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.