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What is a "special" spindle


Apr 21, 2011
Monroeton, PA
When I received my serial number card for my 10L I was hoping it would explain the X in my serial number. The X indicates a "special" spindle.

Serial# 8566RKX14

What does that mean?

Thanks in advance for any help!

The 'X' in the serial no. does denote 'special', but I thought it referred to a flame hardened bed, according to info I was given which was claimed to be verified, whatever that's worth.
I would also would like to know what was speical on this machine. South Bend serial number chart just says "X" is speical.

Mine has the X and Mike with South Bend said the spindle is finished to a different tolerance than others. My build card shows flame hardened and special spindle.

My spindle nose is threaded rather than a cam lock.

I have an adapter that fits into the spindle to make it MT2 but I'm not sure what the spindle is. Looks too large to be MT3.

The SN card reads "HARD. BED" Would that mean flame hardened?

So it's either different tolerance on the spindle or the flame hardened bed I guess.
My 10L has a flame hardened bed which is notable by the lack of scraping marks & the 'bluish' flame mark which is visible on the side of the ways under the head stock near the right side. This is where the torch was stopped as they did not harden under the head stock which is a no wear area. My spindle is also hardened but I thought they all were.