Turning a Replacement Clamp base for Grizzly G9972Z lathe
 

I'm nearly finished with machining a shorter clamp base for the 9x26
G9972Z lathe compound. Since Grizzly has failed in three attempts to
order the part, it was time to suck it up and turn it out.

Why? The stock base is about .100 inch too tall for the cut off tool
holder on my Aloris AXA tool post. I could mill the tool holder's bottom
sides, but that is so gosh.

Ordered a 1/2 inch 4 inch disc of 1018. Chucked it up in my Kalamazoo 6"
with the interior jaw set. Faced it, then Center drilled it, 1/2 inch
drill through, then bored to @.795 for the 20mm shaft. Changed to my
rotary table, used some .5" squares to support it, drilled and
countersunk the mounting bolt holes. Used the table to get the 120
degree spacing, and calculated the bolt circle by measuring the distance
from bolt hole to bolt hole on the original. Whipped out the Machinery's
Handbook, found that for a three sided polygon, r=.2887, got @.987 humma
humma, thank God for DROs...

Turning it to final thickness was a scream. I tried to use an expanding
mandrel. It worked some, but I quit after the squealing got bad. Dropped
back, replaced the exterior jaws, grabbed a 1" junk shaft of SS, cleaned
it up, turned a .795 dia shank, 1" long, then turned a .750 1/2 long,
threaded it for 3/4-16 (with a hand crank). Started to face the bottom,
and I made the belt slip. Quit for the day.

Today, I slid the shank back in the chuck so the clamp base was hard up
against the chuck jaws, tightened, then ran the tailstock forward and
used a live center to further support/jam the disk against the chuck.
Turning a now quite rigid workpiece was like night and day. .010 deep
facing cuts, decent finish for 1018.

It fits the shaft just so, and the mounting bolt holes are right
there... Have to get a 10mm end mill to countersink the 6mm socket heads.