9x20 Lathe Locking & Tramming the Tailstock

9x20 Locking & Tramming the 9x20 Lathe Tailstock
Last updated on Thursday, January 30, 2020 11:00:12 AM Mountain US Time Zone

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Tailstock Lock, Set screws, Handles, Tailstock Tramming, Tramming Animations

Tailstock Lock

This Craftsman wrench allows the nut to pass all the way through. Ratcheting direction is quickly changed
by flipping the small lever on the wrench. When the nut is loose it will not work the ratchet so a short strong
spring was installed, with washers on both sides, between the bottom of the tailstock base & the locking plate.
The ratchet now works even when it is loose. This is a fast & strong method to lock the tailstock securely.
See 9x20 Tailstock DRO

Set screws
tailstock_set_screw.jpg (28274 bytes)
Replaced the 5mm set screw. Under heavy drilling, e.g., using a 1" bit, the original set screw threads
would cut the inside of the groove it engaged. Used an 8mm set screw with the end turned to 5mm.
Removed all the burrs on the groove edges. Used aluminum anti-seize compound on the lock & pin.
A 2nd set screw placed 0.7" toward the spindle, keeps the tailstock from rotating if it is overextended.
The thrust bearings are just steel against steel. Made an oil-impregnated thrust bearing (washer) that
fits inside on the lead screw (far right). Now, the tailstock moves in & out smoother & with less effort.

Handles

Added a chrome-plated steel revolving handle. Drilled out the M5-0.8 thread then & then tapped for a 1/4-20.

Die-cast zinc Kipp adjustable ratcheting locking levers (M6-1 threaded bolts) with a brass washer.
The carriage lock also has a brass spacer that loosely fits the original counterbored hole.
A tight fit could possibly bind when it gets grimy. Dissimilar metals can work more smoothly.
For a smoother finish, lock the carriage when performing facing or cutoff operations.

Tailstock Tramming
A method to tram (center) the tailstock is to mount a dial test gauge in the spindle & an MT2
dead center or just indicate the inner surface of the tailstock taper. Rotate the spindle front &
back while adjusting the tailstock offset screws (replaced with US manufactured), making
half-the-difference changes between them until there are no front-to-back differences. The vertical
top/bottom error was corrected using brass shim stock because it was low by a few thousandth's.

Interapid dial test indicator 312B-1 (Swiss) shown.

It is the tailstock that is moved horizontally (typically opposing set screws) and/or
vertically (shims or grinding) into proper position as indicated by the dial test gauge.
Offset the tailstock for tapers.

Shimming or milling the top of the cast iron tailstock base may be required to tram top to bottom.
The dial test indicator needle moves in the opposite direction when tramming the inside surface.