I have a Seneca 9" lathe with cast iron bearings. The countershaft
assembly has two pulleys, but the motor only has one.

The rpms are as follows:

direct: 558, 350, 222
back gear: 80, 52, 32

The max speed seems kind of low, but I'm not familiar with how
fast these lathes were designed to go. From reading the lathes.co.uk
pages, it seems similarly configured South Bend 9" lathes with cast
iron bearings went up to 1200 rpm.

I had the lathe running for 20 minutes at the top speed yesterday
and the bearing caps weren't warm at all.

So would it be OK to put a bigger pulley on the motor? And if so,
what should the top RPM be?

Thanks for any insight,
Aaron

Correct on the top SB 9" speed. You may be able to simply put a 2-step
pulley on your motor. Max spindle speed and small spindle hole characterize
a lot of older lathes. That's why a lot of guys suggest you don't even
bother with carbide tooling, just get real good at grinding HSS bits.

If your spindle is built as heavily as the SB 9 and if it's lubricated
as well (and finished as well) then it should run close to a similar
speed. Given the uncertainty, however, I think I might not even try. Start
looking for a great deal on your next lathe and just go slower with this
one until you've found your next one, then sell this one and move on ..

GWE

Aaron Kushner wrote:

I have a Seneca 9" lathe with cast iron bearings. The countershaft
assembly has two pulleys, but the motor only has one.

The rpms are as follows:

direct: 558, 350, 222
back gear: 80, 52, 32

The max speed seems kind of low, but I'm not familiar with how
fast these lathes were designed to go. From reading the lathes.co.uk
pages, it seems similarly configured South Bend 9" lathes with cast
iron bearings went up to 1200 rpm.

I had the lathe running for 20 minutes at the top speed yesterday
and the bearing caps weren't warm at all.

So would it be OK to put a bigger pulley on the motor? And if so,
what should the top RPM be?

Thanks for any insight,
Aaron

Aaron Kushner wrote:
I have a Seneca 9" lathe with cast iron bearings. The countershaft
assembly has two pulleys, but the motor only has one.

The rpms are as follows:

direct: 558, 350, 222
back gear: 80, 52, 32

The max speed seems kind of low, but I'm not familiar with how
fast these lathes were designed to go. From reading the lathes.co.uk
pages, it seems similarly configured South Bend 9" lathes with cast
iron bearings went up to 1200 rpm.

I had the lathe running for 20 minutes at the top speed yesterday
and the bearing caps weren't warm at all.

So would it be OK to put a bigger pulley on the motor? And if so,
what should the top RPM be?

Thanks for any insight,
Aaron

Are the bearing journals "superfinished" like the SB lathes are?
That might make the difference.

Ken Grunke

--
take da "ma" offa dot com fer eemayl

direct: 558, 350, 222

The max speed seems kind of low, but I'm not familiar with how

My lathes spend most of their time below 500 anyway.
(even though they go much higher)
I use HSS toolbits most of the time and everybody is happy.

Use it for a while and I bet you won't find it to be a big issue.

chuck

Ken Grunke wrote:

Are the bearing journals "superfinished" like the SB lathes are?
That might make the difference.



Not sure what superfinished means. The journal bearings are shiny
and the handscraping marks are still visible.

Not sure how the South Bends work, but this lathe has an oil sump
and a ring that spins around between each set of bearings that
distributes the oil around.


And to reply to Grant... Yes, I've been getting good and
grinding HSS bits ;-) Is one size more appropriate than an
other? I'm using 3/8" Rex AAA bits that I bought on ebay.
Would smaller (5/16" or 1/4") bits be better for this size
lathe?

Aaron Kushner wrote:

And to reply to Grant... Yes, I've been getting good and
grinding HSS bits ;-) Is one size more appropriate than an
other? I'm using 3/8" Rex AAA bits that I bought on ebay.
Would smaller (5/16" or 1/4") bits be better for this size
lathe?

I'm sure those bits are fine. They have one real good thing going
for 'em, you've ALREADY PAID FOR THEM! :-)

I use a lot of bits in my shop. I recently needed a 3/16" square bit
and sure nuff there was a new one in my "bit bucket". Bits that fit
your toolholders are sure nice. I'm sure you've noticed that the part
that does the work is pretty small, and once you've done the main
grinding you can touch it up for quite awhile with a hand stone or
one of those DMT diamond matrix stones (those are great). Bigger bits
are of course more rigid so they can be extended just a little more,
and smaller bits grind more quickly because there's less material to
remove. - GWE