Okay, on my other recent thread on under lathe storage, I was asked by a couple of people for more information on the screw machine. Here we go.

This machine was described by Rose in his 1888 Modern Machine Shop Practice. The version shown in his book is very similar to mine except for the base and for a couple of shields on the stock feed mechanism. One of the illustrations was useful to me in replacing a couple of missing small parts in the stock feed system.

When I got the machine, the headstock bearings were badly grooved as was the spindle. I turned the spindle down to clean up the bearing surfaces and repoured the babbit bearings. I got a reasonably good pour on about the third try. I then bored the bearings out with a makeshift rig and hand scraped them to align the shaft with the turret. I cleaned everything else up and made some tool holders for the turret out of old electric drill chucks.

First, here is an overall view of the machine and its motive power. The lathe is powered by a DC motor with variable speed control system. The system operation is very simple. An off/on switch, a rheostat speed control knob, and a reversing switch. Turn on the power, select forward or reverse, and dial the speed to what you want. Beyond that, I know nothing except that Pratt & Whitney did not supply it. A previous owner had rigged up the system, then used heck out of the machine with it. My fond hope is that it will continue to function without my having to learn to fix it. Looking at the machine itself, you can see three levers in the picture. The one furthest to the left feeds stock when pulled to the right and closes the collet chuck when pushed to the left. The small one on the cross slide moves tools crosswise as appropriate and has adjustable stops to limit travel. The one on the right rotates the required cutter into position and feeds the turret forward into the work, then out after the operation is completed. Of course, the name hand screw machine tells you what moves the levers.


The second photo is from the turret end and shows the turret with its six tool positions and the six stops which can be individually set to properly limit the tool motion for each tool.


In the next photo I am drilling the mounting hole in the end of a knob
.

Next you see tapping the hole. This is a simple tap holder mounted on a shaft which is free to slide in the tool holder. Since this is just a 6-32 tap, I just grab on to the rubber coated body and hang on until the tap bottoms. At that point I reverse the lathe and hold the chuck while the tap unscrews. Done.

Next, shaping the side of the knob with a form tool in the front tool holder on the cross slide.

Finally, cutting off and shaping the end of the knob with a form tool.
And, the knob ready for final polishing



When I made the “production batch,” the knobs took about 45 seconds apiece to make. Finding all the knobs in the shavings added a bit of time, also. Polishing was done as a separate operation with the knobs screwed onto the end of a screw held in a drill chuck mounted in the collet.

I HATE YOU! Your shop is clean, you do FINE work, you're ingenious, AND you can post pix which is generally a challenge I have trouble getting past.

And meanwhile, that P&W No. "0" (Well, I say that but I don't actually know if there was a size convention back then) still sits up in the top of my barn waiting for time to do a restoration. Actually, the one you see in Joshua Rose's book is mine - and both of ours have the "Parkhurst Feed" - and like you I'm missing the outer cover for the feed mechanism.

Just kidding of course - about the hate part anyway. The rest is irrevocable fact.

Mighty fine.

Well I'd say you should go into knob production, but then again, the Chinese would have a guy paid a bowl of rice a day put you out of business. Of course the knobs would be crap, but the people of this country would buy them anyway rather than support their own economy...

That is a sweet lathe, I could have used it last week at work. I had to make 45 graphite crucibles and that thing would have done the trick well. Thanks for showing. Greyson

nice setup and beautiful machine.

Due to being laid off my P&W turret lathe is about to go up for sale...*sigh*

A beautiful machine....and great to see it back in use making parts! I have a similar small turret lathe, a circa 1905 Bardons & Oliver No.0 (thread: Little Bardons & Oliver Turret Lathe ). I still don't have it restored and running.

A question: About what spindle speed are you running for those form tool cuts on the brass knobs? I'm going to be using mine for similar sized small brass parts, and I haven't rigged up a drive system yet. The DC gearmotor is a good idea. Is that about a 1hp motor?

Trying to send a picture of it.

Joe in NH,
Don't beat yourself up too bad. Mine sat around unused for about 25 years before I go around to fixing it up. Oh, and I only clean the parts of the shop that show in pictures.

Bruce, I had to go measure the speed. It is about 500 rpm for the form tools. I am using Mo-Max high speed steel tools. I started with a lower speed and worked it up until the brass started squealing. The motor is, indeed, 1 hp, but just a straight DC motor, not geared.

I looked at the pictures of your machine. It looks neat. You need to get to work!

thought you might like to see these images from a Pratt & Whitney catalogue dated 1917 - it says in the caption to the picture that it was patented on May 6, 1902. I hope they enlarge sufficiently for you to see them clearly. Is it the same machine?

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ordnance,

That's it. Thanks for the data.

For comparison, here is the earlier picture from Rose in 1888.




The major differences seem to be in the lathe bed and the support bench.

As I noted above, I used one of Rose's drawings to make missing parts for my feed system, so I don't think much changed there.

Dang, I just noticed my new cabinet is going to interfere with using coolant.

those old pics look abit familiar.

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