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Porter McLeod Lathe info needed

44dwarf

Aluminum
Joined
Sep 29, 2009
Location
north central Ma.
Hello All.

I picked up a Porter McLeod lathe February 2015 and have used it a few times after sorting some problems in the head stock gearbox (Mostly due to PO bad repairs).
I've used it a few times but nothing to critical yet. I tried the powered feed and its to fast and Hell NO faster....
My feed chart is damaged as it is on a flat horizontal and the top of the gear box is domed the feed chart has been used as a shelf for 75+ years..

There seems to little to no info out there on Porter McLeod's.

Might anyone have a good picture of a feed chart and an idea on what gear should be where on the left side? (gear info should be on chart) Seems I have only a 32, 35,56 and a 60 tooth gears but am limited as to what I can put where due to clearances.

Thank you for any help.

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I have never hear of Porter McLeod lathes, but, as the saying goes: "A lathe is a lathe". Your photo shows basic "loose change" or "independent" change gears. As it is made up it is "simple" gearing, with the center gear in the train on the quadrant serving as an idler gear. An idler gear does not affect the gear ratio of a train of three (3) gears as your photo shows. However, you do have additional gears that are not in mesh with anything. This is where those "extra" gears come into play if you want finer feeds.

You will need to make up what is known as "compound" gearing. This consists of "stacking" two gears on the "center" stud where the center/idler gear now is.

There should be a bushing with a keyway that is long enough to handle two gears and key them together. Here is how the compound gearing would be set up to give you the finest feed:

driving gear (aka "stud gear") would be the 32 tooth gear. This is always a single gear.

middle "stack" or cluster of two gears: set on bushing and keyed together: the 56 tooth gear is place on the bushing so the 32 tooth stud gear drives it.
the other gear on the stack is the 35 tooth gear, also keyed to the 56 tooth gear so they turn as a single unit.

final gear, known as the "screw gear" since it is on the leadscrew will be the 60 tooth gear.

This is compound feed gearing and gives "double reduction" where the gearing, as you have it presently set up, gives only "single" reduction. As the lathe's feed gearing is presently set up, it looks like about a 4:3 reduction, which is a very coarse feed and very coarse thread.

Once you have sorted out your gearing, your inquiry about threading and lack of a thread chart can be addressed. If you intend to use the lathe to cut screw threads, it becomes a matter of determining the threads per inch of the lead screw on your lathe. Once you have that established, determining the change gear combinations needed to cut different pitches of threads is done with some simple math (remember the concept of ratios from your HS math classes ?).

Example: say your leadscrew (hypothetically, since I have no knowledge of the anatomy of a P-M lathe) has 5 threads/inch. Suppose you wanted to cut a 1/2-20 thread. If the lead screw were geared to the spindle 1:1, it would move the carriage and toolbit to cut a thread with 5 tpi. You would need to take the ratio of 5 threads per inch (leadscrew)/ 20 threads per inch (the thread you want to cut) and you get 5/20 which reduces to 1:4. IOW, for each full turn of the stud gear on the headstock, the lead screw must only make 1/4 turn. You arrange your gearing as simple gearing to give you 4:1 reduction.

For fine feeds, you would need to know the ratio of the gearing in the apron of the lathe. There is some additional reduction gearing which is turned by the leadscrew (or feed shaft if the lathe is so equipped). I would not worry about this gear ratio in the apron as it is not so critical as when figuring gearing to cut a specific thread.

Doing the math for the compound gearing I wrote about, above:

32:56 (first reduction) gives a ratio of 1: 0.571

35:60 (second recution) gives a ratio of 1:0.583

Multiply these two ratios for the total reduction: 0.571 x 0.583 = 0.333

In other words, the stud gear on the lathe headstock will make 3 turns for each turn of the lead screw. Still pretty coarse feed, but better than what your photo shows. You may want to get the pitch of the change gears and purchase a pinion gear or two with much fewer teeth. Firms like Martin Gear and Boston Gear sell "stock" sour gears (gears with "straight" teeth). These gears have a "pilot bore" thru them, and you usually have to bore them to whatever size you need and cut a keyway in them. A couple of pinion gears with much fewer teeth (say about 15-17 teeth) would increase the reduction a great deal and give much finer feeds.
 
If you go after gears, a bit of info you will need will be Diametral Pitch, or "DP"

A way to determine:

Mic clean and burr free OD of one of your gears
Count teeth and add TWO to that count
Divide sum by OD

Example:

2.125" OD
32 teeth
34 divided by 2.125 = 16 DP
 
Pressure Angle of Gears

At the risk of "me too-ism", I want to add that when obtaining gears, one should also match the Pressure Angle (PA) of the original gears. Older machines use a 14.5 Degree PA. Newer machines would be more likely to use a 20 Degree PA.

There must be easy tricks to measure the PA. Since I rarely have to make this measurement, I take a crude approach and use a sheet metal template that I made with the protractor head on my combination square. (I'll bet the people who do these measurements every day just groaned!) I've only had to decide between 14.5 and 20 - never had to wonder about other PA's.

Other gear parameters to match up include:
The width of the teeth.
The diameter of the center hole. (Can be changed by reaming or bushing)
Keyways, if needed. (Making a keyway is easy: With the spindle locked in place, use the carriage as a shaper, cranking it in and out.)
Side holes for bolting together compound gears. (Easy to add unless the gear has spokes.)

The Quick-Change Gearbox was obviously a great advance in lathe-building, but the old-style "Loose Change Gears" lathes are definitely very flexible in the sense that they can cut ANY thread, including Metric, with the correct combination of gears. (Hint: Metric threading uses a compound gear 50:127 to give the 2.54 ratio)

John Ruth
 
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44dwarf

As I wrote, I've never heard of a Porter McLeod lathe. It is obviously a geared headstock machine from your one photo, and has a thrust bearing adjustment at the end of the headstock spindle with the drive gear. From your photo, and from your post making reference to the change gear chart being used as a shelf, it would seem the lathe has some kind of gearbox giving a means of selecting feeds/threads over a narrow range. Some older lathes had this feature, a gear change box with maybe 3 or 4 possible ratios was combined with the loose change gears to give the full range of threads/feeds. The change gear box was not a true "quick change" gearbox, but allowed a lathe user to have several feeds easily available.

I am flying blind as far as being able to help you further with your questions. More photos would be appreciated, as I am curious as to Porter-McLeod. Possibly, P-M was a dealer whose tag is on the lathe, and the actual maker is some more recognized builder. From photos we may be able to determine this. Or, P-M was the actual lathe builder and just one of those obscure makers that I've never heard of. Either way, photos to satisfy our curiosity would be appreciated.
 
That looks to be same lathe. I've reached out to the admin / poster if he could snap some pictures but he was sent the pictures some years back.

I've tried moving the gear I have around and the combo showed it the only one that fits sadly. If I try to put the smaller gear at the top to drive a big gear as the idler the end of the cast hits the gear before tooth contact is made.

I've contacted the only e-bay auction I found and machine is long gone...

I was able to buy a sale pamphlet but it has little real info other then shipping weights...

I will likely just keep an eye out for gear that I can match up and bore and broach keys to the axles.
 
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Here are two more pictures of the lathe.
Yes it has a 8 position quick change feed rate box.
I had more pictures but seem to have lost / misplaced them...
If I can find just one more gear in the 40 tooth range I would be able to set the loose change gears up for double reduction but with what I have something all ways hits or is just short of having the needed range.
A few neat things on this lathe is the main input shaft has a clutch so you don't have to stop the motor and deal with start up amp draw. It also has feed rev on the carriage.
I believe it to be made 1938-39 as it has a "conforms to war board specs" tag

PLEASE NOTE: pictures in this post were at the PO shop. The chips where so packed in you could no longer move the carriage! I filled 8 5 gallon pails with chips. Sad sad sad to abuse a machine this way. I'm not a clean freak by any means but there no accuse for that mess. I would have told him so but he had passed on I bought it from his daughter

Thanks for the help guys. I don't get on to this board much in the past few years like I used too, but its always helpful when I do.

Tony
 
Although I have never heard of the make,looking at the basic construction and the fact that it has a clutched drive,it was definitely mot a cheap lathe.
Surprising that more survivors haven't surfaced.Maybe the company had financial or poor marketing problems and never made many of them.With the war production tag on it there was certainly a large demand for lathes in that time period.It may be that a small company with a high quality product just couldn't compete with the larger lathe makers on price.Has happened before and since then with many products.
 
Aside from never having heard of Porter-McLeod as a lathe builder, I'd never heard of Hatfield, Massachusetts. I looked that town up. It is about 20 miles North of Springfield, MA, and has about 3300 inhabitants. Not a big town, and certainly not in the heart of a machine tool building center like Worcester or Springfield.

Conceivably, P-M was building something else altogether in their plant prior to WWII. With WWII, they may have gotten into building engine lathes for the war effort. The overall design is a basic late 1930's-40's engine lathe with a few differences. Notably, their neighboring lathe builder, Reed & Prentice in Worcester was using handlevers to work the feed clutches. Hendey, another New England machine tool builder, was also using levers to work the feed clutches. The knurled knobs to engage/disengage the feed clutches was an older design which most of the lathe builders by WWII had abandoned in favor of handlevers.

The overall design of the engine lathe is kind of generic, a husky piece of iron with lines not too distant from the other engine lathe builders of that time.

It could be that P-M was building paper mill or textile mill machinery (not unlikely for a New England shop in that era). Making the switch to building engine lathes was probably a big switch, requiring lots of tooling (jigs and fixtures), but if P-M already had a shop equipped with boring mills, planers, lathes and turret lathes, gear hobbers, precision grinders, and a force of skilled machinists and machine tool operators (for production work), they were halfway there. The start of manufacturing the kind of medium duty generic engine lathes like the one in this thread was no small thing. Getting a design worked out in a hurry for a new lathe with no prior models to evolve it from, and getting patterns and coreboxes made in a hurry had to have been a real feat in itself. I find myself wondering if P-M did not work some arrangement with Reed & Prentice or another established lathe builder who had to produce a certain number of lathes for the War Production Board. Perhaps some of the major patterns and coreboxes from another established lathe builder were used for the major castings of the P-M lathes.
Knowing what it took to build a lathe of this sort, P-M had to have a large and well established plant. In a town which has all of 3300 souls inhabiting it, my guess is P-M drew on the surrounding communities, such as Springfield, for more of a workforce. New England abounded with firms producing all manner of precision machined products from small arms and sewing machines to major machine tools. Having fine craftsmen in the form of patternmakers, molders, machinists and toolmakers in large numbers was a given in that era.

This past week, my wife wanted to go to the antique flea market at Brimfield, MA. I drove her there and we browsed until it all became a blur. Several things stood out in my mind. One was the huge number of wood foundry patterns, matchplate patterns, and coreboxes the antique dealers were selling there. All sorts of patterns for all sorts of parts. I felt sad in seeing the patterns on several levels, not the least of which was the fact that the average person has no knowledge of what a foundry pattern is, who a patternmaker was, and the industry and way of life that is gone forever. As I looked at the endless numbers of patterns and coreboxes, I kept thinking of all the shops that once were in New England, all making machinery, machine tools, plant equipment and much more.

The other thing that served to remind me of New England's past was the numbers of factory carts still labelled from different departments in spinning, weaving and dying plants.

At the first area we hit, I found a vendor who had a mess of Starrett and Brown and Sharpe tools. I bought a new Starrett 436 1" mike to give to my next apprentice. The dealer was a bit of a wise guy, and while he knew there was no huge demand for micrometers, he was asking a young fortune for machine tool worklights- knowing what the current fad is. I found the flea market kind of depressing, seeing the steampunk kitsch made from good gauges, lubricators and fittings and tools. I also found the flea market depressing as it reminded me of New England's past. Seeing this thread about the Porter McLeod lathe has carried this line of thought along for me. New England was the cradle of inventiveness and precision, but no more. P-M was probably a typical New England shop in a nice New England village. I'd like to learn more about P-M as a company.
 
Joe.I did find a little info on them.Porter actually started out building lathes after purchasing a foundry in the 1880's.Porter died in early 20'sMcLeod was his son in law and took over and died in 1927.The company had patents assigned to them past the 40's.So they had quite a long run.I thought that the war tag might have been from WW1.Don't know if that was used at that time.If so then it was state of the art ,however if it was WW2 then it was a little dated in its design.
There is a thread from 2006 in the Antique Machinery forum on an 1894 model.
 
Joe,I ment to add that the clutch drive was referring to the main drive motor not the feeds.While certainly nothing new at the time not very many cheap lathes would have had a cluthed drive.On second thought I suppose larger lathes would all have clutches in the drive and larger lathes were never cheap!
 
Yes the clutch is on the main input shaft. It was removed when I took the pictures of the gears as the bearing it over run on was loose on the shaft and the P.O. had mangled the oil seal and did not re-install it properly so I had to pull it a part grind off spot weld etc. to fix it closer to OEM. The clutch is a CARLYLE JOHNSON MAXITORQ multi plate unit still made today however when I asked them about any info they might have on P-M they told me they had no way of checking old records, but did provide me a PDF of the clutch.

The feed knobs are the twist to engage knurled knobs.

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The C/J clutches & brakes work really well.Just be careful when you adjust it.When properly adjusted it should snap into position and not be needed to be held into position.It has a fairly narrow range of adjustment between to loose and to tight.Some have a flat spring that locks into the adjuster collar allowing one notch at a time adjustment and others have a clamp collar that you loosen the clamp bolt and turn the knurled collar then tighten the clamp bolt.All that I have seen were RH threads.
 
Here is a page from the towns official history book. One the page before they talk about the building housing a saw mill (water powered) then a Pistol Company then the lathe shop.hatfeild history book.jpg
 

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Okay guys I could use some more help with this one. I know the change gears are 12DP where I need help is figuring out what the tooth count should be on the missing gear.
From what I can read on the feed chart slowest feed should be 0.00675 using a 30th and 60 tooth gears with tumbler in #1 position and the 3 speed box in "C" range.
So here's what I did with the 60 tooth on the input of the gearbox and tumbler in #1 position and the 3 speed box in "C" range. I put a 1 inch travel dial on the tool post and ran a wire as a pointer to the gear. I turned the gear until the post moved in some zeroed the dial and marked the gear. I turned the gear a full rev recorded and did this for 20 revs of the gear I get 0.0051 so now I know I need the input to turn 1.32 revs per the head stock turning 1 rev.
but I can't seem to wrap my head around all the different gear teeth and figure out the missing number....
On the head stock is a 40th there is 25th on the forward / reverse lever meshed to a 26th (hidden on org pict) on a axle driving a 30th this meshes with the 56th on an axle with 35th meshing with 32th gear on an axle with a spot for the "unknown gear that will mesh with the 60th on the gearbox input.

change gears thooth counts.jpg
 
If you can read the threading chart enough to put the gears in the spot for cutting the same TPI that your lead screw is. If the lead screw is 4 TPI then set the gear box to cut 4 TPI. That way the spindle will turn one time and lead screw should turn once, that makes the gear ratio 1:1. Then you just have to figure out what gear will give you the final 1:1.
 








 
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