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Pratt & Whitney No. 3 Bench Lathe NEW TO ME!

KatRaft

Plastic
Joined
Nov 16, 2019
Hello all first post here! First I'd like to say this site has been a wealth of information and so I'd like to share my pictures with you guys!

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I've recently acquired a Pratt & Whitney No. 3 Precision Bench Lathe. I've tried to find an exact picture of the bed I have on the web with no joy. There is a serial number on the bed 1697 but not sure what year this might reference.

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My dad gave this to me thinking I could sell it. I think it's awesome and can't wait to get it turning - besides who doesn't need a lathe? My dad is a machinist...I am not. I am experienced in the welding fabrication realm. I do plan on restoring some day, but for now just wanna try it out! Thankfully my dad stored this indoors, I have cleaned off most of the rust and have everything sliding/turning as it should. The D. E. Whiton chuck was frozen but finally moving and cleaned. I found a homemade piece screwed onto the face plate. Some pretty rusty collets that will soon see a brass wire wheel. For the most part mostly complete basic set up. Would like to find the rest of the tool rest if anyone knows where some bits are!

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After reading here sounds like a 3/4 hp motor with variable speed control would be ideal? I was thinking of mounting it on a bench with the driving motor and whatnot underneath. Maybe fabricate a little belt cover for over the bench/lathe. With speed control I wouldn't need to change the pulley belt location but I still want the correct size counter pulley so it can be ran as it was designed to...or at least closer to.

I appreciated everything I've learned from this forum and appreciate any advice y'all could give this newbie, thanks!
 
Your pictures are links to google drive, which is why they are not working. Try uploading the files directly to PM.

20191117_152325.jpg

Looks like a nice starting point. Jealous you have the steady rest. I'm looking for one of those. I have the later 3C lathe, but the beds are the same, I think.

For the rust, start with the least aggressive method.

Try evap-o-rust. Available at Advance Auto Parts and other parts stores.

For stuff that is stuck, try a 50/50 mix of automatic transmission fluid and acetone.

Steve
 
A few years ago, I bought a strangely configured lathe. The bed was a P&W, with the name cast in. It had a P&W slide rest and a hinged steady rest. But the headstock, tailstock and end-of-bed milling attachment were Hardinge Cataract. P&W beds look like Cataract beds (same sloping edges), but I think they have wider tops. Possibly, someone had very neatly converted the P&W bed to fit the Cataract head and tail.

They had added four screws to the angled surfaces of the steady base to make it fit the narrower Cataract-size bed. I presume that, with those little screws removed, the steady would fit an original P&W bed.

Here is Tony's P&W info: Pratt & Whitney Lathes He does not show a P&W steady, so I cannot be sure if my hinged steady is for a P&W.

Larry

DSC00055.jpg DSC00056.jpg DSC00057.jpg DSC00058.jpg DSC00059.jpg
 
After reading here sounds like a 3/4 hp motor with variable speed control would be ideal? I

That's more motor than that lathe would need. Mine is run off a 1/3 hp motor, with a VFD for speed control.

Do not wire brush the collets. Learn about electrolytic de-rusting as that is probably the best way to
retain as much accuracy as would be left from those. They are pretty tough to get these days.

Your lathe has a nameplate that I have not seen before - the stampings on the raised area by the headstock.
The ones I've seen are either like mine, with the name cast inlet in the front of the bed, or the later ones
with the name cast proud on the front of the bed. Your machine may be somewhat older than mine.
Watch out as the tailstock taper is not jarno or morse, it is proprietary.

1/3 hp setup:

pw_lathe_vfd_3.jpg


pw_lathe_vfd_2.jpg


It was a bit rough when I got it:

pw_lathe_B4.jpg


serial number:

jrr_sn_pw_lathe.jpg
 
In my case the M880 is the model number I thing. Which would make your four digit serial number
earlier than mine.

In particular the "7" stampings on each look pretty similar.
 
Hello,

Your machine is from the last series of 3pn collet bench lathes that was produce just prior to the introduction of the 3c version bench lathes introduced the 4pn collets. So it is probably from the 1930's or so.
 
Hello,

Your machine is from the last series of 3pn collet bench lathes that was produce just prior to the introduction of the 3c version bench lathes introduced the 4pn collets. So it is probably from the 1930's or so.

That seems odd, as her bed has the name stamped onto a flat on the left side. That looks more like the approach that would have been taken early on in production, with the fancier beds with the name cast in coming later.

Jim's bed has the name cast in and his is serial number 2774, while Kat's is serial number 1697, making it earlier, which fits my theory.

Steve
 
That seems odd, as her bed has the name stamped onto a flat on the left side. That looks more like the approach that would have been taken early on in production, with the fancier beds with the name cast in coming later.
Jim's bed has the name cast in and his is serial number 2774, while Kat's is serial number 1697, making it earlier, which fits my theory.
Steve

+1 on that. What was the 2480 that Kat referenced?

Does your lathe have the T-slot on the back, Kat?

Also it looks like you have a complete compound slide and toolpost for this machine. Not sure you are
missing any parts in that regard.
 
The 2480 number can be seen in many P&W pics. The picture of the "stock" lathe bed Steve posted you can see a tiny 2480 in white near the end of the tool rest mount. Anyway I have no idea what the numbers are probably means nothing.

Yes my lathe has the T slot in the back.

I'm missing the tool rest mount (for freehand work). I have the little flat tool rest itself but the little holder and rail that attach to the bed are not there.

On another note on the Lathes + Machine Tool Archive site he mentions that P&W originally drove this with a 3/4 HP motor. I assume this would be the 2 speed gearbox sometimes seen. Does HP matter so long as the machine isn't ran at RPMs higher than it was designed to be ran at MAX 1208rpm?

I'm loving the serial number /date debate! You'd think a lower number meant an earlier year, but I think it looks more modern than the large name casting beds. Any serial year date sources would be helpful, I won't hold my breath.
 
The 3/4 hp number is probably with this driven off the "Speed Ranger" drive is my guess. That drive
weighs more than the lathe itself and while it is driven via a 3/4 hp motor, the drive consumes a fair
bit of those ponies.

The motor visible in my photos above is a three phase, 1/3 hp motor driven from an inexpensive
variable frequency drive. It provides more than adequate power and torque for that lathe. I typically
keep the belt on the middle sheaves.
 
The motor unit from P&W that would have been likely to have come with your lathe is this one:
img52.jpg


The 3/4 hp speedranger is an undermount motor what would not work with your lathe.

The catalog for your lathe doesn't specify the HP but has the recommended motor for the matching milling machine as 1/2hp.

Steve
 
Thanks to everyone for all the information and recommendations. I will try to find a nice 1\3 -1\2 hp motor to get her going someday. Definitely have more (everything) to learn about machining and looking forward to reading many more threads on this forum.
 








 
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