[TonyW]

I have some specs for my Lathe, have all the manuals, but ya think they would have capacities in the manuals? noooo.. Anyway, I can chuck up to 14.5" Diameter, give or take, but how much weight can the spindle take without it being harmful to lathe? Can't find any weight capacities

[Algirdas]

we had the same question once. Okuma support replied very clearly. Manuals are not adapted to specific machine. You need to ask Okuma.

[Superman]

OKUMA SPACE TURN LB300-M w/OSP-U100L
New 1999,
AS NEW, 98 CUTTING HOURS

12 year old machine = 100 hours on the clock
sounds like a used car salesman, with the speedo wound back

PS. hope you paid the ZONE's advertising fees, and (wrong)

Yuor info doesn't address the question of maximum mass that the spindle would support, with and without a tailstock

Anyway, my 2 cents is...
It should be able to support the max. swing diameter, as long as the length is kept close to the spindle. It would also depend on the material to be turned, obviously you could turn a longer piece of aluminium, than steel.

The effort to start and stop the spindle will be high due to the enertia mass, so start and stop with a lower RPM.

[Algirdas]

It would also depend on the material
of course.
It's not a public information. Depends on many design and component factors. Okuma does modify LB300 every year or maybe even twice per year. No exact answer without knowing building details of the machine.

[m@chinist]

guys, just do not complicate the simple things.
as You look through the maintenance manual for the each single okuma machine You will find some useful informations there.
for the power chuck, with no tailstock nor workrest - if You use standard hard jaws delivered with the chuck, gripping length of the jaws is L1, then the max length of the full bar material is possible to have 4.5 x L1. max diameter is a bit smaller then the chuck diameter - basic condition is the "stones" of the jaws (do not know the exact word in english) do not extend beyond the chuck body.
if the length of the material is longer then 4.5 x L1 then You need to support the material with tailstock / workrest.
long material You can depend on nothing - You need to try.
also with tubes - You can use special jaws or fixture to maximize the tube diameter - and You need to try.
the headstocks are calculated to support the full bar of the material at all the machine length! of course if You do not support long material You will get a vibrations - but they comes from the stiffness of the material against its length. not from the machine. and this information is not confidential. its confirmed by a few of the japan service engineers from Okuma already. standard material is just a standard steel - there is not a big difference in its weight.

[Algirdas]

vibrations - but they comes from the stiffness of the material against its length
It is only part of truth. The same blank, the same part program, works fine on one machine and doesn't works on the another because of vibration. Size and capability of the machines are nearly the same.

[m@chinist]

Algirdas - if You only look at the maintenance manual, if You compare Okuma to Okuma machine and if You calculate the max L value - this is the complete story.
I agree with You that different bearings, construction of bed, slideways, cast material and many many factors will influence on how will the machine work like on extreme conditions.

If You need to turn long shafts - as japaneese guys says "You need to try". Of course big bore spindle will be more rigid than the standard one. of course Okuma headstock could be more rigid then "no name" machine. and of course cutting technology for the long shafts is not so simple - but there again - You need to try.
experience comes from try and errors, You need time to get this.