I shared the Pratt & Whitney’s tolerances in an earlier thread. (Link to that thread: https://www.practicalmachinist.com/...-12c-restoration-pictures.402002/post-3926060) After I moved it into place and did a good long term leveling, the machine is probably a little better than I stated there – something in the range of .00015 to .0002 over about 8-9” or so and something similar between centers.That is drop dead. Unfortunately I'm to the age where this stuff replaces the SI bathing suit issue.
What tolerance can you hold ? Dave
Thanks for your encouragement for me to do this post. And also for your advice and commentary along the way.Your new pics on the new forum format look great on pc and on my phone. What a fabulous machine. You really set the standard on your rebuilds, a high standard indeed. Excellent work.
I've placed this thread in the "Major Rebuilds" sticky in this section as well. The first Pratt & Whitney added there. Anyone looking for this thread in the future can find it easily.
I appreciate the effort you put into this thread as well. Sometimes it can be real work. I'm sure the entire community would love to see your other work too as time prevails. Thanks for taking us through the journey.
That tailstock is probably just as it should be. If you look at the “ Schlesinger “ charts he recommended that the tailstock should point upwards and towards the operator by about 0.0005”. That’s to counteract the weight of the work, when you’re working between centre of course, and to counteract tool push off in the horizontal plane respectively. That would be with a 10” test bar in the tailstock barrel.I shared the Pratt & Whitney’s tolerances in an earlier thread. (Link to that thread: https://www.practicalmachinist.com/...-12c-restoration-pictures.402002/post-3926060) After I moved it into place and did a good long term leveling, the machine is probably a little better than I stated there – something in the range of .00015 to .0002 over about 8-9” or so and something similar between centers.
The tailstock points up a couple tenths and towards the operator a couple of tenths. For these reasons and others, I decided it didn’t need a rebuild. So, I called it a restore. I know the terms mean different things to different people. About the only part of the machine as far as alignment that needed attention was the compound – which I did find odd.
This Pratt& Whitney lathe may have done repeat jobs that used the compound more than carriage travel or needed tailstock use. Wear often tells a story.The tailstock points up a couple tenths and towards the operator a couple of tenths. For these reasons and others, I decided it didn’t need a rebuild. So, I called it a restore. I know the terms mean different things to different people. About the only part of the machine as far as alignment that needed attention was the compound – which I did find odd.
I think there would be a lot of interest. Most of us can't reproduce the look you seem to do regularly.I said earlier I would talk about painting, but I’m not sure how much interest there is in that or how much detail to provide. But I’m willing to respond to any questions there are about it.
Thanks.Great write up and pictures. How did you do the covers for the Moore? Dave
Thanks so much for sharing the journey on this. You did a remarkable job on this machine. I just picked up a P&W model 12c, (same color and everything) and am planning to restore it as well. I'll definitely be referring to this along the way. In regards to one of your first posts, with the scale while lifting the machine, am I correct to assume these are all about 3,400 lbs instead of the listed 2,600 lbs that the manual states? Wouldn't suprise me nonetheless.
Thanks, I haven't got it in its final resting place, but it was hooked to power when I bought it, so I was able to try everything out. This is the day I bought it, just before loading it up. Came with a really nice condition 12" 4 jaw bison chuck, and an older 9" Burnerd 3 jaw chuck, but no adapter for the 3 jaw. I got a good deal on a Pratt Burnerd 12" 3 jaw super precision chuck though, model 1223500 so I will probably never use the old Burnerd chuck. This lathe was used in a diesel machine shop, and they apparently used it for working on pistons. They were moving the shop and needed it out of the way, so I got it for $1,000. I feel like I got a heck of a deal on it, and everything seems in great shape, just dirty.I know that the longer beds would of course way more. And I think in the Pratt & Whitney brochure they list those weights. How accurate they are, I don’t know. I do know that I weigh all of my machines and many of their parts, and I have stated somewhere in an earlier post that at least among the machines I have, the old American machines tend to be heavier than stated. Possibly because they weighed them without the electrics or motors. There may have been other reasons, too.
Congratulations on your 12c. How about some pictures?