Pratt and Whitney Model C 16x30

Hello all,

I've been on the forum for a while but this is my first post in this sub forum, although I am a frequent reader. We recently got a new CNC lathe in the shop where I work, and the boss decided to get rid of this Pratt Model C 16x30. He basically gave it to me. Unfortunately that is where the good news ends. While the lathe was being moved it fell off of the skates and broke several handles. Combined with the fact that there is a very significant amount of wear in the ways, I find myself in an unfortunate position.

Basically, I believe that this lathe is beyond saving, and I have decided that I am going to strip everything that is worth saving and send the rest (hopefully just the casting) to the scrap yard. Before it was moved, the lathe ran very quietly and smoothly, so I believe everything in the headstock is in good shape, although I have not been inside to look. I know that when people restore older machines they often need parts that are hard find and I hope that somebody may be able to use some of the stuff that I take off/out this lathe. I love these old machines and it makes me sick to scrap anything that somebody may be able to use down the road.

Since I have no way to unload the machine from my trailer, I'm going to let it sit for the week and hopefully get it completely stripped this weekend. I will try and label all the parts and store them in an appropriate manner.

I am not trying to do this to make a huge profit or anything, I simply what to save what I can from this beautiful piece of old iron so that maybe it can find life somewhere else.

If anyone has any input on this situation, I would love to hear your thoughts. I will post a few pictures here to show the damage on the machine.

jspivey said:

View attachment 254662 View attachment 254663 View attachment 254664 View attachment 254665View attachment 254666

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That is one of the finest lathes ever made and it would be a crime to scrap it over a few handles. Did any castings get damaged? If not repair is not a big deal. Please post good photos of the damage. Please hold off on stripping it for a few weeks to get some input from forum members on repairs. That shim under the wiper tells you nothing about bed wear. A quick easy accurate check is to move the carriage to the tailstock end, tighten the carriage lock till it just drags, then move it all the way to the chuck and tighten it the same as at the tailstock end taking note of how many fractions of a turn it takes to tighten. Remove the lock bolt, check the threads per inch on the bolt and you will know the wear. A 16 TPI is .062 per turn or .031 per half turn. This will give you an idea how bad it really is. Note it also takes a LOT of bed wear to affect the accuracy.

moonlight machine said:

That is one of the finest lathes ever made and it would be a crime to scrap it over a few handles. Did any castings get damaged? If not repair is not a big deal. Please post good photos of the damage. Please hold off on stripping it for a few weeks to get some input from forum members on repairs. That shim under the wiper tells you nothing about bed wear. A quick easy accurate check is to move the carriage to the tailstock end, tighten the carriage lock till it just drags, then move it all the way to the chuck and tighten it the same as at the tailstock end taking note of how many fractions of a turn it takes to tighten. Remove the lock bolt, check the threads per inch on the bolt and you will know the wear. A 16 TPI is .062 per turn or .031 per half turn. This will give you an idea how bad it really is. Note it also takes a LOT of bed wear to affect the accuracy.

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I think that this picture tells you quite a bit about the wear.

jspivey said:

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I agree that it is hard to judge the damage from the pictures supplied. But, from the last picture it looks like that the cross-slide handle assembly is bent downward and, possibly/likely, the casting also broken.

If you're interested in the lathe, go and get it. The truth is that there are far more old machines than what we could save. This one looks like a very good organ donor candidate to put back in shape a more deserving specimen.

If at all possible, at least for now, it would be advisable to remove the headstock as a single unit and not further disassemble it. But, again, I'd leave it with the current custodian to judge what to do compatibly with the space available, the rigging equipment, and the time constraints.

Lastly, I'd thank him for deciding to part it out, instead of driving it directly to the scrapper.

Paolo

Slope Head - possibly early WW2 or before. Wish I could read that serial - .is it 8XX ?

Serial number is 881. It has a government property tag somewhere on it as well. I’ll get a better picture of the tag if I can.

Paolo_MD said:

I think that this picture tells you quite a bit about the wear.



I agree that it is hard to judge the damage from the pictures supplied. But, from the last picture it looks like that the cross-slide handle assembly is bent downward and, possibly/likely, the casting also broken.

If you're interested in the lathe, go and get it. The truth is that there are far more old machines than what we could save. This one looks like a very good organ donor candidate to put back in shape a more deserving specimen.

If at all possible, at least for now, it would be advisable to remove the headstock as a single unit and not further disassemble it. But, again, I'd leave it with the current custodian to judge what to do compatibly with the space available, the rigging equipment, and the time constraints.

Lastly, I'd thank him for deciding to part it out, instead of driving it directly to the scrapper.

Paolo

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Paolo,

You are correct about the damage on the cross slide handle assembly. It is bent pretty badly and several parts were broken. That picture you referenced really doesn’t do the wear justice. It is pretty bad. I would estimate the “lip” is .050 or so deep on the operator side and worse on the back side.

I believe I would be able to remove the headstock intact. We have a John Deere with a front end loader that should handle it no problem. I also will remove the tail stock, all handles, etc. maybe get into the apron if I can.

In addition to not being able to get it off of the trailer, I also have pretty limited time to mess with it. I am a mechanical engineering student and work part time at a shop.

jspivey said:

Serial number is 881. It has a government property tag somewhere on it as well. I’ll get a better picture of the tag if I can.

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881 is between '43 and '44

johnoder said:

881 is between '43 and '44

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Thank you for the info. That was about what I was guessing. There is also a tag on the back referencing a rebuild in 1981, so it has had almost 40 years of hard work and poor maintenance since then.

Just for curiosity’s sake, how would one even begin to go about restoring the ways on this machine? Send it out to be reground and then put turcite on the ways? I’m pretty clueless when it comes to that sort of thing.

I took my calipers and measures the wear perpendicular form the face of the way and it looks to be about .050 as I had guessed. That’s pretty rough though. I’ll attach a couple pictures. I’m always in a hurry so forgive me if they aren’t the best. Thanks to everyone who had replied so far.

I believe you will find the wear to be much more than .050" total. The saddle has probably .125" or more wear, too. So you can easily say a total of around 3/16". Not a deal breaker, but a lot to think about. My first rebuild lathe had that much and more wear between the bed and saddle. I had to plane close to .090" off the ways to remove all of the bed wear and likewise on the under side of the saddle. Back when I did this, I used Micarta as way bearing material to bring it up to near factory spec. The thickness was around 1/4". Now days, I would suggest Nylotron NSB as way bearing material in a thickness like this. Not sure if Tercite or Rulon is available in this thickness.
Anyways, you are looking at a major job of reworking/rebuilding that lathe. That would be a perfect job for Steve's planer down in Texas if you were a little closer.

Best of luck, Ken

Ken,

Thank you for the words of advice. Yes, if I was a little closer that would certainly lean me towards an attempted restoration. I’t would also likely be several years (3-5) before I would even be able to attempt a restoration. I also have a very old monarch (my first lathe and originally a lineshaft machine) that is first on the list for several reasons.

I’m gonna give myself till the end of the week to convince myself and my father that we need another large piece of “junk” sitting around.

Well, I decided to just keep the lathe together and store it until I have time to give it proper attention down the road. The more I thought about it, I just couldn’t bring myself to send it to the scrap yard. It helps that I’ve come up with a way to get it off the trailer!