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torker
10-20-2013, 09:00 AM
Hey guys! Thought Id share a moment...or so from the new shop Im (trying) to get going.
My supposed partner needed a couple of long bolts.. 3/4 NC x8" for a none critical application.
Hmmm...gee...once again...he has no money....
Yep...I could go buy him a couple...but Im tired of that already...so...

He has a very ancient Pratt and Whitney conehead lathe. It runs through a 3 spd car tranny and an old electric motor of some sort...
He has a rack of salvaged farm machine parts....I find some 5' long spreader bolts from an old combine.
Hmmm...but they are 7/8"NC....wont worky.

Hack two pieces off...pop one in the lathe....grind up proper HSS tooling...turn them down to .750.
Nice old lathe....once I get it all sorted out. The owner doesnt have a clue how to run it.
Oh oh...now...threading...hmmm.....

I look around the lathe...no info there but a small change gear plate.
Tells me the spindle gear and screw gear I need....but nothing about the idler gear.
I look thru the gears...hmm...here's a well used one...try that...
Ooops...nope...50 or so tpi isnt good...
Ok...need a bigger one....dont feel like doing all the math so I grab..this one...
Bingo....10 tpi...lucked out :)

Oh dear...now...the hodge podge bastardized tool holder...thats a big problem.
Grind up a thread cutter....shim it all up on center...get the compound swivelled around..
Ooops....no threading dial.... :(
Never cut threads without one before...but no biggie...Im well armed..
My buddies from HSM told me...years ago...how to do this...
I cut a shoulder where I want the threads to end...take the tool back...spin the tool in to make a light cut..
And let her rip....hit the switch just before the tool gets to the shoulder....stop....a few times had to spin it by hand to finish the cut...put the ol tranny in reverse....back tool out...spin tool in a few thou...put tranny in forward....cut thread....repeat...repeat...bolts are made....it worked perfect!

Now...the guy thinks I walk on water....lol.
But I know...and you guys know...its just....HSM saved my ass again!
Thanks Guys!
Russ

vpt
10-20-2013, 09:44 AM
No pictures?

torker
10-20-2013, 09:51 AM
No Andy...I have no computer anymore...just my smart phone.
I have no idea how to post pics thru it (yet)
Id love to show his early 1900's P&W lathe.
I cant find any info on it anywhere. Tony's UK site has nothing.

vpt
10-20-2013, 10:52 AM
I assume the flat belt is gone since it is transmission driven now? Sounds like a very interesting lathe!

torker
10-20-2013, 12:53 PM
Andy...it is a VERY interesting lathe. I think...its 11" x 40 ish.
It doesnt have the usual levers for feed engagement. It has knobs that you loosen/tighten to engage.
It has power cross feed...and two different speeds for long feed.
The feed knob on the tailstock side is rapid feed...its the one I needed to use for threading.
It had a pretty wide bed...and fairly deep. It has nice cast iron legs.
I showed the guy how the back gear works also.
With the transmission drive...the low gearing on this is insane...lol

LKeithR
10-20-2013, 01:32 PM
Sounds like an interesting lathe and kudos to you for figuring it out...but...if, as it sounds like, you're trying to get a shop--as in business--up and running I think you need to toss that old piece of junk outside and use it as a planter or something. Find a real lathe that can actually make you some money...

torker
10-20-2013, 01:59 PM
Lol...I know Keith...I ran a 18" Mazak for the last two years.
Have owned a few myself.
I know one thing...for now...this ol thing...is waaaay better than no lathe :)

LKeithR
10-20-2013, 05:44 PM
...I know one thing...for now...this ol thing...is waaaay better than no lathe :)

True enough...point taken.

dewat
10-20-2013, 10:54 PM
Russ, your PM inbox is full. Can you send pics via email ? If so I will post them for you,

jim216 at frontiernet.net

Jim

CalM
10-20-2013, 10:55 PM
fun story

The idler tooth count? It doesn't matter!
All the teeth of that one gear hits both change gears equally!

JRouche
10-20-2013, 11:52 PM
Hey Russ. Haven't talked in a bit. Good to see you Mr :) JR

torker
10-21-2013, 12:51 AM
Hi JR!!!! Yer alive :)
Cal...hmmm...how you figure that?
With my first setup...I had 1.18 final drive ratio....the second...gave me 1.46 final drive. Id say it matters...
Thanks Jim...ill get some pics of the ol girl.
Russ

torker
10-21-2013, 01:04 AM
Ok...here it is...
First try... 112/36/76
The one that worked...
112/86/76
The math says idler size matters...no?

malbenbut
10-21-2013, 04:54 AM
Idler gear doesn't matter unless its a compound gear.
your maths must be wrong.
MBB

Richard P Wilson
10-21-2013, 05:09 AM
Ok...here it is...
First try... 112/36/76
The one that worked...
112/86/76
The math says idler size matters...no?

In a 3 gear train, the idler makes no difference to the ratio, its only there to fill the gap between in the input and output gears. That's why the screwcutting chart on your lathe didn't specify the idler, built in the days when the machinist was supposed to have some common sense and work some things out for himself.
Now a compound train, with 2 gears on the idler pin, input meshing with one gear, output gear meshing with the other, that's different

112 input gear, 76 output gear gives 1.474 whatever the idler, in a 3 gear train.

Richard

The Artful Bodger
10-21-2013, 05:26 AM
The threading chart may specify the size of an idler gear where that would be easier than writing "use any gear that fits the gap."

torker
10-21-2013, 08:11 AM
Lol...you guys make my head hurt :)
I gotta get this figured....

Richard P Wilson
10-21-2013, 08:13 AM
Something doesn't sound quite right here anyway. Has this lathe got a screwcutting gearbox? If not, assuming the P&W would have 4, 5 or 6TPI leadscrew, I don't see how 1.474 -1 between the spindle and leadscrew gives 10TPI, or how it could have given 50TPI at the first attempt. Photos would be really usefull.

Richard

torker
10-21-2013, 08:27 AM
Ooops...sorry guys...you re right. I see what I did wrong....had too many numbers wrote down....used the wrong ones for the first calculation.
Dang...yer right again....now I ve figured this out in my tired ol head and it makes sense.
Richard....I think what I must have done...was tightened the slow feed knob the first time....and the rapid feed (the one that worked) the second time.
Ive never seen a setup like this before.
Somehow or another...this is a two speed apron....
I ll get pics of it today for sure now.
Russ

torker
10-21-2013, 08:40 AM
Hmmm...trying to remember...the only other change gear lathes Ive ran...are 9" Southbends...on them...you had to use a specific idler dont you?
Seems to me there are gears you use that had two different sized gears in one that would be the compound gearing you spoke of...no?
Guess thats where I got the idea that I had to have a specific size of idler.

J Harp
10-21-2013, 10:44 AM
Hey Torker;

Glad to see you posting again. I've always found your posts interesting and sometimes very amusing. Keep up the good work.

That old lathe ought to have a place of honor in your shop as long as you have room for it. When it was made people took pride in their products and workmanship, something that is way too scarce now.

Richard P Wilson
10-21-2013, 10:57 AM
Ooops...sorry guys...you re right. I see what I did wrong....had too many numbers wrote down....used the wrong ones for the first calculation.
Dang...yer right again....now I ve figured this out in my tired ol head and it makes sense.
Richard....I think what I must have done...was tightened the slow feed knob the first time....and the rapid feed (the one that worked) the second time.
Ive never seen a setup like this before.
Somehow or another...this is a two speed apron....
I ll get pics of it today for sure now.

Russ

This lathe has a threaded leadscrew running full length doesn't it? Does it also have a keyed plain shaft as well, or just a keyway in the threaded leadscrew? Assuming its got the leadscrew, then somewhere in the apron is a pair of half nuts which engage with the leadscrew for screwcutting. These are normally operated by a short lever on the front of the apron. If your lathe has power feed as well then there will be another knob or lever to engage that, but it won't be the half nuts, normally its driven off a keyed worm which slides up and down on the shaft with the keyway in it. You say your apron has 2 knobs on it which you thought were for fast and slow feeds. If there isn't a lever for the half nuts as I described, then the chances are that one of these knobs is for the halfnuts. You are going to have to get a torch and peer round the back, try and see what happens when you twiddle things. The leadscrew and half nuts are for screwcutting, and shouldn't be used for anything else, if power feed is available. I still don't see how you got 10TPI with the gear train you described.
Yes photos would be a help, my usual fall back, the www.lathes site doesn't have anything on P&W cone head engine lathes.

Richard

Alistair Hosie
10-21-2013, 04:27 PM
Please dont incorporate the word bastard as stevenson only had the one mother and father poor lad. Alistair

Richard P Wilson
10-21-2013, 08:07 PM
]Please dont incorporate the word bastard as stevenson only had the one mother and father poor lad. Alistair[/I]

Did we?

wierdscience
10-21-2013, 09:26 PM
Ooops...sorry guys...you re right. I see what I did wrong....had too many numbers wrote down....used the wrong ones for the first calculation.
Dang...yer right again....now I ve figured this out in my tired ol head and it makes sense.
Richard....I think what I must have done...was tightened the slow feed knob the first time....and the rapid feed (the one that worked) the second time.
Ive never seen a setup like this before.
Somehow or another...this is a two speed apron....
I ll get pics of it today for sure now.
Russ

Hey Russ,I might know what's up with the two speed feed.If both feeds can be engaged at the same time.One speed should turn a 45* and the other should turn a 60*.

JRouche
10-22-2013, 02:16 AM
Hi JR!!!! Yer alive :)
Cal...hmmm...how you figure that?
Russ

Knuckle head :p Ive been down here for a few years. More importantly did you head south into the states and move on?

Sucks starting a new life. Its been a few years Russ. Shoot me a PM so we can update huh? And the gear ratio issue? No doubt you will get that figured out. JR

torker
10-22-2013, 08:02 AM
Lol...Alistair...funny one!
Darin....Im very curious how this works now. I was going to take pics yesterday but the guy never showed up to unlock the shop. He owns a few towtrucks...it snowed....
JR...lol...Im still stumbling thru life as usual...still making mistakes...still learning...
I pm d you a couple days ago....not sure why you never got it.
Russ

dewat
10-23-2013, 09:46 AM
Torker's pic's


http://i.imgur.com/E6Jrt7y.jpg

http://i.imgur.com/ATj47E9.jpg

http://i.imgur.com/PfQ6ZeG.jpg

torker
10-23-2013, 09:59 AM
Cool!!! Thanks Jim!
Ok...in the bottom pic...the knob on the left as you look at it...its in the center of the handwheel.
Thats the one you tighten for fine feed.
The knob in the middle is for crossfeed.
The knob on the right...or nearest the tailstock is the knob you tighten for fast feed.
Thats the one that worked for threading 10tpi.
I looked under the apron....its a very complex geartrain under it.
This is not just clamp halfnuts and go.
The owner was told this lathe is from the late 1800's.
Im very sceptical...I think its much newer....how new....I have no clue.

torker
10-23-2013, 08:45 PM
Hmmm...been hoping someone would chime in..to give me a clue about the age of this ol girl..

J Harp
10-23-2013, 09:49 PM
Hey Torker;

The apron on that lathe looks a lot like one shown in Volume 1, Modern Machine Shop Practice, by Joshua Rose. I can't read the copyright date,it's too dim, but I'm sure it is late 1800's or early 1900's. That lathe just may be an oldie.

Here is a link, if you can get on a computer, start at page 151 and flip pages to the right till you find plate XVI, and it's at the bottom of the page.

https://archive.org/stream/modernmachinesho01roseuoft#page/n209/mode/2up

Bob Ford
10-23-2013, 11:03 PM
The front page lists copyright 1887-1891-1899.

Torker, Good to see you back.

Bob

torker
10-23-2013, 11:29 PM
Hi Bob!
Thanks guys...wow...ok..Im impressed with P&W.
I honestly thought the apron design was ahead of that time.
The whole feed drive system works flawlessly once you figure it out.
Russ

JCHannum
10-24-2013, 07:05 AM
Rather than fine and rapid feeds, the two knobs are probably for cutting and threading feeds. The one in the handwheel probably engages a clutch, the one to the right, the feedscrew.

torker
10-24-2013, 07:38 AM
Jim...I wondered about that. I previously said the one knob produced 50tpi. Lol...I was just guessing.
It was a fairly course cut...but could be usable for cutting shoulders etc.
I havent had a chance to fool with this lathe much yet...but if thats the case it would cure one gripe Ive always had about change gears...you set up for threading and you cant make any other cuts without changing gears.
This one is an even bigger pain. The owner built a bolt on cover for the geartrain.
Its a bolt on deal thats very difficult to remove.