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Pratt and Whitney Model B 12x30 Headstock question

tmacie

New member
Hi All,
I'm relatively new to machining and old heavy iron. I just picked up a P&W Model B 12x30. The previous owner bought it at an estate sale, only had it for a brief time and didn't do anything with it. The story is that a trade school student bought the chuck from it but didn't know how to get it off. Apparently he figured it out as there is no chuck with it, but in the process of trying, he took off the allen cap screws that hold the plate on to the headstock.

The plate was loose with about a .125" gap when I got it. Today, I tried snugging up the screws, as I was snugging the bottom of the plate wasn't drawing in like the top was. I've stopped there as I don't know if there are supposed to be shims under the plate, or if there is some other adjustment that should be made first.

Any guidance would be greatly appreciated.

Thanks,
Travis
 

tmacie

New member
Hi John,
Thanks for the reply. This is the plate behind the spindle nose. Mounted to the head stock, not the spindle itself

Thanks,
Travis
 

johnoder

Moderator
It will be similar to this Model C - and has to go on straight, not crooked

PW Front brg.jpg



Hi John,
Thanks for the reply. This is the plate behind the spindle nose. Mounted to the head stock, not the spindle itself

Thanks,
Travis
 

tmacie

New member
Ok. thanks for that. It looks like there is a register as well as a seal that rides in a groove on the spindle. Hopefully they didn't damage that seal. Do you know if there is a parts manual available out there?


Travis
 

johnoder

Moderator
No rubbing seals - most machine tools - at least WW2 vintage - had LABYRINTH arrangements to keep oil inside

In other words - nothing to pinch in the way of a rubbery seal. There is likely a thin gasket which one would not want to pinch either

Never saw a 12 X 30 Model B parts pub but can email the Model C parts which won't be much for Model B parts. :D


Ok. thanks for that. It looks like there is a register as well as a seal that rides in a groove on the spindle. Hopefully they didn't damage that seal. Do you know if there is a parts manual available out there?


Travis
 

tmacie

New member
I'd appreciate that e-mail. If nothing else I t should give me a better overall understanding of a similar machine. My Profile here should be set so you can do that.

I'll try squaring up that plate tonight and see how things go. I'll report back.
 

tmacie

New member
Well.....Good news and bad news.

Good news: I Now know what was keeping the gap.

Bad news: It is a chunk of the labyrinth seal. I'm guessing that the kid trying to get the chuck off took the bolts out of the plate and then tried jamming a chisel in and hammered. The spindle nose keeps the plate from coming forward enough to let the chunk come out. I can get the chunk to sit in the plate to where it allows the plate to sit properly but I am worried that vibration will kick it into the bearing and cause a very bad day. From what I can see, the only way to get it out would be to take the whole spindle out....ugh.

Travis
 

johnoder

Moderator
the only way to get it out would be to take the whole spindle out....ugh.

But then you'll know WAY more about it - may even want to make a new plate

Yes - a regular PITA - with such as the largest gear being tight on spindle

Here is the B layout right on down to the gearing passing thru rear wall of bed as it comes in from clutch and brake. Not quite as many gears since your 12 has but 8 speeds and the scan is for the 16 speed 20"

Head Stock.jpg
 

tmacie

New member
I'm mostly up for tackling it, but I'm nervous about damaging the unobtainium bearings!!
I also was thinking about it, it's not the labrynth seal, it's the register for the plate and headstock....which may kinda be a labrynth seal itself, but it's not the one on the spindle.
Only other "concern" the auto infeed wont disengage.
I don't have power to the lathe yet, but that's on the way.

Travis
 

johnoder

Moderator
Only other "concern" the auto infeed wont disengage
That would be the "star" knob dead center of apron - these of all lathes that had them are prone to getting stuck

You need to be able to "unscrew" it - like left loose - and it may require "bumping" it in that direction while you hang on to the cross feed "handle"

The way NOT to screw up the bearings is to always PULL on the spindle (after making sure to check for lock screws in any ring nuts that will need to come "undone" as spindle moves to right) - however much set up that requires - rather than beating on things
 

tmacie

New member
I will try gently methods of persuading the star knob....

So you are saying a 10lb sledge hammer to the tail of the spindle is not recommended? I tell you, there is no adventure in that!!

Do you know if the bearings are captured in the races, or are they like like an auto wheel bearing where the bearings and cage are separate from the races? I'm really hoping they are separate as it will make this process a TON easier.


Travis
 

michiganbuck

Active member
OT:
10lb sledge hammer to the..

I saw a couple of millwrights do that to a nice grinder and that grinder went to scrap.
 

tmacie

New member
I just found a post by Troup form 2010...he posted a drawing of the headstock where the spindle nose comes through. From what I can see, what I thought was the "register" is actually the outer bearing race. That said, when everything is together its smooth. I picked this up cheap enough to where I'll get the chunks out and run it until it gets out of tolerance for my needs. Live and learn I suppose!


Travis
 

johnoder

Moderator
or are they like like an auto wheel bearing where the bearings and cage are separate from the races? I'm really hoping they are separate as it will make this process a TON easier.

Typical angular contact ball (though class ABEC 5 precision - with caged balls assembled to the inner race)

The outer race is FLANGED - so it has a useful shoulder for the through bored head stock casting

In here - I'll assume they were IDENTICAL to those used in the 12" Model C - NM0214B up front and NM0214B13 mid way

New Departure NM.jpg

Though looking at the cut away view in the Brochure I emailed (page 4), it appears both bearings are the same
 

thermite

Active member
I just found a post by Troup form 2010...he posted a drawing of the headstock where the spindle nose comes through. From what I can see, what I thought was the "register" is actually the outer bearing race. That said, when everything is together its smooth. I picked this up cheap enough to where I'll get the chunks out and run it until it gets out of tolerance for my needs. Live and learn I suppose!


Travis

Right-decent lathes, especially with "modern" high-precision roller-bearings, so it is WORTH some extra care.

Downright travesty that the impatient chuck-looter-fool couldn't figure out the arrow-right ON them three camlocks on a D1-5 .... or go online, look or ASK!

All the more INSULTING, given the D1 system grew out of a ... ta da..Pratt & Whitney patent... gifted to the rest of the world! Much as USAA fathered a great deal of our EFT and ATM technology.... then gave it away to "seed" the online banking industry..

:(
 

kimberzelik

New member
I am new to machining I have owned a harbor freight many lathe for two years and been teaching myself via YouTube videos. I just purchased a Pratt and Whitney 12 X 30 -B.
It has no chuck. through the little bit of research I was able to do I determined I need a D 1-5. That might as well be Chinese writing because it means nothing to me if I wanted to buy a chuck for this lathe, what would I ask for ? What would I type in a search window. I am also interested in a collet closure and I imagine the information in the search would be the same. I also need a few accessories Steady rest, follow rest QCTP(size)?
If I was successful in my homework I determined the B lathes Were produced between 1942 to 1947.
 

tmacie

New member
Hi,
The D1-5 is the pattern that fits into the holes on the spindle nose. You can do a search for D1-5 Chuck and you'll get hits. There are direct fit chucks but they are $$. What you will likely want and see are "universal" chucks that then use an adapter plate to mount to the spindle.
As for the accessories, they are pretty rare. I have yet to find a steady rest or collets. The collet taper is a rare one. I think #13 Jarno is what its called. QCTP seems to be BXA (in that style) but you can fit other sizes with a little work.

Travis
 








 
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