View Full Version : Pratt & Whitney 20x48 Model B

02-23-2005, 01:46 PM
well i went to look at that Boxford lathe and the guy also had an old P&W Model B. the Boxford was okay looking, but not really anything that interested me. now this monster P&W, THAT was a piece of machinery. it is 10' long and i bet close to 5000#. it is powered by a 7.5HP motor and the top spindle speed is listed as 500 RPM on the speed plate. the lathe comes with a 4-jaw chuck and a taper adapter.

a couple of questions. would a 5HP motor run this bad boy, or does it need the full 7.5HP just to get the headstock spinning? any idea how the chuck is held onto the spindle? the guy thought it was a thread of some sort, but not positive as they had never removed the chuck. is 500 RPM the real top speed, or is that not taking into account the gearbox for hi and low ranges? what is the difference between a Model B and a Model C? i think this is even too big for me and my crazy projects. if it was only 8' long or shorter i would really be thinking about it though.

anyone have any links to any additional info on these old lathes?

andy b.

kap pullen
02-23-2005, 02:08 PM

Be careful of that Pratt and Whitney.

Some of those came with preloaded ball bearings from what I understand. Those bearings wear out fast because of the preload and new bearings are not avalible.

I heard from a machinery dealer, Beth. Steel had loads of these machines and bought the entire stock of spares.

This is all hear say.

Anyone else hear about these machines?

I have a Pratt and Whitney that has been bored, or bushed, by the previous owner for timken bearings.

Mine runs fine but that modification wasn't done for no reason. That was a lot of trouble to go to.

Some of the older machines have bronze bearings. This would not apply to them.

Mine is a war production baby and runs up to 1100 rpm.


02-23-2005, 03:34 PM

this lathe has bronze bearings/bushings in the headstock. it is interesting you mention Beth Steel, as this lathe is in Allentown.

andy b.

02-23-2005, 03:38 PM
5000lbs? That might be a tad light.

James Kilroy

02-23-2005, 04:14 PM
I sometimes use a friends 21" LeBlonde Super Duty. Optical tach measures just over 1,500RPM (and you don't want to be standing close!!!) Probably about 1940-1950 vintage, looks like an old flat-belt, lineshaft machine converted to electric.