Hi,
I have an antique lathe that is getting quite a bit of use. It's a
1941 Dunlap combination woodworking and metalworking lathe. 30"
between centers, 9" swing. The spindle is 3/4" threaded both ends.
I've been considering turning outboard for bowls larger than 9", but
the lathe still has its original motor - a 1/3 HP, single phase, which
I doubt has enough power for anything bigger than 9". Anyone know if
I could replace it with a motor with more HP, providing I stick with a
single phase and something close to the 1750 RPM of the original
motor? If I do replace it do I need to do anything about the
bearings? It's a great lathe (even if it is 66 years old) and
produces some fine bowls, boxes, tops, etc., I would hate to damage
it. Any advise would be much appreciated.

Best Regards,
harry

you may not want to increase HP - my nova mini lathe has a 1 inch spindle
(compared to your 3/4 inch) and it was not happy at 5 inch diameter, my
larger lathe has a 1.25 inch spindle - it seems to me that the HP and lathe
are well matched


"harry" wrote in message
ups.com...
Hi,
I have an antique lathe that is getting quite a bit of use. It's a
1941 Dunlap combination woodworking and metalworking lathe. 30"
between centers, 9" swing. The spindle is 3/4" threaded both ends.
I've been considering turning outboard for bowls larger than 9", but
the lathe still has its original motor - a 1/3 HP, single phase, which
I doubt has enough power for anything bigger than 9". Anyone know if
I could replace it with a motor with more HP, providing I stick with a
single phase and something close to the 1750 RPM of the original
motor? If I do replace it do I need to do anything about the
bearings? It's a great lathe (even if it is 66 years old) and
produces some fine bowls, boxes, tops, etc., I would hate to damage
it. Any advise would be much appreciated.

Best Regards,
harry




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Posted via a free Usenet account from http://www.teranews.com

Hi Harry
Sure you can use a larger motor, keep your bearings oiled and speeds
down when off-balance wood used.
There is of course a limit to the size you can turn on a small lathe
with a 3/4 " shaft, but by being careful and taking your time you
should be able to go to probably 12" D or so if you keep the length
short like 6" or less and on a faceplate, if you want to use chucks,
the sizes will be less as your overhang and total weight goes up.
I would suggest to not go over 1 HP, 3/4Hp should be plenty to turn
all you like on a good little lathe.
Just try to safe some pennys so you are able to buy one of those
little Delta-Jet or Ricon lathes, so you can keep the little Dunlap
alive for the next generation ;-)))
Have fun and take care
Leo Van Der Loo

On Sep 2, 10:40 pm, harry wrote:
Hi,
I have an antique lathe that is getting quite a bit of use. It's a
1941 Dunlap combination woodworking and metalworking lathe. 30"
between centers, 9" swing. The spindle is 3/4" threaded both ends.
I've been considering turning outboard for bowls larger than 9", but
the lathe still has its original motor - a 1/3 HP, single phase, which
I doubt has enough power for anything bigger than 9". Anyone know if
I could replace it with a motor with more HP, providing I stick with a
single phase and something close to the 1750 RPM of the original
motor? If I do replace it do I need to do anything about the
bearings? It's a great lathe (even if it is 66 years old) and
produces some fine bowls, boxes, tops, etc., I would hate to damage
it. Any advise would be much appreciated.

Best Regards,
harry

Hi Harry, Without more info about your lathe, I'll make some
assumptions that may not be true. I assume that since it can turn both
metal and wood that there are no back gears and it has either a jack
shaft or small drive pulley-large spindle pulley set-up. If so I would
just try lowest existing speed and the present motor before doing
anything else. If not substituting a larger motor will still run the
lathe too fast. IOW, since you probably won't turn more than 12" diam
blanks outboard, I think high speed not low hp might be your limiting
factor, but I'm often wrong. Motors of that era listed honest hp,
but I assume yours is split phase with low starting torque.

If the original set up seems too fast for wood blanks larger than the
size designed for and the original motor's shaft extends at both ends,
you could devise a jackshaft by adding a large diam. pulley to your
present motor's unused end and drive it with another, say 1/2hp, motor
having a small diam. pulley. The original motor is left unpowered and
free running, of course.

As I remember Dunlap was Sears less expensive than Craftsman line, so I
assume your lathe has sleeve bearings. If so and there is any slop, I'd
change them. Otherwise I see nothing to be gained by changing.

Careful with what age you call antique.


Turn to Safety, Arch
Fortiter


http://community.webtv.net/almcc/MacsMusings

On Mon, 03 Sep 2007 02:40:40 -0000, harry
wrote:

Hi,
I have an antique lathe that is getting quite a bit of use. It's a
1941 Dunlap combination woodworking and metalworking lathe. 30"
between centers, 9" swing. The spindle is 3/4" threaded both ends.
I've been considering turning outboard for bowls larger than 9", but
the lathe still has its original motor - a 1/3 HP, single phase, which
I doubt has enough power for anything bigger than 9". Anyone know if
I could replace it with a motor with more HP, providing I stick with a
single phase and something close to the 1750 RPM of the original
motor? If I do replace it do I need to do anything about the
bearings? It's a great lathe (even if it is 66 years old) and
produces some fine bowls, boxes, tops, etc., I would hate to damage
it. Any advise would be much appreciated.

I'm just blue-skying here, so take my advice with a grain of salt.

I would think that you could as much HP on it as you want, provided
that you get another 1750 RPM motor (shouldn't be too hard, IIRC,
there are really only two common speeds) If your bearings are
original, it may be getting near time to replace them anyways, so give
it a try and see what happens- if the weight of the blank on the
outboard side is too much for the bearings, you can always replace
them with a more modern set. But, older stuff tended to be overbuilt,
and if it is a metal/wood combo lathe, I can't see how the wood would
be too heavy.

Thanks for the great advice. Much appreciated.

I had a chance to mount a large bowl blank (outboard) yesterday
evening using my existing motor. I used a piece of walnut from one of
my neighbors trees that was just under 12" diameter, trimmed to a
reasonable round shape on my bandsaw. I was pleasantly surprised to
see that the motor turned it just fine. Unfortunately the lathe stand
is not anywhere heavy enough for such a large piece. Vibration would
be an understatement. It was more like a bucking bronco I'm
thinking I might just save my larger blanks for when I get a new lathe
with a larger swing.

Thanks again and keep on turning!
Cheers... harry

For Harry and others with older lathes designed for spindle turning, but
have threaded outboard spindles.

For occasional outboard turning or as a permanent set up, would it be
practical to mount a hardwood blank on an inboard faceplate and turn a
large diam. wooden Vee belt pulley almost equal to the swing or get
fancy and turn a multi-diam. pulley. Then drive the inboard spindle at a
very slow speed for larger outboard work by remounting the present or
another motor that has a small diam. pulley.

Inconvenient and inelegant maybe, but could this be a practical
solution? If not, I'll go back to musing inside the box.


Turn to Safety, Arch
Fortiter


http://community.webtv.net/almcc/MacsMusings

aaah, Harry - 12 inches is a medium sized bowl - it seems really big if you
have been doing only 4 inch pieces - your 3/4 inch spindle should be ok at
12 inches, but I'd worry about it at 48 inches (or even 24 inches) -


"harry" wrote in message
ups.com...
Thanks for the great advice. Much appreciated.

I had a chance to mount a large bowl blank (outboard) yesterday
evening using my existing motor. I used a piece of walnut from one of
my neighbors trees that was just under 12" diameter, trimmed to a
reasonable round shape on my bandsaw. I was pleasantly surprised to
see that the motor turned it just fine. Unfortunately the lathe stand
is not anywhere heavy enough for such a large piece. Vibration would
be an understatement. It was more like a bucking bronco I'm
thinking I might just save my larger blanks for when I get a new lathe
with a larger swing.

Thanks again and keep on turning!
Cheers... harry




--
Posted via a free Usenet account from http://www.teranews.com