Spindle Bore size change on 113b?

Sorry if this is redundant or simply not a smart question. Any way to increase the spindle bore size from 1 inch to 1 3/8, etc?

Thanks

Assuming that model lathe was originally available with a 1 3/8 bore, you just replace the spindle.

It came with a 1 inch spindle.

No.
It would require a complete headstock.

You can swap the spindle on the heavy 10 but not the 13"

The 10R and L are the only SBs that it is possible to swap spindles, well, almost...you can swap a 9" ABC lathe spindle with a 10K spindle.

bummer...I know...but it's a true story.

Thanks for all the info....

In the August 1946 catalog 100-F, you could get a 1 3/8 bore in the 10", but not the 13"

No - not possible.
Yes - it is possible.
Bring money.

Increasing a spindle bore significantly vs std headstock sizes - will crash rigidity values which are the SQN or Sine Qua Non of machine tools.
Rigidity is everything.

But..
It is quite easy to increase the rigidity of the HS.
Internal plates of heavy thickness is easy.
Industrial epoxy glue is more than strong enough.
But..
Stiffen the internal wall-thickness of the spindle.
Add new larger-D precision bearings.
You have probably spent more $$ in cash than a new lathe of the next-size-up costs.

Possible -yes. Is not a thing.
Worthwhile/profitable is another thing.
So, yes, it can be done, and no, You almost certainly cannot do it remotely profitably.

And if You did have a box of "free" super-precision bearings, selling the bearings and buying a bigger lathe is typically 2-5x better in cash terms.