On Tue, 09 Feb 2010 16:22:30 -0600, Jon Elson
wrote:

Dave H. wrote:
Not strictly model engineering (motorbike engineering and supercharging!),
but...

About to arrange a trip to the next town to look at a medium-sized lathe
(English, geared head 6.5/13" x 40", 20" into gap although the spindle
bore's too small for e.g. fork stanchions, has a non-working suds pump and
tank etc.) and may consider it if it's in reasonable shape, one concern is
the speed range - 8 speeds from 30 - 750 RPM - and whether the low top speed
is going to cause problems?
If you only have one lathe, this could be a pain. 750 RPM is not a
massive limitation, but many times for smaller work you might want more.
It may be possible to run this machine well above rated speed with a VFD
on the motor. Depending on the bearings, lube system and such, you may
be able to do this safely, or not.
The only issue I can think of (other than slow
removal of material when cutting!) is that may be a bit slow for
small-diameter work in work-hardening materials, but as this would be my
first lathe since college over 30 years ago any hints and tips would be
appreciated!

Another concern is that the quadrant lever and clutch knob for the sliding
and cross power feeds (ooh, luxury....) appear to be missing - I've a fair
idea how they (should) work and aptitude enough to rebuild car and 'bike
gearboxes, so is this going to be a serious can of worms should there be
problems with 'em? They were manufactured into the 70's and fairly popular
(if a bit pricey new...) and had spares support into the 90's so there may
be spares still around... Famous Last Words?
Missing, as in somebody took the handles off when moving, or broke them?
or, missing, as in, this lathe never had any power feeds other than the
main carriage threading feed?

As manufactured it's Imperial, and bikes seem to all be Metric these days -
apart from threading (which may need a 127 gear or similar made if it has
gone missing over the last 50 years), am I making a rod for my own back by
not going for a Metric lathe? I have a bunch of Metric (and Imperial)
measuring tools and can probably remember 40 thou = 1 mm...

If you are going to be doing a lot of metric threads, having to back up
for every threading pass will drive you round the bend! The transposing
gears get you proper feeds, but with an imperial leadscrew, you cannot
disengage the leadscrew between passes.

Jon

That doesn't bother me a bit, Jon. I often back up even when cutting
inch threads. The threads I cut are usually short, often fine, and
it's as easy to change speeds (gear head lathe) as it is to hit the
right spot on the threading dial. I cut slow so I can stop in time,
back up fast. I've found it works best for me to do it once slowly
rather than thrice quickly get it right third try, since I very seldom
make more than two or three of anything.

Carbide cutters work best at higher speeds, HSS works well at lower
speeds. HSS can take a keener edge than most carbide. I can take
finish cuts of tenths with HSS that produce fuzz or dust rather than
chips. Carbide won't do that, at least not for me. I don't understand
a preference for carbide in a home shop where production isn't an
issue. It's useful when working with hard or abrasive materials, but
for ally, brass, bronze, delrin, nylon, mild steel and some stainless
I much prefer HSS. I often run it dry or with just a few drops of
cutting fluid, still get good surface finish with sharp,
carefully-ground bits.

I have never made anything thatcouldn't be made on a 9 or 10 inch
Logan or South Bend or even a Myford Super 7, but what I have is a
15x50 import clone of a gearhead Colchester or Clausing that belonged
to Mary's dad. Her mom wanted me to have it when he passed because
she thought I might appreciate and respect it as he did. She was
right. The difference in rigidity between it and the smaller lathes is
huge and I like that a lot. Chatter? What's that? I could probably
love a Monarch 10EE or Hardinge a lot, but I'm not in shop-building
mode and I'm quite content with what I have.

I'm retired now, but these attitudes were formed when my shop time was
as limited as that of most guys with a full-time job and a family.
Shop time was relaxation, a respite from the competitive race and
daily grind of bidness. Production efficiency has never been an
objective in my shop. On my time, having fun is job 1.