlebird It looks like you have yet another version! Lol At least you have everything but the shoe. That would be the easiest to make I think. I’m in the same boat as you, just beginning to learn about these machines and haven’t started disassembling or cleaning yet. @tailstock4 is the resident expert on these so I’ll let him elaborate but IIRC, there are round retainer rings with countersunk screws holding each one in.

 

[motormech1]

I remembered yesterday that I’m missing the larger 3 groove top input pulley and was wondering if someone would be kind enough to measure theirs so I can start looking for one? I think I can find a place to make one.

 

[tailstock4]

@hustlebird - Regarding sight glasses:
I replaced the sight glasses with 1/8” lexan which I cut out on a bandsaw and sand down to the correct diameter. I also put a rubberized cork gasket on each side of the lexan – one to seal and the outer one to cushion the lexan.

I will sometimes paint the target area inside the sight glass with either epoxy paint or 2-part urethane enamel both of which are oil resistant. What I prefer to do is to cut the background out of .025 white plastic shim stock. Then I punch out the two fill and vent holes.

I’ve enclosed a picture of a Mayhew hole punch set. It simplifies gasket making if you don't already have a set.

 

[tailstock4]

I remembered yesterday that I’m missing the larger 3 groove top input pulley and was wondering if someone would be kind enough to measure theirs so I can start looking for one? I think I can find a place to make one.

My top pulley measures 8.5” diameter with 1” bore.

 

[tailstock4]

@hustlebird - I’ve posted a picture of how I’ve set up my drain for the headstock. Also, there is a drain in the bottom of the filter housing. This drains a small reservoir that collects sediment scraped off of the filter. This can be drained without draining the headstock oil on my machine.

Note: The "AW68" on the blue handle of the valve is not the correct oil for this machine. I use Mobil heavy/medium which is an ISO 68 R&O oil.

 

[Shiseiji]

Congratulations on your find. From what I can see, it looks complete and in pretty decent shape. Interesting history, too. I also have a 12c. It is a 1954. I did a restoration on this machine, and I’ve posted a few pictures of it after the restoration. If you’re interested, you can also find my restoration documented on the Practical Machinist forum (link below.)

I personally believe these are one of the best toolroom lathes of this size ever made. Best not to get me started on why as I could ramble on. Congratulations again on finding your machine.

https://www.practicalmachinist.com/forum/threads/pratt-whitney-12c-restoration-pictures.402002/

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Really like that back panel!