My Rockwell 11X36 has a 2 1/4 X 8TPI spindle. I sowanted a collet chuck and when I saw the CDCO price i bought it and a blank backing plate threaded to fit my spindle. There are a lot of machine shops around here so I ask a lot of questiond and then tackled the backing plate. #1, I took a face cut to true it with my machine. #2, Measured the recess in the back of the collet chuck, measure 3 times,cut once. #3, After measuring diameter and depth of the recess I turned a positive to fit the collet's hole. #4, I used Heinman? transfer screws to mark the back plate. #5, Drill and counter bore the plate to fit the allen cap screws that mount the chuck to the plate. #6,Take a tiny (read- 0.005) cut in the projected part of the plate to assure the outer lip is in good contact with the chuck. #7,Install plate with mounted chuck on machine. #8, Install collet and test bar (ground round, pin guage, ect) and check runout.
Now, I will admit that I was anal about this mounting but the runout is NIL! On the Last Word guage the needle just bearly moved at all! Now that is a lot of zeros right of the decimal point before there is a whole number. That if you think 0.00001 is a whole number.
I now am tooling up a 13X40 Acra-turn with a D-1-5 spindle and will buy another CDCO plain backed chuck and I found a D-1-5 backing plate. It will be fitted just as the first one and we will see if I was lucky on the first attempt.
I need another D-1-5 backing plate to mount a 4 jaw self centering chuck I've had for years. I do a lot of octagon
barrels and some square work too. It isn't a Buck chuck,if fact it's Polish made,and is accurate enough for 95% of this work. And it's way faster than a 4 jaw independent chuck.