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Seneca Lathe

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PHPaul

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#1
Got involved in a project that was just too big for my Grizzly benchtop (never heard that one before, right? :rolleyes: ) so I went to visit an acquaintance of mine from my volunteer firefighter days. I knew he had a mid-sized lathe and planned to see if I could rent some lathe time from him.

Turns out he now has a half-dozen lathes, only 2 of which see any use to speak of. I was more than welcome to fire any of them up, or...



For $50 I could take this one home with me. Old Seneca from a line shaft shop converted to motor drive. Came with all the important bits: tail stock, 3 jaw chuck, tool post, threading gear sets, Jacobs chuck and a bunch of stuff I'm not entirely sure about:





Spindle bearings seem tight as far as a "grab and wiggle" test goes, ways appear to be in good shape, fired it up and no odd noises until I engaged the threading drive. Sounds like gear lash needs snugged up a bit. It had been "converted" for use as a wood lathe but all the other parts were in a crate under it.

AND, he helped me load it up from his shop and followed me home to help me unload it into my shop/garage! What's that old saying about blind hogs and acorns? :p

Two questions pop up immediately: How to identify the model number and where I might be able to find literature on it.

I'm sure I'll be back with questions as I clean this thing up and check it over.
 

benmychree

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#2
You see so many people looking for "information" ??? You have what looks like a nice lathe, just use and enjoy it; it is much like my 9" Monarch lathe. I assume it is a (Seneca Falls) machine, not uncommon. What I would do is to set up a saved search on E Bay, if anything pops up, you will be given notice of it. Coincidentally, I see two references to Seneca Falls lathes at the bottom of this page!
 

derf

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#3
Check out the "project of the month"...
 

PHPaul

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#4
Thanks for the tips.

So far the only problem I've found is that the captured nut for the compound feed screw (hope that's reasonably correct terminology...) is missing.

The 3 jaw is a little rough and badly mis-timed with one jaw off about 1/4" when the other two are closed. I have it apart cleaning it up and should be able to re-time it when I re-assemble it.

Question: What lube, if any should I use on the ring gear, bevel gears and jaw mating surfaces when I put it back together?

According to the leg casting, it's a #30.
 

PHPaul

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#5
Hey, thanks for the tip on the POTM. Mine is a Star 30 so that thread will be VERY helpful!
 

projectnut

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#6
There are several Seneca Falls catalogs available at the Vintage Machinery website.

http://www.vintagemachinery.org/mfgIndex/detail.aspx?id=734&tab=3

I have had a Star #20 machine for over 20 years. It's a good machine, but a bit slow by todays standards. Take a look at the specifications pages and you'll see most have a top speed of around 600 to 800 rpm. There have been some who like to make them go faster, however I would caution against it if you want the machine to last.
 

benmychree

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#7
Thanks for the tips.

So far the only problem I've found is that the captured nut for the compound feed screw (hope that's reasonably correct terminology...) is missing.

The 3 jaw is a little rough and badly mis-timed with one jaw off about 1/4" when the other two are closed. I have it apart cleaning it up and should be able to re-time it when I re-assemble it.

Question: What lube, if any should I use on the ring gear, bevel gears and jaw mating surfaces when I put it back together?

According to the leg casting, it's a #30.
A light molybdenum grease should be fine; don't over grease the face of the scroll, unless you want to wear it. Timing the jaws should not be difficult, the jaws are stamped with a number that matches a number on the chuck body, find the leading edge of the scroll and start #1, rotate the scroll and start #2, rotate and then number 3, that should put it in time.
 

PHPaul

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#8
Got the 3 jaw apart, cleaned, lubed and reassembled. Also got the motor and belt drive reattached. I need to check the speed with my tach, seems kinda fast.

Next step is to indicate the chuck.
 

FOMOGO

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#9
What is the rpm of your motor? Mike
 

PHPaul

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#10
What is the rpm of your motor? Mike
Haven't looked yet but it sure seems to be too fast. That's one of the things I'll look into tomorrow. At the very least I can go with a smaller pulley on the motor, it has a 4" on it.
 

markba633csi

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#11
Oh yes that motor pulley is way too big, no wonder it's running so fast- there's your first project
Mark
 
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PHPaul

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#12
I indicated the chuck this morning. At the back of the chuck, nearest the spindle, runout is about .003"

With a piece of round stock chucked up and measured as close to the jaws as practical, it's more like .030" Obviously, that's a problem. Not sure where to start looking for the fix.

Also, motor is a 1725 RPM 3/4 hp. 5" on the motor, 10" on the belt pulley shaft so upper pulley set (countershaft?) is running at 860-ish RPM.

Perusing the catalogs at Vintage Machinery, I'm seeing max spindle speeds of 340 RPM for the 9" lathe and countershaft speeds of 175 RPM. Am I reading that right? If so, I need a 10:1 reduction on the motor.
 

markba633csi

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#13
Probably you need more like a 5:1 ratio- spindle max speed about 700-800. I'd go with about a 2" motor pulley, countershaft speed 345
The chuck may very well be shot- used chucks often are. Sometimes you can grind the jaws to get some improvement.
 
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projectnut

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#14
I indicated the chuck this morning. At the back of the chuck, nearest the spindle, runout is about .003"

With a piece of round stock chucked up and measured as close to the jaws as practical, it's more like .030" Obviously, that's a problem. Not sure where to start looking for the fix.

Also, motor is a 1725 RPM 3/4 hp. 5" on the motor, 10" on the belt pulley shaft so upper pulley set (countershaft?) is running at 860-ish RPM.

Perusing the catalogs at Vintage Machinery, I'm seeing max spindle speeds of 340 RPM for the 9" lathe and countershaft speeds of 175 RPM. Am I reading that right? If so, I need a 10:1 reduction on the motor.
Are you using a somewhat precision piece of round stock? To be sure the runout is in the chuck rather than the stock itself I would use a dowel pin. I have several 1"x4" and 3/4" x 4" dowel pins especially for this purpose. The pins are hardened and ground to be within .0001" to .0003". Most chucks give a runout specification at 1" and 3" from the face.

I would also check the face of each of the jaws to be sure there isn't a burr or piece of swarf causing the runout. As a side note I have several 4", 5", 6", and 8" chucks for my Star #20. None has more than .003 runout 1" from the face of the chuck. A couple came with the machine and I bought several of them used.
 

PHPaul

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#15
Good point on the dowel pins. I have some too, just didn't think of it.

Went to the smallest pulley I had on hand that would fit the motor shaft. Didn't think to measure it, but about 1.5 or 2 inches.

With the belt set on the slowest setting, I'm getting 225 RPM at the spindle in direct and about 26 with the back gear engaged. I'll go with that for now.

Any idea where I might find an exploded view of the compound? I need to figure out what's missing for the feed screw and how to lock the angle on the compound.
 

dtsh

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#16
Nice score. What's the most recent patent date on the front of the bed and any other markings?

I've been pretty happy with mine.
 

PHPaul

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#17
Nice score. What's the most recent patent date on the front of the bed and any other markings?

I've been pretty happy with mine.
Jan. 11, 1910 is the last date. It's a Star #30
 

derf

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#18
I used a 9 and a 10" pulley on the countershaft, and a 2 and 3" on the motor. The 10" and the 2" gave a top speed of 697 rpm. With the 3" and the 9", top speed is 1188.
beltpully2.jpg
DSC02480.JPG
 

PHPaul

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#19








These...spacers, for lack of a better term...came with the lathe. Are they part of the change gear system for threading?

There are 2 sizes of square keyways, one set of a sort of half-round keyway, and some with no keyway at all in various thicknesses. Haven't measured but shaft size appears to be the same in all of them.
 

projectnut

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#20
They're spacers for a horizontal milling machine arbor. I just made about 100 different diameters and widths for my US Machine tools horizontal mill. You can buy them from .001" to well over 3". I would guess yours fit a 1" arbor. I made adaptors for my machine to be able to accept 1 1/4", 1 1/2", and 2" cutters. I've found over the years the larger diameters are more readily available and cheaper. Mainly because they fit machines much larger than most hobbyists are able to get into their home shops.

Here's a link to some currently available on eBay:
https://www.ebay.com/i/283225162495?chn=ps
 

PHPaul

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#21
Ah. Thanks very much.

If anyone has a use for them, they can have them for the cost of shipping. A small flat rate box would probably do it.
 

dtsh

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#22
My SF lathe has a couple of keyed spacers which fit over the change-gear shafts to allow for aligning the gears, they're the same width as a gear. Typically one with the spindle gear and one on the leadscrew gear, one inside of the gear and the other the outside.

Here's an example of one on the inside of the spindle gear keeping it lined up with the ouside of the ganged idler gears and a matching spacer on the outisde of the leadscrew gear keeping it meshed with the inside ganged idler. Not sure if any of those are the same or not.
spacer.jpg
 
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PHPaul

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#23
Progress report:

After a couple of hints from @derf I found solutions to both the compound angle lock and the compound lead screw nut.

The compound lock was a case of a broken off set screw jamming up the threads. I thought that was where it would be but couldn't get it to work. Chased it with a bottoming tap to get the broken bits out of the threads and all is well.

The lead screw nut for the compound I had to fabricate, but it also went right where I thought it must. Conveniently enough, the lead screw is a common 7/16-14 thread so I was able to TIG a post to an ordinary hex nut and fix that issue as well.

Now all I need to do is get the 3 jaw chuck tuned up a little better and learn to grind HSS tools (I have printed out @mikey 's excellent instructions) and I should be able to start making chips.
 

projectnut

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#24
Progress report:

After a couple of hints from @derf I found solutions to both the compound angle lock and the compound lead screw nut.

The compound lock was a case of a broken off set screw jamming up the threads. I thought that was where it would be but couldn't get it to work. Chased it with a bottoming tap to get the broken bits out of the threads and all is well.

The lead screw nut for the compound I had to fabricate, but it also went right where I thought it must. Conveniently enough, the lead screw is a common 7/16-14 thread so I was able to TIG a post to an ordinary hex nut and fix that issue as well.

Now all I need to do is get the 3 jaw chuck tuned up a little better and learn to grind HSS tools (I have printed out @mikey 's excellent instructions) and I should be able to start making chips.
I'm thinking somewhere along the line someone replaced the original compound lead screw. First off I've never heard of a 7/16-14 thread on a lead screw. That would make each full revolution of the handle advance the cutting tool about .071". The factory standard compound lead screws are generally 8 or 10 threads per inch. An 8 pitch would advance the cutting tool .125" while the 10 pitch would advance it .100" per revolution.

The compound lead screw on my Star #20 was originally 7/16-10. When it wore out I replaced both the screw and nut with a 3/8-10 (7/16-10 was unobtanium) to keep the graduation dial on the compound accurate. In this case the Star was the only lathe I had at the time. I would have turned a new lead screw 7/16-10 if the lathe was working. Instead I had to order a screw and nut from McMaster. I modified the nut to fit on the mill and adapted the new smaller lead screw to the original handle.
 

dtsh

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#25
Interesting as the cross slide on my SF is a 7/16-8. I'm pretty certain it's the correct and probably original screw, as one full rotation moves the compound in 1/8", which seems an odd fit until you look at the graduations on the dial being 1-250, meaning each tick is 0.0005"
(1/8 = 0.125, 0.125/250 = 0.0005)

Seems they had some variation in the design of these.
 

DiscoDan

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#26
Anyone have a source for the full dimensions of the Seneca 3s or #3 collets? I know the back bearing is 1.000" and length is 4.59". Ultimately I am looking for the angle of the head but if I can find the width of the head and the length of the head I can figure it out with good old geometry. I have searched the interwebs but can't find it. Thanks.
 

derf

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#27
1540934649465.png
I too thought is was odd that the screw was a 14 pitch, but it didn't have a dial either. That comes out to .0714285 per rev. When I made the dial, I cut 72 graduations and called it close enough.
 

projectnut

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#28
Anyone have a source for the full dimensions of the Seneca 3s or #3 collets? I know the back bearing is 1.000" and length is 4.59". Ultimately I am looking for the angle of the head but if I can find the width of the head and the length of the head I can figure it out with good old geometry. I have searched the interwebs but can't find it. Thanks.
The 10th and 13th edition of the Machinery's Handbook have a section on collets. The complete dimensions for both the Seneca #3 and #3s are included. Some other editions may include this information. They are no longer included the 16th edition.
 

PHPaul

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#29


No dial on mine either. Must have been the economy model...
 

DiscoDan

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#30
The 10th and 13th edition of the Machinery's Handbook have a section on collets. The complete dimensions for both the Seneca #3 and #3s are included. Some other editions may include this information. They are no longer included the 16th edition.
If you have one could you send me the dimensions? Or is there a source to view online? I couldn't find anything available here or elsewhere.
 
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