Guys
I have one last boring operation to perform on an aluminum tube for my Crayford style focuser. Photo of my 99% finished Crayford focuser (minus anodizing) is below and the tube in question is at the top. It is about 4" long and has a rough ID of 2".
View attachment 114000 My lathe is Grizzly G4000 and the longest boring bar can stick into the aluminum tube to a depth of about 2.75". The real boring operation to be done is very little. I just need to enlarge the bore to accept a 2" astronomical eyepiece or a 2" adapter. Since my longest boring bar is not long enough I guess after completing the boring operation from one end of the tube I will have to turn the tube around and mount it the other way to continue the operation from the other end. I want to achieve uniform bore without a perceptible step over the entire length on the bore.
I am not sure if I will be able achieve it to truly centered on the chuck when I turn it around to continue boring from the other end. Also, how will I know that I have arrived at the same diameter as I got when I did the boring from the other end? I am lost. Hence this post. I am seeking your advice.
My equipment: G4000 9x19 lathe - unmodified (i.e., I use the original 4-way tool post)
Chuck#1: Original 4" 3-jaw with internal and external jaws
Chuck#2: 6" 4-jaw independent jaw chuck (LMS) and a set of soft covers on top of jaws to prevent denting of aluminum material
Boring bar set: 1/2" shank carbide tipped set of from LMS with holder to suit.
Thank you guys,
Prasad
AB3EH
Wynnewood PA
